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Biology Y13 > Module 5.1.2 - Homeostasis > Flashcards

Module 5.1.2 - Homeostasis Flashcards

1
Q

What is homeostasis?

A

Body maintaining a dynamic equilibrium, with small fluctuations over narrow range of conditions

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2
Q

What do receptors and effectors do for homeostasis?

A
  • receptors and effectors are vital for body to maintain dynamic equilibrium
  • receptors detect environmental change
  • effectors create an appropriate response
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3
Q

What factors control homeostasis?

A
  • blood glucose
  • temperature
  • water content
  • pH
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4
Q

What is negative feedback?

A
  • ideal conditions
  • increase detected
  • responses lower levels
  • ideal conditions
  • decrease detected
    responses raise levels
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5
Q

What is positive feedback?

A
  • conditions change
  • change detected
  • responses reinforce change
    e.g. platelets clotting blood, labour contractions
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6
Q

What is thermoregulation?

A

Maintenance if a relatively constant core body temp to maintain optimum enzyme activity

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7
Q

What does ectotherm mean?

A

Core body temp is dependent on environment to warm body
‘outside heat’

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8
Q

What does endotherm mean?

A

Rely on metabolic processes to warm up, usually stable core body temp no matter the environment
‘inside heat’

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9
Q

What does behavioural responses mean?

A

Changes in an organisms activity in response to a stimulus

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10
Q

What does physiological responses mean?

A

Measurable reaction of the body to an internal or external stimulus

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11
Q

What physical processes cause heating up or cooling down?

A

Exothermic - chemical reactions
Latent heat - evaporation
Radiation - electromagnetic waves
Convection - heat travelling in liquids
Conduction - heat travelling in solids

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12
Q

Why is it good that many ectotherms live in water?

A

Don’t need to thermoregulate because of high heat capacity of water

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13
Q

Why can ectotherms live in difficult habitats with limited food?

A

Require less food due to requiring less energy to regulate temp
- are more vulnerable to fluctuations in environment

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14
Q

What does the hypothalamus do?

A
  • constantly monitors temperature
  • receives info from temp receptors om dermis of skin
  • receptors in hypothalamus detects temp change in brain and blood
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15
Q

What are endotherms?

A

Rely on metabolic reactions to maintain body temp

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16
Q

What are examples of behavioural responses?

A
  • huddling together
  • basking in sun
  • wallowing in mud
  • pressing against warm surfaces
  • digging burrows
  • hibernation
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17
Q

When is the heat loss centre activated in the hypothalamus?

A

When blood temp flowing though increases
- sends impulses through autonomic motor neurone to effectors in skin and muscles
- triggers response that act to lower core temp

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18
Q

When is the heat gain centre activated in the hypothalamus?

A

When blood temp flowing through decreases
- sends impulses through autonomic motor neurone to effectors in skin and muscles
- triggers response to raise core temp

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19
Q

What are some functions of the liver?

A
  • breaks down toxins
  • carbohydrate metabolism
  • detoxification
  • target organ for insulin, glucagon
  • deamination, remove amine group
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20
Q

What is bile made of?

A

Old haemoglobin/red blood cells that the liver has broken down

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21
Q

What is the liver?

A
  • major organ of homeostasis
  • largest internal organ of the body
  • 5% of body mass
  • able to regenerate itself
  • good blood supply by hepatic artery (oxygenated)
  • returns blood to heart in hepatic vein
  • blood loaded with products of digestive from intestines are also delivered to liver via hepatic portal vein
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22
Q

What are heolatocytes?

A
  • liver cells
  • large nuclei
  • prominent golgi apparatus
  • lots of mitochondria
  • divide and replicate to regenerate
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23
Q

What is the structure of the liver?

A
  • blood from hepatic artery and hepatic vein is mixed in sinusoids which are surrounded by hepatocytes
  • sinusoids contain Kupffer cells which inject foreign particles
  • hepatocytes secrete bile from breakdown of blood in spaces called canaliculi
  • bile drains into bile ductile and is taken to gall bladder
24
Q

What are parts of the kidney?

A

Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct

25
Q

What is the Bowman’s capsule?

A

Cup shaped structure that contains the glomerulus , tangle of capillaries , where ultrafiltration takes place

26
Q

What is the proximal convoluted tubule?

A

First coiled region of tubule after Bowman’s capsule, where reabsorption takes place

27
Q

Whatb is the loop of Henle?

A

Long loop of tubule that creates a region with very high solute conc in tissue fluid deep in kidney medulla

28
Q

What is the distal convoluted tubule?

A

Second twisted tubule where the fine-tuning of water balance takes place

29
Q

What are the kidneys?

A

Pair of reddish-brown organs attached to the back of the abdominal cavity, involved in excretion and osmoregulation

29
Q

What is the collecting duct?

A

Urine passes down here through medulla to pelvis, more fine tuning of water balanced takes place

30
Q

How are the kidneys get their blood supply?

A
  • supplied with blood by renal arteries that branch off from abdominal aorta after circulating through the kidneys, blood leaves via the renal vein that drains into the inferior vena cava
31
Q

What happens after the kidneys?

A
  • after being filtered by the nephron, the urine produced passes out the kidneys down tubes ureters
  • it is collected in the bladder, a muscular sac that stores the urine
  • urine passes out of the body via the urethra
31
Q

What is the structure of the kidney?

