The Heart Flashcards
What is the cardiac muscle?
The thick muscular walls of the heart are called the cardiac muscle.
Cardiac muscle is mygoenic meaning it can contract and relat without nervous or hormonal stimulation.
Cardiac muscle never fatigues as long as it has a good oxygen supply
What do the coronorary arteries do?
Supply the cardiac muscle with oxygenated blood.
These branch off from the aorta.
If they become blocked cardiac muscle won’t receive oxygen, therefore will not be able to respire and the cells will die. This results in myocardial infarction (a heart attack)
What are the four chambers of the heart?
2 atria - left and right atrium
2 ventricles - left and right ventricles
What are the atria
Thinner muscular walls
No not need to contract as hard as they are not pumping the blood far (only to the ventricles)
They have elatic walls to stretch when blood enters
What are the ventricles
Thicker muscular walls to enable bigger contraction.
This creates a higher blood pressure to enable blood to flow longer distances (to the lungs and the rest of the body)
The right ventricle
Pumps blood to the lungs. This needs to be at a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange
Therefore, thinner muscular wall in comparison to the left ventricle
What is the function of the left ventricle
Pumps blood to the body. This needs to be at a higher pressure to ensure blood reaches all the cells in the body.
Therefore, much thicker muscular wall in comparison to the right ventricle to enable larger contractions of the muscle to create higher pressure.
What are the two veins in the heart?
Vena Cava
(Means body vein) Carries deoxygenated blood from the body into the right atrium
Pulmonary Vein
Carries oxygenated blood from the lungs to the left atrium
What are the two arteries in the heart
Pulmonary artery - carries deoxygenated blood from the right ventricle to the lungs to become oxygenated.
Aorta - carries oxygenated blood from the left ventricle to the rest of the body
What are the valves in the heart
Semi lunar valves
In aorta and pulmonary artery
Atrioventricular valves
Between atria and ventricles
Bicuspid (left side)
Tricuspid (right side)
What do valves do
Open when pressure is higher behind the valve.
Close when pressure is higher in front of the valve
Prevent backflow of blood
What is the septum
Separates the deoxygenated and oxygenated blood
Maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiring cells.
What are the four types of blood vessels?
Arteries carry blood Away from the heart and into arterioles.
The arterioles are smaller than arteries and connect to the capillaries.
The capillaries connect the arterioles to the veins.
The veins carry blood back into the heart (hint to remember- velNs carry blood IN).
Properties of arteries - mucsle layer
Thicker than veins so that constriction and dilation can occur to control volume of blood.
Properties of arteries elastic layer
Thicker than veins to help maintain blood pressure. The walls can stretch and recoil in response to the heart beat.
Wall thickness of arteries
Thicker wall than veins to help
prevent the vessels bursting due to the high pressure.
Do arteries have valves
No
Muscle layer in the veins
Relatively thin so it cannot control the blood flow.
Elastic layer in the veins
Relatively thin as pressure is much lower
Wall thickness in the veins
Thin as the pressure is much lower so there is low risk of bursting. The thinness means the vessels are easily flattened, which helps the flow of blood up to the heart.
Do veins have valves
Yes
What are capillaries
Capillaries form capillary beds as exchange surfaces, which are many branched capillaries. These all have a narrow diameter to slow blood flow. Red blood cells can only just fit through and are squashed against the walls, and this maximises diffusion.
Muscle layer in arterioles
Thicker than in arteries to help restrict blood flow into the capillaries.
Elastic layer in arterioles
Thinner than in arteries as the pressure is lower
Wall thickness in arterioles
Thinner as pressure is slightly lower.
Muscle and elastic layer in capilaries
None
Wall thickness of capilaries
One cell thick consisting of only a lining layer. This provides a short diffusion distance for exchanging materials between the blood and cells
What are the three stages in the caridac cycle
Diastole
Atrial systole
Ventricular systole
What is diastole
The atria and ventricular muscles are relaxed
This is when blood will enter the atria via the vena cava and pulmonary vein.
