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Higher Biology > Structure of the Cardiovascular System > Flashcards

Structure of the Cardiovascular System Flashcards

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1
Q

What is the cardiovascular system made up of ?

A

Blood vessels and the heart

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2
Q

What are the three types of blood vessels

A

1) Arteries
2) Capillaries
3) Veins

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3
Q

What does each blood vessel have

A

A central cavity, called a lumen

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4
Q

What lines the central lumen ?

A

The endothelium lines the central lumen of blood vessels and is surrounded by layers of tissue.

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5
Q

What is the function and layers of arteries ?

A

Function: Carries blood away from the heart under high pressure.

Structure:
Outer layer - connective tissue containing elastic fibres
Middle layer - Thick smooth muscle, with more elastic fibres.
Inner Layer - Endothelium
Central lumen - narrow

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6
Q

What do the elastic walls of the arteries allow it to do?

A

Allows the arteries to stretch and recoil to accommodate the surge of blood which flows after each contraction of the heart.

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7
Q

What is the function and layers of a vein ?

A

Function: To carry blood into the heart from the body under low pressure.

Structure:
Outer layer - connective tissue, containing elastic fibres
Middle layer - thin smooth muscle
Inner layer - endothelium
Central lumen - wider, with valves to prevent the backflow of blood.

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8
Q

What is the function and layers of a capillary ?

A

Function: Capillaries allow the exchange of substances between blood and cells of the body, through their thin walls.
Capillaries connect arterioles to venules.

Structure:
Outer layer - Endothelium (one cell thick)
Central lumen - very narrow

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9
Q

How do all different types of vessel connect up?

A

Artery –> Arteriole –> Capillary –> Venule –> Vein

———————->Decreasing Pressure—————–>

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10
Q

How do arteries control blood flow?

A

To control blood flow, the smooth muscle in the arterioles can either vasoconstrict (contract) or vasodilate (relax) depending on the requirements of the body.
Arteries can contract as they contain many elastic fibres (in their connective tissue and smooth muscle layer)

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11
Q

How does vasoconstriction/vasodilation affect blood flow ?

A

Vasoconstriction = Smooth muscle contracts, central lumen narrows, blood flow to area decreases.

Vasodilation = Smooth muscle relaxes, central lumen widens, blood flow to area increases.

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12
Q

What does blood consist of

A

Red Blood Cells, White Blood Cells and Platelets, all suspended in plasma; a watery yellow fluid.

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13
Q

What does plasma contain ?

A

Substances dissolved such as glucose, amino acids, respiratory gases (O2 and CO2), plasma protein and useful ions.

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14
Q

What is tissue fluid ?

A

-Is a liquid that surrounds the cells of our body.
-Is similar in composition to blood plasma with the exception of plasma proteins (plasma proteins are too large to be pressure filtered through the capillary walls)
-Tissue fluid supplies cells with glucose, oxygen and other substances. Carbon dioxide and other metabolic wastes diffuses out of the cells and into the tissue fluid to be excreted. Much of the tissue fluid returns to the blood.

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15
Q

What is pressure filtration ?

A

Pressure filtration causes plasma to pass through capillary walls into the tissue fluid surrounding the cells, to allow the exchange of substances between the blood and cells of the body to take place.

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16
Q

Describe how the exchange of substances between blood plasma and tissue fluid takes place on the arteriole side of the capillary bed.

A

-Arteriole blood pressure is greater than the capillary blood pressure.
-As blood is forced into these narrow capillaries, pressure filtration causes blood plasma to pass through the walls of the capillary into the tissue fluid surrounding the cells of the body.
-By diffusion, tissue fluid supplies the cells of the body with glucose, oxygen and other useful substances.
-By diffusion, carbon dioxide and other metabolic waste materials move out of the cells of the body and into the tissue fluid for excretion.

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17
Q

Describe how the exchange of substances between blood plasma and tissue fluid takes place on the venule side of the capillary bed.

A

-Venous blood pressure is lesser than the tissue fluid pressure.
-By osmosis, much of the tissue fluid returns to the blood in the capillaries.
-Lymphatic vessels absorb excess tissue fluid and return it as lymph to the circulatory system via lymphatic ducts located in the upper arm.

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18
Q

Describe lymphatic return

A

Lymphatic vessels absorb excess tissue fluid and return it as lymph to the circulatory system, lymph vessels contain valves to prevent the backflow of lymph and the flow of lymph within the lymphatic system is brought about by muscle contractions during movements of the body.

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19
Q

Compare the presence of protein in arterioles, tissue fluid and the venules.

