Chapter 20: Circulation Flashcards
What are blood vessels?
Pipes or tubes that carry blood.
How many types of blood vessels are there?
5
What are the 5 types of blood vessels?
o Arteries
o Arterioles
o Capillaries
o Venules
o Veins
Arteries becomes smaller arteries called ____.
Arterioles
Arterioles lead on to ____.
Capillaries
Capillaries lead on to smaller and medium sized veins called ____.
Venules
Venules lead on to ____.
Veins
What are arteries?
Blood vessels that carry blood away from the heart.
What are veins?
Blood vessels that carry blood back to the heart.
What do capillaries connect?
The smallest arteries to the smallest veins.
Most arteries carry ____.
Oxygenated blood
There is 1 artery that does not carry oxygenated blood. What is it called?
Pulmonary artery
What kind of blood does the pulmonary artery carry?
Deoxygenated blood
Most veins carry ____.
Deoxygenated blood
There is 1 vein that does not carry deoxygenated blood. What is it called?
Pulmonary veins
What kind of blood does the pulmonary vein carry?
Oxygenated blood
What are arterioles?
Smaller arteries
What are arterioles typically called? Why?
Resistance vessels, because they are the ones that are restricting the flow of blood to the capillaries.
What does it mean that it is a closed circulatory system?
A pipe/tube will start at one place and come back again to the same place.
What are capillaries also called?
Exchange vessels
Why are capillaries called exchange vessels?
Because oxygen and nutrients are exchanged from the capillaries to the cells. Waste products and carbon dioxide are taken from the cells back into the capillaries.
What are the thinnest, smallest, and microscopic blood vessels?
Capillaries
What 3 layers make up the blood vessel wall?
Tunica interna, Tunica media, and tunica externa.
What is the innermost layer of the blood vessel wall?
Tunica interna
What is the middle layer of the blood vessel wall?
Tunica media
What is the outermost layer of the blood vessel wall?
Tunica externa
What is lumen of a blood vessel?
The central space through which blood flows.
Which layer of the blood vessel wall is closest to the blood?
Tunica interna
What type of epithelium is the tunica interna layer of a blood vessel made up of? What is it called?
Simple squamous epithelium. Endothelium
Which arteries are bigger? Elastic or muscular?
Elastic
What are the main elastic/conducting arteries?
Aorta, common carotid, subclavian, pulmonary trunk, and common iliac arteries.
What are the main muscular arteries?
Brachial, femoral, renal, and splenic arteries.
The autonomic nervous system controls the ____ muscle, _____ muscle, and the ____.
Smooth, cardiac, glands
Which autonomic NS controls smooth muscle?
Sympathetic NS
Blood flows to serve ____.
Tissue needs
What 3 factors help in circulation (flow of blood)?
Blood flow, blood pressure, and total peripheral resistance.
Blood flow = ____.
Cardiac output
What is blood flow?
The volume of blood flowing through the entire body in a given period of time.
What is blood flow measured in?
mL/min or L/min
What is blood pressure?
The force exerted by the blood on its vessel wall.
What artery is used to measure blood pressure? What tool is used?
Brachial artery, sphygmomanometer.
What is systolic pressure?
Peak arterial blood pressure taken during ventricular contraction (ventricular systole).
What is diastolic pressure?
Minimum arterial blood pressure taken during ventricular relaxation (diastole) between heart beats.
What is pulse pressure?
The difference between systolic and diastolic pressure.
How do you calculate pulse pressure?
Systolic pressure minus diastolic pressure
Does the heart spend more time in diastole or systole?
Diastole
Exchanges between the blood and surrounding tissues are made only through ____.
Capillary walls
What is venous return?
The flow of blood back to the heart.
When does blood flow?
Only when there is a pressure gradient.
F = ____.
Blood flow
F can also be equal to ____.
Cardiac output
Formula: BP =
(Triangle)Pr
(Triangle) =
Gradient
Pr =
Blood pressure
Greater the pressure, greater the ____.
Blood flow
What is total peripheral resistance (TPR)?
The combined obstruction of all arterioles of the body.
In total peripheral resistance (TPR), peripheral refers to ____?
The arterioles.
Peripheral means ____.
On the outskirt.
In total peripheral resistance (TPR), resistance refers to ____?
Obstruction or constriction.
Greater the obstruction, less the ____.
Blood flow.
What is the formula for blood pressure?
(Triangle)PR divided by TPR.
