What is nutrition
Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body.
What is assimilation
Nutrients used by cells provide energy and make cytoplasm for growth of the cell.
What is peristalsis
The rhythmic, wave like muscular contractions in the wall of the alimentary canal
Functions of liver
- bile production
- deamination of amino acids into urea
- detoxification
- convert excess glucose into glycogen
- breakdown of hormones
Different digestions
- starch —> maltose —> glucose
- protein —> polypeptides —> amino acids
- fats —> fatty acids + glycerol
Harmful effects of alcohol consumption on digestive system
- Alcohol stimulates acid secretion in the stomach leading to an increased risk of gastric ulcers
- Excessive alcohol may lead to cirrhosis of the liver where liver cells are destroyed and replaced with fibrous tissue. This may then lead to haemorrhage in the liber, liver failure and death.
What is homeostasis
The maintenance of constant internal environment.
Factors needed in the negative feedback process
- Set point that needs to be maintained
- Stimulus
- Receptors (that detect the stimulus)
- Control centre
- Corrective mechanism (effector is the thing that carries out the corrective mechanism and causes a final response.)
What is a hormone
A chemical messenger produced in minute quantities by an endocrine gland.
Effects of insulin
- Increases rate of glucose uptake by cells
- Makes cell membrane more permeable to glucose
- Stimulates liver and muscle cells to convert glucose to glycogen for storage
- Increases use of glucose for tissue respiration
Effects of glucagon
- Converts glycogen to glucose in the liver cells
- Converts amino acids and fats to glucose in the liver cells
Effects of antidiuretic hormone (ADH)
Regulates water potential of blood in body through osmoregulation, increases reabsorption of water in the nephrons.
What is deamination
Excess amino acids are transported to the liver by blood where they are deaminated. Part of the amino acid molecule is removed and converted to urea which is removed by the kidneys.
Why is urea harmful
Abnormally high urea concentration in the blood may cause abdominal pain, nausea or vomiting.
What is the human urinary system?
It consists of:
1. A pair of kidneys
2. A pair of ureters
3. Urinary bladder
4. Urethra
How is urine formed
- Ultrafiltration in the Bowman’s capsule to form glomerular filtrate
- Selective reabsorption in the proximal convoluted tubule
What is ultrafiltration
It is the first stage of urine formation. Small molecules are filtered out of the blood by the glomerulus into the Bowman’s capsule.
Selective reabsorption is?
- The second stage of urine formation, useful substances eg amino acids and glucose are reabsorbed into the blood capillaries again.
What is active transport
Net movement if particles from a region of lower concentration to a region of higher concentration, against concentration gradient, with the requirement of ENERGY.
What is osmoregulation
The maintenance of a blood water potential by controlling the water potential and solute concentration in the blood involving the kidneys and skin.
What is water potential?
The tendency of water molecules to move from one place to another. (Eg dilute = higher water potential, concentrated = lower water potential)
