Respiratory Physiology II ( Lectures 46 - 49)

Question 1

Gas exchange in lungs and tissues involves diffusion of ____ and _____ from regions of ______ to ___

Answer 1

CO2 and O2

higher partial pressure to lower partial pressure

Question 2

The total pressure of gas is the sum of _______

Answer 2

pressures of individual gases that make up the mixture

Question 3

What is the partial pressure of a gas

Answer 3

Proportion of pressure of the entire gas that is due to the presence of the individual gas

Question 4

(T/F) pressure equilibrium is the same as concentration equilibrium

Answer 4

False
Pressure equilibrium is not the same as the concentration equilibrium. The ability of gas to dissolve in water depends on the solubility of the gas

Question 5

Because oxygen has _____ solubility in water, the evolution of ______ developed

Answer 5

low

oxygen-carrying molecules in the blood

Question 6

_____ is 20 times more soluble in water than is ____

Answer 6

Carbon dioxide

oxygen

Question 7

Partial Pressure of O2 and CO2 travel. Explain

Answer 7

1. O2 ( 100mm Hg) from the alveoli travels down the partial pressure gradient to the capillaries (40 mmHg)
2. Diffusion goes to equilibrium, and the PO2 of the arterial blood leaving the lungs is 10 mmHg
3. When arterial blood reaches the capillaries, the gradient is reversed,, the intracellular PO2 is < 40 mmHg and O2 travels down its partial pressure gradient ( plasma to cells)
4. PCO2 of arterial blood is 40 mmHg which is lower than the 46 mmHG PCO2 in cells, therefore CO2 diffuses out of the capillaries into the plasma.

Question 8

Each liter of systemic arterial blood normally contains _____ ml of O2

Answer 8

200

Question 9

OUt of the ____ml of O2, _____dissolves in 1 Liter of blood and the other _____ is transported in _____, ____ combined with _____

Answer 9

200
3 mL
197 mL / erythrocytes
reversibly combined with Hb

Question 10

Each _____ molecule is a protein made up of _____ bound together

Answer 10

Hb

4 subunits

Question 11

Each subunit of Hb contains a ____ molecular group and a _____ attached to it. Each of the four _____ groups contains _____ .

Answer 11

heme
polypeptide

heme
one iron atom which the O2 binds to

Question 12

The equation for the _____ reaction between O2 and Hb is ____

Answer 12

reversible

O2 + Hb = HbO2

Question 13

The O2- Hb dissociation curve examines the relationship between _____

Answer 13

partial pressure of O2 and hemoglobin saturation

Question 14

At normal alveolar pressure (____ mm Hg) , ___% of the Hb is bound to O2

Answer 14

100

98%

Question 15

As blood passes through the lungs under normal conditions, Hb picks up nearly _______ of O2 that it can carry

Answer 15

maximal amount

Question 16

(T/F) The more the partial pressure of O2 the more the hemoglobin saturation

Answer 16

False, it stops at around 98% saturation. Any pressure above 100mmHg would make only minor changes to Hb % saturation

Question 17

When Alveolar Partial pressure is > ____ mm, >90% of Hb is saturated

Answer 17

60

Question 18

After _____ , a small decrease in PO2 causes a ___ release of _____

Answer 18

60 large O2

Question 19

The binding of O2 with Hb is an example of ____ . Explain

Answer 19

cooperativity

Each subunit in the Hb can combine with one molecule of O2, the reactions of the four subunits happen sequentially, helping the next one.

Deoxygenated Hb have a low affinity for O2, the binding of O2 to a heme molecule breaks down subunit bonds that leaves the other O2 binding sites to be more exposed

Therefore, the binding of one deoxyhemoglobin increases the affinity of the remaining sites on the same Hb molecule

Question 20

A left shift of curve means ____ O2 affinity and ____ unloading of O2.

