Coordination and Response

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How does sweat keep us cool?

As sweat evaporates, it removes heat energy from the skin

State which direction the plant will grow and explain why?

The shoot will grow towards the left. This is because the light is on the left, and so auxins will accumulate on the right side(which will be in the shade). Auxins stimulate growth in shoots so the right side will grow faster, causing the shoot to lean over to the left.

What happens to make a root grow in the direction of the force of gravity?

The top side grows more than the bottom side?

What effects do auxins have on plants?

Shoot cell growth and root cell inhibition.

What is the cornea?

A transparent layer at the front of the eye that refracts light

Optic nerve

Carries electrical impulses to the brain

What is the retina?

Has photoreceptors that receives messages and sends them as electrical signals through the optic nerve to the brain

Pupil

Gap through which light passes through to the lens

What is the lens?

The lens refracts light and focuses it on the retina

What types of cells does the retina have and what do they do?

The cone cell detects colour. The rod cells detect light.

What is the fovea?

The point where the light on the retina

What is the purpose of the iris reflex?

To ensure the optimum amount of light enters the eye

What do muscles make up the iris?

Circular and radial muscles

What happens to the circular and radial muscles when the pupils constrict?

The radial muscle contracts and the circular muscle relaxes.

What is homeostasis?

The maintenance of stable internal body environment despite changing conditions?

Why does the body need to contain optimal conditions?

For optimal enzyme action and cell function

What is the role of a receptor?

Detects change in the internal or external environment

What is the role of a coordination centre?

Interprets changes and organises a response

Where are the coordination centres located in the body?

Spinal cord and brain

Name two types of effectors and what they can do

Muscles contract when stimulated. Glands release hormones.

Which system is faster at reacting?

Nervous system

Which system acts more generally across the body?

The endocrine systems because hormones are releases into the bloodstream which means it’s spread throughout the body.

Homeostasis relies on a system of……….

Negative feedback

What is the role of effectors?

To carry out the response

Where is auxin produced?

In the tips of roots and shoots

Auxins always accumulate on the……….

Lower and shaded side

Shoots are…….

Negatively geotropic/gravitropic and positively phototropic

What shape should the lens be when looking at a nearby object?

Fat and short

Only muscles……..

contract

When looking at a nearby object?

The suspensory ligaments slacken and the ciliary muscles contract.

What type of lens should glasses for long-sighted people contain?

Convex lens

Does the effect of the endocrine or nervous system last longer?

The endocrine system because hormones stay in the bloodstream for a long time and electrical impulses last for a split-second.

Explain the reflex arc.

The stimulus(heat) us detected by the receptors(thermoreceptors). Impulses are sent along a sensory neuron. In the CNS, the impulse passes to a relay neuron. Impulses are sent along a motor neuron. The impulse reaches an effector which results in an appropriate response to a stimulus.

progesterone

Produced in ovaries, maintains pregnancy and maintains the uterus lining so that the fertilised egg can implant

oestrogen

Produced in ovaries, main sex hormone in females and produces secondary sexual characteristics in females such as developing breasts.

insulin

produced in pancreas and maintains blood sugar/glucose levels

vasodilation

widening of blood vessels as a result of relaxation of smooth muscle cells within the vessel cells to allow more blood to flow closer to the surface of the skin resulting in increased energy transfer from the body and so more heat is lost from the body and the body cools down

adrenaline

Produced in adrenal gland, prepares the body for flight/fight response and increases heart/breathing rate

vasoconstriction

Narrowed blood vessels and so not as much blood flows to the skin surface and this means less bodily heat is lost

thermoregulatory centre

monitors and controls body temperature to ensure it remains the same temperature found in the brain. has receptors that monitor the temperature of the blood. it has receptors that monitor the temperature of the blood. receptors in the skin that send impulses to the thermoregulatory centre

Explain plant tropism in roots

Most roots show positive gravitropism as they grow towards gravity. If a root is horizontal, auxin moves to the lower side. The cells of the root grow more on the side with less auxin, so it stimulates the cells to grow on the upper side. This makes the root bend and grow downwards. This is beneficial as there are more likely to be increased levels of water and nutrients lower down and it provides stability for the plants.

What are neurotransmitters?

The chemical released at one end of a nerve fibre

What is the nervous system?

A bodily system made up of nerve cells that carry impulses around the body

How do electrical impulses travel across a neuron?

An electrical nerve impulse travels along the first axon. This triggers nerve-endings to release neurotransmitters. This is because the electrical impulse cannot directly travel across the synapse and so needs to be converted to a chemical and then back to an electrical impulse. The neurotransmitter diffuses across the synapse and binds to a receptor molecule on the next neuron. This stimulates the next neuron to transmit the electrical impulse.

Nervous System:

Type of signal: Electrical

Transmitter: Nerve cells

Speed of response: very fast

Duration of response: short

Electrical System

Type of signal: Chemical

Transmitter: Hormones in bloodstream

Speed of response: Slower

Duration of response: Long

Explain shivering

Shivering is your body muscles contracting which you respire more, which means more energy is released in your body and this energy is produced as heat energy

3 responses in the body for hot body temp

hairs lay flat, vasodilation and sweating

3 responses in the body for cold body temp

hairs lay up, vasoconstriction and shivering