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138 Cards in this Set

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Respiratory Volumes
• Used to assess a person’s respiratory status
– TIDAL___ (TV)
• volume=inspired and expired during quiet breathing (500 ml)

– Inspired reserve____ (IRV)
• inspired forcefully after a normal inspiration (2100- 3200 ml)

– Expiratory_______ (ERV)
• expired forcefully after a normal expiration (1000 -1200 ml)
– Residual________ (RV)
• remaining in lungs after a max. expiration (1200 ml)
• Keeps alveoli patent open and prevents lung collapse
tidal
Inspired reserve
expires
residual
capacities
Respiratory Capacities

• inspiratory____ (IC)
– Total amount of air that can be inspired after a tidal expiration
– IC = TV + IRV

• _functional_______ (FRC)
– Amount of air remaining in lungs after tidal expiration
– FRC = RV + ERV
• ________________(VC)
– Total amount of exchangeable air
– VC = TV + IRV + ERV

• _________________ (TLC)
– Sum of all lung volumes ( 6000 ml)
inspiratory
functional
vital
total lung
Dead space
• Dead Space
• Inspired air that fills the conducting respiratory passageway and never contributes to gas exchange
• Anatomical dead space: volume of the conducting zone conduits (~150 ml)
• Alveolar dead space: alveoli that cease to act in gas exchange due to collapse or obstruction
spirometer
________: instrument used to measure respiratory volumes and capacities in people with pulmonary disorders
• Spirometry can distinguish between
• Spirometry can distinguish between

–obstructive_—increased airway resistance (e.g., bronchitis)
_restrictive—reduction in total lung capacity due to structural or functional lung changes (e.g., fibrosis due to asbestos or TB)
obs or restrictive
• Increases in TLC, FRC, and RV (hyperinflation of lungs) may occur as a result of obstructive disease (increased airway resistance)
e.g. bronchitis

– Hyperinflation of the lungs means air is trapped in the small airways so the lungs appear larger than usual on a chest x-ray
• Reduction in VC, TLC, FRC, and RV result from restrictive disease (reduction in lung capacity)
e.g. mesothelioma or TB
Pulmonary Function Tests
tests
• Minute ventilation: total amount of gas flow into or out of the respiratory tract in one minute
• Forced vital capacity (FVC): gas forcibly expelled after taking a deep breath
• Forced expiratory volume (FEV): the amount of gas expelled during specific time intervals of the FVC
AVR
Alveolar Ventilation
• Alveolar ventilation rate (AVR): flow of gases into and out of the alveoli during a particular time
– ******A better index of effective ventilation****
• Dead space is normally constant (150 ML)
• Rapid, shallow breathing decreases AVR
AVR
• If there are 12 breaths/min. then
• Breaths/ min. x TV – dead space = 12 x (500- 150 ml)= 4200 ml/min.

• Effective ventilation = AVR /MVR
• Compare the effective ventilation for normal breathing with slow/deep breathing and rapid/shallow breathing
Non respiratory movements
Nonrespiratory Air Movements
reflex action
•: cough, sneeze, crying, laughing, hiccups, and yawns
Gas Exchanges Between Blood, Lungs, and Tissues
Gas Exchanges Between Blood, Lungs, and Tissues

•External respiration- oxygen enters/carbon dioxide leaves blood

•Internal respiration- oxygen leaves/carbon dioxide enters blood

• To understand the above processes, first consider
– Physical properties of gases
– Composition of alveolar gas
Daltons law
Basic Properties of Gases: Dalton’s Law of Partial Pressures
• Total pressure exerted by a mixture of gases is the sum of the pressures exerted by each gas
• The partial pressure of each gas is directly proportional to its percentage in the mixture
Henrys law
Basic Properties of Gases: Henry’s Law
mixture of gases is in contact with a liquid, each gas will dissolve in the liquid in proportion to its partial pressure
The amount of gas that will dissolve in a liquid depends upon its solubility
– CO2 is 20 times more soluble in water than O2
– Very little N2 (78.6% of atmosphere) dissolves in water
Alveolar gas
Carbon dioxide from Pulmonary to Aveoli
Oxygen from the aveoli to pulm
Alveoli more CO2 and water vapor and less O2 than atmospheric air, due to
– Gas exchanges in the lungs
• CO2 diffuses from the pulmonary blood to the alveoli
• O2 diffuses from the alveoli into the pulmonary blood

• Gas in the alveoli is actually a mixture of newly inspired gases and gases remaining in the respiratory passageway between breaths
Ya know this is ridiculous!!

Carbon dioxide from Pulmonary to Aveoli
Oxygen from the aveoli to pulm
external respiration
External Respiration
•Exchange O2 / CO2 across the respiratory membrane
•Influenced
Partial pressure gradients /gas solubilities
Ventilation-perfusion coupling
– Structural characteristics of the respiratory membrane
Partial Pressure Gradients and Gas Solubilities
Partial Pressure Gradients and Gas Solubilities
• Partial pressure gradient for O2 in the lungs is steep
– Venous blood Po2 = 40 mm Hg
– Alveolar Po2 = 104 mm Hg

– O2 diffuses from the alveoli into the pulmonary capillary blood
• O2 partial pressures equilibrium of 104 mm Hg in ~0.25 sec.
• CO2 diffuses in the opposite direction
• Partial pressure gradient for CO2 in the lungs is less steep:
– Venous blood Pco2 = 45 mm Hg
– Alveolar Pco2 = 40 mm Hg

• _CO2 is 2OX's more soluble
• CO2 diffuses in equal amounts with oxygen
Ventilation-Perfusion Coupling
Ventilation-Perfusion Coupling
•Ventilation: amount of gas to the alveoli
•Perfusion: blood flow to alveoli
•Ventilation& perfusion must match (coupled) SYNC gas exchange

•Changes in Po2 in the alveoli = changes in diameters of arterioles
•Where ventilation is inadequate, O2 is low and CO2 is high
–Pulmonary arterioles constrict & blood is redirected / higher Po2
• alveolar ventilation and pulmonary perfusion are synchronized
• ventilation is maximal, O2 is high and CO2 is low
– Pulmonary arterioles dilate, increasing blood flow to respiratory area with lower Po2
• alveolar venti/ pulmonary perfusion are synchronized

– Where alveolar CO2 is low, bronchioles constrict
– Where alveolar CO2 is high, bronchioles dilate
• Allowing CO2 to be elimination!!!!!!
Ventilation-Perfusion Coupling
Vent amt of gas
Perf. flow
couple- sync

LOw constrict high dialate!!!

CO2 levels
thickness of membranE!!!!
Thickness and Surface Area of the Respiratory Membrane
• Respiratory membranes
– 0.5 to 1 mm thick
– Large total surface area (40 times that of one’s skin)

Thickness and Surface Area of the Respiratory Membrane
• Homeostatic imbalance:
– Membranes thicken if lungs become waterlogged and edematous, and gas exchange becomes inadequate
– Reduction in surface area with emphysema, when walls of adjacent alveoli break down
Internal respiration
Internal Respiration
•Capillary gas exchange in body tissues
•Partial pressures& diffusion gradients are reversed compared to external respiration
***Po2 in tissue is always lower than in systemic arterial blood
•O2 moves into tissue and CO2 moves out of tissue
–Po2 of venous blood is 40 mm Hg and Pco2 is 45 mm Hg
reversed compared to external respiration
***Po2 in tissue is always lower than in systemic arterial blood
O2 transport
O2 Transport
• Molecular O2 is carried in the blood
– 1.5% dissolved in plasma
– 98.5% loosely bound to each Fe of hemoglobin (Hb) in RBCs
– 4 O2 per Hb
O2 and Hemoglobin
• Oxyhemoglobin (HbO2): hemoglobin-O2 combination
• Reduced hemoglobin (HHb): hemoglobin that has released O2
O2 and Heme
O2 and Hemoglobin
• Loading and unloading of O2 change in shape of Hb

_O2 binds, changes shape. affinity for O2^
_O2 released," " "" " "" """"""" ", O2 decreases

