nervous and endocrine system

What are the three things organisms must have to survive?

• find favourable external conditions (e.g. locations that are too cold or hot)

• find food

• avoid harm

What detects changes in the environment/stimuli?

specialised receptor cells

where are receptor cells located?

sense organs e.g. nose and eyes, also inside body e.g. pressure receptors in the blood vessels

Where do receptors send signals?

send signals via either the nervous system or the hormonal system to the body’s coordination centres in the brain or spinal cord. They are then sent on to the parts of the body which respond, known as effectors

What are effectors?

either muscles or glands

What do o the receptors in the eye do?

rod and cone cells

detect light intensity and convert light energy → electrical energy

What do receptors in the skin do?

detect pressure, temp, pain, touch

kinetic →electrical

What do receptors in the muscles do?

detect how much muscles are stretched

kinetic → electrical

What do receptors in the hypothalamus do?

detect chemicals and body temp in the blood

chemical → electrical

What do receptors in the ears do?

detect sound, movement and orientation

sound → electrical

kinetic → electrical

What do receptors in the blood vessels do?

detect muscle stretch

kinetic → electrical

What does the human nervous system consist of?

central nervous system (CNS) - brain and spinal cord

peripheral nervous system (PNS) - all of the nerves in the body

What does the nervous system do?

allow the detection of stimuli in our surroundings and the coordination of the body’s responses to the stimuli, info is sent through the nervous system in the form of electrical impulses that pass along nerve cells - neurons

What are the different types of neurones?

• sensory

• relay

• motor

What is a nerve?

a bundle of neurones

What do nerves do?

connect the receptors in the sense organs with the CNS and connect the CNS with effectors

What os the pathway nerves pass through the nervous system along?

stimulus →receptor →sensory neuron → CNS→ motor neuron → effector

What are hormones?

chemical substances produced by endocrine glands and carried by the blood - chemical messengers

What do hormones do?

transmit information from one part of an organism to another and bring about a change by altering the activity of one or more specific target organs

What is faster in action hormones or nerves? what does this mean?

nerve impulses are faster so hormones are used to control functions that do not need instant responses

What is the endocrine system?

endocrine glands that produce hormones in animals are known collectively as the endocrine system

What do endocrine glands do?

endocrine glands secrete hormones directly into the blood

What makes endocrine glands secrete hormones?

the actions of another hormone or the arrival of a nerve impulse

What is the pathway of hormone action?

stimulus → receptor → hormone → effector

e.g. high blood sugar  →cells in the pancreas → insulin → liver cells

What are the glands in the body?

Compare the nervous system and the endocrine system: made up of, type of message, speed of transmission, length of effect