Coordination and Response (The Human Nervous System and Hormones).

Question 1

What does the human nervous system consist of?

Answer 1

The central nervous system (CNS) - brain and the spinal cord.
The peripheral nervous system (PNS) - the nerves outside of the brain and spinal cord which carry impulses to and from the central nervous system.

Question 2

What is the role of the human nervous system?

Answer 2

• Coordinate and regulate body functions.
• Make sense of our surrounding and respond to them.

Question 3

Define stimuli.

Answer 3

Changes in an organism’s environment.

Question 4

What are changes in an organism’s environment sensed by and what does the organism use to respond to them?

Answer 4

Changes in an organism’s environment are called stimuli and are sensed by specialized cells called receptors and the organism responds using effectors.

Question 5

What are effectors and give the two effectors?

Answer 5

Parts of the body that respond to a stimulus.

Muscles are effectors and may respond to stimuli by contracting and glands are also effectors.

For example, if you smell good food cooking, your salivary glands may respond by secreting saliva.

Question 6

Define coordination.

Answer 6

The way in which receptors detect stimuli and then pass information on to effectors is called coordination.

Question 7

Most animals have two methods of sending information from receptors to effectors. Name them.

Answer 7

The fastest is by means of nerves and the slower method is by means of chemicals called hormones (which are part of the endocrine system).

Question 8

Name the three types of neurons.

Answer 8

Sensory, Relay and Motor.

Question 9

What is a sensory neurone?

Answer 9

A neurone the transmits electrical impulses from a receptor to the central nervous system.

Question 10

What is a relay neurone?

Answer 10

A neurone that transmits electrical impulses within the central nervous system.

Question 11

What is a motor neurone?

Answer 11

A neurone that transmits electrical impulses from the central nervous system to an effector.

Question 12

Describe the events that would occur in the case that you touch a hot plate.

Answer 12

• If your hand touches a hot plate a sensory receptor in your finger detects this. This receptor starts off an electrical impulse, which travels to the spinal cord along the axon from the receptor cell. This cell called a sensory neurone, carries an impulse from a sensory receptor.
• In the spinal cord, the neurone passes the electrical impulse to several other neurones. These neurones are called relay neurones because they relay that impulse onto other neurones.
• The relay neurones pass the impulse on to the brain. They also pass it on to a motor neurone to pass to an effector.
• In this case, the effectors are the muscles in your arm. The electrical impulse travels to the muscle along the axon of the motor neurone. The muscles then contract so that your hand is pulled away.

Question 13

What is a reflex arc?

Answer 13

A series of neurones (sensory, relay, and motor) that transmit electrical impulses from a receptor to an effector.

Question 14

What is the schematic movement of a reflex arc?

Answer 14

Receptor → Sensory neurone → Relay neurone → Motor neurone → Effector.

Question 15

What is a reflex action?

Answer 15

A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors.

Question 16

How are nerve fibers adapted to carry nerve impulses much faster?

Answer 16

Nerve fibers are wrapped in a layer of fat and protein called myelin and the signals that neurones transmit are in the form of electrical impulses. The myelin insulates the nerve fibres, so that they can carry these impulses much faster.

Question 17

What is a synaptic gap, a synapse, and a vesicle?

Answer 17

A synaptic gap is a tiny gap between two neurones at a synapse.
A synapse is a junction between two neurones.
A vesicle is a very small vacuole.

Question 18

Describe the events at a synapse:

Answer 18

• an impulse stimulates the release of
  neurotransmitter molecules from vesicles
  into the synaptic gap.
• the neurotransmitter molecules diffuse
  across the gap.
• neurotransmitter molecules bind with
  receptor proteins, because the shape of the neurotransmitter molecules is complementary to the shape of the receptor protein, on the next neurone.
• an impulse is then stimulated in the next
  neurone.

Question 19

What do synapses ensure?

Answer 19

Synapses ensure that nerve impulses travel only in one direction.

Question 20

What are hormones?

Answer 20

Hormones are made in special glands called endocrine glands and are chemicals that are produced by a gland and carried in the blood, which alter the activities of their specific target organs.

Question 21

Name the four glands and the hormones they secrete.

Answer 21

• Adrenal glands: Adrenaline.
• Pancreas: Insulin and Glucagon.
• Testis: Testosterone.
• Ovary: Oestrogen.

Question 22

What is the function of adrenaline?

Answer 22

Prepares body for vigorous action.

Question 23

What is the function of insulin and glucagon?

Answer 23

Insulin: Reduces the concentration of glucose in the blood.
Glucagon: Increases the concentration of glucose in the blood.

Question 24

What is the function of testosterone and oestrogen?

Answer 24

Testosterone: Causes the development of male secondary sexual characteristics.
Oestrogen: Causes the development of female secondary sexual characteristics and helps in control of the menstrual cycle.

Question 25

Give the ‘fight or flight’ adrenaline responses.

Answer 25

• Heart beats faster, supplying oxygen to your brain and muscles more quickly, allowing your muscles to carry out aerobic respiration more quickly, giving them more energy.
• Breathing rate increases, so more oxygen can enter the blood in the lungs.
• The pupils of the eye widen, allowing more light into the eye, which might help you see the danger more clearly.
• Adrenaline causes the liver to release glucose into the blood for the muscles, along with extra oxygen provided by increased breathing and heart rates, allowing the muscles to increase metabolic activity.

Question 26

What are the five main points of the nervous system in response to:

• What it is made up of.
• How is information transmitted.
• What these are transmitted along.
• Speed.
• The durational effect.

Answer 26

• Made up of neurons.
• Information transmitted in the form of electrical impulses.
• Impulses transmitted along neurons.
• Impulses travel very quickly, so action is fast.
• The effect of a nerve impulse usually only lasts for a very short time.

Question 27

What are the five main points of the endocrine system in response to:

• What it is made up of.
• How is information transmitted.
• What these are carried in.
• Speed.
• The durational effect.

Answer 27

• Made up of glands.
• Information is transmitted in the form of chemicals called hormones.
• Chemical carried in the blood plasma.
• Chemicals travel more slowly, so the action is slower.
• Effect of a hormone lasts longer.