• Fully (100%) saturated if all four heme groups carry O2
• Partially saturated when one to three hemes carry O2
O2 binds changes shape affinity for o2^
O2 released" " "" " "" """"""" " O2 decreases
FActors
O2 and Hemoglobin
• Rate of loading and unloading of O2 is regulated by
– Po2
– Temperature
– Blood pH
– Pco2
– Concentration of BPG (2- 3 bisphosphoglycerate)
• product of RBCl glycolysis, binds reversibly with hemoglobin
influence on saturation
Influence of Po2 on Hemoglobin Saturation
• Oxygen-hemoglobin dissociation curve (see below)
• Hemoglobin saturation plotted against Po2 ____NOT LINEAR__
• S-shaped curve
• Shows how binding and release of O2 is influenced by the Po2
nope its SSSSSSSSSSSSSS shaped
influence on saturation
but wait there's more!!
Influence of Po2 on Hemoglobin Saturation
• In arterial blood (normal resting conditions)
– Po2 = 100 mm Hg
– Contains 20 ml oxygen per 100 ml blood (20 vol %)
– Hb is 98% saturated
• Further increases in Po2 (e.g., breathing deeply) produce minimal increases in O2 binding
influence on saturation
but wait there's more!!
• In venous blood (returning to heart)
– Po2 = 40 mm Hg
– Contains 15 vol % oxygen
– Hb is 75% saturated
influence on saturation
•Hemoglobin saturated at a Po2 of 70 mm Hg
• increases in Po2 produces sm. increases in O2 binding
•O2 loading & delivery to tissues is adequate when Po2 is below normal levels e.g. at higher altitudes

***Only 20–25% of bound O2 is unloaded during 1 systemic circula
• If O2 levels in tissues drop
–More oxygen dissociates from hemoglobin and is used by cells
– Respiratory rate or cardiac output need not increase
You can DO THIS!!! hah...maybe with a photogenic memory!!
*shift riGHHHHHHHHHHT
The causes of shift to right can be remembered using the mnemonimnemonic, "CADET, face Right!" for CO2, Acid, 2,3-DPG, Exercise and Temperature.
Inrease to the RIGHT...except PH is opposite!!!!!!!!!!!!!!!!!
decreased affinity, as would appear with an increase in body temperature, hydrogen ion, 2,3-diphosphoglycerate (also known as bisphosphoglycerate) or carbon dioxide concentration (the Bohr effect)
RRRRRRRRRRRRRight...Cool!!
BOHR effect
Major factors involved
pH --> increase results in shift to the left.
PH decrease shift to the right.
Temperature --> increase shift to the right.
TEMP_ decrease shift to the left.
pCO2 --> increase shift to the right.
PCO2 decrease shift to the left.
2,3-DPG -->increase shift to the right.
DPG decrease shift to the left.
Other Factors Influencing Hemoglobin Saturation
Other Factors Influencing Hemoglobin Saturation
• Increases in temperature, H+, Pco2, and BPG
– Modify the structure of hemoglobin and DECREASES its affinity for O2
– Occur in systemic capillaries
_ ENHANCCES CO2 unloading
– Shift the O2-hemoglobin dissociation curve to the right
• Decreases in these factors shift the curve to the left
Factors that Increase Release of O2 by Hemoglobin
Factors that Increase Release of O2 by Hemoglobin
• As cells metabolize glucose
– Pco2 and H+ increase (lower pH) in concentration in capillary blood (↑ CO2 causes ↑ H+ and ↓ pH)

• DECLINING PH__WEAKENS HEMEOGLOBIN BOND

• This is called the BOHR EFFECT!!!!!!!!!!!
• Oxygen is unloaded where it is needed
– Heat production increases
• Increasing temperature directly and indirectly DECREASES__ Hb affinity for O2
Homeostatic Imbalance
• Hypoxia
– Inadequate O2 delivery to tissues

• Too few RBCs
• Abnormal or too little Hb
• Blocked circulation
• Metabolic poisons
• Pulmonary disease
• Carbon monoxide (competes with O2 for heme binding sites)
CO2 transport CARBON DIOXIDE!!!
CO2 Transport CARBON DIO
• CO2 is transported in the blood in three forms
– 7 to 10% ***_DISSOLVE PLASMA
– 20% _Bind to heme (carbaminohemoglobin)
– 70% transported as Bicarbonate Ions_ (HCO3–)
again
Factors that Increase Release of O2 by Hemoglobin
Factors Increase Release of O2 by Hemoglobin
cells metabolize glucose
–Pco2 and H+ increase (lower pH) in concentration in capillary blood

(↑ CO2 causes ↑ H+ and ↓ pH)
20% transports in heme
Transport and Exchange of CO2
Transport and Exchange of CO2
•CO2 combines with water to form carbonic acid (H2CO3),
quickly dissociates === bicarbonate and hydrogen ions:
occurs in RBCs, where _ANHYDRASE (enzyme and rapidly catalyzes the reaction
•Question: what happens as the H+ increases?

AFFINITY DECREASES
Transport and Exchange of CO2 (LEARN THIS !)
systemic capillaries
but wait theres more!!!
Transport and Exchange of CO2 (LEARN THIS !)
•systemic capill.HCO3–(BICARBONATE IONS) from RBCs into the plasma
–The chloride shift occurs: outrush of HCO3– from the RBCs is balanced as Cl– moves in from the plasma
Transport and Exchange of CO2

In pulmonary capillaries
• In systemic capillaries
– HCO3– quickly diffuses from RBCs into the plasma
– The chloride shift occurs: outrush of HCO3– from the RBCs is balanced as Cl– moves in from the plasma
• In pulmonary capillaries
– HCO3– moves into the RBCs and binds with H+ to form H2CO3 (carbonic acid)
– H2CO3 is split by carbonic anhydrase into CO2 and water
– CO2 diffuses into the alveoli
• In pulmonary capillaries
–HCO3(bicarbonate ion) moves into the RBCs and binds with H+ to form H2CO3 (carbonic acid)
–H2CO3 is split by carbonic anhydrase into CO2 and water
–CO2 diffuses into the alveoli
Summary of CO2 transport through the blood
CO2 +H2O= H2CO3(carbonic acid)
HCO3 - bicarbonate +H+ >>> or <<<
Haldane effect
• amount of CO2 transported is affected by the Po2
lower the Po2 & hemoglobin saturation w/ O2, the more CO2 can be carried in the blood
tissues, as more carbon dioxide enters the blood
More oxygen dissociates from hemoglobin (Bohr effect)
As HbO2 releases O2, it forms bonds with CO2 ====carbinohemoglobin
Influence of CO2 on Blood pH
•HCO3– (BICARBONATE ION) in plasma is the alkaline reserve of the carbonic acid (H2CO3)–bicarbonate buffer system
•If H+ blood rises, excess H+ is removed by combining with HCO3–
•If H+ drop, H2CO3 (BICARBONATE ION) dissociates, releasing H+
In the midnight hour she cried more, more, more....with the rebel yell!!!!
Influence of CO2 on Blood pH
•Changes in respiratory rate can alter blood pH
slow shallow breathing = CO2 to accumulate causes pH to drop

Changes in ventilation = adjust pH when it is disturbed by metabolic factors
Control of respiration
• Involves clusters of neurons in the reticular formation of
MEDULLA PONS!
Medullary Respiratory Centers
Dorsal respiratory group (DRG)... input from peripheral stretch and chemoreceptors
Communicates with the ventral respiratory group (VRG)
Rhythm-generating integrative center
–Sets eupnea (12–15 breaths/minute)
nspiratory neurons excite the inspiratory muscles via the phrenic and intercostal nerves .... air rushes into the lungs
– Expiratory neurons inhibit the inspiratory neurons
• Inspiratory muscles relax and the lungs recoil
Pontline
Pontine Respiratory Centers
• Located in pons
• Influence and modify activity of the VRG
• Smooth's out transition between inspiration and expiration and vice versa
- When lesions are made in the pontine center, inspirations become very prolonged
depth and rate
Depth and Rate of Breathing

• Depth is determined by how actively the respiratory center stimulates the respiratory muscles