What is the formula for cardiac output?
MABP divided by TPR.
What does MABP stand for?
Mean arterial blood pressure.
What is the formula for MABP?
CO x TRP
The body maintains homeostasis by ____ and ____.
CO and TPR.
How do you calculate MABP?
o Measure systolic BP and diastolic BP
o Calculate pulse pressure (PP) = Systolic BP – Diastolic BP
o MABP = (Pulse Pressure divided by 3) + Diastolic BP
What is the range of MABP?
90-110 mm of Hg
What nervous system has control over all the blood vessels?
The sympathetic nervous system.
What nervous system has no effect over the blood vessels?
The parasympathetic nervous system.
What nervous system is activated when the MABP falls below 90 mm of HG?
The sympathetic nervous system.
What happens when the MABP falls below 90 mm of HG?
o The sympathetic nervous system is activated.
o It keeps the blood vessels slightly contracted all the time.
o It stimulates the kidneys to release renin.
What is vasomotor tone?
The degree to which blood vessels contract or relax.
What blood vessels are affected when the MABP falls below 90 mm of Hg?
Blood vessels of the skin, digestive tract, and urinary system.
What happens to the skin, digestive tract, and urinary system when the MABP falls below 90 mm of Hg?
o The skin is cold and clammy.
o No digestion.
o Decrease in urine output.
Why does MABP fall below 90 mm of Hg?
Because a loss of blood.
What happens to the kidneys when the MABP falls below 90 mm of Hg?
The kidneys are stimulated to release renin into the blood vessels.
What is renin?
An enzyme.
What happens when the kidneys are stimulated to release renin?
o The liver makes a plasma protein called angiotensinogen (inactive plasma protein).
o Renin acts on Angiotensinogen and converts it into Angiotensin1 (active).
o Angiotensin1 is converted in the lungs to angiotensin2 by an enzyme called angiotensin converting enzyme.
What 5 important factors does Angiotensin2 have?
o It is a potent vasoconstrictor.
o Stimulates thirst center.
o Directly stimulates kidneys to reabsorb sodium and water.
o Stimulates the adrenal gland (located on top of the kidneys) to release a hormone called aldoesterone.
o Stimulates the posterior pituitary to release Antidiuretics hormone to retain water.
What do the 5 factors of angiotensin2 help with?
They help with homeostasis.
What does the hormone aldosterone do?
It indirectly stimulates the kidneys to reabsorb sodium and water.
What does it mean that angiotensin2 is a potent vasoconstrictor?
It causes intense vasoconstriction of blood vessels of the skin, digestive tract, and urinary system.
How does angiotensin2 being a potent vasoconstrictor help in homeostasis?
It increases the TPR. When there is an increase in TPR, the MABP goes up.
What happens when angiotensin2 stimulates the thirst center?
It increases the blood volume, which then increases the cardiac output.
How does angiotensin2 stimulating the thirst center help in homeostasis?
It increases the cardiac output, which increases the MABP.
How does angiotensin2 directly stimulating the kidneys to reabsorb sodium and water help in homeostasis?
Reabsorption increases the blood volume, which increases cardiac output, and the MABP goes up.
How does angiotensin2 stimulating the adrenal gland to release aldoesterone help in homeostasis?
Mineralocorticoid increases the blood volume, which increases the cardiac output, and the MABP goes up.
Antidiuretic hormone is also called ____?
Vasopressin
How does angiotensin2 simulating the posterior pituitary to release antidiuretic hormone help in homeostasis?
Retaining water increases the blood volume, which increases the cardiac output, and the MABP goes up.
What type of feedback is the process the body goes through after the MABP falls below 90 mm of Hg?
Negative feedback
What part of your brainstem receives signals from sensory neurons when there are changes in blood pressure, carbon dioxide, pH, and oxygen?
The medulla oblongata.
What sensory neurons respond to changes in blood pressure?
Baroreceptors
What sensory neurons respond to changes in carbon dioxide, pH, and oxygen?
Chemoreceptors
What autonomic nervous system does the medulla oblongata influence?
The medulla oblongata influences whichever autonomic nervous system that needs to react based on the signals it receives.
Long term control of the MABP is by ____.
The kidneys
Short term control of the MABP is by ____.
TPR
What 3 factors is TPR influenced by?
Blood viscosity, the length of the blood vessels, and has an inverse relation (indirectly related) to fourth power of radius of blood vessels.
