Excretion Flashcards
What are the metabolic reactions within the body do?
They are always creating waste products.
What is excretion?
It is defined as the removal from organisms of toxic materials and substances in excess of requirement
What are the two main sets of excretory organs for removing metabolic waste products?
The lungs that excrete carbon dioxide and the kidneys that excrete urea - excess salts and water.
What supplies blood to the kidneys
The renal artery
What returns blood from kidney to the rest of the circulation
The renal vein
What is the job of the kidney
To filter urea and salts from the blood
What allows urine to leave the body via the urethra?
The relaxation of the bladder sphincter.
What is your urine?
Urine = urea + ions + toxins + water
What happens to amino acids that are in excess
They are not stored. They are changed by the liver to urea.
Why should a balanced diet contain protein
Balance diet will always contain proteins whose constituent amino acid’s will be used by the cells to manufacture the particular proteins we need.
What is the name of the blood vessel that links the kidney with the inferior Vena cava
Renal vein
Why is the removal of faeces not considered to be an important form of excretion?
Faeces are largely undigested Cellulose and lignin(fibre) that has never taken part in a chemical reaction in the body. These chemicals are therefore not excretory products.
The fact that the liver deals with the amino acid’s that have been absorbed from the alimentary can now, means that it is therefore involved in there assimilation.
What is assimilation?
Is the movement of digestive food molecules into the cells of the body where they are used
What happens during the assimilation of amino acid’s
That required amino acid are all linked together to make proteins some of which will be plasma proteins that are then released into the blood
What happens to excess amino acid’s
During a process called daemination, it breaks them down into urea which is released into the blood and into a carbohydrate, which is converted into glycogen and stored into the cells of the liver.
What is daemination
Is defined as the removal of the nitrogen containing part of amino acids to form urea
Why can fruit be put into an atmosphere enriched with carbon dioxide
Corbin dioxide has a narcotic effect on living cells. Fruit can be sorted after picking in an atmosphere in enriched with carbon dioxide to slow down the cells metabolism and thus slowdown the ripening process.
How is the kidney supplied with blood
From the renal artery
What is the outer part of the kidney called
The cortex
What is the inner part of the kidney called
The medulla
What is in the centre of the kidney
Is a space from which the Ureter leads to the bladder
What is the Glomerulus
In each kidney, the renal artery divides burst into Arterioles then into the capillaries . these capillaries form around 1 million minute clumps or knots. The correct name for one of these knots is that glomerulus
What does the glomerulus supply?
Kidney tubules or nephron and each tubule starts with a cup shaped structure called a renal capsule.
All the renal capsules lie in the cortex of the kidney
What happens under the pressure of the renal capsule
The blood in the knot of the capillaries is forced out through the capillary walls and through the walls of the capsule into the renal tubules. The high-pressure at filtration of the blood causes water, glucose, urea, salts and toxins to leave the blood and pass in to the tubule.
What is selective reabsorption
Moving from a knot of capillaries, a capillary passes to the rest of the tubule and wrapped it self in close contact around the tubule. As the filtrate passes through the tubule , The capillary absorbs all of the substances that the body cannot afford to lose the following of reabsorbed into the blood;
All of the glucose unless the person is diabetic
Most of the water
Some of the salts
This leaves in the tubule a concentrated solution of urea, salts and toxins otherwise known as urine
What is Osmoregulation
ensuring that the blood remains at a more or less constant concentration.
How does kidney dialysis work
Kidney dialysis machine removes from a patient’s blood chemicals with small molecules (toxins, urea, and ions). What does not allow larger molecules such as plasma proteins or blood cells to leave the blood
This is achieved by passing the patient’s blood through dialysis tubing that is partially permeable (Permeable to only small particles)
This tubing is then placed in a dialysis or washing fluid which is continuously renewed and washes away the substances removed from the blood. By varied of the concentration of glucose and salts in the washing fluids, the amount of those substances that diffuse from the blood can be controlled and in this way, so can concentration of the plasma in the blood that is then returned to the patient.
What are the advantages of having a kidney transplant
Permanent solution
Patient can live a normal life
Less expensive than dialysis
Fewer restrictions on diet
What are the disadvantages of a transplant
There is a shortage of suitable donors
Anti rejection drugs would have to be taken
Transplanted kidney are made of foreign proteins causing the production of antibodies which may lead to rejection of the organ. The transplant is more likely to be successful if the donor is a close relative with a similar protein type.
What is the advantage of dialysis
Immediate solution
What is the disadvantage of dialysis
Needs to undergo every three days
Risk of infection
Which part of the kidney do the glomeruli Lie?
The cortex
Which substance is filtered from the blood by the kidneys but does not appear in the urine of a healthy persons blood.
Glucose
