Cardiovascular System

Question 1

What is pericardial fluid?

Answer 1

Provides lubrication, reducing friction during heartbeats between the heart and the intrathoracic structures

Question 2

What is the fibrous pericardium?

Answer 2

Protects the heart (barrier against pathogens) and functions to anchor cardiac structures

Question 3

What is the myocardium?

Answer 3

Cardiac muscle, form the walls of the heart chambers

Question 4

What is the endocardium?

Answer 4

A layer of simple squamous endothelial cells that lines the chambers of the heart, covers the heart valves and is continuous with the lining of the blood vessels

Question 5

What is an artery?

Answer 5

Several layers of muscle, elastic and fibrous tissue. Carries blood away from the heart

Question 6

What are arterioles?

Answer 6

Less elastic and several layers of muscle. Carry blood to the capillaries

Question 7

What are capillaries?

Answer 7

Smallest vessels with a layer of endothelium. Site of exchange between the blood and the interstitial fluid

Question 8

What are venules?

Answer 8

Receive blood from the capillaries. Convergent pattern of flow

Question 9

What are veins?

Answer 9

Carry blood to the atria of the heart. Thinner wall and larger diameter than arteries

Question 10

Why are there valves in veins but not arteries?

Answer 10

The arterial system is high pressure due to the elastic recoil. The venous system is lower pressure so requires valves to prevent the back flow of blood

Question 11

How do arteries recoil?

Answer 11

Ventricle contacts

Semilunar valve opens. Blood ejected from ventricles flows into arteries

Aorta and arteries expand and store pressure in elastic walls

Ventricle relaxes

Semilunar valve shuts preventing back flow into the ventricle

Elastic recoil of arteries sends blood forward into rest of circulatory system

Question 12

What are pericytes?

Answer 12

Present in microvessels. Can induce vasoconstriction and vasodilation in capillary beds to regulate vascular diameter and capillary blood flow

Question 13

What is pulmonary circulation?

Answer 13

Carries deoxygenated blood to lungs to get oxygenated by gas exchange in the lung.

Returns oxygenated blood to the heart

Pressure for this circulation circuit comes from the right ventricle

Question 14

What is systemic circulation?

Answer 14

Carries oxygenated blood from the heart to all areas of the body and returns deoxygenated blood to the heart

Pressure for this circulation circuit comes from the left ventricle

Question 15

How does the heart receive blood?

Answer 15

Through the coronary circulatory system, made of coronary arteries, veins and capillaries

Question 16

How is venous blood from the myocardium returned into the right atrium?

Answer 16

By way of the coronary sinus, adjacent to the opening of the caudal vena cava

Question 17

What is a portal system?

Answer 17

A vessel divides into capillaries, recombines to form another vessel, and then redivides into a second capillary bed

Question 18

What roles does the lymphatic system play in?

Answer 18

Fluid homeostasis

Lipid metabolism

Immune control

Question 19

What are lymph vessels?

Answer 19

They have blind beginnings in the interstitial spaces and contains numerous valves permitting flow only towards the heart

Lymph circulation takes place via contractions of the lymph vessels and contractions of muscles that overlie lymph vessels

Lymph vessels form large lymph vessels that eventually reach the vena cava

Question 20

What are lymph nodes?

Answer 20

Nodular structures of varying sizes located along the course of lymph vessels

Filter the lymph and act as one of the first defences against infection by harbouring lymphocytes and macrophages

Question 21

What does lymph contain?

Answer 21

Water

Lymphocytes

Inorganic salts

Proteins

Question 22

How is lymph formed?

Answer 22

Formed from interstitial fluid that does not re enter the capillaries

Question 23

What special set of lymph capillaries in small intestinal villi are only found in mammals?

Answer 23

Lacteals

Question 24

What is a cardiac cycle?

Answer 24

The period between the start of one heartbeat and the beginning of the next

Question 25

What is diastole?

Answer 25

Periods of relaxation

Question 26

What is systole?

Answer 26

Periods of contraction

Question 27

What are the phases of the cardiac cycle?

Answer 27

Atrial systole Atrial diastole Ventricular systole Ventricular diastole

Question 28

What is the cardiac cycle in depth?

Answer 28

1. Atrial systole- atrial contraction forces a small amount of additional blood into relaxed ventricles 2. Atrial diastole- relaxation of atria 3. Ventricular systole first phase- ventricular contraction pushes AV valves closed but does not create enough pressure to open semi lunar valves 4. Ventricular systole second phase- as ventricular pressure rises and exceeds pressure in the arteries, the semi lunar valves open and blood is ejected 5. Ventricular diastole (early)- as ventricles relax, pressure in the ventricles drops. Blood flows back against cusps on semi lunar valves and forces them closed. Blood flows into the relaxed atria 6. Ventricular diastole (late)- All chambers are relaxed. Ventricles fill passively

Question 29

What is the cardiac conduction system?

