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biology > unit 1 AOS 2 > Flashcards

unit 1 AOS 2 Flashcards

regulation of systems

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1
Q

what is homeostasis

A

A condition in which the internal environment of the body remains relatively constant despite changes in the external environment

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2
Q

what arw the two systems that maintain homeostasis

A

the nervous system

the endocrine system

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3
Q

Why is homeostasis important for sustaining life?

A

Homeostasis is important because it allows metabolic processes to continue to function. For example, enzymes within cells work best at an optimum temperature

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4
Q

what is a stimulus

A

A change, either an increase or decrease, in the level of an internal variable

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5
Q

what is a recpetor

A

the structure that detects the change and sends signals to the control center

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6
Q

what is a control centre

A

the structure (central nervous system) that evaluates the change against the set point for that variable and sends signals to the effector about the correction needed

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7
Q

what is an effector

A

the structure that adjusts its output to make the required correction

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8
Q

what is a response

A

The corrective action taken agaisnt the stimulus

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9
Q

what is a negative feedback loop

A

a process in which the body senses a change in a variable and activates mechanisms to reverse the change.
keeps the varible in a narrow range

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10
Q

what is a postive feedback loop

A

Positive feedback leads the variable that has increased to increase further, or the variable that has decreased to decrease even more

a cycle of continuing change in which an original change is increasingly amplified

doesnot keep a variable within a narrow range

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11
Q

compare negative feedback with postive feedback

A

negative feedback loop is where the response is opposite in direction to the original stimulus. if the stimulus is an increase in a variable, then the response is a decrease in the same variable.
For example, if the blood glucose level is too high, negative feedback results in it decreasing to normal.

on the other hand, Positive feedback acts to increase the magnitude of a stimulus, moving it further from a set point. for example postive feeback is used in the process of childbirth

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12
Q

tempreture feedback undertakes what process

A

negative feedback process

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13
Q

what is the bodys homeostatic tempreature

A

37.7 degree celsuis

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14
Q

what montiors core body tempreture

A

the hypothalamus and thermoreceptors

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15
Q

what is function of the hypothalamus

A

Acts like a thermostat - registers change in the core body temperature and receives information about changes from the thermoreceptors in the skin.

restores normal body temperature

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16
Q

how can body heat be lost

A

Heat loss can occur by evaporation of excreted water including sweat, from the pores and from the airways and lungs.

through:
convection
conduction
radiation
evaporation

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17
Q

what happens when body temp is too high (too hot)

A
  1. activivates heat loss centre in hypothalamus
  2. Blood vesicles dilate
  3. Sweat glands are activated
  4. Body temperature decreases - the hypothalamus heat loss centre shuts off
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18
Q

what happens when body temp is too low (too cold)

A
  1. Activates heat promoting centre in the hypothalamus
  2. Blood vesicles constrict
  3. Thyroid gland releases hormones to increase metabolic rate
  4. Rapid contractions of skeletal muscles - causes reflex shivering, which expends energy to generate heat
  5. Body temperature increases - the hypothalamus heat promoting centre shuts off
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19
Q

what does thyrxoine (T4) do

A

speeds up metabolic activity in cells
the increase of metabolic activity also results in the production of heat

T4 production is controlled by negative feedback

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20
Q

what do the thermoreceptors do

A

detect changes in body temperature and send messages to the hypothalamus.

21
Q

the importance of glucose

A

primary source of energy

The body concerts glucose into ATP during cellular respiration

22
Q

control of blood glucose

A

controlled by negative feedback

involves two hormones: insulin and glucagen

23
Q

what does insulin do

A

lowers blood glucose levels by…
promoting the uptake of glucose by cells, where it is converted to energy as ATP or stored as glycogen or fat in the liver (for later use)

24
Q

what does glucagon do

A

increases blood glucose levels by…
promoting the breakdown of glycogen to glucose in the liver. then glucose is released into the bloodstream