•Rate is determined by how long the inspiratory center is active

• Both are modified in response to changing body demands
Chemical Factors
Chemical Factors
•Chemoreceptors ***** two locations:
–Central chemoreceptors are located throughout the brain stem including the medulla
–Peripheral chemoreceptors located in the aortic arch /carotid arteries synapse with the respiratory regulatory centers in the medulla
• Effect the depth and rate of breathing
control
influence of ePco2:
influence of ePco2:
– If Pco2 levels rise (hypercapnia), CO2 accumulates in the brain
– CO2 is hydrated; resulting carbonic acid dissociates H+
– H+_STIMULATES the central chemoreceptors of the brain stem pons/medulla)
– Chemoreceptors synapse with the respiratory regulatory centers, increasing the depth and rate of breathing
Homeostatic Imbalance
Hyperventilation:
Homeostatic Imbalance
• Hyperventilation: increased depth/ rate /breathing exceeds body’s need to remove CO2
–Causes CO2 levels to decline (hypocapnia) (( anxiety attack ))
• Blood pH rises (decrease in H+ )
• cause cerebral vasoconstriction and cerebral ischemia (insuft blood flow to the brain)
• Dizziness and fainting
• Apnea: period of breathing cessation that occurs when Pco2 is abnormally low
Chemical Factors (Continued)
Chemical Factors (Continued)
•Influence of Po2
Peripheral chemoreceptors in the aortic carotid arteries are O2 sensors
•When excited, * cause the respiratory centers to increase ventilation
•Substantial drops in arterial Po2 (to 60 mm Hg) must occur in order to stimulate increased ventilation
–Under normal conditions declining Po2 does not affect ventilation

• Influence of arterial pH
– Can modify respiratory rate and rhythm even if CO2 and O2 levels are normal
– Decreased pH may reflect
• _CO2 RETENTION
• _ACCUMUL> LACTIC ACID
• _EXCESS KETONES..( products of fat metabolism) in patients w= diabetes mellitus
– Respiratory system controls will attempt to raise the pH by increasing respiratory rate and depth
SSUUUMMMARY......yes
Summary of Chemical Factors
•Rising CO2 levels are the***MOST** powerful respiratory stimulant
•Normally blood Po2 affects breathing only indirectly by influencing peripheral chemoreceptor (aortic/ carotid bodies)
sensitivity to changes in Pco2
• arterial Po2 falls below 60 mm Hg, it becomes the major stimulus for respiration (via the peripheral chemoreceptors)
•Changes in arterial pH resulting from CO2 retention or metabolic factors act indirectly through the peripheral chemoreceptors
schedule lobotomy...need new one with better retention...
Under the INFLUENCE of...
Higher Brain Centers
Influence of Higher Brain Centers
•Hypothalamic controls act through the limbic system (emotional brain) to modify rate / depth of respiration
–Ex. breath holding - in anger or gasping with pain
•A rise in body temperature - increase respiratory rate
•Cortical controls are direct signals from the cerebral motor cortex that bypass medullary controls
– Ex.- voluntary breath holding
Pulmonary reflexes
Pulmonary Irritant Reflexes
• Receptors in the bronchioles respond to irritants e.g. noxious fumes and dust
• Promote reflexive constriction/ air passages
• Receptors in the larger airways mediate the cough and sneeze reflexes
hhhhmmmmm
Inflation Reflex
• Hering-Breuer Reflex
– Stretch receptors in the pleurae and airways are stimulated by lung inflation
•Inhibitory signals the medullary respiratory centers= end inhalation and allow expiration to occur
•Acts more as a protective response than a normal regulatory mechanism (prevents excessive stretching of the lungs)
Respiratory exercises
Respiratory Adjustments: Exercise
•Adjustments geared * intensity and duration of exercise
•Hyperpnea-Increase in ventilation (10 to 20 fold) response/ metabolic needs
•Pco2, Po2, and pH sre constant during exercise

•Three neural factors cause increase in ventilation w/exercisbegins
–Psychological stimuli—anticipation of exercise
–Simultaneous cortical motor activation of skeletal muscles and respiratory centers
– Exictatory impulses reaching respiratory centers from proprioceptors in moving muscles, tendons, and joints
Breathe in and breath out!!!!
continued
Respiratory Adjustments: High Altitude
= travel to altitudes ^ 8000 ft= symptoms of acute mountain sickness (AMS)
– Atmospheric pressure and Po2 are lower
– Headaches, shortness of breath, nausea, and dizziness
– severe cases, lethal cerebral and pulmonary edema
Acclimatization to High Altitude
Acclimatization to High Altitude
• Acclimatization: respiratory and hematopoietic adjustments to high altitude -CHEMORECEPTORS MORE RESPONSIVE CO2 WHen DECLINES

– Substantial decline in Po2 _STIMULATES PERIPHERAL RECEPTORS...
– Result: minute ventilation (gas flow) increases and stabilizes in a few days to 2–3 L/min higher than at sea level

Acclimatization to High Altitude
• Decline in blood O2 stimulates the kidneys to accelerate production of EPO__
• RBC numbers increase slowly to provide long-term compensation
EPO high altitudes
Acclimatization to High Altitude
• Decline in blood O2 stimulates the kidneys to accelerate production of _____________
• RBC numbers increase slowly to provide long-term compensation
COPD
• Chronic obstructive pulmonary disease (COPD)
– Exemplified by chronic bronchitis and emphysema
– Irreversible decrease in the ability to force air out of the lungs
• History of smoking in 80% of patients
• Dyspnea: labored breathing (“air hunger”)
• Coughing and frequent pulmonary infections
•Most victims develop respiratory failure (hypoventilation) accompanied by respiratory acidosis
ATHSMA
• Asthma
– Characterized by coughing, dyspnea, wheezing, and chest tightness
– Active inflammation of the airways precedes bronchospasms
– Airway inflammation is an immune response caused by release of interleukins, production of IgE, and recruitment of inflammatory cells
– Airways thickened with inflammatory exudate magnify the effect of bronchospasms

Homeostatic Imbalances
TB
Infectious disease caused by bacterium Mycobacterium tuberculosis

–Symptoms fever, night sweats, weight loss, coug spitting up blood

Treatment 12-month course of antibiotics
Lung Cancer
• Lung cancer
– Leading cause of cancer deaths in North America
– 90% of all cases are the result of smoking
– The three most common types
1. Squamous cell carcinoma (20–40% of cases) in bronchial epithelium
2. Adenocarcinoma (~40% of cases) originates in peripheral lung areas
3. Small cell carcinoma (~20% of cases) contains lymphocyte-like cells that originate in the primary bronchi and subsequently metastasize
Developmental aspects....
Developmental Aspects
•Olfactory placodes invaginate into olfactory pits by the fourth week
• Laryngotracheal buds are present by the fifth week
•Mucosae of the bronchi / lung alveoli are by the eighth week

Developmental Aspects
•By the 28th week, a baby born prematurely can breathe on its own
•During fetal life, the lungs are filled with fluid and blood bypasses the lungs
• Gas exchange takes place via the placenta

Developmental Aspects
• At birth, respir alveoli inflate, and lungs begin to function
•Respiratory rate is highest in newborns and slows until adulthood
• Lungs continue to mature and more alveoli are formed until young adulthood
• Respiratory efficiency decreases in old age
Describe the function of the muscosa/ ciliated epithelium of the trachea. Explain how this function can be impaired
Secretion and absorption.
contain lysosmes and defensins
heat moisturize and filter

smoking
List and describe several protective mechanisms e.g. surfactant, of the respiratory system.
nasal hairs, mucus production, sneezing ,coughing
4Describe the makeup of the respiratory membrane, and relate structure to function.
0.5 air blood barrier
single layer of squamous epithelium
SECRETES SURFACTANT
4Describe the makeup of the respiratory membrane, and relate structure to function.
Describe the gross structure of the lungs and pleurae.
lungs
covered with visceral pleura
attached to mediastinum by a bronchus, blood and lymph vessels, and nerves
Mechanics of Breathing
6. Explain the functional importance of the partial vacuum that exists in the intrapleural space.
The space between the lung surface and the inner chest wall (intrapleural space) has a negative air pressure (partial vacuum) to keep the lungs expanded and ...
7. Relate Boyle’s law to the events of inspiration and expiration.
P1 initial pressure of gas
P2resuting pressure of gas
V1 initial volume of gas
V2 resulting pressure of gas
Pressure up
volume down visa versa
inhale pressure down vol up
exhale
Explain the relative roles of the respiratory muscles and lung elasticity in producing the volume changes that cause air to flow into and out of the lungs.
Active process-
INSPIRATION
Diaphragm ex intercostals contract
VOLUME INCREASES
intapulmonary pressure drops to -1mm
Ppul<Patm
AIR FLOWS in lungs down its gradient
Explain the relative roles of the respiratory muscles and lung elasticity in producing the volume changes that cause air to flow into and out of the lungs.
Henrys law
Henry's Law,
he greater the partial pressure of a gas, the greater the diffusion of the gas into the liquid.
The temperature of the liquid. Solubility decreases with increasing temperature.
Oxygen. The partial pressure of O2 in the lungs is high (air is 21percent O2), but it has poor solubility properties.