In terms of TPR: greater the viscosity, ____.
Greater the TPR.
In terms of TPR: greater the length of the blood vessels, ____.
Greater the TPR.
In terms of TPR: greater the radius, ____.
Greater the TPR.
Which of the 3 factors that influence TPR, has the greatest influence?
The radius
What autonomic nervous system controls the radius of the blood vessels?
The sympathetic NS.
Is TPR directly or indirectly related to blood viscosity?
Directly
Is TPR directly or indirectly related to blood vessel length?
Directly
Is TPR directly or indirectly related to the fourth power of the radius of blood vessels?
Indirectly
What is the ratio of TPR to blood viscosity?
1:1
What is the ratio of TPR to blood vessel length.
1:1
What is the ratio of TPR to the fourth power of the radius of blood vessels?
1:4
What is velocity?
Speed
The velocity of blood flow is inversely related to what?
The cross-sectional area of the blood vessel
What is the measurement of the cross-sectional area of the aorta?
2.5cm2
What is the velocity of blood flow in the aorta?
40-50 cm/sec
What is the cross-sectional area of the capillary?
4500cm2
What is the velocity of blood flow in a capillary?
0.03 cm/sec
What is the cross-sectional area of a vein?
8cm2
What is the velocity of blood flow in a vein?
10cm/sec
Does blood flow the fastest in the aorta, a capillary or a vein?
The aorta
Why does blood flow the fastest in the aorta?
Blood flows with gravity which is why it is the fastest.
Does blood flow the slowest in the aorta, a capillary or a vein?
A capillary
Why does blood flow the slowest in a capillary?
To not damage the capillary. They have thin walls.
Why does blood flow slower in the veins than the aorta?
Blood in the veins flows against gravity while blood in the aorta flows with gravity.
What are the 3 mechanisms of capillary exchange?
Diffusion, transcytosis, and bulk flow.
What is diffusion?
The movement of solutes from the capillaries to the cells.
What is transcytosis?
A vesicle-mediated transport.
What is bulk flow?
The movement of massive amounts of fluid and solutes from the capillaries to interstitial fluid to the cells, and vice versa.
What is bulk flow needed for?
To maintain the volume and composition of interstitial fluid.
Bulk flow includes what 2 functions?
Filtration and reabsorption
Where does the filtration function of bulk flow happen?
It happens at the arterial end of the capillary.
Why does the filtration function of bulk flow happen at the arterial end of the capillary?
Because of blood (hydrostatic) pressure. Blood (hydrostatic) pressure pushes out.
Where does the reabsorption function of bulk flow happen?
It happens at the venular end of the capillary.
Why does the reabsorption function of bulk flow happen at the venular end of the capillary?
Because of osmotic pressure. Osmotic pressure pulls in.
What is the BP of the capillary arterial end?
35 mm of Hg
What is the BP of the capillary venular end?
25 mm of Hg
What is the osmotic pressure of blood?
15 mm of Hg
Is angiotensinogen an active or inactive plasma protein?
Inactive plasma protein
Is angiotensin1 active or inactive?
Active
Where are chemoreceptors contained?
The carotid body and and aortic bodies
Where are baroreceptors contained?
In the carotid sinus
Elastic arteries are also called _____. Why?
Pressure reservoirs because they are able to withstand that much of a pressure gradient from the left ventricle when it contracts and relaxes.
Elastic arteries become smaller and become ____ arteries.
Muscular
Muscular arteries are also called _____ arteries. Why?
Distributing because they distribute blood to specific organs.
What is vasodilation?
The widening of a blood vessel.
How does vasodilation happen?
It occurs from relaxation of the smooth muscle, allowing blood pressure to expand the vessel.
What is vasoconstriction?
The narrowing of a blood vessel.
How does vasoconstriction happen?
It occurs when the smooth muscle of the tunica media contracts.
Why do arteries have so much more elastic than veins do?
Veins are subjected to less pressure than arteries so they have less need for elasticity.
Which arteries are bigger? Elastic or muscular arteries?
Elastic
Describe the role of arterioles in regulation of blood flow from the arteries into
the capillaries
The smooth muscle lining of arterioles allows them to actively change their diameter, either constricting to reduce blood flow or dilating to increase flow.
Describe the difference between filtration and reabsorption in a capillary.
Filtration is the movement of blood from the blood vessels into the surrounding tissues. Reabsorption is the movement of fluid from the tissues back into the blood vessel.
