Respiratory System A&p 2

Front 1

What is expiratory reserve

Back 1

Amt of air beyond tidal volume, expelled w/forceful exhalation

1k-5k

Front 2

Inspiratory reserve

Back 2

amt of air beyond tidal volume, deepest inhalation

2k-3k

Front 3

Tidal volume

Back 3

amt of air involved in normal breath
500mL
shallow breating = low volume

Front 4

MRV

Back 4

amt of inhaled/exhaled in 1 min
tidal volume by respiration per min

12-20 avg

Front 5

Pulmonary volume

Back 5

lung size vary with size/age
capacity diminishes w/age
less efficient
lose elasticity, respiratory muscles

Front 6

Vital capacity

Back 6

tidal volume, insp reserve, exp reserve
3500 5000 mL

Front 7

Residual Arc

Back 7

air ini lungs after forceful exhalation
1k-15k mL
ensure air is in lungs at all times, exchange of gases is continuous

Front 8

Evaluation of Pulmonary Volumes

Back 8

volumes determined with spirometers, measure air movement

Front 9

Mechanism of Breathing

Back 9

Ventilation – the movement of air to and from the alveoli
Inhalation and exhalation – brought about by the nervous system and the respiratory muscles
Respiratory brain centers in the brain are in the medulla and pons
Respiratory muscles – diaphragm and external and internal intercostal muscles
Diaphragm is a dome-shaped muscle below the lungs; contraction causes flattening and downward movement

Front 10

Mech of breathing cont

Back 10

Intercostal muscles found between the ribs
External intercostal muscles pull the ribs upward and outward
Internal intercostal muscles pull the ribs downward and inward
Ventilation results from the muscles producing changes in the pressure within the alveoli and bronchial tree

Front 11

Three Types of Pressure Important for Breathing

Back 11

Atmospheric pressure – pressure of air around us; at sea level –760 mmHg; lower at higher altitudes
Intrapleural pressure – the pressure within the potential pleural space between the parietal pleura and visceral pleural
A potential – not a real space – small amount of serous fluid – causes the pleural membranes to adhere
Intrapleural pressure always slightly below atmospheric pressure (756 mmHg)– negative pressure
The lungs are elastic and tend to collapse and pull the visceral pleural form the parietal pleural

Front 12

Three types continued

Back 12

Serous fluid prevents separation of pleural membranes
Intrapulmonic pressure – pressure within the bronchial tree and alveoli; fluctuates below /above atmospheric pressure during breathing

Front 13

Inhalation

Back 13

Aka inspiration
1. motor impulses from the medulla travel along the phrenic nerves to the diaphragm and along the intercostal nerves to the external intercostal muscles; 2. the diaphragm contracts moving downward – expands the chest cavity from top to bottom; 3. external intercostal muscles pull ribs up and out – expanding the chest cavity from side to side and front to back
Expansion of the chest cavity causes the parietal pleura to expand with it, intrapleural pressure becomes more negative which causes the visceral pleura to expand

Front 14

Inhalation cont

Back 14

This results in expansion of the lungs
Lung expansion results in intrapulmonic pressure fallsing below atmospheric pressure, air then enters the nose and travels through the respiratory passages to the alveoli
Entry of air continues until intrapulmonic pressure equals atmospheric pressure – a normal inhalation
If inhalation continues beyond normal – a deep breath – requires a more forceful contraction of the respiratory muscles to further expand the lungs

Front 15

Exhalation/expiration

Back 15

Begins when motor impulses from the medulla decrease – the diaphragm and external intercostal muscles relax
The chest cavity becomes smaller, lungs are compressed, the elastic connective tissue ,which was stretched during inhalation, recoils and compresses the alveoli
As intrapulmonic pressure rises above atmospheric pressure air is forced out of the lungs until the two pressures are again equal

Front 16

Exhalation cont

Back 16

Inhalation is an active process requiring muscle contraction
Normal exhalation is a passive process – depending to a great extent on the normal elasticity of healthy lungs
Can go beyond normal exhalation and expel more air – such as when talking, singing, ore blowing up a balloon
Forced exhalation is an active process requiring contraction of the internal intercostal muscles
This pulls the ribs down and in – squeezing more air out
Contraction of abdominal muscles (rectus abdominus) compresses the abdominal organs and pushes the diaphragm upward, forcing more air out of the

Front 17

Physiologic Dead Space

Back 17

Not normal
The volume of non-functioning alveoli that decrease gas exchange.
Causes include: bronchitis, pneumonia, tuberculosis, emphysema, asthma, pulmonary edema, and a collapsed lung