Carbon dioxide. The partial pressure of CO2 in air is extremely low (air is only 0.04 percent CO2), but its solubility in plasma is about 24 times that of O2.
Oxygen. The partial pressure of O2 in the lungs is high (air is 21percent O2), but it has poor solubility properties.

Carbon dioxide. The partial pressure of CO2 in air is extremely low (air is only 0.04 percent CO2), but its solubility in plasma is about 24 times that of O2.
Describe the three physical factors that influence pulmonary ventilation.
AIR WAY RESISTANCE
ALVEOLAR SURFACE TENSION
LUNG COMPLIANCE
Friction, resistance
Describe the location, related structures, and functions of: nasal cavity, paranasal sinuses, pharynx, and larynx.
– Nose, nasal cavity, and paranasal sinuses
– Pharynx
– Larynx
– Trachea
1. Nasal cavity: lies in and posterior to the external nose
• Divided by a midline nasal septum
•Posterior nasal apertures (choanae) open into the nasal pharynx
• Roof: ethmoid and sphenoid bones
• Floor: hard and soft palates
Paranasal Sinuses
• In frontal, sphenoid, ethmoid, and maxillary bones
• Lighten the skull and help to warm and moisten the air

Pharynx
• Muscular tube that connects to the
– Nasal cavity and mouth superiorly
– Larynx and esophagus inferiorly
• From the base of the skull to the level of the sixth cervical vertebra
– Nasopharynx
– Oropharynx
– Laryngopharynx

Paranasal Sinuses
• In frontal, sphenoid, ethmoid, and maxillary bones
• Lighten the skull and help to warm and moisten the air
Describe the function of the muscosa/ ciliated epithelium of the trachea. Explain how this function can be impaired
Secretion and absorption.
contain lysosmes and defensins
heat moisturize and filter

smoking
List and describe several protective mechanisms e.g. surfactant, of the respiratory system.
nasal hairs, mucus production, sneezing ,coughing
4Describe the makeup of the respiratory membrane, and relate structure to function.
0.5 air blood barrier
single layer of squamous epithelium
SECRETES SURFACTANT
Describe the gross structure of the lungs and pleurae.
lungs
covered with visceral pleura
attached to mediastinum by a bronchus, blood and lymph vessels, and nerves
Mechanics of Breathing
6. Explain the functional importance of the partial vacuum that exists in the intrapleural space.
The space between the lung surface and the inner chest wall (intrapleural space) has a negative air pressure (partial vacuum) to keep the lungs expanded and ...
7. Relate Boyle’s law to the events of inspiration and expiration.
P1 initial pressure of gas
P2resuting pressure of gas
V1 initial volume of gas
V2 resulting pressure of gas
Pressure up
volume down visa versa
inhale pressure down vol up
exhale
Explain the relative roles of the respiratory muscles and lung elasticity in producing the volume changes that cause air to flow into and out of the lungs.
Active process- INSPIRATION
Diaphragm ex intercostals contract
VOLUME INCREASES
intapulmonary pressure drops to -1mm
Ppul<Patm
AIR FLOWS in lungs down its gradient
Henrys law
Henry's Law, the greater the partial pressure of a gas, the greater the diffusion of the gas into the liquid.
The temperature of the liquid. Solubility decreases with increasing temperature.
Oxygen. The partial pressure of O2 in the lungs is high (air is 21percent O2), but it has poor solubility properties.

Carbon dioxide. The partial pressure of CO2 in air is extremely low (air is only 0.04 percent CO2), but its solubility in plasma is about 24 times that of O2.
Describe the three physical factors that influence pulmonary ventilation.
AIR WAY RESISTANCE
ALVEOLAR SURFACE TENSION
LUNG COMPLIANCE
Friction, resistance
Indicate types of information that can be gained from pulmonary function tests (spirometer).
volume and capacities in people with disorders
Obstrucive (resistance) bronchitis
Restrictive (Reduction) TB Meso
Increase in TLC FRC RV hyperinflation(
trapped air)...obstructive diseases

Reduction VC TLC FRC RV ,,,restrictive diseases
Gas Exchanges Between the Blood, Lungs, and Tissues
14. Describe how atmospheric and alveolar air differ in composition, and explain these differences.
AVR aveolar ventilation rate
AVR X TV -dead space
12X500-150=4200
external resp oxygen enters carbon dioxide leaves blood (lungs)
internal resp. oxygen leaves/ carbon dioxide enters blood tissues
7. Describe how oxygen is transported in the blood, & explain how oxygen loading &unloading is affected by temperature, pH, BPG, and PCO2.
4hemo to RBC
O2 binds, changes shape affinity O2^
O2 releas, "" """ O2v
RATE IS REGULATED BY
PO2, Temp, PH,CO2,BPG
OXYgen/heme/ dissociation curve
Goes up shifts RIGHT
Goes down Shifts left
4 heme to a RBC (saturated)
SSSSSSSS not linear
Describe carbon dioxide transport in the blood.
3 ways
7-10% Dissolves plasma
20% bound to heme
70% Bicarbonate Ions (HCO3)>plasma
DUH!!!!!!!!!!!!!!!!!!!!!
Control of Respiration
19. Describe the neural controls of respiration.
Medulla/Pons
Medullary Respiratory Centers
1Dorsal respiratory group (DRG)
–Integrates input from peripheral stretch and chemoreceptors
– Communicates with the ventral respiratory group (VRG)

Ventral respiratory group (VRG)
– Rhythm-generating and integrative center
Sets eupnea (12–15breaths/minute)
– Inspiratory neurons excite the inspiratory muscles via the phrenic and intercostal nerves
• The thorax expands and air rushes into the lungs
– Expiratory neurons inhibit the inspiratory neurons
• Inspiratory muscles relax and the lungs recoil
Pontine Respiratory Centers
• Located in pons
• Influence and modify activity of the VRG
• Smooth's out transition between inspiration and expiration and vice versa
- When lesions are made in the pontine center, inspirations become very prolonged

Depth and Rate of Breathing

• Depth is determined by how actively the respiratory center stimulates the respiratory muscles
• Rate is determined by how long the inspiratory center is active
• Both are modified in response to changing body demands

Compare and contrast the influences of arterial pH, arterial partial pressures of oxygen and carbon dioxide, volition, and emotions on respiratory rate and depth.
???
What three neural factors increase ventilation during exercise?
Psychological stimuli
Simul cortical motor activation
skeletal muscles and respitory centers
Excitory impulses and then some
22. Do arterial levels of O2 and CO2 change significantly during exercise?
Pco2, Po2, and pH remain surprisingly constant during exercise
•Adjustments geared to both the intensity and duration of exercise
• Hyperpnea (hi”perp-ne’ah)
–Increase in ventilation (10 to 20 fold) iresponse to metabolic needs
•Pco2, Po2, and pH remain surprisingly constant during exercise
Increased ventilation is not the result of decreases in O2 availability or CO2 build up in the blood.
Describe the two respiratory and hemoatopoietic changes that occur during acclimatization to high altitude.
• Quick travel to altitudes above 8000 feet may produce symptoms of acute mountain sickness (AMS)
– Atmospheric pressure and Po2 are lower
– Headaches, shortness of breath, nausea, and dizziness
– In severe cases, lethal cerebral and pulmonary edema

