Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Advanced Physiology > Non-Learning Objective > Flashcards

Non-Learning Objective Flashcards

1
Q

Velocity of signal conduction

A

0.3-0.5m/s along both atrial and ventricular muscle fibres.

Purkinje fibres: 4m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

BPM: SA Node, AV Node, Purkinje Fibres

A

SA Node: 70-80 bpm
AV Node: 40-60 bpm
Purkinje fibres: 15-40 bpm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Autonomic Nervous System - Control of Heart Rhythmicity

A

Parasympathetic:

  • vagus, nerves mainly to the SA and AV node.
  • Release of ACh by post-ganglionic neurons onto muscarinic receptors causes decrease in SA node rhythm and slows down conduction through the AV node.
  • ACh opens ligand-gated K+ channels. Efflux of K+ ions hyperpolarises the nodal cells, taking them further from threshold. So it takes longer to generate an action potential.
  • Same mechanism in AV node.

SYMPATHETIC:
-Distributed to all parts of the heart including AV and SA nodes.

  • Release of norepinephrine by post-ganglionic neurons causes:
  • increased SA node rhythm, AV node conduction speed and force of contraction.
  • Norepinephrine binds to beta-1-adrenergic receptors which mediate effects on heart rate.

CURRENT THEORY: Increases Na+ perm. in SA/AV nodal cells so closer to threshold and increases Ca2+ perm. in cardiomyocytes so increases contractile strength.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Venous Pressures:
Where is central venous pressure?
What is pressure in standing still feet?
Where can you get negative pressures?

A

Central venous pressure is in right arium = 0mmHg

Standing Feet: +90mmHg

Negative pressures can be found in dural sinuses of head (veins in skull are in a non-collapsible chamber and don’t collapse)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What % of blood is usually in the veins?

A

> 60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Most important means by which substances are transferred between plasma and interstitial fluid:

A

diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Exchange between blood and interstitial fluid: lipid v. water soluble

A

lipid soluble substances diffuse directly through the cell membranes of the capillary endothelium

water soluble substances diffuse through intercellular pores in the capillary membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Special cases - acute blood flow control: kidneys

A

mainly through the tubuloglomerular feedback mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Special cases - acute blood flow control:

Brain

A
  • In addition to tissue oxygen, [H+] and [CO2] also play a role.
  • Increase in either causes dilation of cerebral vessels to rapidly wash out excess.
  • Important because level of excitability in the brain is dependent on appropriate control of CO2 and H+ concentration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Special cases - acute blood flow control:

Skin

A

Closely linked to body temperature,

controlled largely by CNS via sympathetic nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Blood supply to the lungs:

A 
High-pressure, low-flow circulation:
Systemic arterial (oxygenated) blood to the lungs and trachea

Low-pressure, high-flow circulation:
Venous blood to the lungs for oxygenation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Blood flow to the lungs is essentially equal to:

A

CO = HR x SV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In general, the pulmonary vessels enlarge/narrow in response to:

A

pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Blood circulation is directed to which areas of the lungs? Why?

A

Most oxygenated alveoli

So the blood is adequately oxygenated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens when oxygen concentrations drop in the alveoli?

A

Blood vessels feeding that area are constricted, increasing the vascular resistance (this resistance is associated with the development of pulmonary oedema)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pressure Gradients in Lungs

A
  • A blood pressure gradient exists vertically through the lungs due to hydrostatic pressure (gravity)
  • Least Pressure: Upper quadrants (above the heart). Zone 2 - Intermittent blood flow, only at peak systolic pressure, exceeds alveoli pressure.
  • Greatest pressure: Lower quadrants (below the level of the heart)
    Zone 3 flow, capillary pressure always higher than alveoli pressure.
  • When lying down or during exercise, Zone 3 blood flow is seen throughout the lungs.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

PP in alveoli as opposed to ATM air:

Why the difference?

A

Nitrogen: 74.9
O2: 13.6
CO2: 5.3
H2O: 6.2

Why?

  • Higher PH2O due to humidification of air as it enters the respiratory system.
  • Changes in CO2 and O2 due to exchange.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Transportation of O2

A

2 ways

  1. Dissolved in plasma (~2% due to poor solubility)
  2. Bound to Hb in RBCs (98%). Hb increases our O2 carrying capacity 30-100x.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

During exercise, tissue demand for O2 rises by how much? And how is this met?

A

20x
Increased cardiac output (7x)
Increased O2 release (3x)

20
Q

At rest, Hb passing through tissue capillaries gives up what % of its bound O2? During exercise, what %

A

At rest: 25%
During exercise: 75%
- Greater drop in PO2 during exercise, steep drop in Hb-O2 dissociation curve

21
Q

How does Hb affinity for O2 change with PO2?

