Exam 3 - Human Circulation and Gas Exchange

Question 1

What are brain centers?

Answer 1

collections of interneurons that receive sensory input and create motor output

Question 2

What is heart rate determined by?

Answer 2

the sympathetic and parasympathetic branches of the autonomic nervous system

Question 3

What are proprioceptors?

Answer 3

• sensory input from muscles and tendons

- informs brain on changes in physical activity

Question 4

What are baroceptors?

Answer 4

• sensory input from blood vessels
• informs brain on changes to pressure in vessels
• detect when arteries stretch due to increased pressure

Question 5

What are chemoreceptors?

Answer 5

• 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

Question 6

What drives gas exchange across respiratory surfaces?

Answer 6

diffusion

Question 7

What is a partial pressure?

Answer 7

the pressure of a particular gas in a mixture of gasses

Question 8

How will gasses diffuse?

Answer 8

according to their partial pressures

Question 9

What structures allow the lungs to contract and relax?

Answer 9

• intercostal muscles

- diaphragm

Question 10

How do the diaphragm and rib muscles act during inhalation?

Answer 10

• rib muscles contract

- diaphragm contracts and moves down

Question 11

How do the diaphragm and rib muscles act during exhalation?

Answer 11

• rib muscles relax

- diaphragm relaxes and moves up

Question 12

Where does gas exchange occur?

Answer 12

in the alveoli

Question 13

How does gas exchange work in the alveoli?

Answer 13

• air enters the alveoli
• gasses in alveoli equilibrate with gasses of blood in capillaries
• gasses will move down their pressure gradients via diffusion

Question 14

What is the partial pressure of O2 in the alveolus?

Answer 14

100 mmHg

Question 15

What is the partial pressure of O2 in the body tissues?

Answer 15

< 40 mmHg

Question 16

What is the partial pressure of CO2 in the alveolus?

Answer 16

40 mmHg

Question 17

What is the partial pressure of CO2 in the body tissues?

Answer 17

> 46 mmHg

Question 18

What is the role of respiratory pigments?

Answer 18

increase the amount of oxygen that can be transported in the blood and body tissues

Question 19

What are the two respiratory pigments, and where are they found?

Answer 19

• hemoglobin: found in the blood

- myoglobin: found in the muscle cells

Question 20

What is the breakdown of oxygen presence in the blood?

Answer 20

• 2% dissolved in blood plasma

- 98% bound to hemoglobin in RBCs

Question 21

What is the breakdown of carbon dioxide presence in the blood?

Answer 21

• 10% dissolved in blood plasma
• 20% bound to hemoglobin
• 70% in the form of plasma bicarbonate

Question 22

What things affect O2 loading and unloading?

Answer 22

• O2 pressure

- pH differences

Question 23

Does O2 or CO2 have a greater effect on respiration?

Answer 23

CO2

Question 24

How does O2 pressure affect O2 loading/unloading?

Answer 24

• PO2 is lower in tissues during exercise than during rest

- lower PO2 measurements drive the release of O2 into the tissues

Question 25

How does pH affect O2 loading/unloading?

Answer 25

• pH is lower when more CO2 is preset

- lower pH drives more O2 unloading

Question 26

How does hemoglobin’s affinity for O2 change with binding?

Answer 26

• affinity for O2 increases as successive molecules of O2 bind
• affinity for O2 decreases as successive molecules of O2 are released

Question 27

What are the characteristics of the Bohr effect?

Answer 27

• involves allosteric interactions between hemes

- based on pH differences