AQA GCSE Biology: Homeostasis and Response

Comprehensive vocabulary flashcards covering homeostasis, the endocrine system, blood glucose regulation, diabetes, kidney function, and renal treatments from AQA GCSE Biology.

Homeostasis

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

Receptors

Specialised cells that detect changes in the internal or external environment, known as stimuli.

Coordination Centres

Structures such as the brain, spinal cord, and pancreas that receive and process information sent from receptors.

Effectors

Muscles or glands that bring about specific responses to restore optimum conditions within the body.

Endocrine System

A communication system composed of specialised glands that secrete chemical messengers called hormones directly into the bloodstream.

Hormones

Chemical substances produced by endocrine glands and transported in the blood plasma to affect specific target cells or organs.

Pituitary Gland

A 'master gland' situated at the base of the brain that secretes several hormones into the blood in response to body conditions, stimulating other glands to produce additional hormones.

Thyroid Gland

An endocrine gland that produces thyroxine to control basal metabolic rate and affect growth.

Adrenal Glands

Glands located above the kidneys that produce adrenaline to prepare the body for 'fight or flight' responses.

Pancreas

An endocrine and digestive gland that produces insulin and glucagon to monitor and regulate blood glucose concentration, as well as digestive enzymes.

Insulin

A hormone produced by the pancreas when blood glucose levels rise, stimulating liver and muscle cells to take up excess glucose from the blood and convert it into glycogen for storage.

Glucagon

A hormone released by the pancreas when blood glucose falls too low, which stimulates liver cells to break down stored glycogen into glucose and release it into the bloodstream.

Glycogen

An insoluble carbohydrate storage molecule synthesized in liver and muscle cells from joined glucose units.

Negative Feedback

A homeostatic mechanism that detects deviations of internal conditions from a normal set point and activates corrective responses to return conditions to that set point.

Type 1 Diabetes

A disorder in which the immune system destroys insulin-producing pancreatic cells, causing the pancreas to fail to produce sufficient insulin and resulting in uncontrolled high blood glucose.

Type 2 Diabetes

A condition in which body cells develop resistance to insulin and stop responding to it effectively, commonly linked to obesity, poor diet, and lack of exercise.

Cell Lysis

The swelling and bursting of body cells caused by an excessive influx of water through osmosis when blood plasma becomes overly dilute.

Deamination

A metabolic process taking place in the liver in which the amino group is removed from excess dietary amino acids to form toxic ammonia.

Ammonia

A highly toxic nitrogenous compound formed by the deamination of excess amino acids in the liver, immediately converted into urea.

Urea

A nitrogen-containing waste substance formed in the liver from ammonia and excreted from the blood by the kidneys in urine.

Kidneys

Excretory organs that filter blood under high pressure, regulate water content, remove metabolic wastes like urea, and adjust ion concentrations to form urine.

Selective Reabsorption

The active and passive reclamation of useful substances needed by the body—including all glucose, some mineral ions, and some water—from the kidney filtrate back into the blood.

Kidney Tubules

Microscopic tubular structures inside the kidneys through which filtrate flows and across which selective reabsorption into blood vessels occurs.

Anti-Diuretic Hormone (ADH)

A hormone secreted by the pituitary gland when blood water levels fall, increasing the water permeability of kidney tubules so more water is reabsorbed into the blood.

Dialysis

A clinical treatment for kidney failure in which a machine acts as an artificial kidney, using a partially permeable membrane to remove urea and rebalance blood salts and water.

Dialysis Fluid

A fluid used in haemodialysis that contains no urea and has glucose and salt concentrations equivalent to normal blood, allowing wastes to diffuse out while preventing the loss of useful solutes.

Kidney Transplant

A surgical treatment for kidney failure involving the surgical implantation of a healthy kidney from a matched donor into a recipient.

Immunosuppressant Drugs

Medications that must be taken lifelong by organ transplant recipients to prevent their immune system from attacking and rejecting the donor organ.

Tissue Typing

A medical testing and matching procedure that assesses cell-surface antigens between organ donors and recipients to minimise the risk of graft rejection.