Transport in Animals Flashcards
What are the left and right sides of the heart separated by?
a wall of muscular tissue called the septum
How does the heart receive its blood supply?
through arteries on its surface called coronary arteries
Why is it important that the coronary arteries remain clear of plaques?
as this could lead to angina or a heart attack
Why does the heart require its own blood supply?
it is a muscle and so requires its own blood supply for aerobic respiration
Why are valves important?
- they keep blood flowing forward in the right direction and stop it flowing backwards
- they also maintain the correct pressure in the chambers of the heart
What are the names of the two blood vessels taking blood away from the heart?
pulmonary artery and aorta
What is the name of the two blood vessels bringing blood to the heart?
vena cava and pulmonary vein
What valve separates the left ventricle and aorta?
aortic valve
What valve separates the left atrium and the left ventricle?
the mitral valve - the bicuspid valve
What valve separates the right ventricle and the pulmonary artery?
pulmonary valve
What valve separates the right atrium and right ventricle?
the atrioventricular valve - the tricuspid valve
When do valves close?
when the pressure of blood in front of them is greater than the pressure behind them
When do valves open?
when the pressure of blood behind them is greater than the pressure in front of them
Why is the septum important?
it ensures blood doesn’t mix between the left and right sides of the heart
Arteries
transport blood away from the heart (usually at high pressure) to tissues
Arterioles
arteries branch into narrower blood vessels called arterioles which transport blood into capillaries
Veins
transport blood to the heart (usually at low pressure)
Venules
these narrower blood vessels transport blood from the capillaries to the veins
What are the three layers of the artery wall?
tunica adventitia/externa, tunica media and tunica intima
What is the tunica intima made up of?
an endothelial layer, a layer of connective tissue and a layer of elastic fibres
What is the structure of the endothelium?
the endothelium is one cell thick and lines the lumen of all blood vessels - it is very smooth and reduces friction for free blood flow
What is the tunica media made up of?
smooth muscle cells and a thick layer of elastic tissue
Why do arteries have a thick tunica media?
- the layer of muscle cells strengthen the arteries so they can withstand high pressure; it also enables them to contract and narrow the lumen for reduced blood flow
- the elastic tissue helps to maintain blood pressure in the arteries; it stretches and recoils to even out any fluctuations in pressure
Describe the type of circulatory system of a bird
double and closed circulatory system
Describe how oncotic pressure is established
- large plasma proteins are too large to fit through fenestrations in capillary endothelial wall
- so remain in blood, lowering water potential and generating a high hydrostatic pressure
- water moves into blood by osmosis
Explain how haemoglobin acts as a buffer
- CO2 and water form carbonic acid
- carbonic acid dissociates giving H+
- H+ binds to haemoglobin
- so CO2 can be carries as HCO3 -
What does atrial fibrillation look like on an ECG?
- no visible P waves
- irregular QRS complexes
- a lot more additional smaller waves of differing sizes
What do the walls of arteries contain so that they can stretch and recoil to maintain blood pressure?
a lot of elastic fibres
How much muscle is in the walls of the venules?
little muscle
Do the walls of arteries contain a lot of muscle fibres to contract and generate pressure in the blood?
No
What is an ectopic heartbeat?
extra heartbeats outside of the normal rhythm
Why do multicellular organisms require transport systems?
- large size (small surface area to volume ratio), subsequently high metabolic rates
- demand for oxygen is high, so need a specialised system to ensure a strong supply to all respiring tissues
Summarise the different types of circulatory system
- Open: blood can diffuse out of vessels e.g. insects
- Closed: blood confined to vessels e.g. fish, mammals
- Single: blood passes through pump once per circuit of the body
- Double: blood passes through heart twice per circuit of the body
Relate the structure of arteries to their function
Thick, muscular walls to handle high pressure without tearing. Elastic tissue allows recoil to prevent pressure surges. Narrow lumen to maintain pressure.
Relate the structure of veins to their function
Thin walls due to lower pressure. Require valves to ensure blood doesn’t flow backwards. Have less muscular and elastic tissue as they don’t have to control blood flow.
Relate the structure of capillaries to their function
- walls only one cell thick; short diffusion pathway
- very narrow, so can permeate tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues
- numerous and highly branched, providing a large surface area
Relate the structure of arterioles and venules to their function
- branch off arteries and veins in order to feed blood into capillaries
- smaller than arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels
What is tissue fluid?
A watery substance containing glucose, amino acids, oxygen, and other nutrients. It supplies these to cells, while also removing any waste materials.
What types of pressure influence formation of tissue fluid?
- Hydrostatic pressure = higher at arterial end of capillary than venous end
- Oncotic pressure = changing water potential of the capillaries as water moves out, induced by proteins in the plasma.
