A & P 2 - Respiratory System 2-3

Front 1

What is the Thoracic Cavity?

Back 1

Walls:
-bone cage and respiratory muscles

diaphragm:
-border between thoracic and abdominal cavity

mediastinum:
-contains heart, large blood vessels, thymus, trachea and esophagus

two lateral parts contain lungs and DO NOT communicate with each other and with mediastinum

Pleural membranes:
Parietal pleura - lines walls of thoracic cavity
visceral pleura - covers lungs

Pleural cavity:
-between 2 pleural membranes

Intrapleural fluid:
-made up by subvisceral pulmonary capillaries and lymphatic system
-lubricates and reduces friction
-adhesive forces

Front 2

What is Pneumothorax, hydrothorax, and hemothorax?

Back 2

Pneumothorax:
-accumulation of air in intrapleural space
inspiration:
-negative pleural pressure lost, collapse of ipsilateral lung and reduced venous return to heart
-mediastinum shifts compressing opposite lung
expiration:
-further impairment of venous return by distortion of venae cavae

Hydrothorax:
-abnormal accumulation of fluid in intrapleural space
-increased production or decreased drainage of plural fluid

hemothorax:
-accumulation of bood

Front 3

What are Costodiaphragmatic Recesses?

Back 3

lungs do not completely fill pleural cavity in inferior area

recesses - space between inferior borders of lungs and pleurae

applied aspect:
-obliterated when there is collection of fluid due to pleura or lung pathology can be sen in X ray in erect position
-fixed by thoracentesis (removal of excess fluid from pleural cavity without damage to lung)
-needle inserted into costodiaphragmatic recess (7th intercostal space)

Front 4

What are the Bronchopulmonary Segments?

Back 4

segment separated by each tertiary (segmental) bronchus (10 in each lung)

consists of lobules - lung tissue wrapped in elastic CT supplied by one branch of a terminal bronchiole, lymphatic vessel, an arteriole and a venule

Each bronchopulmonary segment can be surgically removed without affecting the function of the other segments

Front 5

What are the properties of the Alveoli?

Back 5

Structure:
alveoli - cap shaped outpouching
sacs - several alveoli that share a common opening
-single layer of epithelial cells (simple squamous) and thin basement membrane

2 types of epithelial cells:
Type I pneumocytes - primary lining epithelial cells
Type II pneumocytes - cuboidal epithelial cells which secrete surfactant (phospholipids and lipoproteins)

macrophages

Front 6

What is the Alveolar capillary membrane?

Back 6

composed of:
-pulmonary epithelium
-capillary endothelium
-fused basement membrane

site of exchange of gases between alveolar air and blood

low thickness and decrease velocity of air flow --> facilitates diffusion of gases in alveoli

Front 7

What is the blood supply and innervation of respiration?

Back 7

bronchial circulaiton (systemic):
-supplies conductive system and supportive tissues
-veins are branches of azygos

pulmonary circulation:
-supplies respiratory zone of lungs
-regulation by local factors ( decrease O2 --> vasoconstriction)

innervation:
-skeletal = somatic NS
smooth muscles:
sympathetic:
-activation of Beta2 --> relaxation of smooth muscles fibers --> dilation of airways --> decrease resistance of air flow
parasympathetic:
-M-cholino receptors --> contraction of smooth muscles --> increase resistance to air flow which helps in distribution of air flow to lungs

Front 8

What are the muscles of respiration?

Back 8

Inspiratory muscles:
-inspiration is active process

Diaphragm:
-specialized inspiratory mm, does not participate in other functions
-accounts for 75 % of total change in intrathoracic volume during quiet respiration
-contraction causes flattening and enlargement of thoracic cavity in vertical direction
-innervated by phrenic (C3-C5)

External intercostals:
-elevates and pushes sternum forward, forces rib upward and outward like handle of basket
-accounts for 25 % change in total intrathoracic volume

Accessory inspiratory:
-act during deep inspiration, elevate ribs
-include SCM, scalene, pectoral mm, dilator nasi, traps, rhomboids, serratus anterior

Forced Expiration:
-abdominal wall mm = rectus, oblique transversus; increases intraabdominal pressure and pushes diaphragm upward
-internal intercostal = pulls rib downwards
-quadratus lumborum
-serratus posterior inferior

Front 9

What are the main steps of Respiration?

