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feedback loops Flashcards

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1
Q

homeostasis

A

process of keeping internal environment constant, need primal levels in many things e.g extracellular fluid, nutrients, temp, water
- body must be able to detect changes in internal and external environment and ,ust be able to compensate for changes

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2
Q

feedback systems

A

circular situation in which body responds to change or stimulus and response alters original stimulus

  • can either reinforce a stimulus = positive feedback
  • oppose/inhibit a stimulus = negative feedback
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3
Q

positive feedback

A

when original stimulus and change is reinforced by the response e.g oxytocin is released in childbirth which contracts uterus and stretches cervix which results in further release of oxytocin

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4
Q

negative feedback

A

response causes stimulus to change in direction opposite to that of original stimulus/change e.g body temp rises, body sweats more, body temp decreases

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5
Q

5 components of feedback loop

A
  • stimulus: change in environment
  • receptor: cells that detect and register change
  • modulator: structure where change is processed and info is relayed onto effector (usually the hypothalamus)
  • effector: organs, glands or tissues that are instructed to adjust output of secretions to cause an effect
  • response: outcome of adjustments
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6
Q

steady state

A

dynamic equilibrium where input and output of materials and energy is balanced

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7
Q

thermoregulation

A

regulation of body temp

  • behavioural responses: voluntary behaviours e.g using air conditioner, taking off layers or turning on heater/putting on more layers if cold
  • physiological responses: involuntary behaviours body undergoes e.g sweating, shivering, vasodilation
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8
Q

heat input

A

heat from body processes (metabolism), heat gained from surroundings by conduction and radiation

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9
Q

heat output

A

radiation, conduction, convection to surroundings, evaporation of water from skin and lungs, warm air exhaled/ warm urine/faeces that are expelled from body

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10
Q

conduction, radiation, convection, evaporation (skin: temp regulation)

A

conduction transfer of heat by direct contact between particles
convection: transfer of heat by movement of a liquid or gas
radiation: transfer of heat by infrared radiation being omitted to objects
evaporation : process of a liquid forming a gas which absorbed heat energy

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11
Q

heat production

A

energy produced from body processes (e.g muscles contraction, active transport) is produced in the form of heat

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12
Q

metabolic rate

A

rate at which energy is released by breakdown of food, can be influenced by
exercise: increases due to more energy needed
stress: autonomic NS releases noradrenaline which increases
body temp: increases in body temp cause increases in biochemical reactions

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13
Q

peripheral thermoreceptors

A

in skin and in some mucous membranes, detect changes in external environment and send info to hypothalamus

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14
Q

central thermoreceptors

A

located in hypothalamus, detect changes of internal environment, (blood temp), addition thermoreceptors at spinal cord and abdominal organs gives hypothalamus more info on internal temp

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15
Q

cold receptors

A

cold receptors: stimulated by temp lower than 37°C, when stimulated hypothalamus received info and initiates heat conversion and heat production mechanisms

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16
Q

heat receptors

A

detect temp higher than 37, when stimulated mechanisms operate to reduce heat production and increase heat loss

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17
Q

vasodilation

A

increased diameter of blood vessels in dermis (2nd layer of skin), more blood is carried to capillaries in the skin and increases rate of heat loss

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18
Q

vasoconstriction

A

reduced diameter of blood vessels, less blood is transported to capillaries in skin and rate of heat loss decreases

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19
Q

sweating

A

active secretion of fluid by sweat glands and periodic contraction of cells surrounding ducts to pump sweat to skin surface, sweat contains dissolved substances: sodium chloride with some urea, lactic acid, potassium ions
- evaporation of sweat from skin has cooling effect as heat is removed from skin and when liquid changes into gas (vapour) results in cooling of blood flowing through skin (process that absorbs heat energy)

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20
Q

shivering

A

increase in skeletal muscles tome, produces rhythmic muscle tremors (10-20 per sec)

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21
Q

preventing body temp from falling: physiological changes

A

1: impulses from hypothalamus stimulate sympathetic nerves which stimulate vasoconstriction, involves goosebumps in skin and piloerection: hair standing up
2: noradrenaline and adrenaline secreted: adrenal cortex is stimulated by hypothalamus which increases cellular metabolism
3. shivering: hypothalamus sends a stimulus out to parts of brain to cause shivering
4. increase in thyroxine: increases metabolic rate, long lasting response