A

Arterioles = has protein
Tissue Fluid = no protein
Venules = has protein

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20
Q

Describe the lymphatic system and the flow of lymph

A

-Lymph carries waste products as they need to be carried to an aera where they can be excreted.
-Flow of lymph is brought about by compression when muscle contract during body movements.
-Backflow of lymph is prevented because lymph vessels have vales.
-Lymph eventually returns to the blood stream via two lymphatic ducts, which enter into veins in the arms.

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21
Q

What is the heart

A

A muscular pump made of cardiac muscle

22
Q

What is the role of the right and left side of the heart.

A

Right Side = carries deoxygenated blood from he body to the lungs.

Left Side = carries oxygenated blood from the lungs to the body.

23
Q

Why is the left ventricle wall thicker than the right ventricle wall?

A

The left ventricle pumps blood a much further distance then the right ventricle

24
Q

REVISE DIAGRAM WITH LABELLED HEART VALVES

A

DO IT

25
Q

What are the two types of heart valve

A

Semilunar (artery to ventricle) and atrio-ventricular (R side tricuspid, L side bicuspid)

26
Q

What are the functions of the heart valves

A

Atrioventricular valve = prevents backflow of blood from ventricles into atria.

Semilunar valves = Prevents backflow of blood from arteries leaving heart into the ventricle.

27
Q

What role do the coronary arteries play ?

A

Provide the heart with a continuous supply of oxygen and nutrients

28
Q

Describe the path of blood flow around the body.

A

1) Blood returns back to the heart through the vena cava.
2) Blood enters the right atrium.
3) The right atrium contracts and forces blood through the atrioventricular valve.
4) Blood enters the right ventricle.
5) The right ventricle contracts and forces blood through the semilunar valve.
6) Blood travels to the lungs in the pulmonary artery.
7) When the blood reaches the alveoli, oxygen diffuses into the blood and carbon dioxide diffuses into the alveoli.
8) Blood returns to the heart through the pulmonary vein.
9) Blood enters the left atrium.
10) The left atrium contracts and forces blood through the atrioventricular valve.
11) Blood enters the left ventricle.
12) The left ventricle contracts and forces blood through the semilunar valve.
13) Blood travels to the body in the aorta.
14) When the blood reaches the body cells, oxygen diffuses into the cells and carbon dioxide diffuses into the blood.
REPEAT

29
Q

What volume of blood do the left and right ventricles pump ?

A

The left and right ventricles pump the same volume of blood through the aorta and pulmonary artery.

30
Q

What is cardiac output ?

A

The volume of blood pumped out of a ventricle per minute is called the cardiac output, and depends on two factors:
the stroke volume – the volume of blood pumped by the left ventricle in each heartbeat. A typical value for an adult at rest is 75 ml.
the heart rate – the number of times the heart beats per minute. A typical value for an adult at rest is 70 bpm.

31
Q

How do you calculate cardiac output ?

A

Cardiac Output = stroke volume x heart rate

32
Q

What is the cardiac cycle ?

A

The pattern of contraction and relaxation during one heartbeat.
-It contains three phases, during which the muscles of the atria and ventricles contract and relax and heart valves open and close.
-Lasts approx. 0.8 seconds.

The period of contraction is called systole
The period f relaxation is called diastole.

33
Q

Describe the phases of the cardiac cycle

A

Phase 1 - Atrial Systole
Atria contract simultaneously, blood is forced into the ventricles. AV vales are open, SL valves are closed and lasts approx. 0.1 seconds.

Phase 2 - Ventricular systole.
Ventricles contract simultaneously, blood is forced out of the heart through the aorta and pulmonary artery. AV valves are closed, SL valves are open, lasts approx. 0.3 seconds.

Phase 3 - Atrial and ventricular diastole.
Atria and ventricles relax simultaneously, blood flows into all chambers of the heart. AV vales are open, SL valve are closed, lasts approx. 0.4 seconds.

33
Q

What controls the opening/closing of the valves of the heart throughout the cardiac cycle ?

A

The opening and closing of AV and SL valves throughout the cardiac cycle is controlled by pressure changes in the chambers of the heart.
-high pressure behind the valve forces it open.
-high pressure Infront of the valve forces it to close.

33
Q

Describe valves and heart sounds

A

The opening and closing of the AV and SL valves, during the cardiac cycle, are responsible for the heart sounds, heard with a stethescope.

The LUBB-DUBB sound arises from the closing of the two AV valves and the two SL valves, respectively.
LUBB - at the beginning of ventricular systole when the ventricular pressure exceeds atrial pressure.
DUBB - at the beginning of ventricular diastole when arterial pressure exceeds that of the ventricles.

