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A&P 2 Test 2 Circulatory > Venous Return/BP Regulation > Flashcards

Venous Return/BP Regulation Flashcards

1
Q

Define venous return

A

the volume of blood flowing back to the heart via the systemic veins

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2
Q

What causes venous return

A
  • The pressure from the L ventricle
  • Extravascular pressure (skeletal muscle and respiratory pump)
  • Venous valves
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3
Q

True or False the pressure difference between from the venules to the R atria is vey small

A

True, ~0.1 mm Hg, despite being small it is enough to get blood back to the heart

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4
Q

What happens to venous return when R atria pressure is increased, why does this happen, and give an example

A

Venous return reduces when R atrial pressure is increased d/t back pressure

ex Tricuspid valve regurgitation

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5
Q

Describe the skeletal pump mechanism

A

When muscles contract it pushes through the proximal venous valve (milking) and distal valve closes because blood pushes the valve closed

During relaxation the proximal valve closes because of back flow and the distal valve opens because of BP to allow blood to move forward

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6
Q

Describe the respiratory pump mechanism

A

During inhalation= diaphragm moves downward causing thorax pressure to decrease but abd pressure to increase, resulting in blood being pushed to the thorax cavity/towards the heart

During exhalation= diaphragm moves upward causing thorax pressure to increase and abd pressure to decrease, resulting in thoracic valves closing preventing backflow into the abd

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7
Q

What is BP determined by

A
  1. cardiac output
  2. vascular resistance
  3. blood volume
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8
Q

True False BP stays the same throughout at parts of the circulatory system

A

False, BP progressively decreases the further you get away from the L ventricle

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9
Q

What ways can the body adjust BP

A

By negative feed back systems that change HR, SV, systemic vascular resistance, or blood volume

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10
Q

Where is the cardiovascular center located

A

The medulla oblongata

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11
Q

What does the cardiovascular center control

A

neural and hormonal systems that regulate HR, contractility, and blood vessel diameter

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12
Q

What is the function of the cardio-stimulatory center in the CV center

A

neurons that stimulate the heart, cardiac accelerator nerves arise from here

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13
Q

What is the function of the cardio-inhibitory center in the CV center

A

neurons that inhibit the heart, cardiac vagus nerves arise from here

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14
Q

What is the function of the vasomotor center in the CV center

A

controls vaso dilation and vasoconstriction

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15
Q

How does the higher brain centers of the cerebral cortex and limbic system affect HR

A

Think before starting a race your HR increases

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16
Q

How does the sympathetic nerves of the autonomic system affect cardiovascular system

A

Increase HR, contractility, and controls diameter of arteries/arterioles

-Continually sends impulses to the arteries/arterioles to create vascular tone. A reduction in these impulses reduces vascular tone

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17
Q

How does the parasympathetic nerves of the autonomic system affect cardiovascular system

A

Decreases HR and contractility

-remember no parasympathetic control in systemic vasculature

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18
Q

What is the role of baroreceptors in regulating BP

A

pressure (stretch) sensitive sensory receptors that sense BP for feedback to the CV center

19
Q

Where are BP baroreceptors located

A

aorta, internal carotid arteries, and other large vessels of the neck and chest.

20
Q

What are the 2 most important baroreceptor reflexes

A
  1. Carotid sinus reflex

2. Aortic reflex

21
Q

What is the function of the carotid sinus reflex

A

Helps regulates BP in the brain

22
Q

Describe the path a nerve impulse travels from the carotid sinus to the CV center

A

Nerve impulses propagate from the carotid sinus baroreceptors over the glossopharyngeal nerve (cranial nerve IX) then to the CV center

23
Q

Where is carotid sinus located

A

In-between where the R and L internal carotid arties branch from the R and L common carotids

24
Q

What is the function of the aortic reflex

A

helps regulates systemic BP

25
Q

Describe the path a nerve impulse travels from the aorta to the CV center

A

Nerve impulses propagate from the aorta baroreceptors over the vagal nerve (cranial nerve X) then to the CV center