The blood flowing into the atria increases the pressure within the atria
What is atrial systole
The atria muscular walls contract, increasing the pressure further. This causes the atrioventricular valves to open and blood to flow into the ventricles.
The ventricular muscular walls are relaxed
(ventricular diastole)
What is ventricular systole
After a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria. This causes the atrioventricular valves to close and the semi-lunar valves to open.
The blood is pushed out of the ventricles into the arteries (pulmonary and aorta)
What is cardiac output
The volume of the blood which leaves one ventricle in one minute is the cardiac output.
Equation for cardiac output
Cardiac output = heart rate X stroke volume
What is heart rate and stroke volume
Heartrate = beats of the heart per minute
Stroke volume = volume of the blood that leaves the heart each beat
When do the atriventricular valves open and close
Atriventricular valves open when the pressure is higher in the atria compared to the ventricles.
They close when the pressure is higher in the ventricles compared to the atria
When do the semilunar valves open and close?
Semi-lunar valves open when the pressure is higher in the ventricle compared to the arteries (pulmonary artery or aorta).
They close when the pressure is higher in the arteries compared to the ventricles
What happens in atrial systole
Atria contracts
Volume of atria decreases
Pressure in atria increases
Volume of ventricles increases
Pressure in ventricles decreases
What happens in ventricle systole
Ventricle contracts
Volume of atria doesnt change
Pressure in atria doesnt change
Volume of ventricles decreases
Pressure in ventricles increases
What happens in diastole
Both chambers relax
Volume of atria increases
Pressure in atria increases
Volume of ventricles slow increase
Pressure in ventricles slow increase
Describe the mechanism by which an arteriole regulates blood
flow to capillaries. (2 marks)
- The smooth muscle within the arteriole contracts.
- This contraction leads to the narrowing or constriction
of the arteriole lumen.
Which blood vessel transports blood at the lowest pressure
Capillary
Describe function of coronary arteries
Carry oxygen/glucose
To heart muscle
Name the blood vessel that carries deoxygenated blood from the
body into the heart. (1 mark)
Vena cava
Name the blood vessel that carries blood from the heart to the
kidneys.
Renal artery
Explain how the heart contributes to the formation of tissue fluid
- Contraction of ventricle(s) produces high blood / hydrostatic pressure;
- (This) forces water (and some dissolved substances) out (of blood capillaries);
Suggest how lymphatic system obstruction leads to the development of lymphoedema, a condition characterised by swelling in the legs
Excess tissue fluid cannot be reabsorbed so builds up
Explain why individuals with significantly elevated ventricular blood pressure experience the build up of tissue fluid outside their blood capillaries? (2 marks)
More fluid forced/filtered out of capillary/blood (due to high pressure);
Less return of fluid (into capillary/blood) due to pressure
Or
Lymph(atic) (system) cannot drain away all excess fluid;
Suggest how does the dilation of blood vessels, induced by certain medications aimed at lowering high ventricular blood pressure, lead to a reduction in ventricular blood pressure?
- Larger lumen/volume (of blood vessels);
- Reduces (blood) pressure (in blood vessels);
- Less friction/resistance (in blood vessels);
In an individual with normal cardiovascular function, blood flows unidirectionally through the heart. Give two ways by which this directional flow is maintained.
Pressure gradient / moves from high to low pressure;
2. Valves stop backflow
The aorta has structural features adapted to is function.
State four of the structural features and explain how they relate to its function. (4 marks)
- Elastic tissue to allow stretching smoothes outflow of blood;
- (Elastic tissue) stretches when ventricles contract
- Muscle for contraction;
- Thick wall withstands pressure;
- Smooth endothelium reduces friction;
- Semi-lunar valve prevents backflow.
Why is the mammals circulatory system called a closed, double circulatory system
Closed = the blood remains within the blood vessels.
Double circulatory system = the blood passes through the heart twice in each circuit. There is one circuit which delivers blood to the lungs and another circuit which delivers blood to the rest of the body.