A
  • cortex is dark outer layer where filtering of blood takes place
  • medulla is lighter in colour and contains tubules of nephrons that form pyramids of the kidney and the collected ducts
  • pelvis is central chamber where urine collects before being passed out the ureter
31
Q

What are the nephrons?

A

Blood is filtered in nephrons and majority of filtrate is returned to blood, removing nitrogenous wastes and balancing the mineral ions and water

32
Q

What is the deamination process?

A
  • amino acids absorbed from small intestine and either the creates an amino acid pool for building new proteins or excess amino acid goes to liver
  • if excess amino acids go to liver, amino acid molecule splits
  • then either rest of molecule used in respiration or amino group combines with CO2 to form urea
  • if amino group combines with CO2 to form urea then goes to kidneys to be excreted
33
Q

What is the ornithine cycle?

A

Ammonia produced in deamination of proteins is converted into urea in a set of enzyme controlled reactions called the ornithine cycle

34
Q

What is the process of the ornithine cycle?

A
  • Ammonia combines with ornithine and CO2, H2O leaves to form citrulline
  • Ammonia is added again and H2O removed to form arginine
  • H2O is added and urea is removed to produce ornithine
  • ornithine is then reused in the cycle to combine with ammonia and CO2
35
Q

What is ADH?

A

Anti-diuretic hormone
- produced in hypothalamus
- stored in posterior pituitary gland
- increases permeability of collecting duct and distal convoluted tubule

36
Q

What is the process of ADH when water potential rises?

A
  • water potential rises
  • detected by osmoreceptors in hypothalamus
  • less ADH released, less aquaporins
  • less water reabsorbed from nephron
  • larger volume of dilute urine produced
  • water potential falls
36
Q

What is ADH action?

A
  • ADH binds to receptors on collecting duct cell membrane
  • formation of cAMP is triggered
  • cAMP causes vesicles in cells lining the collecting duct to fuse with cell surface membranes on side of cell in contact with tissue fluid of medulla
  • membranes of these vesicles contain aquaporins (water based protein channels)
  • provide route for water to move out of cell by osmosis
  • is now permeable to water
37
Q

What is the process of ADH when water potential falls?

A
  • water potential falls
  • detected by osmoreceptors in hypothalamus
  • more ADH released, more aquaporins
  • more water reabsorbed from nephron
  • smaller volume of concentrated urine produced
  • water potential rises
37
Q

What does urine contain?

A
  • breakdown of products of a whole range of chemicals (along with water, urea, mineral salts etc)
  • new substances will show up in your urine if you’re affected by 1 or a number of diseases
38
Q

What is hCG?

A
  • hormone found in blood and urine of pregnant women
  • what modern pregnancy tests test for
39
Q

What are monoclonal antibodies?

A

Needed to create all identical antibodies

40
Q

What are the 4 stages of creating monoclonal antibodies?

A
  1. hCG injected into mouse which produces appropriate antibodies that will target and bind to hCG, B cells that make this antibody are removed from the mouse
  2. a myeloma (type of cancer cell that divides rapidly) is grown in culture medium
  3. B cell from mouse and myeloma are fused together to move a hybridoma cell
  4. hybridoma reproduces rapidly, monoclonal antibodies are collected and purified
41
Q

What are anabolic steroids?

A
  • can be tested for using a person’s urine in gas chromatography and mass spectrometry
  • urine is vapourised with solvent and passed along a tube
  • lining of tube absorbs gases and is analysed to give a chromatogram
  • can be read to show presence of drugs
42
Q

What are some of the effects of kidney failure?

A

Death, urea build up, increased blood pressure, decreased water potential, weakened bones, anaemia, loss of electrolyte balance, pain/stiffness in joints

42
Q

Why may kidneys fail?

A
  • infections
  • raised blood pressure
  • genetic conditions
43
Q

What are 2 common symptoms of the kidney not working?

A

Protein or blood in urine

44
Q

What is erythropoietin?

A

Hormone produced by the kidneys which creates red blood cells

45
Q

What is Glomerular fibrillation rate?

A
  • indicates kidney disease
  • uses levels of creatinine in blood to estimate glomerular fibrillation rate
  • creatinine breaks down the product made in muscles
46
Q

What are the 2 types of dialysis?

A
  • haemodialysis
  • peritoneal dialysis
47
Q

What is peritoneal dialysis?

A
  • occurs inside the body
  • making use of the membranes formed by abdominal lining, peritoneum
  • catheter inserted
  • dialysis fluid inserted for 4-6 hours and then drained out
48
Q

What is haemodialysis?

A
  • artificial kidney removes waste products
  • dialysis fluid used
  • no net movement of glucose
  • urea diffuses out of blood into dialysis fluid
  • blood leaves body via artery and returns through vein
  • blood and dialysis fluid have a counter current flow
  • fluid and blood have the same osmatic pressure
49
Q

What are kidney transplants?

A
  • a single healthy kidney from a donor is placed in the body
  • long term dialysis has some serious side effects so transplants are done
50
Q

What are some advantages of kidney transplants?

A
  • no need for regular sessions
  • less expensive than long term dialysis
  • no dietary restrictions for patients
  • long term dialysis can damage the body
51
Q

What are some disadvantages of kidney transplants?

A
  • less readily available
  • transplanted organ don’t last forever
  • risk of rejection due to different antigens
  • immunosuppressant drugs taken increase the chance of infection by diseases

Biology Y13 (8 decks)

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