26
Q

Where is aortic baroreceptors located

A

the ascending arch of the aorta

27
Q

At the baroreceptors what happens when there is a drop in BP

A
  • Baroreceptors stretch less, which causes nerve impulses to be sent slower to the CV center
  • The CV center decreases parasympathetic stimulation and increases sympathetic stimulation
  • This causes the heart to beat faster and w/ more force (contractility) increasing cardiac output
  • Vascular diameter also decreases (increased sympathetic) which increases vascular resistance

All this increases BP

28
Q

At the baroreceptors what happens when there is an increase in BP

A
  • Baroreceptors stretch more, which causes nerve impulses to be sent faster to the CV center
  • The CV center increases parasympathetic stimulation and decreases sympathetic stimulation
  • This causes the heart to beat slower and w/ less force (contractility) decreasing cardiac output
  • Vascular diameter also increases (decreased sympathetic) which decreases vascular resistance

All this decreases BP

29
Q

How does a carotid sinus message help correct tachycardia (SVT)

A

It puts pressure on carotid sinus which think its higher BP which causes CV center to increase parasympathetic stimulation of the heart

30
Q

What is carotid sinus syncope

A

Any hyperextension of the head, tight collars, or carrying a heavy load on shoulder causes pressure on carotid sinus and causes bradycardia.

31
Q

What 2 important chemoreceptor bodies and where are they located

A
  1. carotid bodies
  2. aortic bodies

both found very close to baroreceptors

32
Q

What stimulates chemoreceptors

A
  1. Hypoxia
  2. Acidosis
  3. Hypercapnia

once stimulated this causes vasoconstriction

33
Q

How does the Renin-Angiotensin-Aldosterone (RAA) get activated and how does it affect BP

A
  • Activates when BP at kidneys is low

- It causes water to be retained

34
Q

How does epinephrine/norepinephrine affect BP

A
  • Both increase cardiac output by increase HR and contractility
  • causes vasoconstriction of arterioles of skin and abd organs
  • causes vasodilatation of arterioles of cardiac and skeletal muscle
35
Q

How does the Antidiuretic Hormone (ADH) get activated and how does it affect BP

A

-Released from hypothalamus in response to decreased blood pressure

Increases BP by causing vasoconstriction of arterioles and promoting water retention at the kidneys

36
Q

How does the Atrial Naturetic Peptide/Hormone (ANP/ANHH) get activated and how does it affect BP

A

Caused by atrial stretching

Reduces BP by causing vasodilation and promoting loss of salt and thus water in the urine

37
Q

How does the Erythropoietin (EPO) get activated and how does it affect BP

A

Caused by reduced O2/blood flow to kidneys

Increases RBC production and acts as a vasoconstrictor

38
Q

What is the autoregulation of blood pressure

A

The ability of tissue to automatically adjust its blood flow to match metabolic demands

39
Q

What are the 2 different stimuli that cause autoregulation of blood pressure

A
  1. Physical changes

2. Vasodilation and vasoconstricting chemicals

40
Q

Give examples of physical changes that can cause autoregulation of blood pressure

A

Temp: cold=vasoconstrict, hot=vasodilation

Myogenic stretch: when stretched more smooth muscle of arterioles contract more forcefully

41
Q

Give examples of vasodilation and vasoconstricting chemicals that can cause autoregulation of blood pressure

A

Vasodilating: K, H, lactic acid, NO, adenosine, histamines, kinins

Vasoconstricting: Thromboxane A2, serotonin, endothelins

42
Q

In response to low O2 how does the local systemic vessels react

A

vasodilate to allow more blood in

43
Q

In response to low O2 how does the local pulmonary vessels react

A

vasoconstrict to bypass poorly functioning areas

A&P 2 Test 2 Circulatory (8 decks)

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