C15 (Homeostasis) Flashcards
Excretion
Removal of metabolic waste products from the body
What are the main metabolic waste products for mammals (3)
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.
What does the liver have
A rich blood supply
Hepatic artery function
Supplies the liver with oxygenated blood (for the hepatocytes)
25% blood being supplied
Hepatic vein
Drain, removes the deoxygenated blood out, back to heart through inferior Vena Cava
Hepatic portal vein
Supplies blood loaded with products of digestion (nutrients) straight from intestine (75% of blood being supplied)
Kupffer Cells
Act as the local/ resident macrophages
First line of defence
List features of heptosytis cells
Singular, hepatocyte
Large nuclei
Many mitochondria
Prominent Golgi apparatus
In general they’re metabolically active
Sinusoid
Where the oxygenated blood from the hepatic artery and the deoxygenated blood from the hepatic portal vein mixes
Branch of bile duct function
Carries bile (produced by the hepatocytes) to the gall bladder
Bile, canaliculus
Hepatocytes secrete bile , which drains into the gall bladder, stored
What does mixing the blood in the sinusoid result in
Increase the oxygen content of the blood, supplying enough oxygen needed by the hepatocytes
Kupffer cells function
Ingesting foreign particles and helping protect from disease
How’s bile produced
Bile secreted by the hepatocytes from the breakdown of blood into spaces called canaliculi
List 3 functions of the liver
Carbohydrates Metabolism
Detoxification
Deamination of Excess AA’s
Carbohydrate Metabolism
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).
Detoxification
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.
Deamination
-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.
Anatomy of the kidney
Renal pelvis
Renal medulla
Renal cortex
Ureter
Renal vein
Renal artery
Calyces
Which part of the nephron is the most water reabsorbed into the blood
Proximal convoluted tubule
Walls are impermeable to water
Ascending limb (Loop Henle)
ADH acts on the walls of…
The distal convoluted tubule and collecting duct
What are the main functions of the kidney
-Filtering blood
-Producing urine
-Mainting water levels in body
-Regulating red blood cell levels and blood pressure
Homeostasis
Maintaining optimum internal conditions, despite changes in external environment
What do homeostasis mechanics require to function
Require information transferred between different parts body (communication systems, nervous systems: Nervous and Endocrine systems)
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
Importance of Homeostasis
Help organisms keep their internal body conditions within restricted limits
Why is a stable body temp and pH level essential
Vital for enzyme activity
Negative feedback
If increase detected, responses lower levels back to ideal conditions
If decrease detected, response raise levels back to stable condition
Negative feedback
Examples
-Controlling glucose conc levels
-Body temperature
Positive feedback
Conditions change
Change is detected
Response reinforces change
Positive feedback
Examples
-Blood clotting cascade
-Childbirth, hormone oxytocin (stimulates the uterus to contract)
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
Disadvantages of endotherms (3)
-Use significant proportion of energy intake to maintain body temp in cold (less for growing)
-Need more food
-Overheating risk
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
Disadvantages of ectotherms (2)
-Less active in cool temp
-High risk predators can’t take advantage of food
What do all organisms rely on to help regulate their body temp
Range physiological and behavioural mechanisms (balance can vary greatly)
Endotherms
Animals maintain fairly stable internal body temp through primarily internal physiological mechanisms (birds and mammals)
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
What behavioural responses do Galapagos Iguanas have
Contract muscles and vibrate increasing cellular metabolism to increase body temp
Ectotherms
Physiological Responses
Dark colours absorb more radiation (lizards)
Altering HR, increasing or decreasing metabolic rate affects cooling or warming across body surfaces.
What does excretion enable
Organisms to maintain pH balance and regulate osmotic pressure
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)
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
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
Reducing insulting effect Hair/ Feathers
As body temp increases, erector pili muscles in skin relax, lying flat avoids trapping an insulating layer of air
Anatomical adaptations to cool down for endotherms
Large SA:V ratio (large ears, wrinkly skin)
Pale fur/ feathers, reflects more radiation
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)
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
Raising Body Hair/ Feathers
Erector pili muscles contract, traps insulating layer air, reducing cooling through skin
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
Bowman’s capsule
Cup-shaped
Contains glomerulus
More blood enters the glomerulus than leaves due to ultrafiltration
Where is the loop of Henle located
Renal Medulla
Proximal convoluted tubule
Where many substances needed by the body are reabsorbed
Cortex
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
Collecting Duct
More fine tuning of water
Walls are sensitive to ADH
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)
What cells monitor the water potential of blood
Osmoreceptors in the hypothalamus
ADH levels when hydrated
Water potential high in blood
Posterior pituitary glands stimulated less release of ADH
Less ADH,less permeable, less water reabsorbed
Causes of kidney failure
Infection
Old age
Diabetes
High blood pressure
Genetic disorder (polycystic kidney disease).
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)
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
Treatments for kidney failure
Renal Dialysis (Hamodialysis and Peritoneal Dialysis)
Kidney Transplant
Renal dialysis
Where patients blood is filtered.
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
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
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.
What does the high pressure in the glomerulus lead to
Forces some of the blood contents out and into the Bowman’s capsule
Stages of ultrafiltration
Lumen of capillary
Capillary endothelium
Basement membrane
Bowman’s capsule epithelium (made of podocytes)
Lumen of Bowman’s Capsule
Disadvantages of Haemodialysis
-Feel unwell in between sessions, due build up waste products and fluid
-Not convenient keep going to hospital 3-5hrs
Advantages of Haemodialysis
Less risk infection
Keep patient alive until transplant is ready
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
Disadvantage of Peritoneal dialysis
Risk of infection
Time consuming (no dialysis free days)
Unsupervised
How is urine made
Via filtering the blood
What are urine samples used
Testing for:
Medical problems (diabetes)
Pregnancy
Drug usage
Transplant
New kidney implanted replacing damaged one
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
Advantages of transplant
Cheaper than constantly giving them dialysis for long period of time
More convenient (then regular dialysis)
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
What does PCT consist off
Layer of cuboidal cells with micro villi
How much filtrate is reabsorbed (and what substances are reabsorbed)
85%
All glucose
All AA’s
Water
Some salts
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
Why is it essential that cuboidal cells in PCT have high levels of mitochondria
Supply ATP, active transport, sodium transport
As you go down the Loop of Henle what happens to the water potential
Decreases
(Salt Bath idea)
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
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
What are monoclonal antibodies
Antibodies from a single clone of cells, produced to target particular cells or chemicals in the body
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
Glomerular filtration rate
Vol blood filtered through kidney in a given time
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)
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
Bowman’s Capsule Epithelium
(Made of Podocytes)
Podocytes act as additional filter
Have extensions (pedicels) wrapped around capillaries, that form filtration slits
