M5 CH15 excretion & homeostasis Flashcards
outline how nitrogenous waste is excreted from the body in mammals, with reference to the orthenine cycle
the orthenine cycle
1. excess amino acids are deaminated, and so are converted to ammonia
2. ammonia is highly toxic, and so it is converted to urea
3. urea is then excreted from the body
state the 3 main waste products that need to be excreted from the body
- carbon dioxide
- nitrogenous waste: urea
- bile pigments
what nitrogenous waste do fish excrete?
ammonia
explain how bile pigments are excreted from the body in the liver.
hepatocytes secrete the bile into canaliculi
bile passes into ductules where it then travels to gall bladder to be removed
explain what the term detoxification means
the neutralisation or breakdown of unwanted chemicals
outline the key structural features of hepatocytes, liver cells
(4 points)
large nuclei
prominent golgi apparatus
many mitochondria
contains catalase: involved in breakdown of hydrogen peroxide
outline the role of hepatocytes (liver cells) in regulating blood glucose regulation
-In response to insulin they absorb excess glucose from the blood and convert it back to glycogen (glycogenesis)
(lowers BSLs)
-In response to glucagon, they hydrolyse glycogen back into glucose (glycogenolysis) and release it into the blood
(raises BSLs)
state the blood vessel that delivers oxygenated blood to the hepatic vein in the liver.
hepatic artery
state the blood vessel that delivers deoxygenated blood to the hepatic vein in the liver
hepatic portal vein
state what sinusoids are
(liver)
spaces where oxygenated and deoxygenated blood mix
explain the role of kupffer cells in the liver
act as macrophages, engulfing foreign particles to protect the liver from disease.
state the structure found at the CENTER of the kidney, outline its role
pelvis
where urine collects before it leaves the kidney and travels to ureter
state the structure found in the middle layer of the kidney, and its role
medulla
contains the nephrons: where the blood is filtered
state the structure found in the outside layer of the kidney, and its role
cortex
carries blood from the renal arteries to the nephron (found in medulla)
state the structures found in the medulla in the kidney
loop of henle
collecting ducts
state the structures found in the cortex of the kidney
bowmans capsule
glomerulus
PCT
DCT
state the order that the structures occur in during filtration in the nephron
- glomerulus
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
- collecting ducts
explain the role of the Bowmans capsule
filters the blood before in can pass into glomerulus
its basement membrane acts as a filter
explain what happens at the proximal convoluted tubule
selective reabsorption:
- glucose and amino acids are reabsorbed INTO the blood by active transport
- sodium ions are pumped OUT
state the adaptations of the PCT
- lots of microvili: increases surface A
- lots of mitochondria: provides energy for active transport
outline what happens at the loop of henle
water and salt are reabsorbed back into the blood
state the structure in the nephron where water is reabsorbed, and name the hormone controls the structures membrane permeability
distal convoluted tubule
ADH
what is the role of the collecting duct
takes the end product urine away to the pelvis and ureter
outline the 2 components of the loop of henle, and what each is permeable to
descending limb: water
AsceNding limb: NA ions and CL ions
(tip+ ascending has N and A in)
when observing a diagram of a kidney, which section is usually darker?
the cortex
describe the term “homeostasis” and state the factors that contribute to homeostasis.
the maintenance of stable internal conditions of the body, with only small fluctuations
- temperature
- glucose levels
- ion levels
- water
explain how the release of oxytocin during labour is an example of positive feedback
oxytocin is a hormone that triggers uterus contractions.
when the uterus contracts, oxytocin is released, causing more contractions
explain what an ectotherm is and provide examples
animals that use their surroundings to heat their body up
e.g. fish/reptiles/invertebrates
outline ways that ectotherms thermoregulate
WARM UP:
basking in sun
press body against warm ground
colour variations: darker to absorb more heat
COOL DOWN:
finding shade
colour variations: lighter to reflect the heat
explain what an endotherm is and provide examples:
animals that thermoregulate through their internal metabolic reactions.
humans
mammals
outline the ways that endotherms thermoregulate
WARM UP:
- vasoconstriction: reduces radiation of heat off the surface of skin
- raising body hair/feathers: traps a layer of air, providing insulation
- shivering: rapid contraction/relaxation of voluntary muscles increases metabolic heat
COOL DOWN:
- vasodilation: enabling heat to radiate off surface of the skin
- sweating: uses heat from metabolic reactions to evaporate the sweat off skin surface.
- hair/feathers flat against skin: prevents layer of air being trapped/less insulation
outline what monoclonal antibodies are
antibodies from a single clone of cells that are produced to target particular cells/ chemicals in the body
outline the use of HCG to create monoclonal antibodies in the treatment of cancer
- A mouse is injected with HCG so that it makes the appropriate antibody
- the B cells that make the required antibody are removed (from spleen of mouse) and fused with a myeloma ( type of cancer cell)
- creates a hybridoma- which reproduces rapidly
- these antibodies are collected
outline the steps of a pregnancy test, and the role of monoclonal antibodies in the test.
- the wick is soaked with urine (usually first in morning as has highest HCG levels)
- test contains mobile monoclonal antibodies that have very small coloured beads attached that ONLY bind to HCG
- if woman is pregnant the HCG in her urine binds to the mobile monoclonal antibodies and forms a HCG/antibody complex
- urine reaches first “window” on the test. this is the result window. it has immobilised monoclonal antibodies usually arranged in a line. only HCG/antibody complexes can bind to these. therefore, if the woman is pregnant the complexes will bind and create a coloured line in the result window. (if she isn’t= no colour)
- urine carries on to 2nd window, where there is a line of immobilised antibodies that bind to only mobile antibodies (regardless of presence of HCG) coloured line forms regardless of result, to confirm that the test it working
outline the effects of kidney failure
- loss of electrolyte balance- osmotic imbalances
- build up of urea in blood (toxic) can poison cells
- high blood pressure (kidneys play role in b.p by maintaining water balance of blood)
- weakened bones: calcium/phosphorous balance in blood is lost
- pain/stiffness- build up of abnormal proteins
- anaemia: kidneys are involved in production of epo- forms RBCS. :. RBC count decreases
explain what the glomerular filtration rate is, and how it is estimated.
- A test used to estimate the volume of blood filtered by the glomeruli each minute, used to indicate a loss of function in the kidneys
- blood test measures level of creatinine in the blood.
if levels go up= kidney not working properly
explain what haemodialysis is and how it works
- a dialysis machine is used to carry out the function of the kidney artificially
- all by diffusion
- usually carried out in hospital
- blood leaves patients body from artery and enters machine- flows between partially permeable dialysis membranes (mimicking basement membrane of bowman’s capsule.
- removal of unwanted substances in blood –> urea/mineral ions
- counter current exchange system (dialysis fluid & blood) : opposite directions, dialysis fluid contains NO urea, steep concN gradient created- so almost all urea diffuses from blood into dialysis fluid
explain what peritoneal dialysis is and how it works.
- done at home
- done in the body
- dialysis fluid is introduced into abdomen via catheter
- dialysis takes place across peritoneal membranes (urea diffuses into dialysis fluid,etc)
- fluid drained off and discarded
outline how a kidney transplant takes place, and the + and -ves.
- single healthy kidney placed in the body, BVs joined and ureter of new kidney is inserted into bladder
- risk of rejection: antigens on donor differ from antigens on cells of recipient- immune system will recognise this (can result in rejection/destruction
+ if successful, kidney will function normally for many years
+ dialysis has serious long term side effects