Front 18

Alveolar Ventilation

Back 18

The amount of air that actually reaches the alveoli and participates in gas exchange
Average tidal volume of 500 mL, of which 350 to 400 mL is in the alveoli at the end of an inhalation
Remaining 100 to 150 mL of air is anatomic dead space – air still within the respiratory passages

Front 19

Thoracic Wall and Lung Compliance

Back 19

The normal expansibility, necessary for sufficient alveolar ventilation
May be decreased by fractured ribs, scoliosis, pleurisy, or ascites
Lung compliance will be decreased by any condition that increases physiologic dead space

Front 20

Exchange of Gases

Back 20

Two sites of exchange of O2 and CO2: the lungs and the tissues of the body
External respiration – the exchange of gases between the air in the alveoli and the blood in the pulmonary capillaries
Internal respiration – the exchange of gases between the blood in the systemic capillaries and the tissue fluid (cells) of the body

Front 21

Air

Back 21

Earth’s atmosphere (room air)– approx. 21% O2 and 0.04% CO2
Most is nitrogen (78%) – not physiologically available to us, simply exhaled
Exhaled air also contains about 16% O2 and 4.5% CO2

Front 22

Diffusion of Gases – Partial Pressures

Back 22

Within the body gases diffuses from area of greater concentration to an area of lesser concentration
Partial pressure (P)-- concentration of each gas in a particular site expressed as a value measured in mmHg
The partial pressure of a gas is the pressure it exerts within a mixture of gases, whether the mixture is actually in a gaseous state or is in a liquid (blood)
Fig. 15-8 show P for O2 and CO2 in the body
A gas will diffuse from an area of higher P to an area of lower P

Front 23

Transport of Gases in the Blood

Back 23

Most O2 carried in blood bound to Hgb in RBC’s, only about 1.5% is dissolved in plasma creating the P O2
The oxygen-hemoglobin bond formed in the lungs where high P O2
Bond is unstable, when blood passes through tissues with a low P O2, the bond breaks, oxygen releases into the tissues
Lower oxygen concentration in the tissue, the more oxygen released – ensuring that active tissues receive as much O2 as possible

Front 24

transport cont

Back 24

Other factors that increase the release of O2 from Hgb: high P CO2 and a high temperature, characteristics of active tissues
Another measure of blood O2 is the percent of oxygen saturation of hemoglobin (Sa O2)
Systemic arteries: P O2 – 100, Sa O2 about 97%
Systemic veins: P O2 – 40, Sa O2 about 75%

Front 25

CO2 Transport

Back 25

More complicated, some CO2 dissolved in plasma, some carried by Hgb – only about 20% of total CO2 transport
Most CO2 is carried in the plasma in the form of HCO3-

Front 26

Regulation of Respiration—Nervous Regulation

Back 26

Within the medulla are the inspiration and expiration centers
Inspiration center automatically generates impulses in rhythmic spurts
Travel along nerves to respiratory muscles to stimulate contraction
As lungs inflate, baroreceptors in lung tissue detect this stretching, generate sensory impulses to the medulla, depress the inspiration center
This is the Hering-Breuer inflation reflex – helps to prevent overinflation of the lungs

Front 27

Regulation of Respiration—Nervous Regulation cont

Back 27

Depression of the inspiration center results in a decrease in impulses to the respiratory muscles; which relax to bring about exhalation
When there is a need for more forceful exhalations, such as during exercise; the inspiration center center activates the expiration center

Front 28

Regulation of Respiration—Nervous Regulation cont

Back 28

The 2 respiratory centers in the pons work with the inspiration center to produce a normal rhythm of breathing
The apneustic center prolongs inhalation
It is interupted by impulses from the pneumotaxic center which contributes to exhalation
Normal breathing – inhalation lasts 1-2 seconds, followed by a slightly longer (2-3 seconds) exhalation; resulting in the normal respiratory rate range of 12 to 20 breaths/min.

