HOMEOSTASIS Flashcards

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1
Q

define homeostasis

A

process of keeping body’s internal environment fairly constant

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2
Q

what are the 4 components to be maintained in Homeostasis

A
  1. Body temp
  2. Osmotic pressure/water levels
  3. Blood glucose levels
  4. Oxygen and Carbon Dioxide levels
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3
Q

define negative feedback

A

response counteracting/reducing original stimulus

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4
Q

define positive feedback

A

response amplifies/intensifies original stimulus

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5
Q

what is the Stimulus

A

change in environment causing system to operate

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6
Q

what is a receptor

A

detection of change

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7
Q

what does the modulator/control

A

responsible for processing info received from receptor and for sending message to the effectors

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8
Q

what is an effector

A

structure (hormone/muscle/gland/cell) that carries out response

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9
Q

what is a response

A

change in the internal environment (negative feedback)

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10
Q

Receptor for body temperature

A

Central hot/cold thermoreceptors

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11
Q

modulator for temperature

A

Heat losing/cooling centre of hypothalamus
activates heat loss/gaining mechanisms by sending down sympathetic/parasympathetic pathways

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12
Q

effectors for temp

A

Sweating/Shivering
skin arterioles
hypothalamus release factors acting on thyroid gland
cerebral cortex

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13
Q

define thermoregulation

A

regulation of body temperature

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14
Q

define conduction

A

transferred due to direct contact with solid/liquid object

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15
Q

define convection

A

transfer of heat in liquids and gases by currents

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16
Q

define radiation

A

transfer of heat without direct contact between heat source and receiver

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17
Q

define evaporation

A

heat transferred to liquid particles and used to transform them into gas which is removed taking energy with it

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18
Q

role of peripheral thermoreceptors

A

provide hypothalamus with info about external environment
hypothalamus initiates heat production/convection measures

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19
Q

role of central thermoreceptors

A

detects body’s internal core temperature

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20
Q

what is glucose stored as

A

glucose is stored as glycogen in mainly liver and muscle cells

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21
Q

what does the pancreas/adrenal glands release

A

Glucagon and Insulin hormones released

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22
Q

define glycogenesis

A

making glycogen (glycogen broken down into smaller glucose subunits)
stimulated by INSULIN

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23
Q

define Glycogenolysis

A

the process of converting glycogen back to glucose
stimulated by GLUCAGON

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24
Q

define Gluconeogenesis

A

process of producing glucose molecules from lipids and amino acids

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25
Q

when the hepatic portal vein brings high glucose blood to the liver, what are the 4 things the liver may do:

A
  1. remove some glucose from blood to provide energy for liver function
  2. some is removed by liver/muscle cells - stored as glycogen (glycogenesis)
  3. may continue to circulate in blood - available for other body cells to reabsorb and use
  4. excess glucose is converted into fat for long-term storage
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26
Q

what do Alpha cells secrete and what does this hormone do ?

A

Alpha cells on islets of langerhans secrete GLUCAGON
⬆️ blood sugar levels

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27
Q

what do Beta cells secrete and what does this hormone do ?

A

Beta cells on islets of langerhans secrete INSULIN
⬇️ blood sugar levels

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28
Q

what does insulin do ?

A

decreases BSL
1. accelerating the absorption of glucose from blood into cells, especially skeletal muscles
2. promotes conversion of glucose into glycogen (glycogenesis)
3. stimulates conversion of glucose into fat and adipose tissue (lipogenesis)

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29
Q

define Lipogenesis

A

conversion of glucose into fat and adipose tissue

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30
Q

define Lypolysis

A

The breakdown of lipids (fats) into fatty acids and glycerol used to make glycogen

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31
Q

what does Glucagon do

A

increases BSL
1. stimulates glycogenolysis in liver - conversion/breakdown of glycogen to make glucose and then released into bloodstream
2. stimulates liver to do glyconeogenesis
3. Lipogenesis

32
Q

define glycogenolysis

A

glycogenolysis in liver - conversion/breakdown of glycogen to make glucose and then released into bloodstream

33
Q

define lypogenolysis

A

breakdown of fat to create energy

34
Q

What hormone does the Adrenal Cortex secrete for BSL and what is its role ?

A

Glucocorticoids (eg. Cortisol)
- stimulates conversion of glycogen to glucose (glycogenolysis)
- increases rate at which amino acids are removed from cells (glyconeogenesis)

35
Q

What hormone is secreted by the Adrenal Medulla and what is its role in BSL?

A

Adrenaline / Noradrenaline
- counteracts insulin (lowering BSL)
- stimulates lactic acid production in muscle cells - used to make glucose in liver

36
Q

what receptors detect Blood sugar Levels?

A

Chemoreceptors in pancreas on either Beta or Alpha cells

37
Q

what is the modulator for blood sugar levels ?

A

Beta/alpha cells inside let’s of langerhans of the pancreas release insulin/glucagon

38
Q

what are the effectors for ⬆️ blood glucose levels?

A
  1. body cells
  2. liver/skeletal cells
  3. adipose tissue
39
Q

in increased blood glucose levels, what is the role of body cells ?

A

absorb glucose from the blood because glucose carriers in cell membrane are activated

40
Q

in increased blood glucose levels, what is the role of liver / skeletal cells ?

