transport in animals

what is the main component of liquid blood plasma

lipid plasma consists of 90% water with suspended blood cells and dissolved substances

what role do blood capilarieswhat causes re play in the body

blood capillaries supply cells with oxygen ,glucose amino acids etc and remove waste products of metabolism such as co2 and urea

what causes the filtration of blood plasma t the arterioles end of a capillary

The high blood pressure due to heart contraction causes the filtration of blood plasma.

. What substances pass through the permeable capillary walls to form tissue fluid?

• Smaller molecules such as water, ions, glucose, amino acids, and minerals pass through the capillary walls to form tissue fluid.

Why do blood cells and large plasma proteins remain in the capillary?

• Blood cells and large plasma proteins remain in the capillary because they are too large to pass through the permeable walls.

What is tissue fluid, and what does it contain?

• Tissue fluid is a watery fluid that surrounds body cells and contains glucose, amino acids, fatty acids, oxygen, and ions.

What happens to excess tissue fluid?

• Excess tissue fluid is drained into the lymphatic capillaries, forming lymph.

What is the role of arterioles in blood flow?

• Arterioles control how much blood passes into an organ by contracting or relaxing their smooth muscle walls.

. Why can’t water move back into capillaries on the arteriole side?

• Water cannot overcome the high hydrostatic pressure on the arteriole side.

How does carbon dioxide move back into the blood from tissue fluid?

• Carbon dioxide moves down its concentration gradient into the capillaries, where it is carried away in the blood.

What causes the osmotic uptake of water into capillaries?

• The large plasma proteins that remain in the blood reduce the water potential (make it more negative), causing osmotic uptake of water into the capillaries.

Why does water re-enter capillaries at the venule end?

• The reduced blood pressure at the venule end means that the osmotic potential is greater than the blood pressure, allowing water from the tissue fluid to re-enter by osmosis.

Why can’t all the filtered plasma be reabsorbed into capillaries?

• The process is too slow to reabsorb all the filtered plasma, so some of the tissue fluid enters the lymph capillaries.

What is tissue fluid called once it enters lymph capillaries?

• Tissue fluid that enters the lymph capillaries is known as lymph.

What are lymph capillaries, and where are they located?

• Lymph capillaries are blind-ending vessels located between body cells.

Where does lymph eventually return to the blood?

• Lymph vessels join to form larger lymph vessels, which eventually empty into the subclavian veins below the clavicle.

What is the role of plasma proteins in the formation of tissue fluid?

• Plasma proteins remain in the capillaries, reducing water potential, which helps draw water back into the capillaries by osmosis.

What happens to excess tissue fluid that is not reabsorbed?

• Excess tissue fluid enters the lymphatic system, where it is returned to the blood via the subclavian veins.

Why does tissue fluid contain fewer proteins than blood plasma?

• Large plasma proteins are too large to filter through the capillary walls into the tissue fluid.

What is the significance of the subclavian veins in the lymphatic system?

• The subclavian veins are where lymph is returned to the circulatory system, completing the process of tissue fluid circulation.

What is the function of haemoglobin in red blood cells?

• Haemoglobin is a respiratory pigment that carries oxygen by combining loosely and reversibly with it to form oxyhaemoglobin.

What type of structure does haemoglobin have?

• Haemoglobin has a quaternary structure, consisting of four haem units and four polypeptide chains.

How many oxygen molecules can one haemoglobin molecule bind to?

• Each haemoglobin molecule can bind to four oxygen molecules, one for each haem unit.

What happens to oxygen at the alveoli?

• At the alveoli, oxygen diffuses into the blood and binds to haemoglobin to form oxyhaemoglobin.

How does haemoglobin release oxygen in the body tissues?

• In the body tissues, where oxygen concentration is low, haemoglobin releases oxygen, which diffuses into the cells.

What happens to haemoglobin’s shape as it moves around the body?

• As haemoglobin moves around the body, it changes shape depending on the oxygen and carbon dioxide levels, which affects its affinity for oxygen.

What is the affinity of haemoglobin for oxygen at the gas exchange surface?

• At the gas exchange surface (lungs), haemoglobin has a high affinity for oxygen because of the high oxygen concentration and low carbon dioxide concentration.

What is the affinity of haemoglobin for oxygen in respiring tissues?

• In respiring tissues, haemoglobin has a low affinity for oxygen due to high carbon dioxide concentration, which lowers the pH (due to the formation of carbonic acid )and causes oxygen to be released.

Why is the combination of haemoglobin and oxygen described as reversible?

• It is reversible because haemoglobin can bind oxygen at high concentrations (lungs) and release it at low concentrations (tissues).