Circulatory System

Question 1

Heart

Answer 1

Has 4 chambers

left/right atria and ventricles

Question 2

Atria

Answer 2

blood enters atria first

Question 3

Ventricle

Answer 3

blood pumped out of ventricles

Question 4

Left heart

Answer 4

systemic

Question 5

Right heart

Answer 5

lungs

Question 6

Systemic

Answer 6

oxygenated blood flows to rest of body

Question 7

Systole

Answer 7

contration phase (large blood pressure #)

Question 8

Diastole

Answer 8

relaxation phase (smaller blood pressure #)

Question 9

Sinoatrial (SA) node

Answer 9

pacemaker activity
no stimulus is required
located in right atria
initiates action potential and contraction for sequential contraction of chambers

Question 10

Atrioventricular (AV) node

Answer 10

delays the start of ventricular contraction for about 0.1sec

Question 11

Bundle of His and Purkinje fibers

Answer 11

transmit action potential to ventricle walls

Question 12

Cardiac action potentials

Answer 12

longer than skeletal muscle action potentials

use K+ and Ca2+ ion channels

Question 13

Coordinating contractions

Answer 13

cardiac muscle cells are connected by gap junctions. electrical continuity allows for rapid spread of an action potential. no gap junctions between atria and ventricles

Question 14

Electrocardiogram (ECG/EKG)

Answer 14

P= depolarization and contration of atria
Q,R and S = depolarization of ventricles
T = relaxation and repolarization of ventricles

Question 15

Sympathetic nerves

Answer 15

release (nor)epinephrine (aka adrenaline) to increase heart rate

Question 16

Parasympathetic nerves

Answer 16

release acetylcholine and decrease pacemaker activity to slow heart rate

Question 17

Norepinephrine

Answer 17

released from sympathetic nerves and increases the permeability of Na+ and Ca2+ channels to influence the resting potential of pacemaker cells
The resting potential rises more quickly and action potentials are closer together
smooth muscles contract, vessels constrict, increase in blood pressure, decrease blood flow (exception: skeletal muscle)

Question 18

Acetylcholine

Answer 18

released from parasympathetic nerves
increases the permeability of K+ and decreses the permeability of Ca2+ channels
the resting potential rises more slowly and action potentials are farther apart
relaxes smooth muscle, increases blood flow and decreases blood pressure

Question 19

5 types of vessels

Answer 19

arteries, arterioles, capillaries, venules, veins

Question 20

arteries

Answer 20

carry blood away from the heart

Question 21

arterioles

Answer 21

control distribution of blood to specific capillary beds, have precapillary sphincters

Question 22

capillaries

Answer 22

site of exchange between blood and interstitial fluid
have the most surface area
walls are one cell layer thick
permeable to O2, CO2, glucose, lactate and small ions
in brain, lack of pores in capillaries causes a blood-brain barrier (only lipid-soluble materials can cross)
have pores (except in brain) in the walls that make them leaky

Question 23

venules

Answer 23

return blood to veins

Question 24

veins

Answer 24

return blood to the heart, have valves to prevent backflow of blood
have a high capacity for storing blood due to the walls being very expandable
carry blood back to the heart with the help of skeletal muscle contrations and gravity

Question 25

Arteries and arterioles

Answer 25

have elastic fibers enabling them to withstand high pressures
also have smooth muscle cells allowing them to contract and expand to alter their resistance to aid blood flow

Question 26

Atherosclerosis

Answer 26

hardening of the arteries occurs when the arteries are blocked by plaque build up

Question 27

Precapillary sphincters

Answer 27

in arterioles
alter the diameter and resistance to blood flow
both local and systemic control

Question 28

Local regulation of blood pressure

Answer 28

metabolite and waste concentration affect flow to specific tissues

Question 29

Systemic regulation of blood pressure

Answer 29

responds to changes in central blood pressure and composition mediated by nervous system and hormonal signals

Question 30

Direction of movement b/w blood and interstitial fluid

Answer 30

fluid movement is controlled by balance between blood pressure and osmotic pressure
extra fluid is retuned to the blood by lymphatic system

Question 31

Identity of material movement b/w blood and interstitial fluid

Answer 31

depends of concentration gradients, permeability of capillary walls in specific tissue, availability of pores and endocytosis in some tissues
brain is more selective (blood-brain barrier)
digestive and excretory systems are much less selective

Question 32

Lymphatic vessels

Answer 32

return fluid to mahor vein returning to the heart

aided by skeletal muscle contrations and gravity

Question 33

Gas exchange at alveoli

Answer 33

efficient loading and unloading of gasses
blood moves rapidly through capillaries surrounding alveoli and maintains O2 and CO2 consentration gradients promoting diffusion

Question 34

Red blood cells

Answer 34

small and biconcave which contributes to a high surface area/volume ratio which aids diffusion
anaerobic metabolism, contain hemoglobin

Question 35

Hemoglobin

Answer 35

binds to O2 directly and cooperatively which increases O2 capacity of blood
at normal metabolism 25% of O2 released, 75% reserved
at low PO2, reserves released
O2 binding capacity decreases at low pH (high metabolic rate decreases pH and drives greater O2 release)
Fetal hemoglobin has higher O2 binding affinity (lives at low PO2)

Question 36

Sickle cell

Answer 36

hemoglobin is clumped in RBC, distort and damage RBCs and disrupt flow through capillaries

Question 37

RBC production

Answer 37

stimulated by low O2 content in tissues:

• Stem cells in bone marrow produce RBC
• RBC count increases
• if O2 supply in tissue is too low, HIF-1 is induced
• kidney produces erythropoietin which stimulates the stem cells to produce RBC

Question 38

Carbonic anhydrase

Answer 38

maintains CO2 concentration gradient from cells with high concentration to plasma with low concentration
some CO2 complexes with deoxygenated hemoglobin