Answer 29

Specialised cardiac muscle cells that generate and conduct electrical impulses. Contraction of the shaft is the result of spontaneous depolarisation. This activity is called automaticity or autorhythmicity

Question 30

What is the process of the cardiac conductive system?

Answer 30

Action potentials initiated in the Sinoatrial (SA) node located in the right atrium- pacemaker Impulses from the SA node are conducted to the Atrioventricular (AV) node through the internodal pathways The AV node conducts impulses more slowly than other myocardial cells After leaving the AV node, impulses accelerate through the AV bundle and among the asymmetrical right and left bundle branches (BB) Terminal arborisation of the BB, directly depolarise ventricular cardiomyocytes as the impulse is distributed by Purkinje fibers

Question 31

What is the funny current?

Answer 31

The pace making current in the Sinoatrial node. Funny current channels open when the cell membrane potential is -60mV inducing a depolarisation that reaches threshold at -40mV

Question 33

What is the cardiovascular system controlled by?

Answer 33

Automatic nervous system Endocrine system

Question 34

What is the heart rate?

Answer 34

Frequency of cardiac cycles Measured in bpm

Question 35

What is blood pressure?

Answer 35

Arterial pressure

Question 36

What is the high point of arterial pressure during ventricular contraction called?

Answer 36

Systolic pressure

Question 37

What is the low point of arterial pressure during ventricular relaxation called?

Answer 37

Diastolic pressure

Question 38

How does the nervous system influence the cardiovascular system?

Answer 38

Arteries and veins receive sympathetic intervention however capillaries receive no intervention

Question 39

How does the baroreceptor reflex play a role in the regulation of cardiovascular function?

Answer 39

Mechanoreceptors located within the aortic arch and the carotid sinuses detect increased in blood pressure Mechanoreceptors located within the venae cavae and pulmonary veins detect decreases in blood pressure

Question 40

How do baroreceptor reflexes regulate blood pressure?

Answer 40

Blood pressure rises Mechanoreceptors in the Aortic arch (AA) and carotid artey (CA) are stimulated Signal from the AA are sent to the MO by the vagus nerves and those from the CA are sent to the MO by the GN Two things happen now: 1. Stimulation of the cardioinhibitory centre. Then the Sinoatrial node is stimulated to lower heart rate, which puts blood pressure back to normal 2. Inhibition of the vasomotor centre. Then dilation of the systemic blood vessels, which puts the blood pressure back to normal

Question 41

How does the action potential form then return back to resting potential in cardiac muscle?

Answer 41

Na+ channels open Na+ channels close Ca2+ channels open and fast K+ channels close Ca2+ channels close and slow K+ channels open Returns back to resting potential

Question 42

How do chemoreceptor reflexes control cardiovascular function?

Answer 42

Chemoreceptors located in the carotid and aortic bodies monitor oxygen, carbon dioxide content and pH in the blood Central chemoreceptors located on the ventrolateral medullary surface in the CNS monitor surrounding pH and carbon dioxide levels

Question 43

How would chemoreceptor reflexes respond to hypovolemia or extreme blood loss?

Answer 43

The blood oxygen will have dropped and the pH will have decreased. The levels of CO2 will have increased Action potentials sent to the medullary center Parasympathetic stimulation is decreased, resulting in higher heart rate OR sympathetic stimulation is increased resulting in higher heart rate There will be an increase in gas exchange and respiration Restoration of cardiac output

Question 44

What endocrine hormones influence cardiovascular function?

Answer 44

Antidiuretic hormone (ADH) Renin Angiotensin Aldosterone Atrial-natriuretic peptide All are involved in water reabsorption for the purpose of blood pressure regulation

Question 45

How does ADH regulate osmotic blood pressure?

Answer 45

In case of high osmotic blood pressure: 1. High blood osmotic pressure stimulates hypothalamic osmoreceptors 2. Osmoreceptors activate the hypothalamic neurosecretory cells that synthesise and release ADH 3. Nerve impulses liberate ADH from the axon terminals in the posterior pituitary gland into the bloodstream 4. kidneys retain more water which decreases urine output. Sudoriferous (sweat) glands decrease water loss by perspiration from the skin Arterioles constrict which increases blood pressure In case of low osmotic pressure: 1. Low blood osmotic pressure inhibits hypothalamic osmoreceptors 2. Inhibition of osmoreceptors reduces or stops ADH secretion