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A Level Biology > C15 (Homeostasis) > Flashcards

C15 (Homeostasis) Flashcards

1
Q

Excretion

A

Removal of metabolic waste products from the body

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2
Q

What are the main metabolic waste products for mammals (3)

A

CO2 (waste products in cellular respiration, excreted from lungs)

Bile pigments (formed from breakdown of haemoglobin, from old red blood cells) in the liver to the small intestine

Nitrogenous waste products (urea) formed from breakdown of excess AA’s by the liver, kidney excretes in urine.

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3
Q

What does the liver have

A

A rich blood supply

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4
Q

Hepatic artery function

A

Supplies the liver with oxygenated blood (for the hepatocytes)
25% blood being supplied

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5
Q

Hepatic vein

A

Drain, removes the deoxygenated blood out, back to heart through inferior Vena Cava

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6
Q

Hepatic portal vein

A

Supplies blood loaded with products of digestion (nutrients) straight from intestine (75% of blood being supplied)

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7
Q

Kupffer Cells

A

Act as the local/ resident macrophages
First line of defence

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8
Q

List features of heptosytis cells

A

Singular, hepatocyte
Large nuclei
Many mitochondria
Prominent Golgi apparatus
In general they’re metabolically active

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9
Q

Sinusoid

A

Where the oxygenated blood from the hepatic artery and the deoxygenated blood from the hepatic portal vein mixes

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10
Q

Branch of bile duct function

A

Carries bile (produced by the hepatocytes) to the gall bladder

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11
Q

Bile, canaliculus

A

Hepatocytes secrete bile , which drains into the gall bladder, stored

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12
Q

What does mixing the blood in the sinusoid result in

A

Increase the oxygen content of the blood, supplying enough oxygen needed by the hepatocytes

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13
Q

Kupffer cells function

A

Ingesting foreign particles and helping protect from disease

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14
Q

How’s bile produced

A

Bile secreted by the hepatocytes from the breakdown of blood into spaces called canaliculi

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15
Q

List 3 functions of the liver

A

Carbohydrates Metabolism
Detoxification
Deamination of Excess AA’s

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16
Q

Carbohydrate Metabolism

A

Hepatocytes, homeostasis control glucose levels by their interaction with insulin and glucagon

Glucose increases, insulin levels increase, stimulating hypatocytes covert glucose to glycogen (vise versa, glycogen converted back under influence of hormone glucagon).

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17
Q

Detoxification

A

Urea and other metabolic pathways produce poisonous substances (consumption alcohol and drugs)
Liver detoxification them (harmless)

Detoxifying ethanol, hepatocytes contain, alcohol dehydrogenase, breaks down ethanol to ethanal, ethanal to ethanoate.

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18
Q

Deamination

A

-Excess, through eating and digesting proteins.

-Nitrogen is present in amino group

-Cant usually be stored so must be used (protein synthesis) or broken down and excreted to prevent damaging body.

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19
Q

Anatomy of the kidney

A

Renal pelvis
Renal medulla
Renal cortex
Ureter
Renal vein
Renal artery
Calyces

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20
Q

Which part of the nephron is the most water reabsorbed into the blood

A

Proximal convoluted tubule

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21
Q

Walls are impermeable to water

A

Ascending limb (Loop Henle)

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22
Q

ADH acts on the walls of…

A

The distal convoluted tubule and collecting duct

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23
Q

What are the main functions of the kidney

A

-Filtering blood
-Producing urine
-Mainting water levels in body
-Regulating red blood cell levels and blood pressure

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24
Q

Homeostasis

A

Maintaining optimum internal conditions, despite changes in external environment

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25
Q

What do homeostasis mechanics require to function

A

Require information transferred between different parts body (communication systems, nervous systems: Nervous and Endocrine systems)

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26
Q

Give 6 examples of physiological factors controlled by homeostasis in mammals:

A

-Core body temp
-Blood pH
-Conc glucose in blood
-Conc respiratory gases in blood
-Water potential of blood
-Meatabolic waste

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27
Q

Importance of Homeostasis

A

Help organisms keep their internal body conditions within restricted limits

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28
Q

Why is a stable body temp and pH level essential

A

Vital for enzyme activity

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29
Q

Negative feedback

A

If increase detected, responses lower levels back to ideal conditions

If decrease detected, response raise levels back to stable condition

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30
Q

Negative feedback
Examples

A

-Controlling glucose conc levels
-Body temperature

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31
Q

Positive feedback

A

Conditions change
Change is detected
Response reinforces change

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32
Q

Positive feedback
Examples

A

-Blood clotting cascade
-Childbirth, hormone oxytocin (stimulates the uterus to contract)

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33
Q

What are advantages of endotherms (3)

A

-Can maintain temp regardless of external environment

-Remain active even at low external temp

-Inhabit colder parts of the planet

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34
Q

Disadvantages of endotherms (3)

A

-Use significant proportion of energy intake to maintain body temp in cold (less for growing)

-Need more food

-Overheating risk

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35
Q

Advantages of ectotherms (3)