Front 29

Variations in Breathing

Back 29

Emotions – fear, anger.
Impulses from the hypothalamus modify the output form the medulla
The cerebral cortex enables us to voluntarily change our breathing rate or rhythm to talk, sing, breathe faster or slower, or even to stoop breathing for 1-2 minutes
The medulla will eventually resume control

Front 30

Coughing and Sneezing

Back 30

Reflexes that remove irritants from the respiratory passages; medulla contains the centers for both of these reflexes
Sneezing caused by irritation of nasal mucosa
Coughing by irritation of the mucosa of the pharynx, larynx or trachea
Reflex action: inhalation followed by exhalation beginning with the glottis closed to build up pressure, then it opens suddenly, and the exhalation is explosive
Cough directed out the mouth, sneeze through the nose

Front 31

Hiccups, Yawning

Back 31

Hiccups are also a reflex, spasms of the diaphragm.
A quick inhalation stopped when the glottis snaps shut, causing the”hic” sound.
Stimulus may be irritation of the phrenic nerves or nerves of the stomach
Yawning – stimulus and purpose not known with certainty

Front 32

Regulation of Respiration—Chemical Regulation

Back 32

The effect on breathing of blood pH and blood levels of O2 and CO2
Chemoreceptors which detect changes in blood gases and pH are located in the carotid and aortic bodies and in the medulla
Hypoxia detected by carotid and aortic bodies – sensory impulses sent by nerves to the medulla  increases respiratory rate or depth (or both)

Front 33

Regulation of Respiration—Chemical Regulation cont

Back 33

Hypercapnia (excess CO2)– resulting in lower pH – is detected by chemoreceptors in the medulla increases respiration
The increased respiration causes exhalation of more CO2 which raises the pH back to normal

Front 34

cont

Back 34

Respiration as a source of O2 can decrease or even cease for a few minutes without damage
Respiration as a method of elimination CO2 is more important – the pH drops quickly and cannot be allowed to continue

Front 35

Respiration and Acid-Base Balance

Back 35

The more CO2 increases H2CO3 which ionizes into H+ ions and HCO3- ions
The more H+ ions present in a body fluid, the lower the pH; the fewer H+ ions, the higher the pH
The respiratory system may be the cause of a pH imbalance, or it may help correct a pH imbalance created by some other cause

Front 36

Respiratory Acidosis

Back 36

Occurs when the rate or efficiency of respiration decreases, permitting CO2 to accumulate in body fluids
Causes are pulmonary diseases such as pneumonia and emphysema, or severe asthma

Front 37

Respiratory Alkalosis

Back 37

Occurs when the rate of respiration increases and CO2 in very rapidly exhaled
Not common; severe physical trauma and shock, or certain states of mental or emotional anxiety may be accompanied by hyperventilation
Traveling to a higher altitude

Front 38

Respiratory Compensation –Metabolic Acidosis

Back 38

pH imbalance caused by something other than a change in respiration; a change in respiration may help restore the normal pH
Metabolic acidosis – may be caused by untreated diabetes mellitis, kidney disease, or severe diarrhea
Increased rate and depth of respiration to exhale more CO2 and raise the pH

Front 39

Metabolic Alkalosis

Back 39

Not common, excessive amounts of alkaline medications (antacids); vomiting of stomach contents only decreasing H+ ions
Decrease in respiration to retain CO2 and lower the pH
Respiratory compensation can only be about 75% effective

Front 40

Aging

Back 40

In absence of chemical (tobacco products) respiratory function does diminish but usually remains adequate
Muscles weaken
Lung tissues lose elasticity
Alveoli are lost as wall deteriorate
Cilia deteriorate, alveolar macrophages not as efficient, making the elderly more prone to pneumonia
The interdependence of the respiratory and circulatory systems is particularly apparent in the elderly

Front 41

Division

Back 41

Upper – the parts outside the chest cavity – air passages of nose, nasal cavities, pharynx, larynx and upper trachea
Lower – within chest cavity – lower trachea and lungs including bronchial tubes and alveoli
Also – pleura membranes and respiratory muscles  diaphragm and intercostal muscles

Front 42

Nose & Nasal Cavities

Back 42

Air enter & leaves respiratory system through nose
Composed of bone & cartilage covered with skin
Inside nostrils are hairs – help block entry of dust
Nasal mucosa (lining) – ciliated epithelium, with goblet cells that produce mucus
Conchae – 3 shelf-like or scroll-like bones project from lateral wall of each nasal cavity increasing surface area of nasal mucosa

Front 43

Functions of Nasal Cavities

Back 43

Warm and humidify air
Trap bacteria & particles of air pollution in mucus
Cilia sweep mucus back toward pharynx where it is swallowed
Olfactory receptors in upper cavities detect vaporized inhaled chemicals  olfactory nerves pass through ethmoid bone to brain

