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A-Level OCR Biology > Module 3 - Heart > Flashcards

Module 3 - Heart Flashcards

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1
Q

What is the name of the tissue in the heart

A

Cardiac muscle

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2
Q

Describe how the components of tobacco smoke can affect the cardiovascular system of smokers.

A

Tobbacco contains an addictive substance called nicotine. Nicotine makes more people want to smoke more frequently. This causes the stickiness of platelets.
This in turn leads to more blood clotting such as thrombosis.
Thrombosis can block the pathway of blood flow in the arterioles. This in turn reduces blood flow and less oxygen is supplied.

When tobacco is burned incompletely this produces carbon monoxide, a toxic and colourless gas. This binds to haemogloblin and reduces the capacity of oxygen in the blood to be carried.

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3
Q

How is tissue fluid formed

A

Hydrostatic pressure in the capillary causes tissue fluid formation from plasma

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4
Q

Outline the stages of the cardiac cycle.

A

First atrial diastole occurs, where the atria is relaxed and blood is entering.

Then atria and ventricular diastole occurs where both atria and ventricles are relaxed. Blood flows through the atrioventricular valves and enters in a passive peocess.

After, atria systole occurs where the atria contracts and causes the pressure inside the atria to increase so blood flows theough the atrioventricular valves to the ventricles. This in turn causes the volume in the ventricles to increase.

Finallt ventricular systole occurs where the ventricles contract. This is where the atrioventricular valves are closed to prevent back flow but the semi lunar valves are ope.n.

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5
Q

What is fibrillation?

A

Abnormal rhythm of the heart. They contract very fast and do not contract properly so only some impulses are passed onto the ventricles

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6
Q

What is bradycardia?

A

When the heart rate is too slow

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7
Q

What is tachycardia?

A

When the heartbeat is very fast

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8
Q

What is ectopic heartbeat

A

Extra heartbeats that are out of the normal rhythm

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9
Q 
What ions are important for the role of : 
Production of nitrate ions by bacteria 
Loading of phloem 
DNA structure 
Cofactor for amylase
A

NH4+
H+
PO4 3-
Cl-

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10
Q

Pressure differences at the arterial and venous ends of capillaries are responsible for the formation of tissue fluid.
Explain the movement of fluid in and out of the capillary

A

At the arterial end, hydrostatic pressure is higher than oncotic pressure so fluid moves out of the capillary
At the venous end, hydrostatic pressure is lower than oncotic pressure so fluid moves into capillary.

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11
Q

What type of circulatory systems do insects have

A

Single Open Circulatory System

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12
Q

CO2 released during respiration can affect the % oxygen saturation of haemoglobin.
The tertiary structure of haemoglobin is affected when carbon dioxide reacts with water to form carbonic acid.
This reaction releases hydrogen ions.
Why does this happen

A

The release of hydrogen ions causes the pH to fall , which reduces haemoglobin’s affinity for oxygen

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13
Q

Explain why surface area to volume ratio of an organism determines whether it needs a circulatory system.

A

Larger organisms have smaller SA:VOL ratio so rate of diffusion is too slow.
The body has metabolic demands and need nutrients so needs a circulatory system.

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14
Q

As the heart rate increases, what happens to the time between the T wave and the P wave which signals the start of the next heartbeat

A

Time between them gets less

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15
Q

What is the relative proportions of the components in the aorta
Elastin
Smooth Muscle
Collagen

A

E- 56%
SM - 11%
C - 33%

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16
Q

Which of the muscles in the mammalian ventilation system contract to force air out of the lungs

A

Internal intercostal muscle

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17
Q

What is the equation that shows the reaction catalysed by carbonic anhydrase?

A

CO2 + H2O –> H2CO3

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18
Q

Describe exhalation in mammals

A

Ribcage moves downwards and inwards, external intercostal muscle relax, diaphragm relaxes

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19
Q

State one difference between fetal haemoglobin and adult haemoglobin and give one reason why this difference is essential to the fetus.

A

Fetal haemoglobin has a higher affinity for oxygen so fetal haemoglobin must be able to bind to oxygen in lower partial pressure.

20
Q

Explain why tissue fluid does not contain erythrocytes.

A

Erythrocytes are too large so cannot fit through the gaps/fenestration

21
Q

RBCs are full of haemoglobin.

Describe the role of haemoglobin in transporting oxygen around the body.

A

Haemoglobin has a high affinity for oxygen.
Oxygen binds to the haemoglobin in lungs to form oxyhaemoglobin.
This is then released to where it is needed in the body

22
Q

Most CO2 is transported as hydrogencarbonate ions in the plasma.
Describe how the hydrogencarbonate ions are produced in the erthyrocytes.

A

CO2 diffuses into the erythrocytes.
CO2 combines with H20 and forms carbonic acid.
This dissociates to form hydrogen carbonate ions.

23
Q

Explain why the fetal haemoglobin curve is to the left of the adult haemoglobin curve

A

Fetal haemoglobin has a higher affinity for oxygen.
Fetal haemoglobin takes up oxygen in lower partial pressure because the placenta has low partial pressure of oxygen
At the placenta the adult oxyhaemoglobin will dissociate

24
Q

Explain why cartilage is essential in the trachea

A

Ensure the trachea does not collapse
Ensure airway is open
To help lower pressure in trachea if needed

25
Q

Suggest two advantages of keeping the blood inside vessels

A

Maintains high blood pressure

Increases rate of flow

26
Q

Explain why the wall of the left ventricle is thicker than the wall of the left atrium

A

To create more force/create higher pressure

To ensure blood pumps further

27
Q

what component in the mammalian circulatory system
maintains pressure
transport medium
exchange surface

A
  1. Aorta
  2. Plasma
  3. Capillary
28
Q

How might scientists a century ago have known that termites evolved in the Jurassic geological period?