A

-Less food used in respiration, more energy and nutrients from food used for growth

-Need to find less food

-Can survive long period without food

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36
Q

Disadvantages of ectotherms (2)

A

-Less active in cool temp

-High risk predators can’t take advantage of food

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37
Q

What do all organisms rely on to help regulate their body temp

A

Range physiological and behavioural mechanisms (balance can vary greatly)

38
Q

Endotherms

A

Animals maintain fairly stable internal body temp through primarily internal physiological mechanisms (birds and mammals)

39
Q

Ectotherms
Behavioural responses (3)

A

-Bask in sun
-Oreintating body to maximize SA exposed and even extend body

-Conduction, pressing body against warm ground, also get warmer through exothermic metabolic reactions

-Need to cool down, prevent denaturing, many warming processes reversed

40
Q

What behavioural responses do Galapagos Iguanas have

A

Contract muscles and vibrate increasing cellular metabolism to increase body temp

41
Q

Ectotherms
Physiological Responses

A

Dark colours absorb more radiation (lizards)

Altering HR, increasing or decreasing metabolic rate affects cooling or warming across body surfaces.

42
Q

What does excretion enable

A

Organisms to maintain pH balance and regulate osmotic pressure

43
Q

How is core temperature maintained

A

Thermoreceptors in hypothalamus,. maintain core body temp by detecting blood temp

Thermoreceptors in skin, peripheral, detect external temperature

Hypothalamus sends impulses to effectors in skin (pilo erection, Vasco)

44
Q

Vasodilation

A

Arterioles near surface dilate

Vessels that provide direct connection arterioles and venules (arteriovenous shunt vessels) constrict, forcing blood through capillary networks (close to surface).

Skin flushes and cools as a result of increased radiation

Smooth muscles in peripheral arterioles can constrict

Can also cool via conduction

45
Q

Increased sweating

A

As sweat evaporates from surface heat is lost, cooling blood below surface

Some animals sweat glands restricted less hairy areas, instead often use their mouth and pant (lossing heat as water vapour)

Kangaroos and cats like front legs keep cool

46
Q

Reducing insulting effect Hair/ Feathers

A

As body temp increases, erector pili muscles in skin relax, lying flat avoids trapping an insulating layer of air

47
Q

Anatomical adaptations to cool down for endotherms

A

Large SA:V ratio (large ears, wrinkly skin)

Pale fur/ feathers, reflects more radiation

48
Q

Decrease sweating

A

Rate decreases and production can stop completely. Reduces cooling by evaporation of water from surface (although so evaporation on the lungs still occurs)

49
Q

Shivering

A

The rapid involuntary contracting and relaxing of large voluntary muscles

The metabolic heat from the exothermic reactions warm up body, instead of moving it

50
Q

Raising Body Hair/ Feathers

A

Erector pili muscles contract, traps insulating layer air, reducing cooling through skin

51
Q

Anatomical adaptations for endotherms to keep warm

A

Adaptations that minimise SA:V ratio to reduce cooling (i.e small ears)

Thick layer insulating fat

Hibernation, lowers their metabolic rate

52
Q

Bowman’s capsule

A

Cup-shaped
Contains glomerulus
More blood enters the glomerulus than leaves due to ultrafiltration

53
Q

Where is the loop of Henle located

A

Renal Medulla

54
Q

Proximal convoluted tubule

A

Where many substances needed by the body are reabsorbed

Cortex

55
Q

Distal convoluted tubule

A

Fining of water balance of body temp takes place

Permeability of walls varies in response to levels of anti-diuretic hormone in blood

Further regulation of ion balance and pH of blood

56
Q

Collecting Duct

A

More fine tuning of water
Walls are sensitive to ADH

57
Q

ADH levels when dehydrated

A

Low water potential detected by osmoreceptors

Posterior pituitary gland stimulated release more ADH into blood

More ADH, more permeable, more water reabsorbed (osmosis)

58
Q

What cells monitor the water potential of blood

A

Osmoreceptors in the hypothalamus

59
Q

ADH levels when hydrated

A

Water potential high in blood

Posterior pituitary glands stimulated less release of ADH

Less ADH,less permeable, less water reabsorbed

60
Q

Causes of kidney failure

A

Infection
Old age
Diabetes
High blood pressure
Genetic disorder (polycystic kidney disease).

61
Q

Effects of kidney failure

A

Toxic urea accumulation
Solute/ electrolyte unbalance in blood
Osmoregulation problems, leads to high blood pressure
EPO (hormone) problems (creates red blood cells problems, anaemia)

62
Q

Assessments for kidney failure

A

Urine composition analysis

Glomerular filtration rate (GFR) , normal reading: 90-120cm^3 min-1
Estimated GFR based on creatinine clearance
Kidney failure < 15 cm3min-1

63
Q

Treatments for kidney failure

A

Renal Dialysis (Hamodialysis and Peritoneal Dialysis)

Kidney Transplant

64
Q

Renal dialysis

A

Where patients blood is filtered.

