21.4 Control of Blood Pressure and Blood Flow

Question 1

cardiovasular center

Answer 1

• part of the medulla oblongata which helps regulate heart rate, stroke volume, and neural, hormonal, and local negative feedback systems to regulate blood pressure and blood flow to various tissues
• receives input from higher brain regions and sensory receptors, primarily proprioceptors, baroreceptors, and chemoreceptors
• output flows along sympathetic and parasympathetic neurons of the ANS

Question 2

proprioceptors

Answer 2

• sensory receptors which monitor movements of joints and muscles
• the signals from these during periods of movement is what accounts for increased heart rate during excercise

Question 3

baroreceptors

Answer 3

• sensory receptors which monitor changes in pressure and the stretch of walls in blood vessels
• are inputs to the CV center
• located in the aorta, internal carotid arteries, and other large arteries in the neck and chest

Question 4

chemoreceptors

Answer 4

• sensory receptors which monitor the concentration of various chemicals in the blood
• are inputs to the CV center
• located near barorecptors of the carotid sinus and arch of the aorta
• detect hypoxia (low O2), acidosis (high H+) and hypercapnia (high CO2) to increase sympathetic stimulation in arterioles and veins, increasing blood pressure

Question 5

cardiac accelerator nerves

Answer 5

• output of the CV center which are responsible for changing heart rate
• sympathetic activity on these causes increased HR

Question 6

vagus (x) nerves

Answer 6

• output of the CV center which is responsible for changing heart rate
• parasympathetic activity on these cause decrease in HR

Question 7

vasomotor nerves

Answer 7

-nerves which are outputs of the CV responsible for controlling the contraction of smooth muscle in blood vessel walls

Question 8

vasomotor tone

Answer 8

-the state of moderate vasoconstriction in blood vessels which sets the resting level of systemic vascular resistance

Question 9

carotid sinus reflex

Answer 9

• baroreceptor reflex which helps regulate blood pressure in the brain by monitoring the pressure in small widenings in the left and right carotid arteries
• signals are carried to the brain by the glossopharyngeal (IX) nerves

Question 10

carotid sinuses

Answer 10

-small widenings of the right and left internal carotid arteries just above the point where they branch from the common carotid arteries

Question 11

aortic reflex

Answer 11

• baroreceptor reflex which regulates systemic blood pressure by measuring pressure in the aorta
• these signals are carried to the brain via the vagus (X) nerves

Question 12

carotid bodies

Answer 12

-small structures full of chemoreceptors located next to the baroreceptors of the carotid arteries

Question 13

aortic bodies

Answer 13

-small structures full of chemoreceptors located next to the baroreceptors of the aortic arch

Question 14

renin-angiotensin-aldosterone system

Answer 14

-the process by which decreased blood volume in the kidneys leads to a production of renin, which gets converted into angiotensin II (a potent vasoconstrictor) and aldosterone (which promotes water reabsorption in kidneys), raising blood pressure

Question 15

epinephrine and norepinephrine

Answer 15

• two hormones secreted by the adrenal medulla in response to sympathetic stimulation
• increase cardiac output by increasing the rate and force of heart contraction
• also cause vasoconstriction in skin and abdominal organs, and vasodilation in cardiac and skeletal muscle, increasing blood flow to muscle during exercise

Question 16

antidiuretic hormone (ADH)

Answer 16

• hormone produced by the hypothalamus and released from the posterior pituitary in response to dehydration or decreased blood volume
• promotes movement of water from kidney tubules into the bloodstream, causing an increase in blood volume and decrease in urine output

Question 17

atrial natriuretic peptide (ANP)

Answer 17

• hormone released by cells in the atria of the heart

- lowers blood pressure by causing vasodilation and promoting loss of salt and water in urine, reducing blood volume

Question 18

autoregulation

Answer 18

• the ability of a tissue to automatically adjust its blood flow to match its metabolic demands
• examples would be increased blood flow in the heart and skeletal muscle during activity and altered blood flow to parts of the brain during different mental and physical activities

Question 19

physical changes

Answer 19

• one of the two types of stimuli to cause autoregulatory changes to blood flow
• examples are warming causing vasodilation and vasoconstriction, and the myogenic response of arteriole walls

Question 20

myogenic response

Answer 20

-the tendency of arterioles to contract more forcefully when stretched and relax when stretching lessens

Question 21

vasodilating and vasoconstricting chemicals

Answer 21

• one of the two types of stimuli to cause autoregulatory changes to blood flow
• chemicals which cause an increase or decrease in blood vessel diameter, such as by blood cells, platelets, smooth muscle fibers, macrophages, and endothelial cells