Front 44

Functions of Nasal Cavities cont

Back 44

Paranasal sinuses – air cavities in maxillae, frontal, sphenoid & ethmoid bones – lined with ciliated epithelium, mucus produced drains into nasal cavities
Sinuses lighten skull & provide resonance for the voice

Front 45

Pharynx (throat)

Back 45

Muscular tube posterior to nasal & oral cavities, anterior to cervical vertebrae
Nasopharynx – behind nasal cavities
Soft palate elevates during swallowing to prevent food or saliva from going up
Posterior wall of nasopharynx – adeniod (pharyngeal tonsils) – a lymph nodule contains macrophages

Front 46

Pharynx (throat) cont

Back 46

Eustachian tube from ears open into nasopharynx – allow air to enter or leave middle ear to eardrum can vibrate properly
Nasopharynx – air only

Front 47

Oropharynx

Back 47

Food and air passage
Behind mouth
Mucosa stratified squamous epithelium, continuous with oral cavity
Lateral walls – palatine tonsils (lymph nodes); also lingual tonsils at base of tongue – form ring of lymphatic tissue around pharynx to destroy pathogens that penetrate mucosa

Front 48

Larngopharynx

Back 48

Most inferior
Open anteriorly into larnyx & posteriorly into esophagus
Constriction of muscular wall of oropharynx & laryngopharynx part of swallowing reflex

Front 49

Larynx (voicebox)

Back 49

Two functions – speaking and air passageway between pharynx & trachea
Made of 9 pieces of cartilage connected by ligaments to keep larynx upon
Thyroid cartilage – largest cartilage
Epiglottis – uppermost cartilage which closes over the top of larynx during swallowing
Mucosa – ciliated epithelium, except vocal cords – stratified squamous

Front 50

Larynx (voicebox) cont

Back 50

Cilia sweep upward to remove mucus & trapped dust & microorganisms
Vocal cords (or vocal folds) – either side of glottis – the opening between them
During breathing – vocal cords held at sides of glottis to allow free air passage
During speaking – intrinsic muscles of larynx pull vocal cords across glottis, exhaled air vibrates vocal cords to produce sounds which can be turned into speech

Front 51

Trachea & Bronchial Tree

Back 51

Trachea – 4-5 inches (10-13 cm), extends from larynx to primary bronchi
Contains 16-20 C-shaped pieces of cartilage to keep it open
Gaps are posterior to permit expansion of esophagus when food is swallowed
Mucosa – ciliated epithelium with goblet cells
Rt & Lt primary bronchi – branches of trachea which enter the lungs – structure just like trachea

Front 52

Trachea & Bronchial Tree cont

Back 52

Within lungs each primary bronchus branches into secondary bronchi leading to lobes of each lung (3 right, 2 left)
Bronchial tree – further branching
Bronchioles – smaller branches
No cartilage in bronchioles
Smallest bronchioles terminate in cluster of alveoli

Front 53

Lungs & Pleural Membranes

Back 53

Lungs are either side of heart in chest cavity
Encircle & protected by ribcage
Base of each lung rests on diaphragm
Apex of lung at level of clavicle
Medial surface of each lung in indention called hilus – where primary bronchus & pulmonary artery & vein enter the lung

Front 54

Lungs & Pleural Membranes cotn

Back 54

Pleural membranes – serous membranes of thoracic cavity. Parietal pleura lines chest wall
Visceral pleural – surface of lungs
Between membranes – serous fluid – prevents friction, keeps 2 membranes together during breathing

Front 55

Alveoli

Back 55

Functional units of lungs – air sacs called alveoli
Flat alveolar type I cells form most of alveolar wall are simple squamous
In spaces between clusters of alveoli is elastic connective tissue – important for exhalation
Within alveoli – macrophages that phagocytize pathogens or other foreign material that may not have been swept out by the ciliated epithelium of the bronchial tree

Front 56

Alveoli cont

Back 56

Millions of alveoli in each lung
Each is surrounded by a network of pulmonary capillaries
With simple squamous epithelium these are only two cells between the air in the alveoli and the blood in the pulmonary capillaries – permits efficient diffusion of gases

Front 57

Alveoli cont 2

Back 57

Each alveoli is lined with a thin layer of tissue fluid – essential for the diffusion of gases (a gas must dissolve in a liquid in order to enter or leave a cell
Pulmonary surfactant – lipoprotein secreted by alveolar type II cells – mixes with the tissue fluid within the alveoli, decreasing the surface tension permitting inflation of the alveoli