Acclimatization to High Altitude
• Acclimatization: respiratory and hematopoietic adjustments to high altitude CHEMORECEPTORS MORE RESPONSIVE TO PO@
– Substantial decline in Po2
– Result: minute ventilation (gas flow) increases and stabilizes in a few days to 2–3 L/min higher than at sea level
Compare the causes and consequences of chronic bronchitis, emphysema, asthma, tuberculosis, and lung cancer.
• Chronic obstructive pulmonary disease (COPD)
– Exemplified by chronic bronchitis and emphysema
– Irreversible decrease in the ability to force air out of the lungs
– Other common features
• History of smoking in 80% of patients
• Dyspnea: labored breathing (“air hunger”)
• Coughing and frequent pulmonary infections
• Most victims develop respiratory failure (hypoventilation) accompanied by respiratory acidosis

Homeostatic Imbalances
• Asthma
– Characterized by coughing, dyspnea, wheezing, and chest tightness
– Active inflammation of the airways precedes bronchospasms
– Airway inflammation is an immune response caused by release of interleukins, production of IgE, and recruitment of inflammatory cells
– Airways thickened with inflammatory exudate magnify the effect of bronchospasms

Homeostatic Imbalances
• Tuberculosis
– Infectious disease caused by the bacterium Mycobacterium tuberculosis
– Symptoms include fever, night sweats, weight loss, a racking cough, and spitting up blood
– Treatment entails a 12-month course of antibiotics

Homeostatic Imbalances
• Lung cancer
– Leading cause of cancer deaths in North America
– 90% of all cases are the result of smoking
– The three most common types
1. Squamous cell carcinoma (20–40% of cases) in bronchial epithelium
2. Adenocarcinoma (~40% of cases) originates in peripheral lung areas
3. Small cell carcinoma (~20% of cases) contains lymphocyte-like cells that originate in the primary bronchi and subsequently metastasize
Pharynx
Oropharynx and laryngopharynx
Allow passage of food, fluids, &air
–Stratified squamous epithelium lining
–Skeletal muscle layers: inner longitudinal, outer pharyngeal constrictors
•Contraction propel food into the esophagus
Esophagus
Esophagus
Flat muscular tube/ laryngopharynx to stomach

•__________________________
• Heartburn (gastroesophageal reflux disease)
- Acidic gastric juice regurgitates into the esophagus as a consequence of eating too much

• Has all four of the basic alimentary canal layers
– Mucosa, submucosa, muscularis externa, and adventitia
• Esophageal mucosa contains stratified squamous epithelium
– Abrasive – resistant
– Changes to simple columnar at the stomach
• Esophageal glands in submucosa secrete mucus to aid in bolus (rounded food mass) movement
• Muscularis externa: skeletal superiorly third; smooth inferiorly third

–___________________Adventitia instead of serosa
– Binds esophagus to surrounding structures
Mouth
Digestive Processes: Mouth
• Ingestion
• Mechanical digestion
–Mastication/ voluntary, /reflexi
•Chemical digestion (salivary amylase)
• Propulsion
– Deglutition (__________________________)
Deglutition
Deglutition
• Involves the tongue, soft palate, pharynx, esophagus, and 22 muscle groups

• ________________________________

– Voluntary contraction of the tongue against the hard palate
Bolus is forced into the orapharnyx _________________
– Food is moved through the pharynx and into the esophagus (peristalsis)
– Tongue blocks off mouth
Soft palate rises/ close off the nasopharynx
– Involuntary and triggered by saliva receptors in posterior pharynx
– Swallowing control center in the medulla and lower pons
–Food is moved to the stomach by peristalsis
– Gastroesophageal sphincter relaxes reflexively to allow food to enter the stomach
Gross anatomy
• Cardiac region (cardia)
– Surrounds the cardiac orifice (where food enters stomach)
• Fundus
– Dome-shaped region beneath the diaphragm
• Body
– Midportion
• Pyloric region
– Continuous with body and terminates with the pylorus
• Pylorus
–Continuous with duodenum through the ___________________ (sphinter)

• Greater curvature
– Convex lateral surface
• Lesser curvature
– Concave medial surface

•Lesser omentum (sheet of fat that is covered by peritoneum)
From the liver to the lesser curvature
• Greater omentum
– Drapes from greater curvature
– Anterior to the small intestine
• ANS nerve supply
–Sympathetic via splanchnic nerves and celiac plexus
–Parasympathetic = vagus nerve
• Blood supply
–Celiac trunk
–Veins of the hepatic portal sys
Stomach: Microscopic Anatomy
Stomach: Microscopic Anatomy
• Four tunics : muscularis, mucosa, submucosa, and serosa
•Muscularis and mucosa have been modified for a special role in the stomach
• Muscularis
– Muscularis externa
•Three layers of smooth muscle
– Circular and longitudinal layers
– Inner oblique layer
– allows stomach to churn, mix, move, and physically break down food
• Mucosa
– Simple columnar epithelium composed of mucous cells
• Layer of mucus traps bicarbonate-rich fluid beneath it
–Gastric pits lead into gastric glands
–Gastric glands = gastric juice
•HCl, pepsin, and rennin
Pharynx
Oropharynx and laryngopharynx
Allow passage of food, fluids, &air
–Stratified squamous epithelium lining
–Skeletal muscle layers: inner longitudinal, outer pharyngeal constrictors
•Contraction propel food into the esophagus
Esophagus
Esophagus
Flat muscular tube/ laryngopharynx to stomach

•__________________________
• Heartburn (gastroesophageal reflux disease)
- Acidic gastric juice regurgitates into the esophagus as a consequence of eating too much

• Has all four of the basic alimentary canal layers
– Mucosa, submucosa, muscularis externa, and adventitia
• Esophageal mucosa contains stratified squamous epithelium
– Abrasive – resistant
– Changes to simple columnar at the stomach
• Esophageal glands in submucosa secrete mucus to aid in bolus (rounded food mass) movement
• Muscularis externa: skeletal superiorly third; smooth inferiorly third

–___________________Adventitia instead of serosa
– Binds esophagus to surrounding structures
Mouth
Digestive Processes: Mouth
• Ingestion
• Mechanical digestion
–Mastication/ voluntary, /reflexi
•Chemical digestion (salivary amylase)
• Propulsion
– Deglutition (__________________________)
Deglutition
Deglutition
• Involves the tongue, soft palate, pharynx, esophagus, and 22 muscle groups

• ________________________________

– Voluntary contraction of the tongue against the hard palate
Bolus is forced into the orapharnyx _________________
– Food is moved through the pharynx and into the esophagus (peristalsis)
– Tongue blocks off mouth
Soft palate rises/ close off the nasopharynx
– Involuntary and triggered by saliva receptors in posterior pharynx
– Swallowing control center in the medulla and lower pons
–Food is moved to the stomach by peristalsis
– Gastroesophageal sphincter relaxes reflexively to allow food to enter the stomach
Gross anatomy
• Cardiac region (cardia)
– Surrounds the cardiac orifice (where food enters stomach)
• Fundus
– Dome-shaped region beneath the diaphragm
• Body
– Midportion
• Pyloric region
– Continuous with body and terminates with the pylorus
• Pylorus
–Continuous with duodenum through the ___________________ (sphinter)

• Greater curvature
– Convex lateral surface
• Lesser curvature
– Concave medial surface

•Lesser omentum (sheet of fat that is covered by peritoneum)
From the liver to the lesser curvature
• Greater omentum
– Drapes from greater curvature
– Anterior to the small intestine
• ANS nerve supply
–Sympathetic via splanchnic nerves and celiac plexus
–Parasympathetic = vagus nerve
• Blood supply
–Celiac trunk
–Veins of the hepatic portal sys
Stomach: Microscopic Anatomy
Stomach: Microscopic Anatomy
• Four tunics : muscularis, mucosa, submucosa, and serosa
•Muscularis and mucosa have been modified for a special role in the stomach
• Muscularis
– Muscularis externa
•Three layers of smooth muscle
– Circular and longitudinal layers
– Inner oblique layer
– allows stomach to churn, mix, move, and physically break down food
• Mucosa
– Simple columnar epithelium composed of mucous cells
• Layer of mucus traps bicarbonate-rich fluid beneath it
–Gastric pits lead into gastric glands
–Gastric glands = gastric juice
•HCl, pepsin, and rennin
Objectives
PART 1: OVERVIEW OF THE DIGESTIVE SYSTEM
1. Describe the function of the digestive system, and differentiate between organs of the alimentary canal and accessory digestive organs.
Digestive Processes
2. List and define the major processes occurring during digestive system activity.

