Cardiovascular System

Question 1

Arteries

Answer 1

Types: elastic/conduit & muscular
Compliance: raise pressure by distending & recoiling passively

Question 2

Arterioles

Answer 2

Extrinsic control types: neural input & hormones
Contract – blood diverted away from tissue
Dilate – blood increased into tissue
Pressure regulation – controlling resistance

Question 3

Capillaries

Answer 3

Types: Continuous (skin/muscle – continuous endothelium & basement membrane allows exchange), fenestrated (intestines - pores), sinusoidal (liver – discontinuous endothelium & incomplete basement)
Permeability – water-filled intercellular clefts
Blood flow – other vessels in microcirculation
Substance exchange – slow forward movement

Question 4

Veins

Answer 4

Low pressure return blood heart
Maintain peripheral venous pressure, skeletal muscle & respiratory pump

Question 5

aorta

Answer 5

main and largest artery in the human body. It originates from the left ventricle.

Question 6

aortic valve

Answer 6

lies at the base of the aorta. It permits blood to leave the left ventricle as it contracts

Question 7

inferior vena cava and superior vena cava

Answer 7

carry blood to the right atrium

Question 8

left atrium and right atrium

Answer 8

receive blood returning to the heart from the circulatory system. These upper chambers of the heart have thin walls

Question 9

left ventricle and right ventricle

Answer 9

receive blood from the atria and contract to pump blood into the arteries

Question 10

mitral valve or bicuspid valve

Answer 10

has two cusps (flaps). It lies between the left atrium and the left ventricle

Question 11

myocardium

Answer 11

thick middle layer of the heart wall. It consists of cardiac muscle tissue

Question 12

pericardium

Answer 12

double-layered sac containing the heart and the roots of the large blood vessels to which it attaches

Question 13

pulmonary trunk

Answer 13

starts at the right ventricle and divides to form the pulmonary arteries. It carries blood to the lungs

Question 14

pulmonary valve

Answer 14

valve lies at the base of the pulmonary trunk. It allows blood to leave the right ventricle and prevents backflow

Question 15

pulmonary veins

Answer 15

transfer oxygenated blood from the lungs to the heart

Question 16

septum

Answer 16

separates the left and right atria and ventricles

Question 17

tricuspid valve

Answer 17

has tree cusps (flaps) connected to papillary muscles by chordae tendineae. It allows blood to move from the right atrium into the right ventricle and closes during contraction of the ventricle to prevent backflow

Question 18

Epicardium

Answer 18

Simple squamous epithelium with a layer of loose connective tissue (collagen and elastin) – this provides support for blood vessels and fat below

Question 19

Myocardium

Answer 19

Thick muscular layer, composed of cardiomyocytes joined together by intercalated discs. Bundles of cardiomyocytes, with central nuclei are found with connective tissue in between (lighter areas). The myocardium contains an extensive capillary network. The thickness of the myocardium varies between individuals, and also between health and disease

Question 20

Endocardium

Answer 20

Layer of flattened endothelial cells, supported by fibrous (and some elastic) connective tissue which lines the chambers of the heart

Question 21

Identifying cardiac muscle cells

Answer 21

cross section - rounded cross-section w/ central nucleus
longitudinal section - joined end-end & often branched
Intercalated discs - specialised junction, appear thin, dark perpendicular to muscle fibre
Lipofuscin pigment - lysosomal digestion residue = yellow brown granules

Question 22

Right atrium

Answer 22

receives venous blood from systemic circulation
pectinate muscle (bundles protrude from surface) common

Question 23

heart valves

Answer 23

folds in endocardium anchored to cardiac skeleton(fibrous skeleton)
dense connective tissue
avascular

Question 24

cardiac skeleton

Answer 24

4 fibrous rings of dense irregular connective tissue
attachment site for heart valve leaflets & myocardium
electrically insulates atria above from ventricles below

Question 25

Purkinje Fibers

Answer 25

carry cardiac impulses from AV & branch beneath endocardium
stain lighter than surrounding
larger cells, large amounts of glycogen & fewer myofibrils

Question 26

Tunica Intima

Answer 26

• Endothelium - simple squamous epithelium joined by tight junctions
• Subendothelial connective tissue
• Internal elastic lamina - more prominent in arteries
• Fenestrated sheets of elastic fibers

Question 27

Tunica media

Answer 27

typically the thickest layer in arteries
* Concentric layers of smooth muscle cells
* Various amounts of elastic and collagen fibers are interspersed between the smooth muscle cells
* These fibers are produced by the smooth muscle cells (not fibroblasts)
* External elastic lamina - only present in large arteries
* Fenestrated sheets of elastic fibers

Question 28

Tunica adventitia

Answer 28

typically the thickest layer in veins
* Longitudinally arranged dense connective tissue
* In large veins, bundles of smooth muscle cell are present

Question 29

Arterial size relation to elastic fibres & smooth muscle cells

Answer 29

As arterial size decreases, the relative amount of elastic fibers within their walls decreases and the relative amount of smooth muscle cells increases.

Question 30

Atherosclerosis

Answer 30

hypertension injury to tunica intima - coordinated regulation of apoptosis, cell recruitment, proliferation, migration, and differentiation required for repair

Question 31

Types of cardiomyocytes

Answer 31

Pacemaker (Autorhythmic) – 1%: Located in the sinoatrial (SA) node. Generate electrical impulses (action potentials) spontaneously and depolarize adjacent cells through gap junctions (within intercalated discs).
Contractile cells - 99%: Cells next to pacemaker cells become depolarised and contract.

Question 32

atrial excitation

Answer 32

process by which the sinoatrial (SA) node in the heart generates an electrical signal that causes the atria (top chambers of the heart) to contract

Question 33

How long does AV delay impulse & why

Answer 33

0.09s
eject all blood intro ventricles

Question 34

ventricular excitation

Answer 34

impulse from AV->bundle of His -> bundle branches -> Purkinje fibres and near simultaneous contraction

Question 35

Atrial systole

Answer 35

atrial myocytes contract, blood forced into ventricular chambers

Question 36

Atrial diastol

Answer 36

atrial myocytes relax

Question 37

Ventricular systole

Answer 37

ventricular myocytes contract, blood forced into aorta and pulmonary artery

Question 38

Ventricular diastole

Answer 38

ventricular myocytes relax

Question 39

How is resting membrane potential maintained

Answer 39

NA+ & Ca2+ ions pumped out and K+ pumped in by ion pumps

Question 40

action potential

Answer 40

brief reversal of the polarity of the cell membrane
caused by the movement of ions through voltage gated ion channels – these allow certain ions through at certain values or voltages of membrane potential.
When membrane potential increases (less negative) – the cell is said to be depolarised. When the membrane potential decreases – the cell is said to be repolarised.