Back 9

external respiration:
-pulumonary ventilation = exchange between atmosphere and lungs
-alveolar diffusion of gases

O2 and CO2 transport through pulmonary and systemic circulation

Internal respiration:
-exchange of gases between blood and tissues
-tissue respiration = metabolic reactions that consume O2 and produce CO2 during ATP synthesis

Front 10

What are the two wasy gas is transported?

Back 10

convection:
-bulk flow of all gases in mixture down total P gradient
-movement of volume of gs mixture per unit time
2 types:
laminar - organized; turbulent - chaotic

simple diffusion:
-movement of ions along concentration gradient

Front 11

What are some lung-related pressures?

Back 11

Intrapleural P:
-is always sub atmospheric or negative
-between breaths = 4 mm Hg less than atmospher or -5 cmH2O
Forces that create negative P:
1. retractile tendency of lungs (elastic recoil)
2. expansile tendency of chest wall
3. drainage of intrapleural fluid

Alveolar P (intrapulmonary):
-similar to atmosphere (0 mm Hg or 0 cmH2O)

Transpulmonary P:
-difference between alveolar and intrapleural P = 0 - (-5) = +5 cmH2O

Trans-respiratory system P:
-difference between alveolar and body surface = 0 - 0 = 0 cmH2O

Trans-chest wall P:
-difference between intrapleural and atmospheric P = -5 - 0 = -5 cmH2O

Front 12

What are changes in pressures during quiet breathing?

Back 12

Intrapleural P:
-goes from -5 to -7.5 during inspiration, back to normal during expiration

Alveolar P:
-decreases to -1 during inspiration, rises to +1 during expiration

Transpulmonary P:
-changes from 5 to 6.5 during inspiration, normal during expiration

more negative intrapleural P during inspiration causes decrease in airway resistance

Front 13

What are the factors that determine lung volume?

Back 13

Interactino of transpulmonary pressure and elastic recoil:
-transpulmonary P expands lungs
-elastic recoil collapses lungs
-balance between two leads to lung volume stability

Compliance:
-stretchability
-reciprocal of elasticity
-expressed as changed in volume/change in transpulmonary P

Front 14

What are some factors that determine lung compliance? What is surfactant?

Back 14

Lung compliance determined by:
-Stretchability of lung tissue (elastin, collagen, actomyosin)
-Surface tension forces: increase intra-alveolar P and decrease its stretchability, REDUCED BY SURFACTANT
-decrease compliance: scar tissue in lungs (TB), pulmonary edema, surfactant deficiency, paralysis of intercostal mm

Surfactant:
-mixture of phospholipid dipalmitol/lecithin, cholesterol, apoproteins and Ca2+
function - reduction of surface tension at alveolar-air interface by replacing water molecules with surface active lipid-proteins --> increase compliance, decrease work of respiration

Front 15

What is RDS?

Back 15

Respiratory Distress Syndrome of Newborn

surfactant system develops during late fetal life

results in:
-increased surface tension resulting in collapse of alveoli
-pulmonary edema

treatment:
-assisted breathing
-glucocorticoid and thyroid hormones help maturation of surfactant system

Front 16

What are the distribution of gases in inspired, expired, and alveolar air?

Back 16

N2 (79 %), O2 (21 %), CO2 (.03%), Water vapor, contaminants

water vapor:
-alveolar gas fully saturated with water
-SVP (P of vapor at 37 C)
-Spirometer measures lung volume at Ambient T and P, saturated (ATPS_
-in body it is Body T and P, saturated (BTPS)

Front 17

What are factors that affect airway resistance?

Back 17

physical factors:
-transpulmonary P (Palveolar - Ppleural)
-lateral traction forces

ANS (control of bronchial smooth muscle)

Local (paracrine) agents:
-decrease CO2 concentration in over-ventilated parts of lungs --> bronchoconstriction
-release of histamine, prostaglandins, leukotrienes, kinins --> bronchoconstriction