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BIOL 204 > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

Peripheral Resistance
-_________________ markedly affects blood velocity
-most ____________ influence on blood flow
-only significant way of controlling resistance

A
  • Vessel radius
    -powerful
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2
Q
  • ____________ flow: blood flows in ________, faster in the __________
  • blood flow (F) is proportional to the _______ power of radius (r)= ____________
  • small changes in blood vessel radius can cause ________ changes in flow (mL/min)
  • Decrease radius by a factor of 2, ___________ resistance and ____________ flow by ___x
  • R= _________
A
  • Laminar; layers; center
  • fourth; F ∝ R^4
  • LARGE
  • increase; decrease; 16
  • R=1/(r)^4
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3
Q

Vasoreflexes: changes in _______ _______
1. ______________: smooth muscle of tunic media contracts
2. ______________: brought by muscular passivity (no sympathetic input); smooth muscle relaxes; blood pressure expands vessel

A

vessel radius
1. vasoconstriction
2. vasodilation

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4
Q

______________: collective term for both vasoconstriction and vasodilation
- controlled in part by ______________ center in ______________

A

Vasomotion
- vasomotor; medulla oblongata

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5
Q

From aorta to capillaries, blood velocity (speed) ________________ for three reasons
1.
2.
3.

A

decreases
1. As blood traveled encountered friction against vessel walls
2. Smaller radii of arterioles and capillaries
3. Farther from heart–> number of vessels and their total cross-section area becomes greater and greater

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6
Q

From capillaries to vena cava, velocity ___________
- since veins are larger, they create ________ resistance than capillaries
- Large amount of blood forced into smaller channels
- blood in veins _______ regains velocity it had in large arteries
-veins are further from the pumping heart
-veins are more _________ than arteries

A

increases
- less
- NEVER
- compliant (they stretch more)

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7
Q

Blood vessels where more vasoconstriction/dilation occurs= _______________

A

Arterioles

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8
Q

Arterioles are most ____________ point of control over peripheral resistance and flow:
- On proximal side of capillary beds and best positioned to regulate _______ into capillaries
- _____________ any other type of artery, providing the most numerous control points
- more __________ in proportion to their diameter
- highly capable of changing radius

  • arterioles produce ______ of the total peripheral resistance
A

significant
- flow
- outnumber
- muscular
- half

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9
Q

Regulation of Blood Pressure and Flow
- ______________ is a quick and powerful way of altering blood pressure and flow
- Three ways of controlling vasomotor activity
1.
2.
3.

A
  • vasomotion
    1. Local control
    2. Neural control
    3. Hormonal control
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10
Q

Local Control
- _______________: ability of tissues to regulate their own blood supply
- ____________ response (arterioles): __________ blood flow–> ______ stretch– >arteriole ______–> ________—> blood flow _________

A
  • Autoregulation
  • Myogenic; decrease; decrease; relaxes; dilation; increases
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11
Q

Metabolic theory of auto regulation: if tissue is inadequately ________, wastes _________, stimulating ______________ which increases __________–> _________ in local BP
- Bloodstream delivers oxygen and removes metabolites
- When wastes are removed, vessels __________
- important for heart and skeletal muscle where demand for oxygen and nutrients can ________ _____-fold during physical activity

A

perfused; accumulate; vasodilation; perfusion; decrease
- constrict
- increase; 10

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12
Q

Local Control:
- ____________ ___________: substances secreted by platelets, endothelial cells, and perivascular tissue to stimulate vasomotor responses
-vasodilators include __________,___________,______________

A
  • vasoactive chemicals
    • histamine; bradykinin; prostaglandins
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13
Q

Local Control:
Shear stress
- drag of blood flowing against the endothelial cells (like rubbing your palms together)
-stimulates endothelial cells to secrete ___________= ___________ and ____________

  • ________________ chemicals in response to blood vessel trauma
    -___________ ____________, ___________________, and ______________
A
  • vasodilators= prostacyclin; nitric oxide
  • vasoconstriction
    -superoxide radicals; thromboxane A2; serotonin
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14
Q

Local Control:
- __________ _______________: if blood supply is cut off then restored, flow increases above normal
- ___________________: growth of new blood vessels
-occurs in regrowth of ________ lining, around _____________ artery obstructions, in __________ muscle, and ___________ ________
-controlled by several growth factors and inhibitors

  • the result of these both= ___________ perfusion
A
  • reactive hyperemia
  • angiogenesis
    -uterine; coronary; exercised; malignant tumors
  • increased
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15
Q

Neural Control
- the central and autonomic nervous systems also exert control over blood vessel size
- Vasomotor center of medulla exerts ____________ control over blood vessels throughout the body
-stimulates most vessels to _________, but _________ vessels in __________ muscle to meet demands of ___________
- Vasomotor center is the integrating center for three autonomic reflexes
1.
2.
3.

