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BIOL 336 > Respiratory Physiology II ( Lectures 46 - 49) > Flashcards

Respiratory Physiology II ( Lectures 46 - 49) Flashcards

1
Q

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

A

CO2 and O2

higher partial pressure to lower partial pressure

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2
Q

The total pressure of gas is the sum of _______

A

pressures of individual gases that make up the mixture

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3
Q

What is the partial pressure of a gas

A

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

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4
Q

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

A

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

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5
Q

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

A

low

oxygen-carrying molecules in the blood

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6
Q

_____ is 20 times more soluble in water than is ____

A

Carbon dioxide

oxygen

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7
Q

Partial Pressure of O2 and CO2 travel. Explain

A
  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.
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8
Q

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

A

200

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9
Q

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

A

200
3 mL
197 mL / erythrocytes
reversibly combined with Hb

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10
Q

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

A

Hb

4 subunits

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11
Q

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

A

heme
polypeptide

heme
one iron atom which the O2 binds to

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12
Q

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

A

reversible

O2 + Hb = HbO2

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13
Q

The O2- Hb dissociation curve examines the relationship between _____

A

partial pressure of O2 and hemoglobin saturation

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14
Q

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

A

100

98%

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15
Q

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

A

maximal amount

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16
Q

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

A

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

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17
Q

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

A

60

18
Q

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

A

60 large O2

19
Q

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

A

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

20
Q

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

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

A

greater , less

less, more

21
Q

What affects hemoglobin saturation and how does it affect

A

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

22
Q

Fetal HB has ____ affinity for O2 than adults becuase _____

A

higher

needs to oxygenate blood from exchange with maternal blood

23
Q

_____ has higher affinity for O2 than ___ .

A

Myoglobin

Hb

24
Q

Hb has ___ affinity for CO2 than O2

A

higher

25
Q

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

A
  1. dissolved (7%)
  2. converted to bicarbonate (70%)
  3. binds to hemoglobin (23%)
26
Q

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.

A

soluble
7% / dissolved
97%

27
Q

Explain the conversion of bicarbonate ion

A

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

28
Q

Conversion to bicarbonate ion is a _____ reaction

A

reversible

it depends on substrate concentration and law of mass action

29
Q

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

A

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.

30
Q

Binding of CO2 to Hb forms ____

A

carbaminohemoglobin

31
Q

Put the whole transport process together

A
  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
32
Q

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

A

False.

Deoxyhemoglobin has a higher affinity for H+ than oxyhemoglobin

33
Q

Explain carbaminohemoglobin

A

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

34
Q

The diaphragm and intercostal muscles are ____ muscles

A

skeletal

35
Q

Breathing depends entirely upon _____ excitation by the _____.

A

cyclical respiratory muscle

motor nerves

36
Q

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

A

burst of action potential
spinal motor nerves

action potentials
inspiratory muscles

37
Q

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

A

False

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

38
Q

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

A

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

39
Q

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

A

reciprocal inhibition

motor neurons to the expiratory muscles are inhibited when those supplying to the inspiratory muscles are active

they alternate !

40
Q

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

A

Pontine respiratory group

Pons

41
Q

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

A

cortex which is voluntary

42
Q

What are the pre-Botzinger complex

A

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

BIOL 336 (10 decks)

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