B14 - Coordination and response

What is a synapse?

A synapse is a junction between two neurones

How is a nerve impulse passed across a synapse?

Neurotransmitter molecules are released and diffuse across the synapse to bind with the receptor proteins on the next neurone

What holds the neurotransmitter molecules?

The vesicles

What happens when the neurotransmitter molecules bind to the receptor proteins?

They carry over the electrical impulse to the next neurone

Where is the cornea?

The cornea is the transparent outer layer found at the front of the eye

Where is the iris?

The iris is located behind the cornea and in front of the lens

What does the lens do?

The lens focuses light onto the retina

What does the optic nerve do?

The optic nerve carries impulses from the receptors on the retina into the brain

Where is the blind spot?

The blind spot is where the optic nerve leaves the eye

What is the fovea?

The fovea is a specific area of the retina that contains cone cells

What are the two different cells in the retina?

Cones and rods

What do synapses ensure about the direction of electrical impulses?

They ensure that the electrical impulses travel in one direction

Where is the lens?

The lens is behind the iris

Where is the optic nerve?

At the bottom back of the eye

Where is the retina?

The retina is runs along the back of the eye

Where is the fovea?

The fovea is above the optic nerve

Where is the pupil?

The pupil sits right in front of the lens

What does the cornea do?

The cornea refracts light

What does the iris do?

The iris controls how much light enters the pupil

What does the retina do?

The retina contains light receptors with some being sensitive to light of different colors

What are the features of rods?

Rods are very sensitive to light meaning they work well in dim light and give information in black and white

Where are the rods located in the eye?

The rods are mainly found at the outside edges of the retina

How many different types of cones are there?

Three

What is the feature of a cone?

Cones are less sensitive to light than rods and give information in color

Why is bright light dangerous?

Bright light is dangerous since it can damage the retina

What happens when the light receptors detect a high light intensity?

A reflex action is triggered that reduces the diameter of the pupil

What are the two different types of muscles the iris contains?

The radial and circular muscles

Which iris muscles make the pupils wider?

The radial muscles

Which iris muscles make the pupils smaller?

The circular muscles

What is the purpose for the rods sensitivity?

To help humans see in the dark

When humans look at near objects what happens to the lens?

The lens thickens and becomes fat which increases how much the light refracts

When humans look at far objects what happens to the lens?

The lens becomes thin so it refracts the light less

What muscles contract and relax when the lens thickens?

The ciliary muscles contract and the suspensory ligaments slacken

What muscles contract and relax when the lens thins?

The suspensory ligaments turn tauten and the ciliary muscles relax

How is type 1 diabetes treated?

With insulin therapy

What is phototropism?

Phototropism is the response in which parts of a plant grow towards or away from a source of light

What is gravitropism?

Gravitropism is the response in which parts of a plant grow towards or away from gravity

What are phototropism and gravitropism examples of?

They are both examples of chemical control of plant growth

Where is auxin produced and how does it move in a plant?

It is produced in the tip of the shoot and moves via diffusion

What is auxin do?

Auxin is a plant hormone that chemically controls growth near the tip of the shoots

What does auxin stimulate?

Auxin stimulates cell elongation in the cells just behind the tips

How is auxin distributed in a plant?

It is distributed unequally in response to light and gravity

Are the suspensory ligaments muscles?

No