65
Q

Haemodialysis

A

Passed through dialysis machine
Blood flows one side of PPM and dialysis fluid flows on the other
Waste products, excess ions and water diffuse into dialysis fluid
Blood cells and larger mol (proteins) remain
Each session 3-5 hrs, 2/3x a week

66
Q

Peritoneal Dialysis

A

DF through tube passing outside abdomen into abdominal cavity
Waste products diffuse into DF across the peritoneum (membrane lining abdominal cavity)
Fluid drained via tube
At home serval times per day or long overnight session

67
Q

Describe the lining of the Bowman’s Capsule and the glomerulus

A

They’re connected and continuous, with podocytes of the Bowman’s capsule wrapping around the blood capillaries of the glomerulus.

68
Q

What does the high pressure in the glomerulus lead to

A

Forces some of the blood contents out and into the Bowman’s capsule

69
Q

Stages of ultrafiltration

A

Lumen of capillary
Capillary endothelium
Basement membrane
Bowman’s capsule epithelium (made of podocytes)
Lumen of Bowman’s Capsule

70
Q

Disadvantages of Haemodialysis

A

-Feel unwell in between sessions, due build up waste products and fluid
-Not convenient keep going to hospital 3-5hrs

71
Q

Advantages of Haemodialysis

A

Less risk infection
Keep patient alive until transplant is ready

72
Q

Advantages of Peritoneal Dialysis

A

More convenient (got on with day to day activities)
Frees up hospitals and staff
Keep patient alive until transplant is ready

73
Q

Disadvantage of Peritoneal dialysis

A

Risk of infection
Time consuming (no dialysis free days)
Unsupervised

74
Q

How is urine made

A

Via filtering the blood

75
Q

What are urine samples used

A

Testing for:
Medical problems (diabetes)
Pregnancy
Drug usage

76
Q

Transplant

A

New kidney implanted replacing damaged one

77
Q

What are the conditions that must be met for a successful transplant

A

Same blood type
Same tissue type
Can be supplied by relatives or organ donors

78
Q

Advantages of transplant

A

Cheaper than constantly giving them dialysis for long period of time
More convenient (then regular dialysis)

79
Q

Disadvantages of transplant

A

Undergo major operation, risky
Immune system rejecting transplant, patient has to take drugs to suppress it (side effects)
Long waiting list/ time

80
Q

What does PCT consist off

A

Layer of cuboidal cells with micro villi

81
Q

How much filtrate is reabsorbed (and what substances are reabsorbed)

A

85%
All glucose
All AA’s
Water
Some salts

82
Q

Selective reabsorption stages

A

-Sodium actively transported out of the PCT epithelium, across basal membrane by stadium/ potassium pumps, using energy from ATP.

-Lower conc sodium, inside PCT epithelium

—Sodium diffuses from lumen (PCT) into PCT epithelium via co-transport proteins (glucose exported with it), even against conc gradient

-Glucose diffuses down conc grad, across basil membrane via carrier protein

-Water follows down water potential grad, osmosis

83
Q

Why is it essential that cuboidal cells in PCT have high levels of mitochondria

A

Supply ATP, active transport, sodium transport

84
Q

As you go down the Loop of Henle what happens to the water potential

A

Decreases
(Salt Bath idea)

85
Q

Loop of Henle stages

A

Ascending Limb, no water diffuses out because walls are impermeable to water, sodium pumped out (Chloride follows)

Tissue fluid left in the nephron becomes more concentrated as the water potential decreases within

In the Descending limb water moves out back into capillary network via osmosis, no active transport of sodium here

Collecting duct, water moves down and out by osmosis

86
Q

What does the Loop of Henle act as

A

A counter current system/ multiplier, to ensure tissue fluid in medulla is increasingly conc (lower water potential) compared to the filtrate in the nephron

87
Q

What are monoclonal antibodies

A

Antibodies from a single clone of cells, produced to target particular cells or chemicals in the body

88
Q

How are monoclonal antibodies made for pregnancy tests

A

-Mouse injected HCG (makes appropriate antibodies)

-B cells that make required antibody, removed from spleen of mouse and fused with myeloma (type cancerous cell, divides rapidly)

-New fused cell= hybridoma, each reproduces rapidly, results millions clones of ‘living factories’, making desired antibodies

-Antibodies collected and purified, the used variety ways

89
Q

Glomerular filtration rate

A

Vol blood filtered through kidney in a given time

90
Q

Why is the blood in the capillaries of the glomerulus forced out

A

Wide afferent (incoming) arteriole
Blood leaves narrower efferent (outward) arteriole
Resulting in considerable pressure in capillaries
(Endothelium, leaky)

91
Q

Basement membrane

A

Fluid passes BM
Made up off network of collagen fibres and other proteins, create sieve like structure
Blood cells and many protein retained in capillary

92
Q

Bowman’s Capsule Epithelium
(Made of Podocytes)

A

Podocytes act as additional filter
Have extensions (pedicels) wrapped around capillaries, that form filtration slits

A Level Biology (20 decks)

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