GSCE Biology - Coordination

What is the name of A?

Dendronites

What is the name of B?

The cell body.

What is the name of D?

Myelin sheath

What is the name of E?

Axon

What is the name of F?

Axon terminals.

Myelin sheath

An insulating layer, or sheath, that forms around nerves, including those in the brain and spinal cord.

Cell body

The spherical part of the neurone that contains the nucleus

Axon

Where electrical impulses from the neurone travel to be received by other neurone.

Dendrite

The receiving or input portions of a neuron

Motor neurone

Cells in the brain and spinal cord that allow us to move, speak, swallow and breath by sending commands from the brain to the effectors (muscles) that carry out these functions.

Sensory neurone

A nerve cell that detects and transmits sensory information from the environment to the brain

Relay neurone

A cell in the CNS that acts as a messenger between sensory and motor neurones

1

Cornea

2

Aqueous humour

3

Pupil

4

Iris

5

Tear duct

6

Suspensory ligaments

7

Lens

8

Ciliary muscle

9

Sclera

10

Choroid

11

Retina

12

Fovea

13

Optic nerve

14

Vitreous humour

15

Blind spot

Cornea

It refracts light and protects the eye

Iris

Controls how much light enters the pupil

Lens

Focuses light onto the retina

Optic nerve

Bundle of sensory neurones that carry impulse to the brain

Retina

Layer of tissue at the back of the eye that contains light receptor cells (rods + cones)

Fovea

Area of the retina with the highest concentration of cone cells that provide sharp vision

Aqueous humour

Maintains pressure in the eye and nourishes the cornea

Vitreous humour

Maintains the shape of the lens in accommodation

Sclera

Tough outer layer that the muscle that moves the eyeballs attach to

Pupil

Hole in the center of the eye that lets light in

What happens to the eye in bright light?

• circular muscle contracts

• Radial muscles relax

• Pupils constrict

What happens to the eye in dim light?

• circular muscles relax

• Radial muscles contract

• Pupil dilate

What happens to the eye when it’s focusing on a distant object?

• ciliary muscles relax

• Suspensory ligaments pulled tight (stretched)

• Lens flatten

What happens to the eye when its focusing on a nearby object?

• ciliary muscles contract

• Suspensory ligaments slacken

• Lens more rounded (convex)

Homeostasis

The maintenance of a constant internal environment e.g. temperature

Nervous control system

• nerve impulses

• Travel fast

• Short-lived effect

• Localised effect

Hormonal control systems

• hormone in blood

• Travel more slowly

• Long-lived effect

• Widespread effect

What happens to the body when we are too hot?

• Tiny blood vessels called capillary loops - blood flow through these loops, radiating heat to the outside, cooling the body

• Reduce muscle activity

• Vasodilation - arterioles dilate increasing blood flow to skins surface

• Sweat glands - produce greater amounts of sweat - the energy supplied to evaporate sweat is from body heat

• Hairs - relax flat on skins surface

What happens when we are too cold?

• hair - stands up trapping a layer of air for insolation

• Vasoconstrictions - arterioles contract = less blood flow - less heat lost

• Shiver - muscle contract respirations generating heat

1

Hair

2

Nerve

3

Epidermis

4

Dermis

5

Fatty tissue

6

Arteriole

7

Sweat gland

8

Capillaries

9

Muscle

Geotropism

the growth of an organism according to gravity

• shoots will always grow upwards (negatively geotropic)

• Roots will always grow downwards (positively geotropic)

Phototropism

The growth of an organism according to light

• shoots always grow towards light

• They are positively phototropic

• Roots are not sensitive to light