A
  • sympathetic
    -constrict; dilate; cardiac; exercise
  1. Baroreflexes
  2. Chemoreflexes
  3. Medullary ischemic reflex
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16
Q

Neural Control
Baroreflex:
- automatic, _________ feedback response to change in ________ __________
- govern _____-_______ regulation of BP
-adjustments for rapid changes in ________
-not helpful in correcting ______ hypertension
-after 2 days or less, they adjust their set point

  • this reflex usually responds to _______ BP to cause vasodilation (________ BP), but can also do the opposite–> respond to drop in BP when ___________ _______
  • in the ________ the reflex can be sluggish, causing dizziness when they stand up too quickly
A
  • negative; blood pressure
  • short-term
    -posture
    -chronic
  • increased; decrease; standing up
  • elderly
17
Q

Neural Control
- Chemoreflex: primary role is to adjust respiration to changes in blood chemistry (O2, CO2, pH)
-_____________, ______________, and _________ stimulate chemoreceptors
- secondary role is vasomotion
-act through vasomotor center to cause widespread _______________
-____________ BP and lung perfusion= ___________ gas exchange–> bring in more O2, increase CO2 exhalation
- chemoreceptors also stimulate ______________ so that increased blood flow matches increased perfusion

A
  • hypoxemia; hypercapnia; acidosis
  • vasoconstriction
  • increase= increased
  • breathing
18
Q

Neural Control
- Medullary ischemic reflex: automatic response to a __________ in ___________ of the _________
- Medulla oblongata monitors its own blood supply
- cardiac and vasomotor centers sends __________ signals to heat and blood vessels
-____________ heart rate and contraction force
-causes widespread _______________
-_________ BP and restores normal perfusion to the brain

  • Other brain centers can affect vasomotor center
    -__________,__________,____________ can increase BP
A
  • drop; perfusion; brain
  • sympathetic
    -increase
    -vasoconstriction
    -increases
  • stress; anger; arousal
19
Q

Hormonal Control
- Hormones can influence blood pressure
-via ____________ effects
-via regulating _______ balance
- ________ pathway: _______-__________-__________
-________ blood pressure
-_______ vasoconstrictor

A

-vasoactive
-water
- RAA: Renin- Angiotensin II- Aldosterone
-increases
-potent

20
Q

Renin-Angiotensin-Aldosterone Mechanism
1. _________ blood pressure or volume
2. _________ release _______ in response
3. ________________:
-______________
- stimulates __________
-stimulate adrenal cortex to release ___________
4. ________________:
- ________ absorption
- ________ absorption

  • Result: ___________ BP
A
  1. decreased
  2. kidneys; renin
  3. Angiotensin II
    -vasoconstriction
    -thirst
    -aldosterone
  4. Aldosterone
    -Na+
    -H2O
    - increased
21
Q

_________ ______________ ____________: vasodilation, lowers BP
- secreted by the cells in the _______ of the heart in response to _________ of the atria
- lower BP by:
-increase _______ excretion by the kidneys
-reduces blood __________
- _______ follows in urine

A

Atrial Natriuretic Peptide (ANP)
- atria; stretching
- Na+
- volume
- water

22
Q

_______________: produced by hypothalamus & released by posterior pituitary gland
- promotes water retention and _______ BP (urinary system)
- At pathologically high concentrations, it also acts as a __________________
- aka ________________
- action is inhibited by what college pastime (__________)

A

Antidiuretic hormone
- raises
- vasoconstrictor
- vasopressin
- drunk–> you pee more

23
Q

_______________ and ______________ (ANS & endocrine)
- _____________ blood pressure
- adrenal and sympathetic catecholamines
- in most blood vessels:
-bind to ____-__________ receptors on smooth muscle
-cause _______________

A

Epinephrine; norepinephrine
- increase
- alpha-adrenergic
- vasoconstriction

24
Q

Two Purposes of Vasomotion
- Method of rerouting blood from one region to another for ____________ of individual organs
-either _________ or ___________ controlled
-during exercise, sympathetic system reduces blood flow to __________ and _________ ______ and increased blood flow to ___________ __________
-_____________ ____________ in a tissue affects local circulation without affecting circulation elsewhere in the body
- if a specific artery contracts, the pressure downstream ___________, pressure upstream _______

