heart + haemoglobin Flashcards

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1
Q

structure of haemoglobin

A
  • large protein with quaternary structure
  • 4 polypeptide chains
  • each chain has a haem group, that contains an iron ion each

oxygen binds to haemoglobin to make oxyhemoglobin
reversible reaction - can dissociate

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2
Q

in high pO2

A

haemoglobin has a high affinity

more oxygen loaded to form oxyhaemoglobin

blood is saturated with oxygen
eg in the lungs

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3
Q

in low pO2

A

haemoglobin has a low affinity

more oxygen unloaded

low saturation of oxygen in blood
eg in repairing tissues

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4
Q

Bohr Effect

A

curve shifts right in high pCO2
- saturation of blood with oxygen lower for a given pO2

  • cells release CO2 when they respire, increases partial pressure of CO2
  • oxygen increases rate of unloading, more O2 released
  • allows respiring cells to get more oxygen
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5
Q

why is the curve s shaped?

A

when haemoglobin combines with first oxygen, it alters shape
makes it easier for other molecules to join

but when the haemoglobin gets more saturated, it’s harder for oxygen to bind

creates shallow curve at each end, steep in the middle where its easiest to bind

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6
Q

organisms living in low concentrations of O2

A

haemoglobin has a higher affinity for oxygen - more loading
curve shift left

blood in more saturated with O2 for a given partial pressure than human

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7
Q

organisms with high O2 demand (eg active)

A

haemoglobin has lower affinity for oxygen
curve shifts right

blood less saturated for a given partial pressure than humans
more unloaded for cells to respire

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8
Q

Adaptations of arteries

A

Carry blood from heart - body
Oxygenated except pulmonary

Thick muscular walls and elastic tissue - maintain high pressure
Endothelium folded - can stretch, maintain pressure

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9
Q

Adaptations of veins

A

Carry blood back to heart
Deoxygenated except pulmonary

Wide lumen
Little muscular tissue - blood under low pressure
Valves to stop back flow
Flow helped by contraction of muscles surrounding

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10
Q

Adaptations of arterioles

A

Arteries divide into arterioles
Form a network
Carry blood to capillaries

Elastic walls - changes in pressure
Muscular walls - can constrict or relax to divert blood flow

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11
Q

Adaptations of capillaries

A

Allow for exchange of molecules between blood and cells
Make up capillary beds
Adapted for efficient diffusion

One cell thick walls - short diffusion distance
Close to cells
Many of them - large surface area
leaky - allow fluid out

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12
Q

Formation of tissue fluid

A

Arteriole end - higher hydrostatic pressure
Forces fluid out of leaky capillaries (into spaces around cells)
Fluid loss lowers hydrostatic pressure
Venule end - lower hydrostatic pressure

Loss of fluid = lower water potential at venule end (higher concentration of plasma proteins)
Some fluid moves back in by osmosis

Excess fluid drained by lymphatic system and dumped back into the circulatory system

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13
Q

Adaptations of the heart

A

Left ventricle thicker (more muscular tissue)
- needs to pump blood around body (right just to lungs)

Ventricles thicker then atria
- pump blood out of heart not just to ventricles

Atrioventricular valve- stop back flow into atria
Semilunar valves - stop back flow in heart (in arteries)

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14
Q

How do valves work?

A

Determined by pressure
Means blood flows in one direction

Higher pressure behind = opened
Higher pressure in front = closed

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15
Q

Cardiac cycle

A

Blood enters atria
Atria contract - decreasing volume
Pressure in atria increases
Forces atrioventricular valve open - blood flows into ventricles
Atria relax and ventricle contract
Decreases volume and increase pressure
Pressure higher in ventricles so AV valve shuts
Pressure higher then aorta and pulmonary artery - SL valves open
Blood forced into arteries
Higher pressure in arteries closed SL valves
Atria and ventricles relax
Blood enters again through vena cava and pulmonary vein

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16
Q

Cardiac cycle on a graph

A

Increases in pressure when it contracts
Volume decreases

When relaxed volume increases
So pressure decreases

17
Q

What causes a myocardial infarction?

A

Heart muscle supplied with blood through coronary arteries
Delivers oxygen so heart muscle can respire

Can become blocked, cut off so heart receives no blood or oxygen
Causes damage and death of heart muscle

18
Q

atheroma

A

damage to endothelium = lipids and white blood cels clump under lining

build up and harden = fibrous plaque

partially blocks lumen of artery and restricts blood flow
= higher blood pressure

19
Q

aneurysm

A

atheromas weaken arteries
create high blood pressure

blood pushed through = swelling
can burst

20
Q

thrombosis

A

atheromas can rupture endothelium
damage artery wall = blood clot

can block lumen

21
Q

Risk factors for cardiovascular disease

A

High blood cholesterol / poor diet
- causes fatty deposits that form atheromas
- lead to increased blood pressure and clots
- can cause myocardial infarction

Smoking
- nicotine increases blood pressure
- carbon monoxide reduces carrying ability of haemoglobin, less oxygen in blood

High blood pressure
- increases risk of damage to artery walls
- could cause atheromas and clots
- myocardial infarction

As well as anything that increases blood pressure eg obesity, not exercising