LEC 14

Question 1

What happens inside the alveoli: (2)

Answer 1

1. Gas exchange occurs
2. Transportation of gases in the blood begins

Question 2

What happens during gas exchange: (2)

Answer 2

1. Pressure inside our lungs matches atmospheric pressure when we are resting between breaths
2. Diffusion occurs due to partial pressures

Question 3

Partial pressure (recall Dalton’s Law from CHM) (2)

Answer 3

1. In a mixture of gases, each will exert its own pressure
2. Proportional to its percentage of the total gas composition

Question 4

Partial pressure unit

Answer 4

mmHg

Question 5

Normal atmospheric pressure

Answer 5

760 mm Hg

Question 6

Partial pressure of O2 in air

Answer 6

160 mm Hg

Question 7

A gas will always diffuse _______ its partial pressure gradient (from area of ______ pressure to area of ________ pressure).

Answer 7

1. down
2. high
3. low

Question 8

Exchange of O2 and CO2 (2)

Answer 8

1. Between alveoli and blood is passive (NO ATP)
2. Due to partial pressure differences of the two gases

Question 9

Diffusion due to partial pressure gradients net effect

Answer 9

homeostasis of the concentrations of oxygen and carbon dioxide is maintained

Question 10

External Respiration (2)

Answer 10

1. Exchange of gases between air and blood
2. Oxygen into blood from air, carbon dioxide out of blood into air

Question 11

External Respiration gas exchange movement due to :

Answer 11

differences in the partial pressures of both gases between the blood & lungs

Question 12

Internal Respiration (2)

Answer 12

1. Exchange of gases with tissue fluids
2. Interstitial fluids pass oxygen and carbon dioxide between blood and cells

Question 13

Internal Respiration gas exchange movement due to :

Answer 13

differences in partial pressures between the two fluids (tissue and interstitial)

Question 14

Hemoglobin

Answer 14

Molecule in blood responsible for the transportation of gases in the body

Question 14

Without hemoglobin, tissues would not receive enough _________ to sustain life

Answer 14

oxygen

Question 15

Oxygen is transported one of two ways:

Answer 15

1. Bound to hemoglobin in RBC’s (approx. 98%)
2. Dissolved in blood plasma (approx. 2%)

Question 16

Each hemoglobin can bind _____ molecules of oxygen to it

Answer 16

4

Question 17

Forms “oxyhemoglobin” (HbO2) reaction

Answer 17

Hb + O2 = HbO2

Question 18

Hemoglobin binds oxygen most efficiently in conditions of _______ pH and relatively _______ temperatures (both found in lungs)

Answer 18

1. neutral
2. cool

Question 19

Hemoglobin has a ________ affinity for CO when compared to O2 = Hemoglobin’s affinity for oxygen is _________ by the presence of carbon monoxide

Answer 19

1. higher
2. decreased

Question 20

Inhaled air has ______ O2 than blood in pulmonary capillaries

Answer 20

more

Question 21

OXYGEN: TRANSPORT IN BLOOD (3)

Answer 21

1. O2 diffuses to region of lower concentration and then into RBC’s
2. RBC’s contain hemoglobin that binds O2
3. Weak bond, O2 will release in regions where the partial pressure of O2 is lower than in blood

Question 22

Carbon dioxide is continually produced as a ________ product during cellular respiration

Answer 22

waste

Question 23

_________ is a transport medium for this CO2 waste material

Answer 23

Blood

Question 24

CO2 diffuses into blood capillaries from any tissue where the partial pressure is higher than it is in the blood

Answer 24

1. CO₂ diffuses from tissues (high pressure) into blood (low pressure). 2. It is transported in blood and then exhaled in the lungs

Question 25

CO2 transported to the lungs in 3 forms:

Answer 25

1. plasma (10%) 2. hemoglobin (20%) 3. bicarbonate (70%)

Question 26

carbaminohemoglobin

Answer 26

hemoglobin and CO2

Question 27

O2 binds to ______ CO2 binds to __________

Answer 27

heme globin

Question 28

CO2 Transport: bicarbonate

Answer 28

1. CO2 enters RBCs from tissues. 2. CO₂ + H₂O → Carbonic acid (H₂CO₃) (catalyzed by carbonic anhydrase). 3. Carbonic acid breaks into bicarbonate (HCO₃⁻) and hydrogen ions (H⁺). 4. Bicarbonate (HCO₃⁻) diffuses out of RBCs into the plasma. 5. Chloride shift: Chloride ions (Cl⁻) enter RBCs to balance the charge. 6. Bicarbonate is transported in blood plasma to the lungs. 7. In the lungs, bicarbonate is converted back into CO₂, which is exhaled.

Question 29

Carbonic acid breakdown equation

Answer 29

CO2 + H2O = H2CO3 = HCO3- + H+

Question 30

CO2 Transport: at lungs (2)

Answer 30

1. Dissolved CO2 diffuses out of blood and into alveolar air 2. Results in lower partial pressure of CO2

Question 31

The basic pattern of breathing is established by the ________ centre within the _________ __________.

Answer 31

1. respiratory 2. medulla 3. oblongata

Question 32

CO2 Transport: at lungs causes

Answer 32

chemical conversion of bicarbonate to carbonic acid and eventually back to CO2 and H2O HCO3- + H+ = H2CO3 = CO2

Question 33

RESPIRATORY CENTRE

Answer 33

1. area with groups of nerve cells that automatically generate a cyclic pattern of electrical impulses every 4-5 sec 2. Travel to the diaphragm & intercostal muscles and stimulate contraction

Question 34

Respiration is primarily controlled by blood _______ levels, but also by a substantial drop in _____ or for short periods of time, by ________ control

Answer 34

1. CO2 2. O2 3. conscious

Question 35

RESPIRATORY CENTRE: During inhalation

Answer 35

1. Respiratory muscles contract, rib cage expands, diaphragm is pulled downward & we inhale 2. Respiratory centre in the brain receives sensory input from stretch receptors in the lungs – limit inhalation & initiate exhalation

Question 36

RESPIRATORY CENTRE: During exhalation

Answer 36

1. Nerve impulses from respiratory centre to muscles end 2. Respiratory muscles relax, ribcage returns to “normal” & diaphragm moves upward & we exhale

Question 37

How are chemical receptors involved?

Answer 37

Monitor levels of CO2, H+ and O2

Question 38

chemical receptors and CO2

Answer 38

1. Certain cells in medulla oblongata detect changes 2. Indirect – actually measure [H+] in cerebrospinal fluid 3. Rise in [CO2] results in rise of [H+] 4. Change of 2-3% initiates response in body 5. Causes respiratory centre to increase rate and depth of breath to eliminate excess CO2

Question 39

chemical receptors and O2

Answer 39

1. Receptors located in the carotid and aorta 2. If [O2] drops below 80 mm Hg (or about 20% decrease), receptors signal respiratory centre to increase rate and depth of breath to raise [O2] to normal

Question 40

BREATHING: CONSCIOUS CONTROL

Answer 40

1. have the ability to exert conscious control to regulate breathing for short periods of time 2. Higher brain centres – cortex Allows us to speak & sing, choose to hold our breath, breathe rapidly 3. Conscious control quickly becomes overpowered by automatic regulatory mechanisms if we try to hold our breath for too long!