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biology test 1 > homeostasis > Flashcards

homeostasis Flashcards

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1
Q

what is the purpose of homeostasis?

A

to keep everything working efficiently

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2
Q

what is the optimum temperature for enzymes?

A

37 degrees C

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3
Q

why should there be a constant amount of water in the body?

A

so that cells are not damaged by losing or gaining water through osmosis

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4
Q

why is a constant concentration of glucose needed?

A

cells need a steady amount of glucose to respire, or they won’t be able to release the energy they need

brain cells die quickly without glucose

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5
Q

what is the problem with too much blood glucose?

A

too much can cause water to leave the cells via osmosis, then they cannot carry out metabolic reactions

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6
Q

how is blood glucose concentration controlled?

A

by hormones produced by the pancreas called insulin and glucagon

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7
Q

what is insulin?

A

a hormone secreted by the pancreas which decreases blood glucose concentration

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8
Q

what are islets?

A

they are clusters of cells the produce hormones.

they look like islands in the sea of other cells, and they are scattered throughout the pancreas

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9
Q

what happens if blood glucose concentration increases?

A

the pancreas secretes insulin into the blood which reaches liver

causes liver to absorb glucose from the blood and store it as glycogen

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10
Q

what is glycogen?

A

an insoluble polysaccharide which glucose is converted in to be stored

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11
Q

what happens if blood glucose concentration decreases?

A

pancreas secretes glucagon

causes liver cells to break down glycogen into glucose and release it into blood

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12
Q

what is the set point for blood glucose concentration?

A

the normal range is 0.8-1.1mg per cm cubed

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13
Q

which two organs work together to keep blood glucose concentration within the set point?

A

the liver and pancreas

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14
Q

what is negative feedback?

A

a mechanism that detects a move away from the set point and brings about actions that take that value back towards the set point

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15
Q

what is type one diabetes?

A

when insufficient insulin is secreted by the pancreas so blood glucose is not controlled

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16
Q

what is type 1 diabetes thought to result from?

A

the body’s immune system attacking itself

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17
Q

when does type 1 diabetes usually develop?

A

in childhood, usually

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18
Q

what happens to type 1 diabetic patients after they eat a high carb meal?

A

the blood glucose increases but there is no secretion of insulin

19
Q

what are the symptoms of type 1 diabetes?

A

dry mouth, blurred vision, thirst, high heart and breathing rate

20
Q

why is it bad that no insulin is secreted?

A

the liver has no stores of glycogen

so between meals low glucose levels mean the person’s cells cannot release energy

21
Q

how do people with type 1 diabetes manage it?

A

they check their blood sugar regularly using a sensor

they check urine for glucose levels using a dipstick

22
Q

why do they check their urine for glucose levels using a dipstick?

A

urine shouldn’t normally contain glucose, but if blood sugar is high and the kidneys cannot absorb it all some is excreted in urine

23
Q

what eating habits do diabetics have?

A

they eat little and often

they eat more around exercise

24
Q

what are the two types of insulin? describe them.

A

rapid acting insulin:
taken just before or after eating a meal. dose adjested based on the amount of carbohydrates they will eat

long acting insulin:
taken once a day, providing a “background” dose of insulin

25
Q

what is the most important organ in temp regulation?

A

the skin is.

26
Q

what does the skin do?

A

it prevents water evaporating out of living cells

it keeps out pathogens

27
Q

what do sweat glands do?

A

extract water and ions from the blood to produce sweat

travels up the sweat duct and is released through a pore

28
Q

what do the small blood vessels in skin do?

A

they carry blood to all cells

ex - arterioles, capillaries, and venules

29
Q

what do hair erector muscles do?

A

pull the hair upright

30
Q

what types of receptors are there?

A

receptors for temp. and pressure.

31
Q

what do the layers of fat underneath do

A

insulate body and act as energy reserve

32
Q

what is the hypothalamus?

A

the part of the brain involved in controlling body temperature

33
Q

how does the hypothalamus control body temp?

A

it has temp receptors to sense the temp of blood running through it

34
Q

what does the hypothalamus do if the blood temperature is above or below 37 degrees C?

A

it sends electrical impulses to parts of the body to help keep the temp and blood at its set point

35
Q

what does the hypothalamus do when body temperature falls?

A

sends impulses to the skin, muscles, and liver

36
Q

describe what happens when you shiver when body temperature falls

A

muscles contract and relax quickly using energy from respiration

heat generated by the muscles warms that blood as it flows past

37
Q

what happens to your metabolism when body temp falls?

A

the speed of chemical reactions in other tissues may increase

ex - liver cells respire faster, this releases HEAT

38
Q

what do your hairs do when body temp falls?

A

erector muscles in skin contract, pulling hairs straight

in humans this doesn’t do anything important except goosebumps (in mammals this traps a thick layer of warm air near skin acting as an insulator)

39
Q

describe vasoconstriction

A

arterioles near the skin become narrower, blood therefore flows mainly through the larger vessels beneath the insulating fat tissue

stops blood losing heat to the air

40
Q

what do sweat glands do when you get cold?

A

reduce secretion of sweat to avoid cooling down even more

41
Q

what do hairs do when body temp rises?

A

hairs lie flat

erector muscles relax, allowing heat to leave the skin into the air

42
Q

describe vasodilation

A

arterioles near the skin’s surface widen

more blood flows near surface so more heat lost

43
Q
A

biology test 1 (5 decks)

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