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A Level Biology > C15 (Homeostasis) > Flashcards

C15 (Homeostasis) Flashcards

(92 cards)

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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
What do homeostasis mechanics require to function
Require information transferred between different parts body (communication systems, nervous systems: Nervous and Endocrine systems)
26
Give 6 examples of physiological factors controlled by homeostasis in mammals:
-Core body temp -Blood pH -Conc glucose in blood -Conc respiratory gases in blood -Water potential of blood -Meatabolic waste
27
Importance of Homeostasis
Help organisms keep their internal body conditions within restricted limits
28
Why is a stable body temp and pH level essential
Vital for enzyme activity
29
Negative feedback
If increase detected, responses lower levels back to ideal conditions If decrease detected, response raise levels back to stable condition
30
Negative feedback Examples
-Controlling glucose conc levels -Body temperature
31
Positive feedback
Conditions change Change is detected Response reinforces change
32
Positive feedback Examples
-Blood clotting cascade -Childbirth, hormone oxytocin (stimulates the uterus to contract)
33
What are advantages of endotherms (3)
-Can maintain temp regardless of external environment -Remain active even at low external temp -Inhabit colder parts of the planet
34
Disadvantages of endotherms (3)
-Use significant proportion of energy intake to maintain body temp in cold (less for growing) -Need more food -Overheating risk
35
Advantages of ectotherms (3)
-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
36
Disadvantages of ectotherms (2)
-Less active in cool temp -High risk predators can't take advantage of food
37
What do all organisms rely on to help regulate their body temp
Range physiological and behavioural mechanisms (balance can vary greatly)
38
Endotherms
Animals maintain fairly stable internal body temp through primarily internal physiological mechanisms (birds and mammals)
39
Ectotherms Behavioural responses (3)
-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
What behavioural responses do Galapagos Iguanas have
Contract muscles and vibrate increasing cellular metabolism to increase body temp
41
Ectotherms Physiological Responses
Dark colours absorb more radiation (lizards) Altering HR, increasing or decreasing metabolic rate affects cooling or warming across body surfaces.
42
What does excretion enable
Organisms to maintain pH balance and regulate osmotic pressure
43
How is core temperature maintained
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
Vasodilation
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
Increased sweating
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
Reducing insulting effect Hair/ Feathers
As body temp increases, erector pili muscles in skin relax, lying flat avoids trapping an insulating layer of air
47
Anatomical adaptations to cool down for endotherms
Large SA:V ratio (large ears, wrinkly skin) Pale fur/ feathers, reflects more radiation
48
Decrease sweating
Rate decreases and production can stop completely. Reduces cooling by evaporation of water from surface (although so evaporation on the lungs still occurs)
49
Shivering
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
Raising Body Hair/ Feathers
Erector pili muscles contract, traps insulating layer air, reducing cooling through skin
51
Anatomical adaptations for endotherms to keep warm
Adaptations that minimise SA:V ratio to reduce cooling (i.e small ears) Thick layer insulating fat Hibernation, lowers their metabolic rate
52
Bowman's capsule
Cup-shaped Contains glomerulus More blood enters the glomerulus than leaves due to ultrafiltration
53
Where is the loop of Henle located
Renal Medulla
54
Proximal convoluted tubule
Where many substances needed by the body are reabsorbed Cortex
55
Distal convoluted tubule
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
Collecting Duct
More fine tuning of water Walls are sensitive to ADH
57
ADH levels when dehydrated
Low water potential detected by osmoreceptors Posterior pituitary gland stimulated release more ADH into blood More ADH, more permeable, more water reabsorbed (osmosis)
58
What cells monitor the water potential of blood
Osmoreceptors in the hypothalamus
59
ADH levels when hydrated
Water potential high in blood Posterior pituitary glands stimulated less release of ADH Less ADH,less permeable, less water reabsorbed
60
Causes of kidney failure
Infection Old age Diabetes High blood pressure Genetic disorder (polycystic kidney disease).
61
Effects of kidney failure
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
Assessments for kidney failure
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
Treatments for kidney failure
Renal Dialysis (Hamodialysis and Peritoneal Dialysis) Kidney Transplant
64
Renal dialysis
Where patients blood is filtered.
65
Haemodialysis
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
Peritoneal Dialysis
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
Describe the lining of the Bowman’s Capsule and the glomerulus
They’re connected and continuous, with podocytes of the Bowman’s capsule wrapping around the blood capillaries of the glomerulus.
68
What does the high pressure in the glomerulus lead to
Forces some of the blood contents out and into the Bowman’s capsule
69
Stages of ultrafiltration
Lumen of capillary Capillary endothelium Basement membrane Bowman’s capsule epithelium (made of podocytes) Lumen of Bowman’s Capsule
70
Disadvantages of Haemodialysis
-Feel unwell in between sessions, due build up waste products and fluid -Not convenient keep going to hospital 3-5hrs
71
Advantages of Haemodialysis
Less risk infection Keep patient alive until transplant is ready
72
Advantages of Peritoneal Dialysis
More convenient (got on with day to day activities) Frees up hospitals and staff Keep patient alive until transplant is ready
73
Disadvantage of Peritoneal dialysis
Risk of infection Time consuming (no dialysis free days) Unsupervised
74
How is urine made
Via filtering the blood
75
What are urine samples used
Testing for: Medical problems (diabetes) Pregnancy Drug usage
76
Transplant
New kidney implanted replacing damaged one
77
What are the conditions that must be met for a successful transplant
Same blood type Same tissue type Can be supplied by relatives or organ donors
78
Advantages of transplant
Cheaper than constantly giving them dialysis for long period of time More convenient (then regular dialysis)
79
Disadvantages of transplant
Undergo major operation, risky Immune system rejecting transplant, patient has to take drugs to suppress it (side effects) Long waiting list/ time
80
What does PCT consist off
Layer of cuboidal cells with micro villi
81
How much filtrate is reabsorbed (and what substances are reabsorbed)
85% All glucose All AA’s Water Some salts
82
Selective reabsorption stages
-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
Why is it essential that cuboidal cells in PCT have high levels of mitochondria
Supply ATP, active transport, sodium transport
84
As you go down the Loop of Henle what happens to the water potential
Decreases (Salt Bath idea)
85
Loop of Henle stages
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
What does the Loop of Henle act as
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
What are monoclonal antibodies
Antibodies from a single clone of cells, produced to target particular cells or chemicals in the body
88
How are monoclonal antibodies made for pregnancy tests
-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
Glomerular filtration rate
Vol blood filtered through kidney in a given time
90
Why is the blood in the capillaries of the glomerulus forced out
Wide afferent (incoming) arteriole Blood leaves narrower efferent (outward) arteriole Resulting in considerable pressure in capillaries (Endothelium, leaky)
91
Basement membrane
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
Bowman’s Capsule Epithelium (Made of Podocytes)
Podocytes act as additional filter Have extensions (pedicels) wrapped around capillaries, that form filtration slits

A Level Biology (20 decks)

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