Lecture 21- Vascular Foundations I: the circulatory system Flashcards

1
Q

CV system transports substances entering the body:

A

oxygen, nutrients, water

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2
Q

CV system substances leaving the body:

A

metabolic waste, heat, CO2

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3
Q

CV system substances moved around the body:

A

wastes, hormones, immune cells and antibodies

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4
Q

The arteries are described as a “…”

A

pressure reservoir
(maintains the pressure); elastic
–> stretches to accomodate
–> snaps back to maintain pressure

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5
Q

Arterioles are described as “…”

A

adjustable screws that can tighten or loosen
–> main site of blood pressure regulation (through vasoconstriction or vasodilation

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6
Q

exchange between O2 and CO2 takes place at

A

exchange epithelium in the capillaries

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7
Q

Veins are describes as a “…”

A

volume reservoir; compliant
stretches but does not snap back

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8
Q

blood flow= flow rate=

A

volume/time= cardiac output (L/min)

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9
Q

there is a — times increase in cardiac output with sympathetic stimulation

A

5

ex. at rest CO= 5.8 L/min,
during exercise CO= 25.6 L/min

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10
Q

why is variable distribution of blood flow to tissues possible?

A

due to parallel arrangement of arterioles

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11
Q

pressure — with distance due to —

A

decreases with distance due to friction

heart contracts –> creates a driving pressure –> blood flows out

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12
Q

resistance to blood flow increases as radius of a blood vessel —

A

decreases

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13
Q

resistance in a blood vessel: vasodilation vs. vasoconstriction

A

vasodilation= decreased resistance
vasoconstriction= increased resistance

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14
Q

arterioles ONLY receive — input

A

sympathetic input

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15
Q

“white water rafting”

A

in the aorta, blood flow is very turbulent and high velocity

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16
Q

“lazy floating down the river”

A

in arteries, it is more calm.
wide, lazy, floating down the river, slow velocity

17
Q

pressure — as we move away from the heart

18
Q

velocity of blood flow (cm/min)

A

= distance traveled by a fixed volume of blood per unit time (cm/min)

19
Q

when does velocity of blood increase or decrease?

A

increases as flow rate (L/min) increases

decreases as CSA of blood vessels increase (larger tubes= slower flow)

20
Q

explain why pressure drops with distance from the heart?

A

as blood flows through circulation it loses pressure, which creates a pressure gradient

pressure is lost due to FRICTION:
- friction within the blood
- friction between blood and vessel walls

21
Q

blood and laws of fluid flow (3)

A

flow is prop to pressure gradient
F ∝ ΔP

flow is inversely prop to resistance
F ∝ 1/R

together…
F ∝ ΔP/R

22
Q

very low pressure in the veins…

A
  • need help to be pumped back up
  • skeletal muscle pump
  • valves prevent backflow
23
Q

what would happen if valves aren’t working properly?

A

varicose veins, edema, blood pooling

24
Q

venous return (VR)=

A

the flow of blood into the right atrium from the peripheral vessels

  • skeletal muscle pump helps maintain VR
25
blood flow is slowest through the...
capillaries - capillaries have greatest CSA - exchange is happening at the capillaries so we want it to be slow to ensure O2 and CO2 is properly exchnaged
26
what determines the velocity of blood flow through that vessel type?
the TOTAL cross sectional area of the vessels
27
capillaries have the smallest individual diameter but they have the...
largest total cross sectional diameter ...therefore slowest velocity!!!
28
precapillary sphincter
ring of smooth muscle that can tighten or relax to close off capillaries in response to local signals --> or maximize response when needed
29
metarterioles
= bypass divert blood flow if sphincters are closed they also allow larger materials (ex. WBCs) to bypass narrow capillaries and reach venous circulation
30
capillary density is related to....
your bodies' needs
31
single layer of flattened epithelial cells: movement of...
-diffusion of gases - osmosis (water) - movement of materials through larger pores
32
do proteins leak out of capillaries?
no
33
about ----L per day of fluid is filtered out of capillaries
3L/day -excess tissue fluid is picked up by lymphatic vessels and returned to venous system
34
lymph is dumped back in at the...
subclavian vein -but also checked by lymph nodes, spleen etc. first