Digestive System Organs: Relationships
3. Describe the location and function of the peritoneum.
4. Define retroperitoneal and name the retroperitoneal organs.
5. Define splanchic circulation.
6. Indicate the importance of the hepatic portal system.
7. Describe the tissue composition and the general function of each of the four layers of the alimentary canal.
PART 2: FUNCTIONAL ANATOMY OF THE DIGESTIVE SYSTEM
The Mouth and Associated Organs
8. Describe the functions of the mouth (hard palate, soft palate, salivary glands, and tongue)
9. Describe the structure and function of the pharynx, and esophagus.
10. Describe the composition and functions of saliva, and explain how salivation is regulated.

Digestive Processes: Mouth to Esophagus
11. Describe the mechanisms deglutition .
The Stomach
12. Identify structural modifications of the wall of the stomach that enhance the digestive process.
13. Name the cell types responsible for secreting the various components of gastric juice and indicate the importance of each component in stomach activity.
14. Explain how gastric secretion and stomach motility are regulated.
15. Describe how the mucosal barrier helps to protect the stomach.
16. Describe the function of the pyloric valve
The Small Intestine and Associated Structures
17. Identify and describe structural modifications of the wall of the small intestine that enhance the digestive process.
18. Differentiate between the roles of the various cell types of the intestinal mucosa.
19. Describe the function of local intestinal hormones and paracrines.
20. Describe the functional anatomy of the portal triad (see liver).
22. Describe the digestive functions of liver cells.
23. State the role of bile in digestion and describe how its entry into the small intestine is regulated.
24. Describe the role of the gallbladder.
25. Describe the endocrine function of the pancreas
26. Describe the exocrine function of the pancreas.
27. State the role of pancreatic juice in digestion.
28. Describe how entry of pancreatic juice into the small intestine is regulated.
29. Describe the functional role of the ileocecal valve
The Large Intestine
30. List the major functions of the large intestine.
PART 3: PHYSIOLOGY OF CHEMICAL DIGESTION AND ABSORPTION
Chemical Digestion
31. List the enzymes involved in chemical digestion; name the foodstuffs on which they act.
32. List the end products of protein, fat, carbohydrate, and nucleic acid digestion.
Absorption
33. Describe the process of absorption of breakdown products of foodstuffs (carbohydrate,, protein, and lipids) that occurs in the small intestine.
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Gastric Glands
• Cell types
Gastric Glands
• Cell types
– Mucous neck cells (secrete thin, acidic mucus)
– Parietal cells
– Chief cells
– Enteroendocrine cells
Gastric Gland Secretions
Gastric Gland Secretions
• Glands in the fundus and body produce most of the gastric juice

• ____________________________________________________
– HCl
• ® pH 1.5–3.5 denatures protein in food, activates pepsin, and kills many bacteria
– Intrinsic factor
• Glycoprotein required for absorption of vitamin B12 in small intestine

• Chief cell secretions

– ____________________________________________________

– Activated to pepsin by ______________and by pepsin itself (a positive feedback mechanism)
• Enteroendocrine cells
• Enteroendocrine cells
– Secrete chemical messengers into the lamina propria
• Paracrines
– Serotonin and histamine
• Contraction of smooth muscles and release of HCl respectively
• Hormones
– Somatostatin and gastrin (regulates stomach secretion and motility
ucosal Barrier
Mucosal Barrier
• Stomach protects itself:
• Layer of bicarbonate-rich mucus
• Tight junctions between epithelial cells prevent gastric juice from leaking into underlying tissues
• Damaged epithelial cells are quickly replaced by division of stem cells
imbalance
Homeostatic Imbalance
• Gastritis: inflammation caused by anything that breaches the mucosal barrier
• Peptic or gastric ulcers: erosion of the stomach wall

– Most are caused by ___________________________________ bacteria
• Destroys protective mucosal layer
– Other cases caused by anti-inflammatory drugs e.g. ibuprofen
Digestive Processes in the Stomach
Digestive Processes in the Stomach
• Physical digestion
___________________________
• Enzymatic digestion of proteins by pepsin (and rennin in infants)

____________________ pass easily through the stomach mucosa into blood
• Secretes intrinsic factor required for absorption of vitamin B12
– Lack of intrinsic factor ® pernicious anemia (RBC don’t divide)
• Delivers chyme (creamy paste) to the small intestine
Regulation of Gastric Secretion
Regulation of Gastric Secretion
• Neural and hormonal mechanisms
• Stimulatory and inhibitory events occur in three phases:
1. Cephalic (reflex) phase: ________________________________________________________________
- aroma, taste, sight, and thought of food activate neural mechanisms that stimulate stomach secretions
2. Gastric phase: 3–4 hours after food enters the stomach
• stomach distension, peptides, and low acidity (due to protein foods) stimulate stomach secretions
3. Intestinal phase:
Two phases
• Brief stimulatory effect as partially digested food enters the duodenum
– Release of intestinal gastrin causes gastric glands to continue their secretory phase
• Followed by inhibitory effects (enterogastric reflex)
– Gastric secretory activity declines (protects small intestine from excessive acidity)

–____________________________________________________

» Secretin
» Cholecystokinin (CCK)
» Vasoactive intestinal peptide (VIP)
Regulation and Mechanism of HCl Secretion
Regulation and Mechanism of HCl Secretion
• 1. Protein foods enter stomach and raise pH
• 2. Gastrin secreted
• 3. H+ released from ______________________________________ into stomach lumen
• 4. Cl- follows the H+ into stomach lumen and forms HCL
Response of the Stomach to Filling
Gastric Contractile Activity
Regulation of Gastric Emptying
Response of the Stomach to Filling
• Stomach stretches to accommodate incoming food and rising pressure
– relaxation of smooth muscles
• Coordinated by the swallowing center of the brain stem (via vagus nerve)
Gastric Contractile Activity
• Peristaltic waves move toward the pylorus at the rate of 3 per minute
• Distension of stomach wall and gastrin increase force of contraction
• Chyme passes through partially open pyloric valve into the duodenum

Regulation of Gastric Emptying
• As chyme enters the duodenum
– Receptors respond to stretch and chemical signals
– enterogastrones inhibit gastric secretion and duodenal filling
• Carbohydrate-rich chyme moves quickly through the duodenum
• Fatty chyme remains in the duodenum 6 hours or more (requiring more enzyme digestion
Small Intestine: Gross Anatomy
Small Intestine: Gross Anatomy
• Major organ of digestion and absorption
• 2–4 m long; from pyloric sphincter to ileocecal valve (joins large intestine)
• Subdivisions
1. Duodenum (du”o-de’num) ( 10 inches long)
2. Jejunum (je-joo’num) (8 feet long)
3. Ileum (12 feet long)
Duodenum
Duodenum
• The bile duct and main pancreatic duct
– Join at the hepatopancreatic ampulla
– Enter the duodenum at the major duodenal papilla

– Are controlled by the _____________________________
Structural Modifications of Small Intestine
Structural Modifications of Small Intestine
• Increase surface area of proximal part for nutrient absorption
– Circular folds
– Villi
– Microvilli

• Circular folds
– ~1 cm deep
– Force chyme to slowly spiral through lumen
– Allow time for full nutrient absorption

• Villi
• Motile fingerlike extensions (~1 mm high) of the mucosa
– Villus epithelium
• Simple columnar food molecule absorptive cells
• Goblet cells – mucous secreting
– Lacteal
• Lymph capillary that absorb fat molecules

• Microvilli
• Projections (brush border) of absorptive cells

• Bear _________________________________________________________ complete carbohydrate and protein digestion
Intestinal Crypts
Intestinal Crypts
• Intestinal crypt epithelium
– Tubular glands between the villi
– Secretory cells that produce intestinal juice (see below)
– Enteroendocrine cells
• Release enterogastrones- e.g. secretin and cholecystokinin
– T- cell lymphocytes
• Release cytokines that contribute to destroying infected cells
– Paneth cells
• Secrete antimicrobial agents (defensins and lysozyme)
submucosa
Submucosa
• Peyer’s patches (lymphoid follicles) protect distal part against bacteria from entering bloodstream
• Duodenal (Brunner’s) glands of the duodenum secrete alkaline mucus
– Neutralizes acidic chyme moving from stomach

