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Animal Physiology: Homeostasis > Week 2 > Flashcards

Week 2 Flashcards

1
Q

What are the 3 basic principles of Circulatory Function

A
  1. Blood flow to most tissues is controlled according to tissue needs
  2. CO is the sum of all the local tissue blood flows
  3. Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control
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2
Q

Def: Flow

A

The movement of substances or heat from one point to another, driven by energy gradients between those two points

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3
Q

What directly impacts the rate of flow

A

Magnitude of energy gradient

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4
Q

What energy gradient causes the flow of molecules

A

concentration

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5
Q

What energy gradient causes the flow of heat

A

temperature

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6
Q

what energy gradient causes the flow of gases

A

partial pressure

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7
Q

What energy gradient causes the flow of fluids

A

oneiric pressure or hydrostatic pressure

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8
Q

What energy gradients cause the flow of ions

A

Concentration and voltage (electrochemical)

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9
Q

Def: Blood Pressure

A

a hydrostatic pressure, which reflects the force exerted by blood against a unit area of vessel wall

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10
Q

Def: Resistance

A

the impediment to flow due to friction, both external (against vessel wall) and internal (due to viscosity)

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11
Q

Def: Conductance

A

1/resistance

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12
Q

Methods of measuring blood flow

A

Invasive: ultrasonic doppler flowmeter

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13
Q

Methods for measuring blood pressure

A

invasive: intravascular pressure transducer
noninvasive: blood pressure sphygmomanometer

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14
Q

Cardiac Output animal differences

A

Total blood flow through the aorta
Humans: 5 L/min
Giraffe: 60 L/min
Mouse: 0.02 L/min

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15
Q

Def: Change in pressure

A

The difference in mean blood pressure between the aorta and the right atrium
- Little variation between species

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16
Q

Def: total peripheral resistance

A

The resistance of the entire systemic circulation

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17
Q

Sum of resistances in series

A

Sum individual resistances to get total resistance
- Total resistance is greater than any individual resistance

18
Q

Sum of resistances in parallel

A

Total resistance is equal to 1 over the sum of 1/rs
- total is less than any single resistance

19
Q

Def: Laminar Flow

A

Blood usually flows smoothly in ‘streamlines’ through vessels, with reactively little mixing in a radial direction

20
Q

Def: Turbulent Flow

A

Blood flow can become disorderly, whirling in a radial direction to form what are called ‘eddy currents’
- Usually occurs in largest vessels at highest flow rates, around obstacles or during vasodilation
-Increases the resistance to blood flow due to internal resistance

21
Q

Determinants of resistance in laminar flow

A
  • Small changes in vessel diameter have large effect on blood flow
  • in larger vessels, more streamlines of blood are far from the vessel wall where flow is much slower, blood flows at a higher velocity
    -Viscosity and vessel length also affect resistance but don’t change over short periods of time
  • reduction in vessel diameter reduces blood flow at a given pressure gradient (arterioles)
22
Q

Poiseuille’s Law

A

F=(pi change in pressure r^4)/8nL
R= 8nL/pir^4

23
Q

Changes in blood viscosity

A

Changes in hematocrit can alter blood viscosity
-more red blood vessels increases friction between adjacent cells and vessel wall
Decrease: anemia - can occur during menstrual cycle and/or in response to blood loss
increase: polycythemia - occurs at high elevation, in response to sleep apnea, pulmonary disease etc.

24
Q

Pulmonary Circulation

A
  • Picks up O2 at lungs
  • Low pressure system (20mmHg)
  • RV to Lungs to LA
25
Q

Systemic Circulation

A
  • Delivers O2 to other organs and tissues
  • High pressure system (100mmHg)
  • LV to tissues to RA
26
Q

Layers of the Pericardium

A
  • Epicardium
  • Pericardial space
  • Parietal Pericardium
  • Fibrous Pericardium
27
Q

Layers of the heart walls

A
  • Endocardium
  • Myocardium
  • Pericardium
28
Q

Heart muscle histology

A

Cardiomyocytes
- Striated
- Interconnected at intercalated disks

29
Q

Heart Fiber Structure

A
  • Subendocardial fibers run oblique to subepicardial fibers
  • aids in left ventricle ejection and relaxation
  • Shortening of fibers during contraction cause wringing motion that pulls the base towards the apex and reduces lumen diameter
  • At the end of systole, the left ventricle is similar to a loaded spring that recoils during diastole and rapidly expands lumen diameter
30
Q

How do heart valves help direct blood flow?

A

Open and closed passively in response to pressure gradients

31
Q

What is the relationship between flow and the volume of blood in the ventricle

A

Amount of time blood is flowing

32
Q

What causes blood flowrate to change?

A

change in pressure gradient

33
Q

Can anything cause blood flow to stop entirely?

A

Valves

34
Q

Ventricular Filling

A
  • Begins when A-V valve opens
  • Ends when A-V valve closes
  • P atrium >P ventricle
  • At end of stage atrial systole occurs resulting in a boast in pressure and volume
35
Q

Isovolumetric Contraction

A
  • Begins when A-V valve closes
  • Ends when P ventricle > P aorta causing aortic valve to open
  • P atrium < P ventricle < P aorta
  • Increase in pressure due to increase force with decrease ventricle space
36
Q

Ejection

A
  • Begins when aortic valve opens
  • P ventricle greater than P aorta
  • Aortic valve takes time to close once pressure gradient shifts due to stiffness
  • Ends when aortic valve closes
37
Q

Isovolumic Relaxation

A
  • Begins when Aortic valve closes
  • Ends when P ventricle < P atrium causing A-V valve to open
  • P aorta > P ventricle > P atrium
38
Q

Atrioventricular Valves

A
  • Very thin
  • open/close very easily in response to forward/backward pressure gradients
39
Q

Semilunar Valves

A
  • Stronger and heavier
  • do not open and close as easily
40
Q

Pressure-Volume Loops

A
  • Useful way of showing the changes in pressure and volume during the cardiac cycle
  • The area of the loop represents the net external work of one cardiac cycle

Animal Physiology: Homeostasis (12 decks)

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