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22
Q

el reverting body temp from falling: behavioural response

A

may occur if we become consciously aware of cold condition, leg put on extra layers of clothing, going inside away from cold weather, curl up into a ball, rub skin to create friction/heat

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23
Q

preventing body temp from rising: physiological response

A
  1. vasodilation: increase blood flow causing skin to be reddish, surface temp rises, greater heat loss through radiation/convection
  2. sweating: cooling effect only occurs if environment is dry (if humid sweat cannot evaporate and does not absorb from body)
  3. decrease in metabolic rate: results in less heat being produced from body (reduction of thyroxine in blood)
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24
Q

behavioural responses to prevent body temp from rising

A

turning on fan, removing extra clothing, reducing physical activity

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25
Q

control of thermoregulation: hypothalamus

A

monitors temperature of blood and receives impulses from peripheral thermoreceptors, through negative feedback loops it controls diameter of skin arteriales, sweating shivering and other mechanisms for maintaining pressure

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26
Q

heat stroke

A

when temperature and humidity are high it is difficult for body to lose heat by radiation, treatment: cooling body off as quickly as possible, e,g cold water

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27
Q

heat exhaustion

A

due to extreme sweating and vasodilation, loss of water reduces volume of blood plasma and vasodilation reduces resistance to blood flow resulting in lowered blood pressure

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28
Q

hypothermia

A

if persons core temp falls below 33 metabolic rate is so low heat production is unable to replace heat lost and body temp continues to fall

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29
Q

glucose

A
  • stored as glycogen in liver and skeletal muscle cells
  • 500g of glycogen can be stored in body
  • 400g in skeletal muscle cells
  • 100g in liver
  • blood glucose is controlled by liver, pancreas and adrenal glands
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30
Q

glucose to glycogen & vice versa conversion

A

glucose — blood glucose level high > glycogen — blood glucose level too low > glucose

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31
Q

role of liver

A
  • able to convert glucose into glycogen for storage or glycogen into glucose for release into blood
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32
Q

actions of glucose

A
  • be removed from blood by liver to provide energy for live functioning
  • be removed by liver and/or by muscles and converted into glycogen for storage
  • continue to circulate in the blood, available for body cells to absorb and use as energy
  • be converted into fat for long term storage if it is in excess of that required to maintain normal blood sugar and tissue glycogen levels
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33
Q

glycogenesis (stimulated by insulin )

A

glucose molecules chemically joined in long chains to form glycogen molecules, stimulated by insulin
- glucose into glycogen

34
Q

glycogenesis stimulated by glucagon

A

process of converting glycogen back into glucose , stimulated by glucagon

35
Q

islet of langerhans

A

clusters of hormone secreting cells

36
Q

alpha cells

A

found in islet of langerhans, secrete glucagon

  • stimulate conversion of glycogen into glucose in liver
  • stimulate production of sugar molecules from fats and amino acids in liver, breakdown of lipids (lipolysis)
  • has mild stimulating effect on protein breakdown
37
Q

beta cells

A

found in islet of langerhans, secrete insulin

  • accelerates transport of glucose from blood into body cells
  • accelerates convection of glucose into glycogen in liver and skeletal muscle cells
  • stimulates conversion of glucose into protein
  • stimulates conversion of glucose into fat in fat storage tissue (lipogenesis)
38
Q

when blood glucose levels rise above normal

A

chemoreceptors in beta cells of langerhans stimulate those cells to secrete insulin, as blood glucose decreases these cells are no longer stimulated and production is reduced

39
Q

when blood glucose levels fall below normal

A

chemoreceptors in alpha cells of islet langerhans stimulate those cells to secrete glucagon, as blood glucose levels increase cells are no longer stimulated and production is reduced

40
Q

role of adrenal cortex in blood increasing blood glucose

A

secreted cortisol which stimulates conversion of glycogen into glucose in liver and stimulated protein breakdown in muscles and conversion of amino acids into glucose in liver

41
Q

role of dreamland medulla in increasing blood glucose levels

A

secretes adrenaline and noradrenaline which stimulate breakdown of glycogen in liver and release of glucose into blood

42
Q

water content

A

contains dissolved substances and plays important roles including transporting substance from one area of body to another, facilitating movement of movement across membrane, being site of chemical reaction

