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Biology Paper 2 > Homeostasis And Response > Flashcards

Homeostasis And Response Flashcards

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1
Q

What is homeostasis?

A

Homeostasis is the maintenance of a constant internal environment in order to maintain optimum conditions for enzyme and cellular function.

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2
Q

Give examples of conditions maintained by homeostasis in the body.

A
  • Blood glucose concentration
  • Body temperature
  • Water levels
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3
Q

What two types of responses are used in body control systems?

A

Nervous and chemical (hormonal)

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4
Q

What three components do all control systems have?

A
  • Receptors
  • Coordination centres
  • Effectors
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5
Q

What is the function of a receptor?

A

Receptors detect changes in the environment (stimuli).

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6
Q

What is the function of a coordination centre?

A

Coordination centres obtain and process information from receptors.

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7
Q

What is the function of an effector?

A

Effectors (muscles or glands) bring about responses to stimuli.

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8
Q

What is the function of the nervous system?

A

The nervous system allows the body to react to its surroundings and coordinate an appropriate response.

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9
Q

How does a stimulus lead to a response being carried out by the body?

A
  • Stimulus is converted to an electrical impulse
  • The electrical impulse passes along sensory neurones to the central nervous system (CNS).
  • The CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector, which carries out the response.
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10
Q

What is the order of events for a response to stimuli?

A

Stimulus -> receptor -> coordinator -> effector -> response

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11
Q

What is a reflex action?

A

A reflex action is an automatic and rapid response which does not involve any conscious input from the brain

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12
Q

Why are reflex actions important?

A

Reflex actions aid survival by preventing harm to the body.

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13
Q

Describe how a reflex action occurs via a reflex arc

A
  • Stimulus is detected by a receptor
  • An electrical impulse passes along a sensory neurone to the spinal cord (part of the CNS)
  • At a synapse between a sensory neurone and a relay neurone, neurotransmitters diffuse across the gap and stimulate a new impulse which passes along the relay neurone.
  • The same process occurs at a synapse between a relay neurone and a motor neurone
  • At an effector, an appropriate response is carried out.
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14
Q

What is the difference between a reflex pathway and a conscious pathway?

A

Within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord/unconscious part of the brain. In a conscious pathway, the coordination centre is the conscious part of the brain.

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15
Q

What is the name of the body’s coordination system which involves hormones?

A

The endocrine system

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16
Q

What is a hormone?

A

A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ where it causes a response.

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17
Q

What type of effector secretes hormones?

A

Glands

18
Q

Which gland controls many other glands in the body?

A

The pituitary gland

19
Q

Why is the pituitary gland considered a ‘master gland’?

A

Secretes a wide range of hormones, some of which stimulate other endocrine glands.

20
Q

What is the role of the thyroid gland in the endocrine system?

A

Secretes the hormone thyroxine - controls metabolism, heart rate, and body temperature.

21
Q

What is the role of the pancreas in the endocrine system?

A

Secretes the hormones insulin and glucagon - controls blood glucose levels

22
Q

What is the role of the adrenal gland in the endocrine system?

A

Secretes adrenaline - controls the body’s ‘fight or flight’ response.

23
Q

What is the role of the ovaries in the endocrine system?

A

Secrete oestrogen, which coordinates the menstrual cycle and the development of female secondary sexual characteristics.

24
Q

What is the role of the testes in the endocrine system?

A

Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics.

25
Q

How does the pancreas respond when blood glucose levels are too high?

A

The pancreas secretes the hormone insulin. insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored.

26
Q

How does the pancreas respond when blood glucose levels are too low?

A

The pancreas secretes the hormone glucagon. Glucagon binds to liver cells causing glycogen to be converted into glucose and released into the blood.

27
Q

What is type 1 diabetes?

A

Type 1 diabetes is when the pancreas does not produce sufficient insulin to control blood glucose concentration. As a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss.

28
Q

How can type 1 diabetes be treated?

A
  • Insulin injections before meals - allows glucose to be converted into glycogen
  • Limiting carbohydrate intake
  • Doing regular exercise which helps to remove excess glucose from the blood.
29
Q

What is type 2 diabetes?

A

Type 2 diabetes is a disorder in which the body’s cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. It’s development is linked with increasing age and obesity.

30
Q

How can type 2 diabetes be treated?

A
  • Following a carbohydrate controlled diet
  • Doing regular exercise
  • Use of drugs which increase insulin production and effectiveness
31
Q

What is the function of sex hormones during puberty?

A
  • Males: Cause the development of secondary sexual characteristics
  • Females: Cause the development of secondary sexual characteristics and the maturation of eggs
32
Q

What is the main male sex hormone?

A

The main male sex hormone is testosterone, which is produced by the testes and controls sperm production.

33
Q

What is the main female sex hormone?

A

The main female sex hormone is oestrogen, which is produced by the ovaries and is involved in the menstrual cycle.

34
Q

What is the menstrual cycle?

A

The menstrual cycle is the monthly cycle of physiological changes that occur in females, involving the shredding of the uterus lining (menstruation) and ovulation.

35
Q

Describe the events of the menstrual cycle

A
  • Uterus lining thickens and eggs begin to mature in the ovaries
  • An egg is released from one of the ovaries (ovulation) - uterus lining remains thick
  • If the egg is fertilised, pregnancy may occur. If not, both the egg and the uterus lining are shed during menstruation.
36
Q

What is ovulation?

A

Ovulation is the release of a mature egg from the ovaries, which occurs approximately every 28 days.

37
Q

Name the four main hormones involved in the menstrual cycle

A
  • Oestrogen
  • Progesterone
  • Follicle stimulating hormone (FSH)
  • Luteinising hormone (LH)
38
Q

What is the role of FSH in the menstrual cycle?

A

FSH is secreted by the pituitary gland. It controls the maturation of eggs with in the ovaries (inside a follicle) and triggers the production of oestrogen by the ovaries.

39
Q

What is the role of oestrogen in the menstrual cycle?

A

Oestrogen is produced by the ovaries and released due to the action of FSH - it causes the regrowth of the uterus lining.
It triggers the production of LH and restricts the release of more FSH.

40
Q

What is the role of LH in the menstrual cycle?

A

LH is produced by the pituitary gland as a result of oestrogen. It’s release triggers ovulation.

41
Q

What is the role of progesterone in the menstrual cycle?

A

Progesterone is secreted from the follicle of the ovary. It sustains the uterus lining and inhibits FSH and LH.

Biology Paper 2 (1 decks)

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