A right shift of curve means_______ O2 affinity and _____ unloading of O2

Answer 20

greater , less

less, more

Question 21

What affects hemoglobin saturation and how does it affect

Answer 21

DPG concentration / Temperature / pH
– increased level of DPG, acidity, and temperature metabolizes activity which causes more unloading, a right shift to the curve, lower affinity

– a decrease in these factors causes the dissociation curve to shift left, therefore, Hg has a greater affinity for O2

Question 22

Fetal HB has ____ affinity for O2 than adults becuase _____

Answer 22

higher

needs to oxygenate blood from exchange with maternal blood

Question 23

_____ has higher affinity for O2 than ___ .

Answer 23

Myoglobin

Hb

Question 24

Hb has ___ affinity for CO2 than O2

Answer 24

higher

Question 25

What are the 3 ways that CO2 is transported in the blood. Percentages

Answer 25

1. dissolved (7%) 2. converted to bicarbonate (70%) 3. binds to hemoglobin (23%)

Question 26

While CO2 is more ______ in body fluids that O2, only about ____% of CO2 carried by the venous blood is ______ in the blood. The remaining _____ % diffuses into RBC.

Answer 26

soluble 7% / dissolved 97%

Question 27

Explain the conversion of bicarbonate ion

Answer 27

Conversion to CO2 to bicarbonate ion depends on the presence of carbonic anhydrase (CA) found in RBCs Diffused CO2 goes to the RBC and interacts with H2O with the presence of CA. Carbonic Acid dissociates readily to form bicarbonate ions

Question 28

Conversion to bicarbonate ion is a _____ reaction

Answer 28

reversible | it depends on substrate concentration and law of mass action

Question 29

What are the 2 mechanisms that remove free H+ and HCO3- from RBC

Answer 29

1) An antiport protein exchanges HCO3 for Cl -- this is called the chloride shift 2) Deoxyhemoglobin acts as a buffer and binds with the H+ in the reaction.

Question 30

Binding of CO2 to Hb forms ____

Answer 30

carbaminohemoglobin

Question 31

Put the whole transport process together

Answer 31

1. CO2 diffuses out of the cells into the systemic capillaries 2. About 7% of it is dissolved within the plasma 3. 23% of it binds to Hb forming carbaminohemoglobin 4. 70% of the CO2 is converted to bicarbonate and H+. Some of the hemoglobin buffers H+ while some HCO3- enters the plasma in exchange for the Cl- - - At various stages, CO2 is transported into the lungs 5. At the lungs, dissolved CO2 diffuses out of the plasma 6. By the law of mass action, Co2 uninds from Hb and diffuses out of RBC 7. Carbonic acid reaction reverses pulling HCO3 back into the RBC and converting it back to CO2

Question 32

(T/F) oxyhemoglobin has a greater affinity for H+ than deoxyhemoglobin

Answer 32

False. | Deoxyhemoglobin has a higher affinity for H+ than oxyhemoglobin

Question 33

Explain carbaminohemoglobin

Answer 33

About 23% of the CO2 leaves the venous blood and binds to Hb directly. When O2 leaves the binding sites on the Hb molecules, CO2 binds with free Hb exposed amino groups forming carbaminohemoglobin

Question 34

The diaphragm and intercostal muscles are ____ muscles

Answer 34

skeletal

Question 35

Breathing depends entirely upon _____ excitation by the _____.

Answer 35

cyclical respiratory muscle | motor nerves

Question 36

Inspiration is initiated by a______ in the _____ to inspiratory muscles. When the ____ cease, the ______ relax and expiration occurs as the elastic lungs recoils

Answer 36

burst of action potential spinal motor nerves action potentials inspiratory muscles

Question 37

(T/F) During exercise, nerves still do not contract during expiration

Answer 37

False | During exercise, contraction of expiratory muscles facilitates expiration, nerves to these muscles will start to fire

Question 38

What controls the activity of the inspiratory spinal motor neurons ? Location? Explain

Answer 38

The integrating center for the control of breathing is located in the medulla oblongata. This medullary respiratory system is located in the RF. Within the medullary respiratory system, there is a small group of pacemaker cells called the pre-Botzinger complex located on each side of the medulla. These neurons fire rhythmically and produce rhythmic discharges in the phrenic neurons

Question 39

Inspiratory and expiratory neurons in the medulla show _____, which is ...

Answer 39

reciprocal inhibition motor neurons to the expiratory muscles are inhibited when those supplying to the inspiratory muscles are active they alternate !

Question 40

The ______ of the ____ fine-tunes the transition between inspiration and expiration.

Answer 40

Pontine respiratory group | Pons

Question 41

The actions of the pons and medulla are modulated by the ____, which is (voluntary/ involuntary)

Answer 41

cortex which is voluntary

Question 42

What are the pre-Botzinger complex

Answer 42

They include pacemaker cells which are located on either side of the medulla. These neurons will fire rhythmically to produce rhythmic discharges in the phrenic neurons