cardiac system 6.2 Flashcards

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1
Q

Outline the role of elastic and muscle tissue in arteries

Describe the mechanism used to maintain blood flow in arteries between heartbeats

A

muscle fibres help to form a rigid arterial wall that is capable of withstanding the high blood pressure without rupturing between pumps. can also contract to narrow the lumen.
-> helps to maintain blood pressure throughout the cardiac cycle

The elastic fibres allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen

pressure exerted on the arterial wall is returned to the blood when the artery returns to its normal size (elastic recoil)
elastic recoil helps to push the blood forward through the artery as well as maintain arterial pressure between pump cycles

vasoconstriction (contraction of circular muscles) and vasodilation (relaxation of circular muscles), directly control the flow of blood through the body.

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2
Q

Describe the structure and functions of the three layers of artery wall tissue

A

Tunica intima
innermost layer, direct contact with blood in the lumen. includes the endothelium that lines the lumen of all vessels; forming a smooth, friction-reducing lining.

Tunica media
middle coat, mainly made up of smooth (involuntary) muscle cells + elastic fibres arranged in roughly spiral layers. layer is usually the thickest of the three layers.

Tunica adventitia
outermost coat, tough layer consisting largely of loosely woven collagen fibres that protect the blood vessel and anchor it to surrounding structures.

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3
Q

Define systolic and diastolic blood pressure

A

Systolic refers to the part of the heartbeat when the muscle is contracting. 120 and 200 mm Hg.

Diastolic pressure When cardiac muscle is relaxing. Lower pressure than systolic.

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4
Q

Describe the structure and function of capillaries

A

arteries divide to form smaller arterioles that in turn divide successively to form very fine blood vessels called capillaries. These vessels then fuse together to form venules, and many venules fuse together to form veins.

Capillaries have walls that are only one-cell thick with a diameter of around 3–4 µm; they have no muscle fibres or other layers, are rather leaky.
allows the exchange of materials; oxygen and nutrients with cells in tissues, and waste products, such as carbon dioxide and urea, back into the capillaries to be transported by blood. White blood cells can also exit capillaries through gaps between the endothelial cells.

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5
Q

Describe the cause and effect of diffusion of blood plasma into and out of capillary network

A

effect: Blood flows slowly at a low pressure through the capillaries to allow for material exchange, which occurs by diffusion or active transport, is greatly enhanced. .

cause:
High hydrostatic pressure at the artery end of the capillary forces material from the blood stream into the tissue fluid.
Lower hydrostatic pressure at the vein end of the capillary allows materials from the tissues to enter the bloodstream.

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6
Q

State the function of veins

A

Veins transport blood back from the tissues of the body and return it to the atria (upper chambers) of the heart.

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7
Q

Outline the roles of gravity and skeletal muscle pressure in maintaining flow of blood through a vein

A

Gravity
Veins have very low pressure, which can make it difficult for blood to move against the downward force of gravity.
So, they contain numerous valves to prevent the backflow of blood and maintain circulation.

Skeletal
Veins pass through skeletal muscle groups which use periodic contractions to maintain flow.
When skeletal muscles contract, they squeeze the vein and cause it to flow from the site of compression.
Veins run parallel to arteries and so the same effect can be achieved by the bulging of the arteries created by a pulse.

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8
Q

Outline the structure and function of pocket valve

A

structure : three cup-shaped flaps of tissue
function : allow blood to only flow in one d irection. Ensure that blood circulates in the body.

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9
Q

Draw a diagram to illustrate the double circulation system in mammals

A

see notion

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10
Q

Compare the circulation of blood in fish to that of mammals

A

Humans/mammals have a two circulations of blood (blood is pumped twice). One circulation (systemic circulation) goes from the left ventricle to the rest of the body and back to the right atrium. The second circulation (pulmonary circulation) goes from the right ventricle to the lungs and returns to the left atrium of the heart.

Fish have a single circulation.
Blood is pumped at high pressure to their gills to be oxygenated.
After flowing through the gills the blood still has enough pressure to flow directly, but relatively slowly, to other organs and then back to the heart.

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11
Q

Explain the flow of blood through the pulmonary and systemic circulations.

A

Pulmonary
To and from the lungs
Recieves deoxygenated blood that has returned from systemic circulation.

Systemic
To and from all other organs, including the heart muscle
Systemic circulation receives blood that has been oxygenated by the pulmonary circulation.

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12
Q

Explain why the mammalian heart must function as a double pump

A

essential that blood flowing to and from the two circulations is not mixed. The heart is a double pump because it delivers blood under different pressures to separate circulations.

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13
Q

Describe factors that will increase heart rate

A

Altitude
Exercise
Caffeine
Increased body temperature
Epinephrine hormone

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14
Q

Describe factors that will decrease heart rate

A

Anticipation of relaxation
Decreased body temperature
Reduced oxygen availability in cardiac cells

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15
Q

Outline conditions that will lead to epinephrine secretion

A

Epinephrine is produced by the adrenal glands. The secretion of epinephrine is controlled by the brain and rises and increases when vigorous physical activity may be necessary.

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16
Q

Explain the effect of epinephrine on heart rate

A

It increases the heart rate by activating the same chemical pathways as the neurotransmitter neoadrenaline.

17
Q

Outline the effect of a coronary occlusion on heart function

A

Lead to blood clots which cause coronary heart disease.
Myocardial (heart) tissue requires oxygen and nutrients which are transported via coronary arteries to maintain function
If a coronary artery becomes blocked, a heart attack will result

18
Q

Explain the relationship between atrial and ventricular pressure in the opening and closing of heart valves

A

As the left atrium fills with blood the pressure increases so the AV valves open and the pressure in the left atrium decreases as the left ventricle fills up with blood.

AV closes and when the ventricles contract, the pressure increases. This forces the semilunar valves to open which lets the blood flow out. The ventricles relax and the pressure decreases.

19
Q

Given a micrograph, identify a blood vessel as an artery, capillary or vein.

A

artery: red on the outside, white on the inside.
capilarries: same color scheme as artiereis but multiple with black dots
veins: red on the outisde and red on the inside as well.