Relationship between the different variables that affect diffusion: Rate of diffusion = (surface area x concentration difference) / thickness of membrane
Nephron
Long tubules in the kidney where filtration occurs and reabsorption of useful substances
Vasodilation
The widening of blood vessels leading to the skin surface increasing blood flow into the surface capillaries
Stomata
Small gaps in the leaves that allow gas exchange (of oxygen, carbon dioxide and water vapour) to occur in and out of the plant
Progesterone
Hormone, released by the ovaries and maintains the lining of the uterus
Type 2 diabetes
A condition caused by high blood sugar levels as the body cells no longer respond to insulin or too little insulin is produced
Cardiac output
The volume of blood pumped by the heart in one minute
Phagocyte
Non-specific white blood cells which engulf and digest pathogens
BMI
Body mass index, calculated as mass (in kg) divided by the square of their height (in m)
Homeostasis
The maintenance of a constant internal environment of the body at stable levels
Mutation
A change in the base sequence of DNA
Genotype
The alleles an individual has for a specific gene
Diploid
Nucleus containing two sets of chromosomes
Mitosis
process of cell division which results in two genetically identical diploid daughter cells
Micrometer
Unit of length, there are 1000 micrometers in 1 millimetre. The unit is μm
ciliated epithelial cell
Specialised cell with cilia (hair like structures) that move and sweep substances like mucus along, they are found lining the airways and reproductive tracts
Osmosis
The diffuse of water from an area of low solute concentration to high solute concentration across a partially permeable membrane
Cerebellum
Part of the brain which controls balance, coordination of movement and muscular activity
short-sighted
A condition where the lens is too curved so it refracts light too much and the light rays focus in front of the retina
Urea
Molecule produced in the liver from the break down of excess amino acids and is excreted in urine
DNA nucleotide
a molecule consisting of a phosphate group and a sugar with one of 4 bases attached (A, T, C or G)
Asexual Reproduction
Type of reproduction that involves one parent and produces genetically identical offspring
Pathogen
Organisms that cause disease
Antibiotics
Medication that inhibits the processes in bacteria so that they are killed
Enzyme
Biological catalyst molecule that speeds up a reaction and is produced by a living organism
motor neurone
cell that carries electrical impulses from relay neurones in the CNS to an effector to bring about a response
Phenotype
The visible characteristics of a gene displayed as a result of the interaction between genotype and environment
anaerobic respiration
reaction that releases a small amount of energy from glucose and does not involve oxygen, it produces lactic acid in humans
Diffusion
movement of molecules from an area of high concentration to an area of low concentration
FSH
hormone released from the pituitary gland which causes an egg to mature in the ovary