Topic 5: Homeostasis

What is homeostasis?

The maintenance of a constant internal environment to keep conditions optimal for cell function.

What are the three components of a control system?

Receptors, coordination centres (e.g. brain), and effectors (e.g. muscles or glands).

What is the function of sensory, relay, and motor neurons?

• Sensory: carry impulses from receptors to CNS

• Relay: connect sensory to motor neurons in CNS

• Motor: carry impulses from CNS to effectors

What is a reflex arc?

An automatic, rapid response that bypasses the conscious brain to prevent harm.

What is the role of synapses?

Tiny gaps between neurons where impulses are transferred via chemical messengers.

What happens when body temperature is too high?

Sweating increases and vasodilation occurs to cool the body.

What is the endocrine system?

A system of glands that secrete hormones into the blood to regulate body processes.

What is the role of insulin?

Lowers blood glucose by converting glucose into glycogen in the liver.

What is the role of glucagon?

Raises blood glucose by converting glycogen in the liver into glucose.

What is Type 1 diabetes and how is it treated?

The pancreas produces little/no insulin; treated with insulin injections.

What is osmosis?

The movement of water from a high to low concentration across a partially permeable membrane.

What is the role of FSH in the menstrual cycle?

Stimulates egg maturation and oestrogen production.

What is the role of LH?

Triggers ovulation.

How does the contraceptive pill work?

Contains oestrogen and/or progesterone to prevent egg maturation and ovulation.

What is IVF?

Fertility treatment involving fertilisation of eggs in a lab and implantation of embryos.

What is negative feedback?

A process where a change is detected and reversed to maintain a constant internal environment.

What is the function of adrenaline?

Prepares the body for ‘fight or flight’ by increasing heart rate and breathing.