Why do mamals require a double circulatory system
Mammals require a double circulatory system to manage the pressure of blood flow.
The blood flows through the lungs at a lower pressure. This prevents damage to the capillaries in the alveoli and also reduces the speed at which the blood flows, enabling more time for gas exchange.
The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that the blood reaches all the respiring cells in the body.
What are the blood vessels attatched to the heart
(vena cava, aorta, pulmonary artery and pulmonary vein
What are the blood vessels attatched to the lungs
(pulmonary artery and pulmonary vein)
What are the blood vessels attatched to the kidney
(Renal artery and renal vein
What is tissue fluid
Fluid containing water, glucose, amino acids, fatty acids, ions and oxygen which batches the tissue.
How is tissue fluid formed
• Capillaries have small gaps in the walls so that liquid and small molecules can be forced out
• As blood enters the capillaries from the arterioles, the smaller diameter results in high hydrostatic pressure so water, glucose, amino acids, fatty acids, ions and oxygen are forced out. This is called ultrafiltration.
What remains in the capillary during tissue formation
• Red blood cells
• Platelets
• Large proteins
How are useful molecules absorbed into the capillaries after tissue formation
Large molecules remain in the capillaries and therefore create a lowered water potential.
Towards the venule end of the capillaries, the hydrostatic pressure is lowered due to the loss of liquid but water potential is very low.
Water reenters the capillaries by osmosis.
Where does tissue fluid that hasnt been absorbed go to
Not all liquid will be reabsorbed by osmosis as equilibrium will be absorbed
The rest of the tissue fluid is absorbed into the lymphatic system and eventually drains back into the bloodstream near the heart.
What is the lymphatic system
Lymphatic system has lymph vessels which are very similar to veins because they contain valves. And they surround the blood vessels.
So any liquid that doesnt get reabsorbed back into the capillaries will get reabsorbed into the lymphatic systems called lymph. Eventually the liquid will travel back into the blood.
Give the pathway a red blood cell takes when travelling in the human
circulatory system from a kidney to the lungs
1.Renal vein;
2. Vena cava to right atrium;
3. Right ventricle to pulmonary artery
Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system.
Plasma) proteins remain;
2. (Creates) water potential gradient
OR
Reduces water potential (of blood);
3. Water moves (to blood) by osmosis;
4. Returns (to blood) by lymphatic system;
Explain how an arteriole can reduce the blood flow into capillaries.
Muscle contracts;
2. Constricts/narrows arteriole/lumen;
What can you conclude from the appearance of valves in the image above about heart muscle activity and blood movement between:
(Ventricles and arteries)
1. Ventricle (muscles) relaxed
OR
Arteries recoiled;
Describe the advantage of the Bohr effect during intense exercis
Increases dissociation of oxygen;
- For aerobic respiration at the tissues/muscles/cells
Anaerobic respiration delayed at the tissues/muscles/cells
Less lactate at the tissues/muscles/cells;
Describe and explain the effect of increasing carbon dioxide concentration
on the dissociation of oxyhaemoglobin
ncreases/more oxygen dissociation/unloading
2. OR
Deceases haemoglobin’s affinity for O2;
Accept more readily
Accept releases more O2
(By) decreasing (blood) pH/increasing acidity;
Binding of one molecule of oxygen to haemoglobin makes it easier for the second oxygen molecule to bind. Explain why
Binding of the first oxygen changes tertiary/quartenary structure of haemoglobin
Thie creates another binding site/ uncloves another iron haemoglobin group to bind with
E xplain the role of the heart in the formation of tissue fluid.
Contraction of ventricle(s) produces high
blood / hydrostatic pressure;
2. (This) forces water (and some dissolved
substances) out (of blood capillaries);
Lymphoedema is a swelling in the legs which may be caused by a
blockage in the lymphatic system.
Suggest how a blockage in the lymphatic system could cause
lymphoedema
Excess tissue fluid cannot be (re)absorbed / builds
up;