34
Q

What controls the heart beat ?

A

The heartbeat is brought about by the activity of the pace maker and the cardiac conducting system of the heart - is autorhythmic (heartbeat originates in the hart itself)

35
Q

Describe the role of the SA node as part of the cardiac conducting system.

A

-Natural pacemaker of the heart.
-Located in the walls of the right atrium.
-Auto-rhythmic cells of the SA Node set the heart rate at which the heart contracts.
-SA node sends spontaneous electrical impulses across the walls of the atria, causing them to contract during atrial systole
- the timing of cardiac muscle cell contraction is controlled by impulses, from the SAN, spreading though the atria, causing atrial systole.
-SA node causes the heart to beat 60-80 times per minute without any input from the nervous system.

36
Q

Describe the role of the AV node as part of the cardiac conducting system

A

-Electrical impulses send by the SA node are picked up by the AV node.
-Located in the centre of the heart
-AV node sends electrical impulses down fibres in the central wall of the heart and up through the walls of the ventricles causing them to contract during ventricular systole.

37
Q

How is the rate of the SA node regulated ?

A

-The medulla regulates the rate of the sinoatrial node through the antagonistic action of the autonomic nervous system. (ANS)
-A sympathetic nerve releases noradrenaline which increases heart rate.
-A parasympathetic nerve releases acetylcholine which decreases the heart rate.

Under certain circumstances (exercise or stress) the sympathetic nervous system acts on the adrenal glands, making them release the hormone adrenaline. This hormone increases the heart rate.

38
Q

What is the ANS?

A

The autonomic nervous system
-works automatically without conscious control
-consists of sympathetic and parasympathetic systems.
-The medulla regulates the rate of the sinoatrial node through the antagonistic action of the autonomic nervous system

39
Q

Name the two nodes that make up the cardiac conducting system

A

Sino-atrial (SA) Node
Atrio-ventricular (AV) Node

40
Q

What are artificial pace makers.

A

Devices implanted in people whose heart’s electrical conductive system is not working properly (SAN not firing, blockage/disruption of impulses between the SAN and AVN, or in the conducting fibres)
-Pacemakers monitor the heart’s electrical activity and stimulate the ventricles or atria to contrast when necessary. Impulses are transmitted down electrodes implanted in the muscular walls.

41
Q

What is an electrocardiogram (ECGs) ?

A

Impulses in the heart generate currents that can be detected and monitored by an electrocardiogram.
-Several electrodes are attached to specific places on a person’s chest and limbs. These detect changes in the heart by measuring current at the skin’s surface.
-The results of ECG can be used to calculate heart rate and periods of systole and diastole.

42
Q

What do the different components of an ECG represent (also revise diagrams)

A

P wave - Atrial systole
QRS complex - ventricular systole
T Wave - Diastole

43
Q

Describe pressure changes in the heart

A

Throughout the cardiac cycle, pressure changes take place in the atria, ventricles and arteries.
-Blood pressure increases during ventricular systole and decreases during diastole.

44
Q

How is blood pressure measured ?

A

Blood pressure increases during ventricular systole and decreases during diastole.
-An inflatable cuff (sphygmomanometer) stops blood flow, in the artery, and deflated gradually. The blood starts to flow(detected by a pulse) at systolic pressure. The blood flows freely through the artery (and a pulse is not detected) at diastolic pressure.
-Normal blood pressure is 120(systolic)/80(diastolic) mmHg
-Two values given as systolic and diastolic pressures are measured - looking for pressure during different phases of the cardiac cycle.

45
Q

Why does pressure decrease ?

A

There is a progressive drop in blood pressure as blood travels away from the heart.
-As blood flows through smaller and narrower blood vessels, friction occurs between the blood and the vessel wall, making the wall resist blood flow. This resistance causes a decrease in pressure.

Smaller the vessel = more friction = more resistance = greater the drop in blood pressure.

46
Q

Which blood vessel shows the greatest decrease in blood pressure ?

A

The arterioles
-One artery branches into many arterioles which increases surface area which increases levels of friction.

47
Q

What is hypertension ?

A

Hypertension (high blood pressure) is a major risk factor for many diseases including coronary heart disease and stroke.
-Prolonged elevation of blood pressure when at rest, resting BP greater than 140/90mmHg

48
Q

Name the piece of equipment used to listen to the sound of a heartbeat

A

A stethescope

49
Q

Define the term blood pressure

A

A measure of force that your heart use to pump blood around the body.

Higher Biology (15 decks)

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