Exam 3 - Human Circulation and Gas Exchange Flashcards
What are brain centers?
collections of interneurons that receive sensory input and create motor output
What is heart rate determined by?
the sympathetic and parasympathetic branches of the autonomic nervous system
What are proprioceptors?
- sensory input from muscles and tendons
- informs brain on changes in physical activity
What are baroceptors?
- sensory input from blood vessels
- informs brain on changes to pressure in vessels
- detect when arteries stretch due to increased pressure
What are chemoreceptors?
- sensory input from blood vessels
- informs brain on changes of carbon dioxide or oxygen levels in the blood
- important in the respiratory system but has some affect on heart rate
- monitor pH
What drives gas exchange across respiratory surfaces?
diffusion
What is a partial pressure?
the pressure of a particular gas in a mixture of gasses
How will gasses diffuse?
according to their partial pressures
What structures allow the lungs to contract and relax?
- intercostal muscles
- diaphragm
How do the diaphragm and rib muscles act during inhalation?
- rib muscles contract
- diaphragm contracts and moves down
How do the diaphragm and rib muscles act during exhalation?
- rib muscles relax
- diaphragm relaxes and moves up
Where does gas exchange occur?
in the alveoli
How does gas exchange work in the alveoli?
- air enters the alveoli
- gasses in alveoli equilibrate with gasses of blood in capillaries
- gasses will move down their pressure gradients via diffusion
What is the partial pressure of O2 in the alveolus?
100 mmHg
What is the partial pressure of O2 in the body tissues?
< 40 mmHg
What is the partial pressure of CO2 in the alveolus?
40 mmHg
What is the partial pressure of CO2 in the body tissues?
> 46 mmHg
What is the role of respiratory pigments?
increase the amount of oxygen that can be transported in the blood and body tissues
What are the two respiratory pigments, and where are they found?
- hemoglobin: found in the blood
- myoglobin: found in the muscle cells
What is the breakdown of oxygen presence in the blood?
- 2% dissolved in blood plasma
- 98% bound to hemoglobin in RBCs
What is the breakdown of carbon dioxide presence in the blood?
- 10% dissolved in blood plasma
- 20% bound to hemoglobin
- 70% in the form of plasma bicarbonate
What things affect O2 loading and unloading?
- O2 pressure
- pH differences
Does O2 or CO2 have a greater effect on respiration?
CO2
How does O2 pressure affect O2 loading/unloading?
- PO2 is lower in tissues during exercise than during rest
- lower PO2 measurements drive the release of O2 into the tissues