Biology

Endocrine gland

A ductless gland that secretes hormones directly into the bloodstream rather than through a duct.

Exocrine gland

A gland that secretes its products through a duct onto an internal or external surface, such as salivary glands.

Hormone

A chemical messenger produced by an endocrine gland, transported in the blood, that alters the activity of specific target organs.

Target organ

An organ with specific receptors on its cell membranes that bind to a particular hormone, triggering a response.

Difference in transmission mode

The nervous system transmits electrical impulses along nerve cells, while the endocrine system transmits hormones through the blood.

Difference in speed of response

Nerve impulses travel extremely fast for almost instant effects, whereas hormonal responses travel more slowly.

Difference in duration of response

Nervous system responses are short-lived, while endocrine system responses are usually longer-lasting.

Difference in response localization

Nerve impulses target individual muscle cells or glands for localized effects, while hormones can affect multiple target organs widespread across the body.

Pituitary gland location

Found at the base of the brain, positioned just below the hypothalamus.

FSH (Follicle Stimulating Hormone) function

Secreted by the pituitary gland to stimulate egg development in females and sperm production in males.

LH (Luteinising Hormone) function

Secreted by the pituitary gland to trigger ovulation in females and stimulate testosterone production in males.

ADH (Antidiuretic Hormone) function

Secreted by the pituitary gland to control the water content of the blood by targeting the kidneys.

Thyroxine function

Secreted by the thyroid gland to regulate the body's basal metabolic rate and chemical reactions.

Insulin function

Secreted by the pancreas to lower blood glucose levels by converting glucose into glycogen for storage.

Glucagon function

Secreted by the pancreas to raise blood glucose levels when they fall too low.

Adrenaline function

Secreted by the adrenal glands to prepare the body for physical activity during fight-or-flight situations.

Testosterone function

Secreted by the testes to control the development of male secondary sexual characteristics.

Oestrogen function

Secreted by the ovaries to control female secondary sexual characteristics and regulate the menstrual cycle.

Progesterone function

Secreted by the ovaries to regulate the menstrual cycle and maintain the lining of the uterus.

Adrenal glands location

Situated right on top of the kidneys.

Adrenaline effect on heart rate

Increases heart rate to pump more oxygen and glucose to active muscles faster for respiration.

Adrenaline effect on breathing

Increases breathing rate and depth to absorb more oxygen into the blood and remove carbon dioxide.

Adrenaline effect on blood flow

Diverts blood flow away from the digestive gut and skin towards the skeletal muscles.

Adrenaline effect on glycogen in the liver

Causes the liver to break down stored glycogen into glucose, releasing it into the blood for cellular respiration.

Adrenaline effect on pupils and hair

Causes pupils to dilate for better vision and body hair to stand erect to make an animal appear larger to enemies.