Circulatory System

Question 1

“Pumping phase.” Both ventricles contract, pushing blood out through the aortic and pulmonary valves.
Tricuspid and mitral valves are closed.
This is the phase of highest arterial blood pressure.

Answer 1

Systole

Question 1

Circulatory pathway

Answer 1

Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta → systemic circulation (arteries → veins)

Remember: right heart → pulmonary circulation & left heart → systemic circulation
Mnemonic for order of valves: Toilet Paper My A**

Question 2

“Filling phase.” Ventricles relax, allowing filling from the atria.
Pulmonary and aortic valves are closed.
This is the phase of lowest arterial blood pressure.

Answer 2

Distole

Question 3

Deoxygenated vs oxygenated blood

Answer 3

Question 4

Blood pressure regulation

Answer 4

Low blood pressure leads to activation of the renin-angiotensin-aldosterone hormone system which works by increasing sodium re-absorption.
High blood pressure leads to secretion of ANP (atrial natriuretic peptide)

Question 5

Blood osmolarity regulation

Answer 5

High blood osmolarity leads to increased release of ADH leading to increased water resorption.

Question 6

Thermoregulation

Vasodilation vs Vasoconstriction

Answer 6

Vasodilation (increasing blood flow) occurs in the arterioles to cool the body down.
Vasoconstriction (decreasing blood flow) occurs to conserve heat.

Question 7

Cardiac output equation

Answer 7

Cardiac output = Stroke volume x Heart rate

Question 8

Blood pressure equation

Answer 8

Blood pressure = Q x R = (cardiac output) x (resistance)
Example: if there is vasoconstriction, then resistance increases, therefore blood pressure increases.

Question 9

Protein found in RBCs that carries oxygen, bound to the heme group which contains iron.

Answer 9

Hemoglobin

Question 10

Hemoglobin’s oxygen affinity displays – of binding with a – binding curve.

Answer 10

positive cooperativity, sigmoidal

Question 11

Bohr shift of hemoglobin

Answer 11

Refers to the decrease in oxygen binding affinity due to a rightward shift of the binding curve, under conditions of high CO2 or high H+.

Question 12

Hemoglobin versus myoglobin

Answer 12

Myoglobin is found in muscle cells.
It has a hyperbolic-shaped binding curve, with overall higher oxygen binding affinity compared to hemoglobin.

Question 13

2,3-bisphosphoglycerate (2,3-BPG)

Answer 13

2,3-BPG is a molecule that affects heme-oxygen binding affinity.
Increased 2,3-BPG causes heme to release O2, decreasing binding affinity and shifting the curve rightward
Myoglobin only has one subunit and therefore is not affected by 2,3-BPG.

Question 14

arteries vs veins

Answer 14

Question 15

Oxygenation of umbilical veins vs umbilical arteries

Answer 15

Umbilical veins carry oxygenated blood
Umbilical arteries carry dexoygenated blood.

Question 16

Fetal hemoglobin

Answer 16

Compared to adult hemoglobin, fetal hemoglobin has higher binding affinity for oxygen due to having only one subunit.
Higher binding affinity lets fetal Hb “take” oxygen away from the mother’s blood.

Question 17

Three major shunts, two that allow blood to skip the lungs of a fetus and one that skips the liver

Answer 17

Foramen ovale: from right atrium to left atrium.

Ductus arteriosus: from pulmonary artery to aorta, skipping the lungs.

Ductus venosus: skips the liver.

Question 18

Sequence of conduction

Answer 18

SA node → AV node → Bundle of His → Purkinje fibers → Ventricles
Mnemonic: Suck A Big Pecker

Question 19

Primary pacemaker of the body. Heart rate is increased by sympathetic and decreased by parasympathetic nervous system tone.
Located at the upper right atrium.

Answer 19

Sinoatrial (SA) Node

Question 20

Secondary pacemaker, receives signal from SA node.
Located at the junction of the atria and ventricles.

Answer 20

Atrioventricular (AV) Node

Question 21

Bundle of His in conduction pathway

Answer 21

A delay in conduction occurs between the AV node and Bundle of His to allow for atrial contraction and ventricle filling.
The bundle of His then conducts the signal from the AV node to the ventricles.

Question 22

Fast conduction. Final connection directly to the ventricles.

Answer 22

Purkinje fibers

Question 23

Also called erythrocytes.
Do not have nuclei or organelles like mitochondria.
Produced in bone marrow and destroyed in spleen.

Answer 23

RBC

Question 24

The liquid component of blood. Composed of 90% water and 10% ions, proteins, etc.
Plasma without clotting factors is called serum.

Answer 24

plasma

Question 25

Key role in immune system. Produced in the bone marrow
Divided into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, lymphocytes).

Answer 25

WBC

Question 26

Also called thrombocytes. These are cell fragments whose main function is clotting.
They collect at wound sites and form into a platelet plug that is reinforced by a protein called fibrin.
Produced in the bone marrow

Answer 26

Platelets

Question 27

A measure of the volume of RBCs as a percent of total blood volume.
Normal values are around 45%.

Answer 27

Hematocrit

Question 28

Blood vessel structure sequence

Answer 28

artery → arteriole → capillary → venule → vein

Question 29

Elastic vessels that carry blood away from the heart.

Answer 29

Arteries

Question 30

Smaller vessels that connect to capillaries.
Surrounded by smooth muscle tissue.
Play a big role in vasoconstriction.

Answer 30

Arterioles

Question 31

Single cell layer.
Main function is gas and solute exchange (through diffusion).

Answer 31

Capillaries

Question 32

Thin, relatively inelastic vessels that carry blood toward the heart.

Answer 32

Veins

Question 33

The innermost layer of blood vessels with single-cell thickness.
Acts as a barrier and allows for smooth flow of fluids.

Answer 33

Endothelium