A
  • perfusion
    -centrally; locally
    -kidneys; digestive tract; skeletal muscles
    -metabolite accumulation
  • drops; rises
25
Q

Redirection of Blood Flow in Response to Changing Metabolic Needs
- Resting (dozing in armchair after big meal)
-vasoconstriction in lower limbs ______ BP above the limbs, redirecting blood to ____________ arteries
- SLUDD (parasympathetic)–> ____________,___________,____________,__________,________________

A

-raises; intestinal
- Salivation, Lacrimation, Urination, Digestion, Defecation

26
Q

Redirection of Blood Flow in Response to Changing Metabolic Needs
- Exercise
- vigorous exercise ________ arteries in lungs, heat, and muscles
- ________________ occurs in kidneys and digestive tract
- E’s of Sympathetic activity:

A
  • dilates
  • vasoconstriction
  • Exercise, Excitement, Emergency, Embarrassment
27
Q

Capillaries are ___________ vessels
- where _________, _________,_________, and __________ pass between the blood and tissue fluid
-the “__________ _____” of the cardiovascular system
- Structure/Function: composed of ___________ and ________ ________

Three capillary types distinguished by permeability
1.
2.
3.

A

exchange
- gasses; nutrients; wastes; hormones
- “business end”
- endothelium; basal lamina

  1. Continuous capillaries
  2. Fenestrated capillaries
  3. Sinusoids
28
Q

Capillary exchange: ____-____ movement of _____ across capillary walls
- transport of ______, oxygen, ________, AAs, _______, minerals, _________, hormones, wastes, CO2, ___________

A

two-way; fluid
- water; glucose; lipids, antibodies; ammonia

29
Q

3 Routes of Fluid Exchange Across the Capillary Wall:
1.
2.
3.

A
  1. Filtration & Reabsorption (bulk flow)
  2. Transcytosis (vesicular transport)
  3. Diffusion
30
Q

Filtration and Reabsorption
- fluid filters out of the _______ end of capillary and ____________ reenters ________ end; delivers materials to the cell & removes metabolic waste

A
  • arterial; osmotically; venous
31
Q

Transcytosis
- ________- mediated, __________ or __________- mediated endocytosis; ferried across cell then exocytosis; _______ mechanism but important for ______________

A
  • vesicle; pinocytosis; receptor; minor; hormones
32
Q

Diffusion
- _______ ___________ form of capillary exchange
- ________, _______ blood to tissue/ _______ & waste tissue to blood

A
  • most IMPORTANT
  • glucose; O2/ CO2
33
Q

Forces of Capillary Filtration and Reabsorption:
- ______________: the force exerted by a fluid on the wall of a vessel (tends to drive fluid out of blood)
- _____________: the osmotic force created by the concentration gradient of proteins across the capillary wall (tends to drive fluid back into blood)
- net filtration pressure ____ net absorption pressure

A
  • hydrostatic pressure
  • colloid osmotic pressure
  • > (13 mmHg > 7 mmHg)
34
Q

Venous Return:
The flow of blood back to the heart relies on:
- __________ _________
- _____________
- __________ ________ __________
- _____________ ___________
- ____________ ___________

A
  • pressure gradient
  • gravity
  • skeletal muscle pump
  • thoracic pump
  • cardiac suction
35
Q

Pressure gradient
- ________ ____________ is the most important force of venous return
- ___ to _____ mmHg venous pressure gradient toward heart
- venues (____ to _____ mmHg) to central venous pressure: point where the vena cavae enter the heart (~5 mmHg)

Gravity
- drains blood from _____ and ______

Skeletal muscle pump
- contracting limb muscles _________ blood out of compressed part of vein
- _______ keep blood moving toward heart

A
  • blood pressure
  • 7 to 13 mmHg
  • 12 to 18 mmHg
  • head; neck
  • squeezes
  • valves
36
Q

Thoracic (respiratory pump)
- ___________ expands thoracic cavity
-thoracic pressure on the inferior vena cava ___________
-abdominal pressure on the inferior vena cava __________
-blood is forced upward toward heart

  • blood flows faster with _________
  • Central venous pressure
    -direct measurement of BP in the right atrium and vena cava
    -fluctuates during respiration due to thoracic pump
    -inhalation:
    -exhalation:
A
  • inhalation
    -decreases
    -increases
  • inhalation
    -2 mmHg
    -6 mmHg

BIOL 204 (28 decks)

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