T4 - Exchange and Transport Flashcards
Name the chambers of the heart
Top - left and right atrium
Bottom - left and right ventricle
Name the chamber that receives deoxygenated blood from the body
Right atrium
Name the chamber that receives oxygenated blood from the lungs
Left atrium
Name the chamber that pumps deoxygenated blood to the lungs
Right ventricle
Name the chamber that pumps oxygenated blood to the body
Left ventricle
Name the structure that separates the two sides of the heart?
Septum
Name the blood vessel that carries deoxygenated blood to the lungs
Pulmonary artery
Name the blood vessel that carries deoxygenated blood to the right atrium
Vena cava
Name the blood vessel that carries oxygenated blood to the left atrium
Pulmonary vein
Name the blood vessel that carries oxygenated blood to the body
Aorta
Explain why the ventricles have thicker walls than the atria
More muscle to pump with more force, so blood pressure is higher to pump blood out of the heart into the arteries
Explain why the left ventricle has a thicker wall than the right ventricle
Right ventricle pumps blood shorter distance to lungs.
Left ventricle has more muscle to pump with more force, so blood pressure in aorta is higher so blood can travel greater distance around the body.
Name the valves found in the heart
Atrioventricular valves (tricusid on right, bicuspid on left)
State the function of the atrioventricular valves
Prevent backflow of blood from ventricles to atria
Explain the consequences of leaky atrioventricular valves
There will be backflow of blood into the atrium during
ventricular contraction, so blood pressure in the atrium rises and lowers in the ventricle
Therefore less oxygenated blood flow into aorta to muscles, so there is less aerobic respiration in muscles cells.
Results in less ATP being produced, so less energy is released for contraction of muscle cells.
This results in muscle weakening, shortness of breath, heart rate increasing to compensate.
Explain the consequences of atrial or septal defects (holes in septum)
Septal defect results in mixing of oxygenated blood (left side of heart) with deoxygenated blood (right side).
Therefore blood flowing to muscles via aorta contains less oxygen, resulting in less aerobic respiration in muscles cells.
Results in less ATP being produced, so less energy is released for contraction of muscle cells.
This results in muscle weakening, shortness of breath, heart rate increasing to compensate.
State the function of arteries
Carry oxygenated blood from heart to body (except pulmonary which carries deoxygenated to lungs)
Why do arteries have thick muscluar walls?
Withstand high blood pressure without bursting
Why do arteries walls contain elastic fibres?
Allows them to stretch with every pulse of blood,
and to maintain high blood pressure during diastole.
Why do arteries have a small lumen?
Maintains high blood pressure
State the function of plasma
Transport of water soluble substances including glucose, amino acids, and metabolic products including carbon dioxide, urea.
Acts as a buffer to pH changes.
Helps to maintain body temperature as transfers heat around body.
Contains platelets and clotting factors involved in blood clotting.
List the main functions of the blood
Transport
Defence
Formation of lymph and tissue fluid
State the function of platelets
Blood clotting; to prevent too much bloos loss after injury and
prevent pathogens entering the blood.
Name the clotting factor that changes prothrombin into thrombin
Thromboplastin
Name the clotting factor that changes fibrinogen into fibrin
Thrombin
Explain the clotting cascade
Platelets stick to damaged endothelium and release clotting factors, including thromboplastin
Thromboplastin catalyses change of prothrombin into active form - thrombin.
Thrombin catalyses change of soluble fibrinogen into insoluble fibrin, which forms a mesh to cover the wound.
State the meaning of the term atherosclerosis
Hardening of the arteries
Describe how atherosclerosis develops
Damage to the endothelial lining of an artery is caused by hypertension/ smoking.
Macrophages move into the artery wall at site of damage, causing LDL cholesterol to build up inside the artery wall.
Atheroma (plaque) forms, which is hardened by build up of calcium salts.
This causes the wall to harden, and lumen to narrow, raising blood pressure, restricting blood flow or blocking the artery.
What factors increase the risk of atherosclerosis?
Avoidable - smoking, diet high in saturated fat
Unavoidable - age: the older you are, the higher the risk, gender: males more at risk than females, genetic factors
List the health effects of an atheroma
Aneurysm, raised blood pressure, angina, heart attack, stroke
What is an aneurysm?
Swelling of the artery walls
Explain the cause and consequences of an aneurysm
Cause
Atheromas weaken the artery walls.
Due to increased blood pressure caused by the blockage, these weakened points swell to form a balloon-like blood-filled structure called an aneurysm.
Consequence
Aneurysms frequently burst, leading to haemorrhage.
This then leads to a loss of blood in that region of the body.
What is angina?
Chest pain
Explain how angina is caused
Narrowing of the coronary artery due to an atheroma reduces blood flow,
Therefore there is reduced oxygen supply to the heart muscle.
This results in the heart muscle respiring anaerobically, which results in a build up of lactic acid.
Lactic acid triggers nerve endings to signal pain.
What is an ischaemic stroke?
Interruption to the blood supply to the brain e.g. due to blood clot in an artery in the brain caused by an atheroma.
Explain how coronary heart disease leads to a heart attack.
Damage to the endothelial lining of coronary artery is caused by hypertension/ smoking.
Macrophages move into the artery wall at site of damage, causing LDL cholesterol to build inside the artery wall.
Atheroma (plaque) forms, which is hardened by build up of calcium salts.
This causes the wall to harden, and lumen to narrow, raising blood pressure, and restricting blood flow to cardiac muscle.
Thrombus (blood clot) formation can block the coronary artery, stopping blood flow to cardiac muscle below the blockage.
This means cardiac muscle cells cannot respire as no oxygen or glucose supply.