A

Observing fossils In the jurassic era

29
Q

What new source of evidence might help today’s scientists to help find out how closely related termites are to cockroaches.

A

Looking at DNA

30
Q

Explain how CO2 produced in the respiring body cells of worker termites is removed to the air outside the termite mound

A

CO2 diffuses down the concentration gradient out of the respiring cell
It is carried through body from cell to tracheoles by blood passing out
Respiration generates heat

31
Q

Suggest why african termites need to build mounds in this shape and orientation

A

The shape increases surface area to volume ratio

The smallest area is exposed to greatest heat

32
Q

How are hydrogen carbonate ions formed in the blood

A

CO2 comes from respiring tissues
It diffuses into the red blood cell
Here it reacts with water to form carbonic acid
This is then catalysed by an enzyme called carbonic anhydrase
Then carbonic acid dissociates into h+ and hco3- ions
HCO3- ions diffuse out of the red blood cell and into the plasma
The charge inside the RBC needs to be maintained so chloride ions from plasma enter RBC - causing chloride shift

33
Q

Describe the events taking place at W,X,Y and Z an explain how these events are related to the changes in pressure shown in the diagram

A

At Y the ventricles begin to contract
Between W and Y the ventricles are relaxing. At Y the atria ventricular valve is closed and it opens at X
The semilunar valves open at Z and close at W
Atria contraction has already been completed before Y so it is relaxed at W,X,Y,Z

At W ventricular pressure falls below aortic pressure
At Z ventricular pressures rises above aortic pressure

At Y ventricular pressure rises above atrial pressure
At X ventricular pressure falls below atrial pressure

34
Q

Outline the reasons why insects and other animals need well developed transport systems.

A

They have high metabolic demands
need large oxygen supply
diffusion is too slow so needs a transport system

35
Q

How does a heartbeat work?

A

SAN node in the wall of the right atrium sets the rhythm of the heart beat by sending regular waves of electrical activity to atrial walls, causing left and right to contract at same time

Non conducting collagen prevents electrical activity passing down to ventricle instead transferred to Atrioventricular node

AVN passes electrical activity to bundle of His with slight delay to make sure ventricle contracts after atria has emptied

Wave of excitation from bundle of his passes down to apex of heart

the wave of excitation passes through purkyne fibres at apex and causes ventricle to contract, empties out more efficiently

36
Q

High concentrations of carbon dioxide in the blood reduces the amount of oxygen transported by haemoglobin.
Name this effect and explain why it occurs

A

Bohr shift
Reduces affinity of haemoglobin for oxygen
And the formation of haemoglobinic acid occurs , it prevents the fall in pH

37
Q

Outline how the difference in lumen size between arteries and veins is related to their function

A

In arteries small lumen to maintain pressure

veins have a large lumen to provide friction because of low pressure

38
Q

What makes the lub noise in a heart

A

Closing of the atrio ventricular valve

39
Q

Explain why the blood offloads more oxygen to actively respiring tissues than to resting tissues

A

Higher levels of carbon dioxide produced

Lowered affinity of haemoglobin for oxygen

40
Q

VSD is a hole in the septum of the heart

Describe and explain why people with VSD can easily become tired

A

Blood leaks from left to right ventricle during ventricular systole
More oxygenated blood is delivered the lungs
Less deoxygenated blood is pumped around the body so less oxygen available for respiration

41
Q

Explain why the oncotic pressure of the blood depends only on the concentration of large plasma proteins

A

Large plasma proteins cannot leave the blood but other solutes can
The imbalance of large plasma proteins between blood and tissue fluids results in oncotic pressure

42
Q

A scientist planned to investigate the effect of pH on the activity of carbonic anhydrase
State 2 factors that the scientist would need to control during this investigation

A

Temperature

Enzyme concentration

43
Q

Human blood is maintained at a pH of 7.4 by reactions that occur in red blood cells
Explain how a pH of 7.4 is maintained

A

H+ reacts with haemoglobin to form haemoglobinic acid which lowers the pH
H+ + HCO3- = H2CO3 which lowers pH
H2CO3 dissociates raises the pH

44
Q

Suggest why reduced heart rate is sometimes seen in people who are very aerobically fit

A

Increased volume of ventricle

Increase thickness of heart muscle

45
Q

Describe how the structure of each type of blood vessel is adapted to its function

A

Artery carry blood away from the heart. It has a thick elastic layer which enables them to withstand pressure. It can stretch and recoil.
Collagen provides structure/support
Smooth muscle contracts and relaxes to change the size of the lumen.

Vein carry blood back to the heart. Thinner elastic layer, blood under less pressure. Has valves to prevent backflow of blood. More collagen than arteries to give structural support as large volume of blood is carried

Capillaries allow substances to be exchanged between blood and surrounding cells. Walls are one cell thick short diffusion distance. Only large enough to allow one RBC at a time.

46
Q

Which of the valves is pushed open by oxygenated blood entering a ventricle

A

bicuspid valve

two flaps

47
Q

Blood is sourced from right ventricle

Which valve does it go to? And where does the blood end up?

A

Right semilunar valve

Pulmonary Artery

A-Level OCR Biology (29 decks)

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