Intestinal Juice
• Hormones, enzymes, and mucous
• Secreted in response to distension or irritation of the mucosa
• Slightly alkaline
• Facilitates transport and absorption of nutrients
Liver
Liver
• Largest gland in the body
• Four lobes—right, left, caudate, and quadrate

Liver: Associated Structures
• Lesser omentum anchors liver to stomach
• Hepatic artery and vein at the porta hepatis
• Bile ducts
– ________________________________________________________ leaves the liver

– __________________________________ connects to gallbladder

– __________________________________ formed by the union of the above two ducts
• Bile travels toward duodenum



Liver: Microscopic Anatomy
• Liver lobules
– Hexagonal structural and functional units
• Filter and process nutrient-rich blood
• Composed of plates of hepatocytes (liver cells)
– Longitudinal central vein

• Portal triad at each corner of lobule
• Portal triad (three basic structures)
• Portal artery branches from the hepatic artery
– Carries oxygen-rich arterial blood to the liver
• Portal venule (a branch of the hepatic portal vein)
– Carries venous blood with nutrients from the digestive viscera to the liver
• Bile duct
– carries bile from liver to the small intestine
• Hepatocyte (liver cells) functions
– Process bloodborne nutrients
– Store fat-soluble vitamins
– Perform detoxification
– Produce ~900 ml bile per day
Bile
Bile
• Yellow-green, alkaline solution containing
– _________________________________: cholesterol derivatives that function in fat emulsification and absorption

– _________________________________: pigment; waste product of heme group of hemoglobin; formed by breakdown of erythrocytes
– Cholesterol, neutral fats, phospholipids, and electrolytes
Gallbladder
The Gallbladder
• Thin-walled muscular sac on the ventral surface of the liver
• Stores and concentrates bile
• Releases bile via the cystic duct, which flows into the bile duct
• Gallstones formed as the result of too much cholesterol
• When gallbladder or its duct contracts, cholesterol crystals cause agonizing pain
Pancreas
The Pancreas
• Location
– Mostly retroperitoneal, deep to the greater curvature of the stomach
– Head is encircled by the duodenum; tail abuts the spleen

• Endocrine function

• ___________________________________________ (eye-lets) aka islets of Langerhans secrete insulin and glucagon
• Exocrine function
– Acini (clusters of secretory cells) secrete pancreatic juice
– Zymogen granules of secretory cells contain digestive enzymes
– Pancreatic juice drains into the main pancreatic duct into the duodenum


Pancreatic Juice
• Watery alkaline solution (pH 8) neutralizes acidic chyme
• Electrolytes (primarily HCO3–)
• Enzymes
– Amylase, lipases, proteases, and nucleases

Proteases (protein- digesting enzymes) are actived in duodenum
– Trypsinogen is activated to trypsin by brush border enzyme _______________________________

• Becomes the protein digesting enzyme __________________

– Procarboxypeptidase and chymotrypsinogen are activated by __________________
• Become the protein digesting enzymes _____________________and _________________

• Bile secretion is stimulated by
– Secretin from intestinal cells exposed to HCl and fatty chyme

• Gallbladder contraction is stimulated by

– ___________________________ (CCK) from intestinal cells exposed to proteins and fat in chyme
• CKK also causes the hepatopancreatic sphincter to relax

Regulation of Pancreatic Secretion
• CCK induces the secretion of enzyme-rich pancreatic juice by acini
• Secretin causes secretion of bicarbonate-rich pancreatic juice by duct cells
sm intestines
Digestion in the Small Intestine
• Chyme from stomach contains
– Partially digested carbohydrates and proteins
– Undigested fats

Requirements for Digestion and Absorption in the Small Intestine
• Slow delivery of chyme
• - Because it is hypertonic
• - Prevents loss of water from the blood into the intestinal lumen
• Delivery of bile, enzymes, and bicarbonate from the liver and pancreas
• Mixing

Motility of the Small Intestine
• Segmentation
– Mixes and moves contents slowly and steadily toward the ileocecal valve
• Peristalsis
– Meal remnants, bacteria, and debris are moved to the large intestine

• Local enteric neurons coordinate intestinal motility
– Causes contraction of the circular muscle proximally and of longitudinal muscle distally
– Forces chyme along the tract

Motility of the Small Intestine

• ________________________________ relaxes and admits chyme into the large intestine when
– force of segmentation in the ileum
– Gastrin release (increases the motility of the ileum)
• Ileocecal valve flaps close when chyme exerts backward pressure
lg intestines
Large Intestine
• Unique features
– Teniae coli
• Three bands of longitudinal smooth muscle in the muscularis
– Haustra
• Pocketlike sacs caused by the tone of the teniae coli
Large Intestine
• Regions
– Cecum (pouch with attached vermiform appendix)
– Colon
– Rectum
– Anal canal
colon
Colon
• Ascending colon and descending colon are _________________________________________
• Transverse colon and sigmoid colon are anchored via mesocolons (mesenteries)
Rectum and Anus
• Rectum
– Three rectal valves stop feces from being passed with gas
• Anal canal
– The last segment of the large intestine
• Sphincters
– Internal anal sphincter—smooth muscle (involuntary)
– External anal sphincter—skeletal muscle (voluntary
lg intestines
Large Intestine: Microscopic Anatomy
• Mucosa of simple columnar epithelium except in the anal canal (stratified squamous)
• Abundant deep crypts with goblet cells
• - Secrete mucous that eases passage of feces and protects intestinal wall from acids, gases, and bacteria
• Superficial venous plexuses of the anal canal form hemorrhoids if inflamed

Bacterial Flora
• Enter from the small intestine or anus
– Colonize the colon
– Ferment indigestible carbohydrates
– Release irritating acids and gases
– Synthesize B complex vitamins and vitamin K
""
Bacterial Flora
• Enter from the small intestine or anus
– Colonize the colon
– Ferment indigestible carbohydrates
– Release irritating acids and gases
– Synthesize B complex vitamins and vitamin K

Functions of the Large Intestine
• ____________________________________________________________________________________
• Major function is propulsion of feces toward the anus
• Colon is not essential for life
– If removed, the terminal ileum can be brought out to the abdominal wall (ileostomy)
Motility of the Large Intestine

• ___________________________________________________
– Slow segmenting movements
– Haustra sequentially contract in response to distension
• ___________________________________________________
– Initiated by presence of food in the stomach
– Activates three to four slow powerful peristaltic waves per day in the colon (mass movements)
– Bulk or fiber in the diet increases the strength of colon contractions and softens the stool
Defacation
Defecation
• Mass movements force feces into rectum
• Distension initiates spinal defecation reflex
• Parasympathetic signals
– Stimulate contraction of the sigmoid colon and rectum
– Relax the internal anal sphincter
• Conscious control allows relaxation of external anal sphincter
chem dig
Chemical Digestion
• Catabolic process by which large food molecules are broken down into monomers
– Governed by enzymes
– Hydrolysis or addition of water molecules to each molecular bond to be broken

Chemical Digestion and Absorption of Carbohydrates
• Digestive enzymes
– Salivary amylase splits starch into oligosaccharides (composed of more than three simple sugars )
– pancreatic amylase acts on any starches that were not acted upon by salivary amylase
– brush border enzymes of small intestine
• Dextrinase and glucoamylase act on oligosaccharides
• lactase, maltase, and sucrase hydrolyze their respective sugars
See below:
absorption
Chemical Digestion and Absorption of Carbohydrates
• Absorption
– ______________________________________________________________________________

– ______________________________________________________________________________
• Enter the capillary beds in the villi
• Transported to the liver via the hepatic portal vein

Chemical Digestion and Absorption of Proteins

• Enzymes: ______________________ in the stomach

• ____________________________________________ in small intestine
– Trypsin, chymotrypsin, and carboxypeptidase

• _______________________________________________________
– Aminopeptidases, carboxypeptidases, and dipeptidases
• Absorption of amino acids into absorptive cells is coupled to ATP dependent active transport of Na+