Cells die, muscle cannot pump, which leads to heart attack.
Explain how the structure of an artery is related to its function
Arteries transport blood under high pressure to body tissues so they have:
Think muscular walls to withstand high pressure without bursting
Elastin fibres in wall allow them to stretch with every pulse of blood and recoil to maintain high blood pressure during diastole
Small lumen maintain high blood pressure
State the function of capillaries
Site of exchange of nutrients and metabolic waste products via diffusion
Why are capillaries only one cell thick?
Short diffusion distance increases rate of diffusion
Why are capillaries numerous and highly branched?
Provides larger surface area for maximum rate of diffusion
Explain how the structure of capillaries are related to their function
Capillaries are the site of exchange of nutrients and metabolic waste products via diffusion
Provides larger surface area for maximum rate of diffusion
Short diffusion distance increases rate of diffusion
State the function of veins
Carry deoxygenated blood under low pressure to heart from body except pulmonary which carries oxygenated from lungs
Why do veins have the largest lumen?
Blood pressure is low so larger lumen does not restrict the blood flow
Why do veins have thin muscular wall with few elastic fibres
Blood pressure is very low so will not burst
Why do veins have valves
Prevents backflow of blood
What type of circulatory system is found in mammals?
Double
What type of circulatory system is found in fish?
Single
What are the advantages of a double circulatory system?
Keeps oxygenated blood separate so systemic side can carry blood with higher partial pressure of oxygen
Two circuits means blood can be pumped at different pressures
Pulmonary circuit carries blood at lower pressure so it doesn’t damage blood capillaries in lungs and blood flows slower so more time for oxygen to diffuse in
Systemic circuit can carry blood at higher pressure so it can flow a greater distance around the body
Name the three stages of the cardiac cycle
Diastole
Artial systole
Ventricular systole
What happens during diastole
Heart is relaxed, passivly refills with blood
What happens during atrial systole
Atria contract
causing blood pressure in atria to increase
which forces AV valves open
so blood flows into ventricles
What happens during ventricular systole
Ventricles contract and atria relax
Causing blood pressure in ventricles to increase
which forces AV valves to close and semilunar to open
so blood flows into aorta and pulmonary artery
Name the pace maker cells within the heart
Sinoatrial node SAN
State what is meant by the myogenic stimulation of the heart
The SAN can initiate a heart beat without stimulation by the autonomic nervous system
Where is the SAN
Wall of right atrium
Explain how the cardiac cycle is stimulated
SAN initiates a wave of depolarisation which spreads across both atria causing the atria to contract (artial systole)
Layers of non conducting tissue between atria and ventricles stops wave spreading down the ventricles
AVN initiates depolarisation after delay of 0.1 - 0.2 s to allow time for atrial systole to complete and ventricles to fill
Electrical impulses travels down bundle of HIS then along the purkinje fibres from apex upwards through ventrioles causing ventricles to contract (ventricular systole)
What is an ECG?
Electrocardiogram - graph showing electrical activity inside the heart
On the ECG trace what to the letters represent
P wave - atrial depolarisation
QRS complex - ventricular depolarisation
T wave - ventricular repolarisation
What would an ECG trace showing normal sinus rythem show?
QRS complexes normal and evenly spaced
heart rate 60-100 bpm
What is bracycardia
Heart rate too slow
What would an ECG trace showing bracycardia show
QRS complexes normal and evenly stacked
heart rate less than 60bpm
Explain why athletes have heart rates lower than 60bpm but do not have bradycardia
Training increases size and strength of heart muscles
Muscles can therefore contract with more force per beat so they have a higher stroke volume
Heart therefore can beat less often but acheive same cardiac output as average adult
Suggest a cause of bradycardia
Damage to heart muscle tissue due to ageing heart disease/ heart attack
beta blockers
what is tachycardia
heart rate too fast
What would an ECG trace showing tachycardia show?
QRS complex normal and evenly spaced
heart rate over 100bpm
Give a risk factor for tachycardia
Smoking heavily
Taking illegal drugs e.g. cocaine
Cornary artery disease
Explain the consequences of tachycardia
Heart beats too fast and ventricle do not fill properly
Less oxygenated blood pumped to body cells
Less respiration, resulting in less ATP and therefore less released
Results in fatigue, shortness of breath and fainting
State what is meant by fibrillation
Uncoordinated contractions of either atria or ventricles
What is arrhythmia
Irregular heartbeat
What would an ECG trace showing arrythmia show?
All complexes/waves normal but irregularly spaced
List the the four components of the blood
Plasma
Erthrocytes
leuocytes
Platelets
State the function of an erythrocyte
Transport oxygen as oxyheamogloblin to body cells
Explain how the structure of an erythrocyte is adapted to its function
Millions of molecules of heamogloblin to bind to oxygen and form oxyheamogloblin for transport
No nucleus so more space to carry more oxyheamogloblin
Biconcave which gives large surface area to increase rate of absorption of oxygen
Small and flexible (7 micrometer diameter) to squeeze through capilaries
Name the different types of leuocytes
Neutrophils
macrophages
eosinophils
monocytes
lymphocytes (B and T)
Which leuocoytes is the most abundent
Neutrophile
State the function of monocytes
Engulf and digest pathogens by phagocytosis
State the function of neutrophills
Engulf and digest pathogens by phagocytosis
State the function of eosinophils
Involved in allergic responses and protection against viruses
Describe the functions of lymphocytes
Part of specific (adaptive) immune response
Recognise antigens on pathogens
T-lymphocytes - Helper t cells activate B lymphocytes and cytotoxins (killer) T cells which kill viral infectes/cancer cells
B-Lymphocytes produce antibodies and antitoxins
