2- homeostasis Flashcards

1
Q

Q: What is homeostasis?

A

A: The regulation of internal conditions (e.g. temperature, pH, glucose levels, water content) to maintain optimum conditions for enzyme action and cell function.

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2
Q

Q: Why is homeostasis important?

A

A: It maintains stable conditions for cell activity and survival. Even small deviations can affect enzyme function or be fatal.

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3
Q

Q: What two systems are used for homeostasis communication?

A

A: The nervous system (fast, electrical impulses) and the endocrine system (slower, chemical hormones).

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4
Q

Q: What monitors and regulates body temperature?

A

A: The thermoregulatory centre in the brain and temperature receptors in the skin.

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5
Q

Q: What is vasodilation and how does it cool the body?

A

A: Arterioles widen → more blood to skin capillaries → more heat lost via radiation.

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6
Q

Q: What is vasoconstriction and how does it reduce heat loss?

A

A: Arterioles narrow → less blood near skin surface → less heat lost.

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7
Q

Q: What other mechanisms help regulate temperature?

A

A:

Sweating (cooling by evaporation)

Shivering (muscle contractions produce heat)

Hair erection (insulates or allows heat loss depending on position)

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8
Q

Q: What organ regulates water content in humans?

A

A: The kidneys.

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9
Q

Q: How is water content adjusted?

A

A:

Too much water → less reabsorbed in kidneys → dilute urine

Too little water → more reabsorbed → concentrated urine

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10
Q

Q: What hormone controls water balance?

A

A: ADH (antidiuretic hormone) – increases water reabsorption in kidneys.

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11
Q

Q: What are the two main parts of the nervous system?

A

A:

CNS (Central Nervous System): brain and spinal cord

PNS (Peripheral Nervous System): all other nerves

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12
Q

Q: What is the nervous system’s function?

A

A: Rapid communication via electrical impulses to coordinate responses to stimuli.

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13
Q

Q: What is the typical nerve signal pathway?

A

A: Stimulus → Sensory neurone → Relay neurone → Motor neurone → Effector → Response

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14
Q

Q: What is a synapse?

A

A: The gap between two neurones where neurotransmitters transfer signals.

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15
Q

Q: How is a nerve impulse transmitted across a synapse?

A

A: Electrical impulse triggers release of neurotransmitters → cross synaptic cleft → bind to receptors on next neurone → new electrical impulse.

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16
Q

Q: Why do impulses travel in one direction only?

A

A: Only presynaptic neurones release neurotransmitters, and postsynaptic neurones have receptors.

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17
Q

Q: Example pathway of a reflex?

A

A: Stimulus (e.g. pin) → Receptor → Sensory neurone → Relay neurone (spinal cord) → Motor neurone → Effector (muscle) → Response

18
Q

Q: What is a reflex arc?

A

A: A rapid, automatic response to a stimulus that bypasses the conscious brain.

19
Q

Q: What are the key structures of the eye and their functions?

A

Cornea: refracts light

Iris: controls pupil size

Lens: focuses light on retina

Retina: contains rods (light) and cones (color)

Optic nerve: sends impulses to brain

Ciliary muscle & Suspensory ligaments: adjust lens shape

20
Q

Q: How does the eye focus on near vs. far objects?

A

Near: ciliary muscles contract, lens thickens → more refraction

Far: ciliary muscles relax, lens thins → less refraction

21
Q

Q: What is the pupil reflex?

A

A: In bright light: pupil constricts; in dim light: pupil dilates.

22
Q

Q: What is a tropism?

A

A: A directional growth response to a stimulus.

23
Q

Q: Types of plant tropisms?

A

Phototropism: response to light

Geotropism: response to gravity

24
Q

Q: How do auxins affect tropisms?

A

\A:

Accumulate on shaded side of shoots → cells elongate → shoot bends toward light.

In roots, auxin inhibits elongation, so growth bends downward.

25
Q

Q: What is a hormone?

A

Q: What is a hormone?
A: A chemical messenger produced by a gland, transported in the blood to a target organ.

26
Q

Q: What is a hormone?

A

A: A chemical messenger made by a gland, transported in the blood, that affects the activity of a specific target organ.

27
Q

Q: How are hormones different from nerve impulses?

A

A: Hormones are chemical signals that act more slowly but last longer, while nerve impulses are fast, electrical, and short-lived.

28
Q

Q: How are hormones different from nerve impulses?

A

Q: How are hormones different from nerve impulses?
A: A system of glands that secrete hormones directly into the bloodstream to regulate body functions.

30
Q

Q: What are the general characteristics of hormonal responses?

A

A: They are slower to act but have longer-lasting effects than nervous responses.

31
Q

Q: What is the function of adrenaline?

A

A: Prepares the body for ‘fight or flight’ by increasing heart and breathing rates, redirecting blood to muscles, and increasing blood glucose levels.

32
Q

Q: Where is adrenaline produced?

A

A: In the adrenal glands.

33
Q

Q: What is the function of insulin?

A

Q: Where is adrenaline produced?
A: Lowers blood glucose levels by promoting glucose uptake into the liver and muscles where it is stored as glycogen.

34
Q

Q: Where is insulin produced?

A

A: In the pancreas.

35
Q

Q: What is the function of testosterone?

A

A: Develops male reproductive organs and secondary sexual characteristics (like deep voice, facial hair).

36
Q

Q: Where is testosterone produced?

A

A: In the testes.

37
Q

Q: What is the function of progesterone?

A

A: Maintains the uterine lining during pregnancy to support the developing embryo.

38
Q

Q: Where is progesterone produced?

A

A: In the ovaries.

39
Q

Q: What is the function of oestrogen?

A

A: Regulates the menstrual cycle and develops female secondary sexual characteristics (like breasts and wider hips).

40
Q

Q: Where is oestrogen produced?

A

A: In the ovaries.