B4 Organizing animals and plants Flashcards
what are the adaptations of red blood cells?
- Biconcave discs, increased surface area to volume ratio for diffusion
- Packed with haemoglobin that binds to oxygen
- No nucleus, more space for haemoglobin which carries oxygen
describe the function and structure of arteries
- Carry blood away from your heart to the organs of your body
- This blood is usually bright-red oxygenated blood
- Thick layer of muscle and elastic fibres
- Small lumen
Why is it very dangerous if an artery is cut?
The blood in the arteries is under pressure, so blood will spurt out rapidly every time the heart beats if an artery is cut
describe the function and structure of veins
- Carry blood away from the organs towards your heart
- This blood is usually low in oxygen and therefore a deep purple-red colour
- Veins do not have a pulse.
- Thinner walls than arteries and often have valves to prevent the backflow of blood
- Valves open as the blood flows through them towards the heart, but if the blood starts to flow backwards the valves close and prevent a backflow of blood
- Large lumen
describe the function and structure of capillaries
- Form a huge network of tiny vessels linking the arteries and the veins
- Narrow with very thin walls (walls a single cell thick), enables substances (such as glucose and oxygen) to diffuse easily out of your blood and into your cells
- Tiny vessel with narrow lumen
The blood plasma as a transport medium
The plasma transports all of the blood cells and some other substances around the body:
- waste carbon dioxide produced by the cells is carried to the lungs
- urea formed in your liver from the breakdown of excess proteins is carried to your kidneys where it is removed from the blood to form urine
- the small, soluble products of digestion pass into the plasma from the small intestine and are transported to the individual cells
What is the function of heart valves?
Prevent back flow of blood
What is the double circulatory system?
One part carries blood between heart and lungs; the other carries blood between heart and other organs
what is the function of the vena cava?
Brings deoxygenated blood into the heart through the right atrium
what is the function of the pulmonary vein?
Brings oxygenated blood from the lungs into the left atrium
what is the function of the atria?
Top chambers of the heart where the blood enters; contract together to force blood down into the ventricles
what’s the function of ventricles?
Contract and force blood out of the heart
what is the function of the right ventricle?
Forces deoxygenated blood to the lungs in the pulmonary artery
what is the function of the left ventricle?
Pumps oxygenated blood around the body in the aorta
what is the function of the pulmonary artery?
Takes deoxygenated blood to the lungs
what is the function of the aorta?
Carries oxygenated blood around the body
Why is the muscle wall of the left ventricle thicker than the right ventricle?
To generate more pressure to force blood all over the body
How do stents work?
- Used to keep narrow or blocked arteries open
- A stent is a metal mesh that is placed in the artery, a tiny balloon is inflated to to open up the blood vessel and the stent at the same time
- The balloon is deflated and removed but the stent remains in place, holding the blood vessel open
- The blood in the coronary artery flows freely
- Many stents also release drugs to prevent the blood clotting
How do statins work?
- Reduce cholesterol levels in the blood, this slows down the rate at which fatty material is deposited in the coronary arteries
- Reducing the risk of coronary heart disease
What are platelets?
Small fragments of cells that start the clotting process at wound sites
State differences in the blood flowing in arteries and veins
Arteries:
- oxygenated blood
- contains more nutrients
- contains less waste
Veins:
- deoxygenated blood
- contains less nutrients
- contains more waste
Why can substances diffuse easily between capillaries and the cells?
Capillary walls are very thin, only one cell thick, which provides short diffusion distances
What is the function of xylem?
Transports water and mineral ions from roots to other parts of the plants
What is the function of phloem?
Transports dissolved sugars from leaves to the rest of the plant
What is transpiration?
Loss of water vapour by evaporation from the leaf surface through the stomata
Describe the transpiration stream
Constant movement of water through xylem from roots to leaves
Factors affecting rate of transpiration
- Temperature
- Humidity
- Air flow
- Light intensity
How does temperature affect the rate of transpiration?
- Higher temperature increases the rate of transpiration, because the molecules move faster as the temperature increases, so diffusion occurs more rapidly
- The rate of photosynthesis also increases as the temperature increases, so more stomata will be open for gas exchange to take place
How does humidity affect the rate of transpiration?
- Higher humidity decreases the rate of transpiration
- Humidity is a measure of moisture (water vapour) in the air; when the air is saturated with water vapour the concentration gradient is weaker so less water is lost
How does wind or air flow affect the rate of transpiration?
More wind increases the rate of transpiration because it maintains a steep concentration gradient, so diffusion occurs rapidly
How does light intensity affect the rate of transpiration?
- Greater light intensity increases the rate of transpiration
- Increased light intensity increases the rate of photosynthesis, so more stomata open up to let in carbon dioxide, the rate at which water is lost by evaporation and diffusion increases, therefore rate of transpiration increases
Name the equipment used to estimate transpiration rate
Potometer
What is the difference between translocation and transpiration?
Transpiration is the loss of water vapour by evaporation from the leaf surface through the stomata. Translocation is the movement of sugars from the leaves to the rest of the plant through the phloem.
define the term double circulatory system
- blood is pumped to the lungs by the right side of the heart
- blood is pumped to the body by the left side of the heart
explain how having only one ventricle makes the circulatory system less efficient than having two ventricles
- oxygenated and deoxygenated blood mixes
- so less oxygen reaches the body’s cells
how does an artificial pacemaker work?
placed on the right atrium, sends strong, regular, electrical signals to the heart to stimulate it to beat properly
describe how the structure of an artery is different from the structure of a vein
arteries have thick walls contain muscle and elastic fibres, veins have thin walls
arteries have a small lumen, veins have a large lumen