Chemical Digestion and Absorption of Lipids
• Pre-treatment—emulsification by bile salts
• Enzymes—pancreatic lipase
– Breaks down triglycerides into glycerol and short chain fatty acids
• Absorption of glycerol and short chain fatty acids
– Absorbed into the capillary blood in villi
– Transported via the hepatic portal vein

Chemical Digestion and Absorption of Lipids
• Absorption of monoglycerides and fatty acids
– Cluster with bile salts and lecithin to form ___________________________________
– Transported and released by micelles before diffusing into epithelial cells
– Combine with proteins to form _______________________________________________

– Enter ___________________________________ and are transported to systemic circulation

Chemical Digestion and Absorption of Nucleic Acids
• Enzymes
– ________________________________________________________________________________
• Absorption
– Active transport
• Transported to liver via hepatic portal vein
absorp
Vitamin Absorption
• In small intestine
– Fat-soluble vitamins (A, D, E, and K) are _____________________________________ and then diffuse into absorptive cells
– Water-soluble vitamins (vitamin C and B vitamins) are absorbed by ___________________________________

_____________________________________________________.
– Vitamin B12 binds with intrinsic factor, and is absorbed by endocytosis

• In large intestine
• Vitamin K and B vitamins from bacterial metabolism are absorbed

Electrolyte Absorption
• Mostly along the length of small intestine
• Iron and calcium are absorbed in duodenum
– Na+ is coupled with absorption of glucose and amino acids
– Ionic iron is stored in mucosal cells with ferritin
– K+ diffuses in response to osmotic gradients
– Ca2+ absorption is regulated by vitamin D and parathyroid hormone (PTH)

Water Absorption
• 95% is absorbed in the small intestine by osmosis (most of the rest absorbed by the large intestine)
• Net osmosis occurs whenever a concentration gradient is established by active transport of solutes
• Water uptake is coupled with solute uptake)
developmental
Developmental Aspects
• Fetal nutrition is via the placenta, but the GI tract is stimulated to mature by amniotic fluid swallowed in utero
• The newborn’s rooting reflex helps the infant find the nipple; the sucking reflex aids in swallowing

Developmental Aspects
• During old age
– GI tract activity declines, absorption is less efficient, and peristalsis is slowed
– Diverticulosis, fecal incontinence, and cancer of the GI tract
Cancer
• Stomach and colon cancers rarely have early signs or symptoms
• Metastasized colon cancers frequently cause secondary liver cancer
• Prevention
– Regular dental (oral cancer) examination
– Early stages of colon cancer removed during colonoscopy
Digestive Sytem processes
Digestive Processes
• Six essential activities

1. __INGESTION_- taking in food through oral cavity

2. _Propulsion__- moving food through alimentary canal
-Swallowing
-Peristalsis
3. __MECHANICAL dig_ – physically preparing food for enzymatic digestion
- chewing
- churning stomach
- segmentation- constrictions of the small intestine
4. ___Chemical dig - food molecules broken down by enzymes

5. _Absorption_____ – passage of digestive end products from the GI tract into blood or lymph
-small intestine

6. _Defecation - elimination of undigested substances via anus
2 groups of Organs
Digestive System
• Two groups of organs
1. __Alimentary Can ____ (gastrointestinal or GI tract)
• Digests and absorbs food
• Mouth, pharynx, esophagus, stomach, small intestine, and large intestine
• MPESII

2. _Accessory digestive Organs
- Teeth, tongue, gallbladder
- Digestive glands
- Salivary glands
- Liver
- pancreas TTGDSLP
Basic Functional Concepts
Basic Functional Concepts

GI tract regulatory mechanisms
1. Mechanoreceptors and chemoreceptors in walls of tract organs
• Respond to stretch, changes in osmolarity and pH, and presence of substrate and end products of digestion
• Initiate reflexes that
– Activate or inhibit digestive glands that secrete digestive juices or hormones
– Stimulate smooth muscle to mix and move lumen contents
• Intrinsic and extrinsic controls
• Enteric nerve plexuses (digestion brain) initiate short reflexes in response to internal stimuli in the GI tract
• Sensory information from the digestive system can be received, integrated and acted upon by the enteric system alone (no CNS involvement).

• Long reflexes in response to stimuli inside or outside the GI tract involve CNS centers and autonomic nerves
• Long reflexes to the digestive system involve a sensory neuron sending information to the CNS, which integrates the signal and then sends messages to the digestive system
• Hormones from cells in the stomach and small intestine stimulate target cells in the same or different organs
Digestive System Organs: Relationships
Relationship of the Digestive organs to the Peritoneum
Digestive System Organs: Relationships
Relationship of the Digestive organs to the Peritoneum

Peritoneum and Peritoneal Cavity
• __PERITONEUM___: serous membrane of the abdominal cavity
– _VISCERAL >>on external surface of most digestive organs
– _Parietal….. lines the body wall
• __Peritoneal cavity
– Between the two peritoneums
– Fluid lubricates mobile organs
mesentary
• __Mesentary is a double layer of peritoneum
– Routes for blood vessels, lymphatics, and nerves
– Holds organs in place and stores fat
– REtroperitoneal______ lie posterior to the peritoneum
– e.g. large intestine
• _INTRAPERITONEAL__ are surrounded by the peritoneum
– e.g. stomach
splanchnic
Blood Supply: Splanchnic Circulation

• Includes arteries that branch off the abdominal aorta to serve the digestive organs and the hepatic portal circulation
• Arterial supply
– Hepatic, splenic, and left gastric branches of the celiac trunk (serving the liver, spleen, and stomach)
– Inferior and superior mesenteric (serving the small and large intestine)
• Hepatic portal circulation
– Drains nutrient-rich venous blood from digestive organs
– Delivers it to the liver for processing
Mucosa
Mucosa
• Lines the lumen
• Functions
– Secretes mucus, digestive enzymes and hormones
– Absorbs end products of digestion
– Protects against infectious disease
• Three sublayers: epithelium, lamina propria, and muscularis mucosae

Mucosa (continued)
• Epithelium
– Simple columnar epithelium and mucus-secreting cells
• Mucus
–PROTECTS FROM ENZYMES
– Eases food passage
– May secrete enzymes and hormones (e.g., in stomach and small intestine)


• Lamina propria
– Loose areolar connective tissue
– Capillaries for nourishment and absorption
– Lymphoid follicles (part of MALT) - immune function
• Muscularis mucosae:
• smooth muscle that produces local movements of mucosa

Submucosa and Muscularis Externa
• Submucosa
– Dense connective tissue
– Blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus

• Muscularis externa (muscularis)

Responsible for SEGMENTATION/Peristalis
– Inner circular and outer longitudinal layers of smooth muscles
– Sphincters in some
Serosa
Serosa
• Visceral peritoneum
– Protective outermost layer of intraperitoneal organs
– Replaced by the fibrous adventitia in the esophagus
– Retroperitoneal organs have both an adventitia and serosa
enteric
Enteric Nervous System

• The alimentary canals PNS nerve supply (enteric neurons)
• Regulates digestive system activities
– Submucosal nerve plexus (sensory and motor neurons)
• Regulates glands and smooth muscle in the mucosa
– Myenteric nerve plexus
• Controls GI tract motility (segmentation and peristalisis)

• Linked to the CNS via afferent (sensory) visceral fibers
• Long ANS (motor) fibers synapse with enteric plexuses
– Sympathetic impulses inhibit secretion and motility
– Parasympathetic impulses stimulate
Palates
Palate
• Hard palate: palatine bones and palatine processes of the maxillae
– Slightly corrugated-Create friction against tongue_
• Soft palate: fold formed mostly of skeletal muscle
– _Closes off nasopharnyx during swallowing
• Can you breath and swallow at the same time?
– Uvula projects downward from its free edge

Tongue
• Functions include
– Repositioning and mixing food during chewing
– Formation of the bolus
– Initiation of swallowing, speech, and taste
LINGUAL FRENULUM________: attachment to the floor of the mouth
• Surface bears papillae (taste buds)
1. Filiform—whitish, give the tongue roughness and provide friction
2. Fungiform—reddish, scattered over the tongue
3. Circumvallate (vallate)—V-shaped row in back of tongue
• These three house taste buds
4. Foliate—on the lateral aspects of the posterior tongue