43
Q

intracellular fluid

A

fluid inside cells, cytosol

44
Q

extracellular fluid

A

fluid outside cell including blood plasma (intravascular fluid) and interstitial fluid (fluid between cells)

45
Q

transcellular fluid

A

fluid in specific body regions, included cerebrospinal fluid, fluid surrounding heart, fluid in joints, lymph

46
Q

continuous exchange of materials between different body fluids

A
  • plasma is separated from interstitial fluid by thin walls of capillaries and there is an exchange of materials them, water moves easily through plasma membranes and difference in osmotic pressure between intracellular and extracellular doesn’t last long (evens quickly)
47
Q

osmotic pressure

A

tendency of solution to take in water, greater difference in osmotic concentration between two substances the greater the osmotic pressure

48
Q

maintaining fluid balance

A

fluid gain must be equal to fluid lost

49
Q

metabolic water

A

small amount of water is obtained as byproduct of chemical processes occurring in cells

50
Q

fluid loss

A

fluids are lost from body via kidneys through skin, from surface lung and alimentary canal, 2.5L of fluid lost each day

51
Q

water intake vs water loss

A

intake: 2500mL
- food 700ml
- metabolic water: 200ml
- drink 1200ml

loss: 2500mL
- lungs: 300 ml
- skin 500 ml
- kidneys (urine) 1500mL
- alimentary canal (faeces) 200ml

52
Q

excretion

A

removal of waste products of metabolism from body

53
Q

organs involved in excretion

A
  • lungs: exterior of CO2 and H2O, produced during cellular respiration, carried in blood until it reaches lungs then exhaled
  • sweat glands: secrete waste containing byproducts of metabolism e,g urea , lactic acid, salt
  • alimentary canal: passes out bile pigments, breakdown products haemoglobin
  • kidneys: principle excretory organ, responsible for maintaining constant concentration of materials in body fluids
54
Q

kidney role

A

regulating composition of body fluid as water loss from kidneys can be regulated to achieve constant concentration of dissolved substances in body fluids

55
Q

ureter

A

leaves each kidney and drains into bladder which outside through urethra

56
Q

parts of kidney

A

renal veins: take blood away from kidney
renal artery: takes blood to kidney
urethra: tube from bladder to outside
kidneys: produce urine
ureter: tube that drains urine away from kidney into bladder
bladder: muscular bag that holds urine until it is passed out of body

57
Q

nephron

A

functional unit of kidney, carries out excretion and water regulation

58
Q

filtration

A

filtration of blood from capillaries of glomerulus, high pressure of afferent forces water and small dissolved molecules out of blood and into glomerular capsule this new substance is called filtrate

59
Q

reabsorption

A

filtrate passes through proximal convoluted tubule, loop of henle distal convoluted tubule and collecting duct
- water, sodium, potassium, chloride and bicarbonate ions, glucose are reabsorbed into peritubular capillaries back into blood, occurs through passive transport at PCT and loop of henle and active transport at DCT and collecting duct

60
Q

secretion

A

materials that need to be removed body are secreted into kidney tubule from capillaries to be expelled elf s hydrogen and potassium ions, creatine and drugs

61
Q

urine components

A

water and dissolved substances that remain from filtrate make up urine and it is carried by collecting duct to ureter then to bladder

62
Q

controlling water loss

A
  • strenuous physical activity or extreme heat, can increase water loss due to sweating and exhaled breath
  • as water is lost plasma becomes more concentrated and has higher osmotic pressure
  • then water moves from interstitial fluid and more water diffuses out of cells making the cell dry and shrink from dehydration
  • osmoreceptors then detect the increase in osmotic pressure and trigger responses that increase water content and decrease osmotic pressure
63
Q

volume and production of urine

A

depends on how much water ther is in body fluids

  • more water = larger volume of diluted urine
  • less water/dehydrated = smaller volume of concentrated urine
64
Q

level of active reabsorption at DCT and collecting duct

A
  • controlled by antiduretic hormone which is produced by hypothalamus and is released from posterior pituitary lobe
  • controls permeability yo walls of DCT and collecting duct: when concentration of ADH is high in blood plasma then walls of kidney tubules are very permeable to water, water is able to leave tubule and enter capillaries easily, when concentration of ADH is low then the kidney tubule walls will be not very permeable to water to very little water is reabsorbed into plasma of blood
65
Q

aldosterone in water regulation

A

aldosterone secreted by adrenal cortex in response to decrease in concentration of sodium in blood, decrease in blood volume, decrease in blood pressure and increase in concentration of potassium ions