A

High PO2 = higher affinity (e.g. in pulmonary capillaries where it loads oxygen)
Low PO2 = lower affinity (e.g. tissue capillaries where it unloads oxygen)
This is the basis for reversible transport of oxygen.

22
Q

The binding of the first O2 to Hb causes what?

A

Conformational change in the shape of the other chains from taut T shape to relaxed R shape, increases their affinity for O2.

23
Q

The rate at which haemoglobin reversibly binds/releases O2 is dependent on:

A 
PO2
Temperature
pH
PCO2
DPG levels
24
Q

What happens to the dissociation curve during exercise, as a result of elevated levels of PCO2, body temp, drop in pH?

A

Right-shift in the dissociation curve. Promotes O2 release.

25
Q

What is the effect of DPG on Hb?

A

2,3-DPG (or 2,3-BPG) binds to Hb lowering its affinity for O2, thus promoting its release.

26
Q

What shifts Hb-O2 curve left?

A

Increased O2 affinity:

Inc. pH
Dec. DPG, Temp, PCO2

27
Q

What shifts Hb-O2 curve right?

A

Decreased O2 affinity:

Dec. pH
Inc. DPG, Temp, PCO2

28
Q

Why can CO2 be transported in greater quantities than O2?

A
  1. Can diffuse 20 times faster than O2.

2. Blood solubility is significantly higher.

29
Q

How is CO2 transported o the lungs?

A
  1. Dissolved within the blood (7%)
  2. Bound to Hb (23%)
  3. Converted to bicarbonate ions (70%)
30
Q

What catalyses the inter-conversion of CO2 and water to bicarbonate ions:
(include equation)

A

carbonic anhydrase

CO2 + H2O <> H2CO3 <> H+ + HCO3-

31
Q

Why is venous blood returning from tissue capillaries slightly acidic compared to arterial blood?

A

Some H+ diffuses out of RBCs when CO2 is converted for transport.

32
Q

Where are the bicarbonate ions converted back to CO2?

A

At the alveoli epithelium which contain large amounts of carbonic anhydrase

33
Q

How does the respiratory system regulate body pH?

A

regulates the removal of CO2, and hence H2CO3 from the extracellular fluid.

34
Q

Fall in blood pH - effect on respiratory rate?

A

Induces a rise, increased removal of CO2

35
Q

A rise in blood pH is associated with what CO2 levels and has what effect on respiratory rate?

A
  • associated with decreased blood CO2 levels (hence a decrease in [H+])
  • Induces a fall in respiratory rate (decreased removal of CO2)
36
Q

What is polycythaemia and what causes it to increase?

A
  1. Greater release of erythropoietin, therefore RBC mass and Hb mass.
  2. Acclimatisation to altitude.
37
Q

Respiratory Centre

A

3 major regions

MEDULLA:
Dorsal Respiratory Group: regulates inspiration
Ventral Respiratory Group: regulates expiration

PONS:
Apneustic & Pneumotaxic centres which regulate rate/depth of breathing.

38
Q

How does DRG regulate breathing?

A

Regulates inspiration by stimulating expansion of lungs through contraction of inspiratory muscles.

39
Q

How does VRG regulate breathing?

A

Regulates expiration by stimulating compression of lungs through contraction of expiratory muscles:
abdominal muscles
internal intercostal muscles

40
Q

Quiet Breathing Cycle

A

Inspiration (Active): stimulation of DRG - expansion of lungs (2 seconds)
Expiration (Passive): inhibition of DRG - slow depression of lungs (3 seconds)

41
Q

Forced Breathing Cycle

A

Inspiration (Active): stimulation of DRG - expansion of lungs
Expiration (Passive/Active): inhibition of DRG, activation of VRG - causes rapid/greater depression of lungs

42
Q

Apneustic Centre - Function

A

APPEARS TO increase the rate and depth of breathing.

43
Q

Pneumotaxic Centre - Function

A

APPEARS TO decrease the rate and depth of breathing

44
Q

Respiratory Chemoreceptors:

A

CENTRAL CHEMORECEPTORS:

  • located in medulla
  • detect changes in PCO2 & pH
  • analyse CSF

PERIPHERAL CHEMORECEPTORS:

  • located in carotid body & aortic arch
  • detect changes in PO2, pH, indirectly PCO2 via pH
  • analyse arterial blood supply
45
Q

Baroreceptors - relation to respiratory system

A

Drop in BP: Increase CO and resp. rate

Rise in BP: Decrease CO and resp. rate

46
Q

Lung - protective reflex - Mechanoreceptors

A

Hering-Breuer: Prevents over/under Inflation of the lungs:

Inflation Reflex: over-inflation is detected by stretch receptors in the smooth muscle surrounding the bronchioles. Information is transmitted to the DRG/VRG: inhibits DRG and stimulates VRG.

Deflation Reflex: under-inflation is detected by stretch receptors in the alveoli. Inhibits VRG, Stimulates DRG.

Advanced Physiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions