BIO B13 Coordination and response

Sensitivity

The ability to detect and respond to changes in the environment

What is the change in the organism’s environment that gets detected by its receptors?

Stimuli

What is a receptor?

Specialised cells or organs that detect changes in an environment

What is an effector?

A muscle or gland that brings a response to a stimulus

What does the nervous system do to carry out fast paced responses?

It transmits electrical impulses which travel through neurones

What do the responses help organisms with?

Regulate body functions and behaviour, react to surroundings

What does the central nervous system consist of and what are they linked to?

Brain and spinal cord. They are linked to sense organs by neurones which form the peripheral nervous system.

what are neurones

specialised cells which carry electrical impulses

Describe the pathway of the nervous system (brief)

stimulus→receptors→sensory neurones→CNS (with brain)→motor neurones→ effectors→response

mnemonic:

really silly cats may eat rice

Reflect nervous system pathway

Stimuli→receptors→sensory neurones→relay neurones→motor neurones→effectors→response

mnemonic:

really silly rats may eat rice

key differences between nervous system and endocrine system

Nervous:

• electrical (impulses)

• faster, shorter lasting

• controls reactions

• affects few effectors

Endo:

• chemical (hormones)

• slower, longer lasting

• controls processes in body

• affects several organs

chemical substances produced by endocrine glands

hormones

medium of hormone transport

blood plasma

Which hormone increases breathing and heart rate, converting glycogen to glucose?

Adrenaline, its effects also include increased pupil diameter to improve vision

Which hormone lowers blood sugar levels

Insulin

Which hormone increases blood sugar levels

Glucagon

Which hormone stimulates sperm production

Testosterone

Which hormone stimulates development of egg follicle and controls menstrual cycle

Oestrogen

Where are insulin and glucagon produced

pancreas

target organ for insulin and glucagon

liver

what 2 processes of the body are examples of homeostasis

Body temperature and blood glucose levels

The maintainance of a constant internal environment

homeostasis

what occurs when conditions change from set point and a response occurs to return conditions to set point

negative feedback

parts of skin involved in thermoregulation

• Hair

• Hair erector muscles

• sweat glands

• blood vessels

• receptors

• sensory neurones

Body responses to increase in temp

• Vasodilation: more heat is lost through radiation

• Sweating: cool the body

• Skin hairs lie flat: less insulation

Body responses to decrease in temp

• Shivering: muscle contractions generate heat

• Vasoconstriction: reduces heat loss through radiation

• Skin hair erect: layer of insulation to trap heat

What happens when blood glucose levels increases (eat food)

Pancreas releases insulin→ stimulates liver and muscle cells to take up excess glucose from blood and convert them to glycogen→ blood glucose levels decrease

What happens when blood glucose levels decreases

Pancreases releases glycagon→ stimulates liver to break down glycogen to glucose and release it to bloodstream→ blood glucose levels increase

Note: adrenaline produced in the adrenal glands also help speed up the conversion of glycogen to glucose during fight or flight mode.