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Biology B1 > Nerve and hormones > Flashcards

Nerve and hormones Flashcards

1
Q

What does the nervous system enable humans to do?

A

It enables humans to react to their surroundings and coordinate their behaviour.

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2
Q

What is a stimulus?

A

It is a change the the environment, which you may need to react to.

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3
Q

What are receptors?

A

They are a group of cells that are sensitive to a stimulus.

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4
Q

Name receptor and the stimuli they detect.

A

1) Receptors in the eyes - sensitive to light
2) Receptors in the ears - sensitive to sound, changes in position and enable us to keep our balance
3) Receptors on the tongue and in the nose - sensitive to chemicals and enable us to taste and to smell
4) Receptors in the skin - sensitive to touch, pressure, pain and to temperature changes

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5
Q

What is the central nervous system?

A

It is where all the information from the sense organs is sent, and where reflexes actions are coordinated.
It consists of the brain and spinal cord ONLY.

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6
Q

What are sensory neurons?

A

They are the nerve cells that carry signals as electrical impulses from the receptors in the sense organs to the CNS.

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7
Q

What are relay neurons?

A

They are the nerve cells that carry signals from the sensory neuron to the motor neuron inside the CNS.

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8
Q

What are the motor neurons?

A

They are the nerve cells that carry signals from the CNS to the effector.

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9
Q

What is an effector?

2 examples.

A

An effector brings about a response e.g.

  • Muscle contract
  • Glands secrete hormones.
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10
Q

What are synapses and how are nerve impulses transferred along it?

A

Synapses are a small gap in which two neurons connect
The nerve impulse is transferred by chemicals (neurotransmitters) which diffuse across the gap.
These chemicals then set off a new electrical signal in the next neuron.

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11
Q

What is meant by a reflex?

What is the benefit of reflexes?

A

Reflexes are rapid, automatics responses.

The benefit is that they can protect us from danger.

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12
Q

Stages in a simple reflex action.

A
  • Impulses from a receptor pass along a sensory neurone to the central nervous system
  • At a junction (synapse) between a sensory neurone and a relay neurone in the central nervous system, a chemical is released that causes an impulse to be sent along a relay neurone
  • A chemical is then released at the synapse between a relay neurone and motor neurone in the central nervous system, causing impulses to be sent along a motor neurone to the organ (the effector) that brings about the response
  • The effector is either a muscle or a gland, a muscle responds by contracting and a gland responds by releasing (secreting) chemical substances.
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13
Q

One word pathway of a reflex arc.

A

Stimulus—> Receptor—> Sensory neurone—> Relay neurone—> Motor neurone—> Effector—> Response.

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14
Q

What are hormones?

A

Hormones are chemical messengers which travel in the blood to activate target cells.

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15
Q

What are hormones secreted by?

A

Hormones are secreted by various glands such as the pituitary gland and the ovaries.

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16
Q

What is FSH?

A

Follicle stimulating hormone

  • Secreted by the pituitary gland
  • Causes eggs to mature in the ovaries.
  • Stimulates the ovaries to produce oestrogen
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17
Q

What is oestrogen?

A

oestrogen

  • Secreted by the ovaries
  • Stimulates pituitary gland to produce LH
  • Inhibits the further production of FSH
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18
Q

What is LH?

A

Luteinising hormone

  • Produced in the pituitary gland
  • Stimulates the release of eggs from the ovary around the middle of the menstrual cycle.
19
Q

What does oral contraceptives contain?

A
  • They contain hormones to inhibit FSH production so that no eggs mature.
  • They may also contain oestrogen and progesterone to inhibit egg maturation.
20
Q

How does oestrogen in the pill reduce fertility?

A

If oestrogen is taken everyday to keep the levels of it permanently high, it inhibits the production of FSH, and after a while egg development and production stops.

21
Q

How does progesterone in the pill reduce fertility?

A

Progesterone stimulates the production of think cervical mucus which prevents any sperm getting through and reaching the egg.

22
Q

Describe the problems with early contraceptive pills and how these were solved in modern versions.

A

Early contraceptive pills contained high doses of oestrogen and caused side effects.
Modern pills contain much lower doses of oestrogen or progesterone only. These have ewer side effects.

23
Q

How can FSH and LH increase fertility?

A

Some women have levels of FSH that are too low to cause their eggs to mature. This means no eggs are released and the woman can’t get pregnant.
The hormones FSH and LH can be injected to stimulate egg release in their ovaries.

24
Q

What does IFV involve?

A

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs. The eggs are collected from the mother and fertilised by sperm from the father. The fertilised eggs develop into embryos. At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus (womb).

25
Q

What are plants sensitive to?

A

Light, Moisture and Gravity

26
Q

What is tropism?

A

It is plant growth response to a stimulus.

27
Q

Describe how plant shoots are sensitive to light and gravity.

A

Plant shoots grow towards light (positive phototropism) and away from gravity (negative gravitropism)

28
Q

Describe how plant roots are sensitive to moisture and gravity.

A

Plant roots grow towards moisture and towards gravity.

29
Q

What are auxins?

A

Auxin is a plant hormone that controls the growth of a plant near the tips of shoots an roots.

30
Q

What do auxins control?

A

They control the growth of a plant in response to light (phototropism), gravity (gravitropism or geotropism) and moisture.

31
Q

Describe how auxins are used in shoots to grow towards

light.

A

In shoots, auxins trigger cell division. There is a higher level of auxin on the darker side of a shoot, so this side grows faster than the light side. This causes the shoot to grow towards light.

32
Q

Describe how auxins are used in roots to grow towards gravity.

A

In roots, auxins inhibit cell division. There is a higher level of auxin at the bottom side of a root. This side grows slower than the top, so the root grows downwards (towards gravity).

33
Q

How are plant hormones used by gardeners?

A

Plant hormones are used by gardeners to kill weeds and to encourage roots to grow on plants.

34
Q

How is auxin useful for selective week killers?

A

Auxins make broad leaved plants grow out of control and die.

35
Q

How is auxin useful for rooting powder?

A

Auxins make cuttings develop roots quickly.

36
Q

How is auxin useful for seedless fruit?

A

Flowers sprayed with hormones to make fruit develop but not seeds.

37
Q

How is auxin useful for fruit ripening?

A

Farmers use hormones to control fruit ripening.

38
Q

What is homoeostasis?

What do scientists describe it as?

A

Homeostatic is how the body keeps conditions inside it the same.
Scientists describe it as the maintenance of a constant internal environment.

39
Q

What bodily fluids need to be controlled?

A
  • Ion content
  • Water content
  • Sugar content
  • Temperature
40
Q

State three ways that water can leave the body.

A

1) The lungs breathing out
2) The skin in sweating to keep cool
3) The kidneys producing urine.

41
Q

State two ways that ions are released from the body.

A

1) The skin in sweating

2) The kidneys when urine is produced.

42
Q

Why is it important that the body temperature is controlled?

A

The body temperature must be controlled so that it is at the temperature that the enzymes work best at.

43
Q

Why must the bloody sugar levels be controlled?

A

Blood sugar levels must be controlled to provide cells with a constant supply of energy.

Biology B1 (3 decks)

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