Coordination and response

How does the structure of a motor neurone compare to...?

- A relay neurone: have a cell body, dendrites and an axon ( no myelin sheath )

- A sensory neurone: have a cell body, long dendrites and a short axon off both sides  

- A motor neurone: have cell body, rodes of ranvier, shwann cells and an axon

How is information passed along the length of a neurone?

- throught the release of chemical substances into the pace between the axon and the    dendrites. 

- electrical impulses flowing along the length ofa neuron whch are clled nerve impulses

What is the function of the myelin sheath?

- protects the axons

- helps speed nerve transmissions

Outline the general sequence of events involved in a reflex arc ( from stimulus to response ).

Stimulus → receptor cell → sensory neurone → relay neuron in the CNS

→ motor neurone→ effector (muscle or gland) → response

Define what a reflex action is. Provide two examples.

- a protective, automattic and rapid response to a stimulus 

Examples:

                  - moving hand away from something hot

                  - blinking 

What is a synapse? 

- a junction between two nerve cells or between a nerve cell and an effector cell such    as a muscle or a gland.

Outline what happens there.

- the electrical signals are converted into chemicals that can easily cross the gap and pass on to the next neuron where they again get converted into electrical signals

Outline the function of each of the following structures:

Cornea: protects eye from outside infiltratesand ultraviolet radiation 

Iris: controls how much light the upil lets in and reaches the retina

Lens: to transmit and focus light onto the retina

Retina:captures light that enters the eye and helps translate it into the images you see

Optic nerve: transmits electrical impulses from your eyes to your brain 

Describe what happens to the iris in the following conditions:

What is accomodation?

- the shape pf the lens changes shape allowing the eye to focus on objects at different    distances.

Describe how it aids vision

What is the endocrine system?

- a coordination system which secretes hormones into the bloodstream from glands      throughout the body.

Name six glands:

- Adrenal glands             - Testes

- Pituitary glands            - Thyroid

- Ovaries                        - Endocrine gland

What is the menstrual cycle? What is its purpose?

- monthly cycle of events preparing a woman’s uterus for the possible implantation of    a fertilised egg. It is controlled by hormones from the pituitary gland.

- Lasts 28 days on average