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BIOL 432 > Blood pressure > Flashcards

Blood pressure Flashcards

1
Q

What is another name for blood pressure? What is blood pressure?

A

hydrostatic pressure - the force blood exerts against vessel walls

BP = Cardiac Output x Peripheral vascular resistance

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2
Q

What relationship does blood velocity and cross sectional area have?

A

inverse

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3
Q

Describe systolic and diastolic blood pressure. What is mean arterial pressure, and how do you calculate it?

A

systolic - highest pressure in arteries, closest to aorta

diastolic - heart is at rest

MAP = diastolic + pulse pressure/3

pulse pressure= systolic - diastolic

MAP is closer to diastolic

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4
Q

What is cardiac output? What affects it?

A

volume of blood pumped out of one ventricle over one minute
- greater the cardiac output = greater the force pushing on vessel walls

affected by:
- heart rate
- stroke volume: volume of blood per stoke

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5
Q

How is heart rate affected by the following:
parasympathetic
sympathetic

A
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6
Q

How is heart rate affected by the following:
parasympathetic
sympathetic
thyroid hormone
estrogen
cortisol
hyperalkemia

A

parasympathetic - ACH from vegas decreases cAMP - lowers HR
sympathetic - NE/EPI increases cAMP - increases HR
thyroid hormone - increase HR
estrogen - decreases heart rate - inhibitory effect on vg Ca
cortisol - increases
hyperalkemia - decreases

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7
Q

How does blood viscosity, vessel length and radius affect peripheral resistance?

A

blood viscosity - thicker the blood, the higher the BP

length of the vessel - higher the BP
- greater the force of the heart is needed to pump
- adipose tissue has more vessels = obese people have higher peripheral resistance

larger the radius - lower the peripheral resistance
- factor of 4

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8
Q

what are the three vasoconstrictors?

A

norepinephrine
angiotensin II
vasopressin

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9
Q

What is hematocrit?

A

% cell volume/plasma volume
higher RBC # = higher viscosity

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10
Q

What affects the viscosity of blood?

A

Increases viscosity
- diuretics - loss of fluid
- atrial natruietic hormone - loss of urine
- dehydration
- blood doping - increases RBC
- erythropoietin - Increase RBC
- high altitude

decreases viscosity
- ADH/aldosterone - increase fluid
- anemias - decrease cell count

plasma proteins, chemical composition (CO2, O2, H+), temp, drugs

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11
Q

What is the main coordinating center for blood pressure in the brain? Where are the reflex controls of blood pressure?

A

medulla oblongata

baroreceptors in the aortic arch
chemoreceptors in the carotid sinus
atrial receptors in wall of R atrium

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12
Q

Describe how the barometer reflexes work

A

minute to minute basis
increased in MAP is sensed by baroreceptors
- increase in PS activity: decreases HR
- decrease in Sympathetic activity: decrease HR, decreases stroke volume, decreases peripheral resistance

all decrease MAP

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13
Q

How do hormones regulate blood volume?

A

ADH from posterior pituitary - increases H2O reabsorption in kidneys
- vasoconstriction
- increases volume, venous return, end-diastolic volume, stroke volume, cardiac output, blood pressure

Aldosterone - from adrenal glands
- increase Na absorption in kidneys - along with H2O
- increases everything - BP

Atrial naturietic peptide - decreases Na reabsorption from kidneys
- opposite of aldosterone
- released when there is too much blood in R atrium - too much stretching
- responds by releasing ANP
- diuretic - increased peeing

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14
Q

What are the vasoconstrictors?

A

NE - binds to a1 receptors - activate IP3 - Ca release - smooth muscle contraction
angiotensin II
ADH
dopamine
endothelin

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15
Q

What are the vasodilators?

A

Epi - binds B2 receptors - activated cAMP system - dephosphylation of myosin - smooth muscle relaxation
nitrous oxide
CO2

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16
Q

Describe the baroreceptor reflex

A

operate minute to minute
located in aortic arch and carotid sinus

increased BP stretches walls - baroreceptors release NTs to neurons in vessel walls
- APs conducted by vagus and glossopharyngeal nerves to medulla
- medulla tells PS to decrease HR, inhibits sympathetic from increasing HR/contractility
- vasomotor center decreases sympathetic innervation - vasodilation

17
Q

Describe the chemoreceptor reflexes for blood pressure

A

responds to decrease in O2 tension/increased CO2/H+ concentrations
chemoreceptors in aortic arch and carotid sinuses

changes in chemicals may increase/decrease release of NTs which determines rate of AP formation of glossophayngeal and vagus nerves

medulla responds to decreased O2, increased CO2/H
- causes decreased PS response, increase sympathetic
- increased HR, stroke volume, increased vasoconstriction

18
Q

How does the adrenal medullary mechanism affect blood pressure?

A

activated by large decreases in blood pressure: sudden, substantial increase in physical activity/stress

adrenal medulla releases epi resulting in increased HR, stroke volume, vasoconstriction of blood vessels in skin and viscera
- short, rapid acting

19
Q

How does the renin-angiotensin-aldosterone mechanism regulate blood pressure?

A

in response to low pressure - kidneys release renin
renin activates angiotensinogin in blood - produces angiotensin I

angiotensin I goes into the ling and activated by enzyme to angiotensin II (active): causes vasoconstriction of arterioles and slightly in veins
- increases peripheral resistance and venous return

angiotensin II also:
stimulates release of aldosterone by adrenal cortex - increase Na and water reabsorption
stimulates ADH secretion which stimulates H2O reabsorption and vasoconstriction

20
Q

How does atrial natriuretic hormone regulate blood pressure?

A

released by atrial cells due to increased venous return - stretches atrial muscle site
- ANH binds to receptors in the kidneys to increase Na loss in urine
- dilates arteries and veins - decreasing in blood volume, venous return and blood pressure

21
Q

Describe hypovolemic shock.

A

shock due to low blood volume that results in decreased cardiac output
caused by hemorrhage, dehydration, trauma

22
Q

Describe vasogenic shock

A

release of toxic substances resulting in vasodilation
- neurogenic - nerves decrease sympathetic NT release
- anaphylactic - release of histamine from basophils and mast cells
- septicemia - material toxins

23
Q

Describe cardiogenic shock

A

decreased pumping ability of the heart
- myocardial infarct
- cardiac arrhythmias
- congestive heart failure

24
Q

describe obstructive shock

A

external pressure on the heart decreases cardiac filling/outpuf
- pericardial cardiac tamponade
- pulmonary embolism

25
Q

What are the stages of circulatory shock?

A
  1. Non-progressing (compensatory)
    - rapid compensation - baroreceptor, chemoreceptor reflexes
    - intermediate compensation - renin-angtiotensin and fluid shift mechanism
    - long term - restoration of fluid/RBC numbers
  2. Progressive - compensatory mechanisms are unable to stop progression
  3. Irreversible shock and death

BIOL 432 (25 decks)

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