Chapter 23 - Respiratory System Flashcards
respiratory system
- exchange of gases
- moves air to and from exchange surfaces of lungs
mucus
along respiratory tracts
Respiratory defense system
nose removes large particles
Mucous cells and mucous glands
produces mucous to cover exposed surfaces
cilia
gather mucus, trapped debris, microorganisms toward pharynx to be swallowed
Alveolar macrophages
eat small particles that reach lungs
Bronchioles
– Bronchioles branch into terminal bronchioles
– Bronchioles have no cartilage
• Dominated by smooth muscle
autonomic nervous system
– Controls bronchioles diameter by regulating smooth muscle
– Controls airflow in lungs
bronchodilation
– Caused by sympathetic activation
– Enlarges diameter of airway
– Reduces resistance to airflow
bronchoconstriction
- Parasympathetic activation
– Reduces diameter of airway - Histamine release (allergic reactions)
Alveolar cell layer
pneumocytes type I -thin walls -site of gas exchange -monitored by macrophages pneumocytes type II -produces surfactant
surfactant
– Oily secretion
– phospholipids + proteins
– Coats alveolar surface and reduces surface tension
respiratory distress syndrome
– Alveoli collapse after each exhalation
– Caused by inadequate amounts of surfactant due to injury or genetic abnormalities
Pneumonia
– Inflammation of lung tissue
– Causes fluid to leak into alveoli
– Compromises function of blood air barrier
Gas exchange across blood air barrier is quick and efficient
– Because distance for diffusion is short
– And O2 and CO2 are small and lipid soluble
Blood pressure in pulmonary circuit
– Lower than that in systemic circuit
– Pulmonary vessels are blocked by blood clots, fat, or air bubbles
pulmonary embolism
A blocked branch of pulmonary artery that stops
blood flow to lobules or alveoli
external respiration
exchange of O2 and CO2 with external environment
internal respiration
- Uptake of O2 and release of CO2 by cells
* Result of cellular respiration
hypoxia
Low tissue oxygen levels
anoxia
Complete lack of oxygen in tissues
inhalation
inspiration
exhalation
expiration
the lower the pressure
the lower the diffusion
resistance
bronchodilation and bronchoconstriction
compliance
factors that affect compliance?
– A measure of expandability
– Lower compliance requires greater force to fill lungs
– Factors that affect compliance
• Connective tissue of lungs
• Level of surfactant production
• Mobility of thoracic cage
at sea level the partial pressure is
760 mm Hg
the other atoms (partial pressure)
N- 78%
0- 21%
water vapor - 0.5%
CO2- 0.04%
solubility of gases in body fluid
– CO2 is highly soluble
– O2 is somewhat less soluble
– N2 has very limited solubility
Partial pressures in plasma of pulmonary vein
– PCO2 =40mmHg
– PO2 =100mmHg
– PN2 =573mmHg
Blood arriving in pulmonary arteries has
- Low PO2
* High PCO2
concentration gradient causes
- O2 to enter blood
* CO2 to leave blood
internal respiration what happens?
– Oxygenated blood mixes with deoxygenated blood
– Lowers PO2 of blood entering systemic circuit to about 95 mm Hg
interstitial fluid
• PO2 40mmHg,PCO2 45mmHg
Concentration gradient in peripheral capillaries is opposite of lungs
• CO2 diffuses into blood, O2 diffuses out of blood
red blood cells have a higher affinity for
O and CO2
O2 binds to ??? in hemoglobin (Hb) molecules
iron ions
• In a reversible reaction
• Forming oxyhemoglobin (HbO2)
1 RBC has
1 Hb molecule binds
280 million Hb molecules
4 oxygen molecules
hemoglobin saturation
% heme units containing bound oxygen at any given moment
factors affecting Hb saturation
– PO2 of blood
– Blood pH
– Temperature
– Metabolic activity within RBCs
When temperature increases, hemoglobin
When temperature decreases, hemoglobin
releases more oxygen
holds oxygen more tightly
the more BPG released
more oxygen released
• Due to increase in pH or certain hormones
fetal hemoglobin
higher affinity for hemoglobin
• binds more O2 than does adult Hb, takes O2 from maternal blood
70% of co2 in solution transported as
23% is
bicarbonate ions (HCO3-)
bound to protein portions of Hb molecules
in RBCs
• Forming carbaminohemoglobin
baroreceptors
in aortic or carotid sinuses sensitive to changes in blood pressure
aging
elastic tissue deteriorates in lungs
Emphysema
- Affects individuals over age 50
- exposure to respiratory irritants (cigarette smoke)