A

glycogenesis - storing glucose as glycogen and converting glucose into glycogen

41
Q

in increased blood glucose levels, what is the role of adipose tissue ?

A

Lipogenesis - storing glucose as fat

42
Q

what are the effectors for ⬇️ blood glucose levels ?

A

liver
adipose tissue

43
Q

in decreased blood glucose levels, what is the role of the liver (2)

A
  1. glycogenolysis - breaking down of glycogen to make glucose then released into blood
  2. glycogenesis - making glucose from amino acids/ fatty acids / glycerol
44
Q

in decreased blood glucose levels, what is the role of adipose tissue ?

A

Lipolysis - breaking down fat into glycerol and fatty acids to be used to make glucose

45
Q

define intracellular fluid

A

inside cells (2/3 boy water)

46
Q

define extracellular fluid

A

outside cells (1/3 body water)

47
Q

define plasma

A

fluid part of blood (1/4 extracellular fluid)

48
Q

define intercellular

A

fluid between cells (3/4 extracellular fluid)

49
Q

define osmotic pressure

A

measure of tendency of a solution to take in a pure solvent (water)
higher solute concentration = higher osmotic pressure

50
Q

what happens during fluid balance

A

fluid GAIN must balance out fluid LOSS to keep constant

51
Q

define excretion

A

removal of metabolic waste products from body

52
Q

3 stages in the Nephron

A
  1. Filtration
  2. re-absorption
  3. secretion
53
Q

what occurs during filtration in the nephron

A

blood plasma and dissolved substances are filtered from blood into capsule to form filtrate

54
Q

what occurs during reabsorption in the nephron

A

some substances reabsorbed back into the blood away from filtrate
eg, glucose, amino acids, salt, water

55
Q

what occurs during secretion in the nephron

A

additional of extra substances into filtrate

56
Q

what is ADH and where is it produced

A

Antidiuretic Hormone ADH
produced in hypothalamus - released in POSTERIOR pituitary gland

57
Q

when would ADH be secreted

A

osmoreceptors in hypothalamus detect increased osmotic pressure and ADH is secreted

58
Q

what is the role of ADH

A

makes kidney tubules (distal convoluted tubule / collecting duct) more permeable due to increased amount of aquaporins opening
therefore more water can be reabsorbed

59
Q

what is the role of aldosterone and where is it secreted from

A

Secreted from the Adrenal Cortex
regulates water output (salt retention hormone)

acts on kidney tubules to increase sodium reabsorption into blood

60
Q

what receptor is used in low bodily fluid homeostasis

A

osmoreceptors in hypothalamus

61
Q

what modulator is used in low water levels

A

Hypothalamus signalled to make ADH and release it i to blood via PPG

62
Q

what is the modulator for low salt levels in the body

A

HYPOTHALAMUS receives message and sends rf to ANTERIOR PITUITARY which secretes ACTH which acts on ADRENAL CORTEX which secretes ALDOSTERONE

63
Q

what modulator is used in the thirst reflex

A

hypothalamus sends messages to cerebrum/cerebral cortex

64
Q

what are the 3 effector in the thirst reflex

A

person has conscious feeling of thirst
will seek water and drink it
water absorbed into blood @ intestines

65
Q

in cellular respiration, cells produce carbon dioxide. How is this transported in the blood (3)

A

bicarbonate ions
attach to haemoglobin to form carbaminohaemoglobin
dissolved in plasma

66
Q

what is the equation for CO2 transported in blood as bicarbonate ions

A

CO2 + H2O ➡️⬅️ H2CO3 ➡️⬅️ H+ + HCO3-

carbon dioxide + water = carbonic acid = hydrogen ions + bicarbonate ions

67
Q

what does an increase in CO2 mean for concentration of H + ions

A

⬆️ CO2 = ⬆️ H+

= acidic ( high conc of H + ions)

68
Q

what are the two structures involved in regulation of breathing ?

A

Diaphragm
Intercostal muscles

69
Q

what nerve stimulates the diaphragm?

A

Phrenic Nerve

70
Q

what nerve stimulates the Intercostal Muscles ?

A

IC nerve

71
Q

what are the nerve impulses travelling to diaphragm and IC muscles controlled by ?

A

Respiratory centre of the MEDULLA OBLONGATA

72
Q

2 functions controlled by respiratory centre

A
  1. Expiration (breathing out)
  2. Inspiration (breathing in)
73
Q

what receptors detect blood gas levels ? (2)

A

Peripheral chemoreceptors - Aortic and coratid bodies
Central chemoreceptors - medulla oblongata

74
Q

what is the modulator for Blood gas levels

A

Respiratory centre of medulla oblongata receives message from receptors and sends nerve less frequent/more frequent nerve impulses to diaphragm and IC muscles via phrenic and IC nerves

75
Q

what controls voluntary breathing ?

A

connections from cerebral cortex to descending tracts in spinal cord

76
Q

what happens if you hold your breath?

A

build up of CO2 stimulates medulla oblongata to override voluntary control forcing you to breathe

77
Q

define hyperventilation

A

rapid, deep breathing can provide more oxygen than required and remove more CO2 than necessary