25
Q

what happens when blood glucose levels are too high

A

High blood glucose stimulates beta cells in the liver secrete insulin

26
Q

what happens when blood glucose levels are too low

A

Low blood glucose stimulates alpha cells in the liver to secrete glucagon

Glucagon promotes the breakdown of glycogen to glucose in the liver

Glucose is released into the blood

27
Q

what is the process called for regulating water balance

A

osmoregulation

28
Q

what does the antidiuretic hormone (ADH) do

A

promotes the reabsorption of water from the kidney and regulates urine volume

29
Q

what does osmoregulation do

A

sensors in the body that detect changes in water balance away from homeostatic levels. Stimulates the release of the ADH

  • Osmoreceptors are in the hypothalamus - they monitor blood osmolarity, if its too high or too low it will send messages to the pituitary gland (part of the brain), which will regulate the amount of ADH released
30
Q

what happens when Solute concentration increases above normal range (low water)

A

Hypothalamus detects increased osmolarity

Hypothalamus creates feelings of thirst

Hypothalamus sends a message to the posterior gland to release more ADH

31
Q

what happens when Solute concentration falls below normal range (high water)

A

Hypothalamus detects low osmolarity

Pituitary gland release of ADH stops.

Less water is reabsorbed from the kidney

higher urine output

32
Q

regulation of water balance in plants

A

Plants rely on water balance for photosynthesis (plants make their own food) and survival

Plants respond to a shortage of water by closing their stomata to stop water loss through transpiration

33
Q

what is transpiration in plants

A

evaporative water loss through plant leaves that results in the movement of water through the plant

34
Q

how is water important for plants

A

An input for photosynthesis (vital for their survival)

A means for cooling plants by evaporation of water from leaves during transpiration

35
Q

how is water loss regulated in plants

A

Plants have regulatory mechanisms and structural adaptions which maintain water balance

36
Q

what is Regulatory mechanisms

A

active responses by plants that are because of changes in water balance

37
Q

what is structural adaptions

A

heritable physical traits (their leaves) that have evolved in plant populations and equip plants to survive and reproduce under their particular environmental conditions

38
Q

controlling wtaer up take in plants

A

Roots are the plants organs that are specialised for locating and absorbing water

Roots supply the water on the input side of the water balance equation in plants

when guard cells lose turgor, stomata close, preventing water loss.

39
Q

controlling water loss in plants

A
  • Leaves are the source of water loss from plants

Water loss occurs when guard cells are turgid, causing the stomata to open

The major loss of water in plants occurs when water vapor is lost by transpiration from the leaf stomata.

40
Q

what is the stomata

A

pores in leaves

  • Plants can actively regulate water loss by the opening and closing of their stomata.
41
Q

conditions favouring stomata open

A

high levels of water and sunlighgt

When conditions favor having stomata open, ions move into the guard cells. Water then follows these ions by osmosis into the guard cells. This results in the stomata opening.

42
Q

conditions favouring stomata close

A

When water levels are low to prevent loss through transpiration.

Water and ions move out of the guard cells, causing the guard cells to become flaccid. This results in the stomata closing.

43
Q

what is type 1 diabetes mellitus

A

a condition in which blood glucose is high, because the body’s cells cannot take up glucose in the normal way

44
Q

why do people with diabetes have high blood glucose

A

In type 1 diabetes, the body’s immune system is damaged therefore the pancreas cannot make insulin, leading into high levels of blood glucose

in type 1 diabetes, the insulin producing beta cell of the pancreas are destroyed by the immune system, and the pancreas cannot make insulin

Patients must have insulin injections to stabilise blood glucose levels

45
Q

what is Hyperthyroidism

A

in hyperthyroidism, excessive production of thyroid hormones drives up the basal metabolic rate, affecting many functions

Hyperthyroidism leads on to graves disease

46
Q

what are some symptoms of Hyperthyroidism

A

→ Nervousness
→ Weight loss
→ Increased heart rate
→ Brittle hair
→ Elevated body temperature

47
Q

what is graves disease

A

Thyroid increases in size

48
Q

Where in the body would you find the receptors detecting an increase in blood glucose levels?

A

The pancreas OR the beta cells of the pancreas

49
Q
A

biology (4 decks)

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