  • acts one DCT and collecting ducts to increase the amount of sodium ions reabsorbed into blood stream and amount of potassium ions secreted in urine
  • uses active transport: by using sodium potassium pump, for every 3 sodium ions reabsorbed, 2 potassium ions are secreted
66
Q

thirst response

A

osmoreceptors stimulate hurts Centre I’m hypothalamus which prompts person to drink water, fluid is absorbed across wall of alimentary canal into blood, decreasing osmotic pressure

67
Q

dehydration

A

when water loss exceeds water intake and there is not enough water in body fluid to carry out normal function
- symptom: dizziness, severe thirst, low blood pressure, headache

68
Q

water intoxication

A

occurs when body fluids become diluted and cells take in extra water by osmosis, may occur if person loses a lot of water and salt through sweating and replaces losses with plain water
- symptoms: lightheadedness, vomiting, headache, collapsing

69
Q

cellular respiration

A

occurs in cells to provide energy for functioning, requires constant supply of oxygen and removal of CO2
- 6O2 + C6H1206 —> 6CO2 + 6H20 + ENERGY

70
Q

role of circulatory system in gas regulation

A

carries O2 from lungs to cells and takes CO2 being produced and delivers it to the lungs to be exhaled from body

71
Q

diaphragm

A

muscle that separates thorax from abdomen, skeletal muscle that requires stimulation from phrenic nerve to initiate contraction

72
Q

intercostal muscle

A

muscles between ribs, skeletal muscle is stimulated by intercostal nerve to imitate contraction

73
Q

respiratory centre

A

controls nerve impulses that travel to diaphragm and intercostal muscles, located in medulla oblongata

74
Q

peripheral chemoreceptors (gas regulation)

A

groups of cells located in walls of aorta and carotid arteries that are sensitive to changes in concentration of oxygen, CO2, hydrogen ions in blood plasma, when stimulated nerve impulse is sent to area of respiratory centre that regulates breathing

75
Q

central chemoreceptors (gas regulation)

A

located medulla oblongata, sensitive to changes in concentration of CO2 in blood and hydrogen ions in cerebrospinal fluid, when stimulated nerve impulse is sent to area of respiratory centre that regulates breathing

76
Q

oxygen concentration

A

as oxygen is used its concentration in blood decreases, if concentration of O2 falls below normal levels while other factors are constant, breathing rate and depth increases
- however needs to fall to very low levels before it has major stimulating effect, if this occurs peripheral chemoreceptors are stimulated and nerve impulse is sent to respiratory centre which stimulate transmission of message to diaphragm and intercostal muscle to increase depth and rate of breathing

77
Q

carbon dioxide concentration

A
  • small increase in concentration of CO2 is enough to stimulate an increase in depth and rate breathing
  • concentration of CO2 in blood plasma is associated with concentration of hydrogen ions (increase in CO2 causes increase in H)
  • concentration of both of these chemicals in blood stimulates central (most sensitive to changes of CO2 in blood but takes several minutes to respond) and peripheral chemoreceptors (stimulated by increased H, immediate response) , these transmit nerve impulses to respiratory centre and results in an increase in depth and rate of breathing
78
Q

hydrogen ion concentration

A

as hydrogen ion concentration in blood increases, pH decreases directly stimulates aortic and carotid chemoreceptors which transmits nerve impulses to respiratory centres , resulting in increasing rate and depth of breathing

79
Q

transmission of nerve impulses from respiratory centres

A

messages are sent along descending tract of spinal cord and then to phrenic and intercostal nerve which stimulates/cause a contraction and relaxation in the diaphragm and intercostal muscles which increases rate and depth of breathing and increases inhalation and exhalation of carbon dioxide therefore increases concentration of oxygen in blood plasma and decrease concentration of carbon dioxide

80
Q

hyperventilation

A

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

  • can occur voluntarily or be stimulated by physical stress e,g severe pain or emotional stress e.g severe anxiety
  • usually corrects itself bc reduced CO2 concentration in blood plasma means that chemoreceptors are not stimulated, reducing rate and depth of breathing until CO2 levels return to normal

Human Biology (8 decks)

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