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IB Biology HL > Topic 6.2 > Flashcards

Topic 6.2 Flashcards

1
Q

Who discovered the circulation of the blood with the heart acting as the pump?

A

William Harvey

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2
Q

Arteries

A
  • Vessels that carry blood from the heart to the tissues of the body
  • Thick walls and elastic fibres
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3
Q

Ventricles

A
  • Main pumpting chambers of the heart
  • Left ventricle pumps to the entire body
  • Right ventricle pumps to the lungs
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4
Q

What do ventricles have to pump blood

A
  • Thick strong muscles (with elastic tissues)
  • Small space in the middle to allow for passive recoil
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5
Q

Why do arteries have thick walls?

A
  • Withstand the constanty changing and intermittently high blood presure without bulging outwards (aneurysm) or bursting
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6
Q

Annotate the diagram of artery

A

Refer to picture

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7
Q

Systolic pressure

A
  • Peak pressure reached in an artery (when blood is pumped from the ventricle)
  • Pushes the wall of the artery outwards, widening the lumen and stretching elastic fibres in the wall
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8
Q

Diastolic pressure

A
  • Minimum pressure in the artery
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9
Q

What mechanism does the body use to prevent diastolic pressure from becoming too low?

A
  • The stretched artery walls recoil and squeeze blood in the lumen
  • Saves energy while maintaining relatively high pressure
  • Ensure the steady and continuous blood flow
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10
Q

Vasoconstriction

A
  • Wall of the artery contract
  • Circumference is reduced and the lumen is narrowed
  • Increases blood pressure
  • Restricts bloodflow to part of the body
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11
Q

Capillaries

A
  • Narrowest blood vessels
  • Thin wall
  • Small diameter
  • Branch and rejoin repeatedly to form a capillary network
  • Transport blood to almost all tissues in the body
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12
Q

Why is the capillary wall one layer thin

A
  • Permeable
  • Allows nutrient and waste exchange
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13
Q

Outline the process of nutrient and waste exchange at the capillary

A
  • Permeable capillary walls allow part of the plasma to leak out and form tissue fluid (contins oxygen, glucose, monomer nutrients)
  • The fluid flows between the cells in the tissue, allowing the cells to absorb useful substances
  • Cells excrete waste products into the tissue fluid
  • Tissue fluid reenters the capillary network with the waste products
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14
Q

Why does the permeability of capillary wall differ between tissues?

A
  • Particular proteins and other large particles can reach certain tissues but not others
  • Permeability also changes overtime in response to the needs of the tissues
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15
Q

Veins

A
  • Collect blood at low pressure from the tissues of the body
  • Carry blood back to the atria of the heart
  • Veins do not require thick walls and contain fewer muscle and elastic fibres
  • Have valves
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16
Q

Atrium

A
  • Receives blood from veins
  • Right atrium receives blood from the entire body
  • Left atrium receives blood form the lung
17
Q

Outline the function of the valves in veins

A
  • Prevent backflow due to low pressure
  • if blood starts to flow backwards, it gets caught in the flaps of the pocket valve, which blocks the lumen when filled with blood
  • When blood flows towards the heart, it pushes the flaps to the sides of the vein, opening the valve
  • One direction only
18
Q

Label the diagram of the heart

A

Refer to picture

19
Q

Outline the double circulation in the human body

A
  • One circulation to and from all other organs (systemic ciruclation)
  • One circulation to and from the lung (pulmonary circulation)
  • Blood is oxygenated by the pulmonary circulation
20
Q

Atherosclerosis

A

Development of fatty tissues called atheroma in the artery wall adjacent to the endothelium

21
Q

Describe how atheroma is formed

A
  • Low density lipoproteins (LDL) containing fats and cholesterol accumulate
  • Phagocytes engulf the fats and cholesterol by endocytosis and grow very large
  • Smooth muscle cells migrate to form a touch cap over the atheroma
  • Artery wall bulges into the lumen, narrowing it and impeding blood flow
22
Q

Coronary occlusion

A
  • Narrowing of hte arteries that supply blood containing oxygen and nutrients to the heart muscle
  • Lack of oxygen causes pain, known as angina, and impairs the muscle’s ability to contract
  • The heart beats faster to maintain blood circulation
23
Q

Describe what happens when the atheromas ruptures

A
  • The fibrous capcovering atheromas sometimes ruptures
  • Stimulates the formation of blood clots that can block arteris supplying blood to the heart and cause acute heart probems
24
Q

Outline causes (increased risk) of atheroma

A
  • High blood concentrations of LDL (low density lipoprotein)
  • Chronic high blood glucose concentrations, due to overeating, obesity or diabetes
  • Chronic high blood pressure due to smoking, stress, or any other cause
  • Consumption of trans fats, which damage the endothelium of the artery
  • Infection of the artery wall
25
Q

Sinoatrial node

A
  • Specialized muscle cells in the right atrium
  • Initiate heartbeat
  • Pacemaker of the heart
26
Q

Describe the initiation of heartbeat

A
  • Membrane of a heart muscle cell depolarizes when the cell contracts
  • Activates adjacent cells to contract
  • Sinoatrial nodes are the first to depolarize in each cardiac cycle
27
Q

Outline treatment for defective sinoatrial node

A
  • An artificial pacemaker can regulate the heartbeat
  • An electronic device that is placed under the skin with electrodes implanted in the wlal of the heart
  • Initiate each heartbeat in place of the sinoatrial node
28
Q

Describe the propagation of electrical signal in each heartbeat

A
  • SA node initiates the heartbeat while sending an electrical signal that spreads throughout the walls of the atria
  • Electrical signals propagate across interconnections adjacent fibres
  • The fibres are branched so the signal can be passed on to several places
  • This propagation of the electrical signal causes the whole of both left and right atria to contract
  • After a time delay, the electrical signal is conveyed to the ventricles (the atria pump blood to ventricles during the time delay)
  • Ventricles contract and pump blood out into the arteries
29
Q

With the help of a graph, describe how pressure changes in the atria and ventricles during the cardiac cycle

A
30
Q

State the structure in the brain that regulate the heartbeat

A

Medulla

31
Q

Describe how the cardiovascular centre regulate heartbeat

A
  • Recieves inputs from receptors that monitor blood pressure, pH and oxygen concentration
  • Low blood pressure/low oxygen concentration/low pH cause the medulla to send a message to increase the flow rate of blood to the tissues
32
Q

Outline the effect of epinephrine on heart rate

A

Increases heart rate to prepare for vigorous physical activity

33
Q

Fill in the following chart of the cardiac cycle events

A

IB Biology HL (23 decks)

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