Module 5 Burnell Flashcards by Sebastian Mckie

how do pregnancy tests work?

Wick soaked in urine
Test contains mobile antibodies that bind to hCG (hormone). They also are attached to a dye
They carry along test to reach window
bind to immobolised antibodies that only bind to a hCG-antibody complex. If pregnant, a first line shows
More immobolised antibodies that only bind to free antibodies. This forms a second line regardless of pregnancy/hCG presence. This is to show it works

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how are anabolic steroids tested for?

by testing urine and doing gas chromatography.

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How are drugs tested for?

in urine. Broken into two samples, using monoclonal antibodies on one and gas chromatography on the other

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what are early symptoms of kidney failure?

protein in the urine- are filtered out when they shouldn’t be
blood in the urine- filtering process not working

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what happens when kidneys fail completely, as a result of urea and mineral ions building up?

loss of osmotic balance due to bad electrolyte balance
build up of toxic urea
high blood pressure

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what is glomerular filtration rate and what is it useful for?

It is used as a measure to indicate kidney disease. The amount of creatinine (breakdown product of muscles) is measured in the blood. If levels of creatinine go up, it is a sign that the kidneys are not working properly

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What other factors need to be taken into account when looking at GFR?

decreases with age

Those with more muscle mass (Men) have higher levels of creatinine

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How does haemodialysis work?

blood flows into machine, and flows between partially permeable membranes that mimic the Bowman’s capsule. The other side of the membrane has dialysis fluid that has normal plasma levels of glucose and mineral ions so there is no net movement, and no urea so there is a large concentration gradient for it to flow down. A countercurrent system is used.

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How does peritoneal dialysis work?

It is done inside the body, making use of the natural dialysis membrane in the abdomen. The dialysis fluid is introduced into the body by a catheter. It lasts a few hours, then the fluid is drained.

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What are the main problems with kidney transplants and how can these be resolved?

rejection- can be treated with immunosuppressants, and only using donors that have a very similar tissue and blood type (often relative). Immunosuppressants must also be taken for the rest of your life.
Waiting for a donor is also a big problem

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what are the advantages and disadvantages of dialysis?

keeps you alive until you get a donor
more readily available

expensive
must be hooked up for 8 hours, multiple times per week
can cause damage when used long term

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what is homeostasis?

the maintenance of a steady internal environment within a narrow range, despite the external conditions. often through negative feedback loops

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what is an ectotherm?

an animal that uses its surroundings to warm their bodies

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why don’t underwater ectotherms have much problem regulating their temperature

due to water being a very stable environment due to its high specific heat capacity, and because ice floats

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how can ectotherms warm up?

bask in the sun
face the sun/expose maximal surface area to the sun
press against warm surfaces
contract muscles/vibrate
be a darker colour
increase heart rate

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how can ectotherms cool down?

seek shade/ dig burrows
press against cool surfaces
move into water
minimise movement 
reduce heart rate
be a lighter colour

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what is an advantage of being an ectotherm?

needing less food as less energy is used on thermoregulation

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what is an endotherm?

an animal that maintains a very stable core temperature regardless of its environment

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where are thermoreceptors in the body?

In the skin and in the hypothalamus

what behavioral adaptations do endotherms have to warm up?

bask in sun
press against warm surfaces
hibernation
clothes
houses

what physiological adaptations do endotherms have to cool down?

vasodilation
increased sweating
panting
have large SA:V 
hair/feathers life flat to not trap insulation air (opposite of goosebumps)

what physiological adaptations do endotherms have to warm up?

Vasoconstriction
decreased sweating
goosebumps
shivering
low SA:V
blubber
black skin
fur to insulate

What are the two control centres in the hypothalamus?

Heat loss centre and heat gain centre

What is excretion?

removal of waste products of metabolism from the body

What are the three waste product in mammals?

CO2 Bile urea

what blood vessels flow to and from the liver?

hepatic vein and artery | hepatic portal vein supplies blood loaded with products of digestion straight from the intestines

describe the structure of hepatocytes

Hepatocytes are liver cells that have large nuclei, prominent Golgi and lots of mitochondria.

What happens to the blood once it reaches the liver?

the blood from both the hepatic portal vein and the hepatic artery is mixed in the sinusoids (spaces surrounded by hepatocytes). This gives enough oxygen for the hepatocytes.

what are Kupffer cells?

macrophages in the liver that ingest foreign particles and protect against disease.

what do Hepatocytes do?

Convert glucose to glycogen and vice-versa transamination- converting between amino acids deamination- removal of amine group, converting it to ammonia and eventually urea. This allows amino acids to be stored/used in respiration

what is the ornithine cycle?

a process where ammonia from deamination is converted to urea via some complex biochemistry

how is the liver involved in detoxification?

urea breakdown of H2O2 via catalase breakdown of ethanol via alcohol dehydrogenase into ethanal

describe the structure of the nephron

Bowman's Capsule- contains the glomerulus and capillaries Proximal convoluted tubule- coiled region of tubule Loop of Henle Distal convoluted tubule Collecting duct

What happens in ultrafiltration?

The glomerulus is supplied with a wide afferent arteriole, and leaves through a narrow efferent arteriole. The high pressure in here (due to width) causes the blood to be forced out of the capillaries. It then passes through the basement membrane, letting most of the contents through other than blood cells and proteins due to size. Cells called podocytes also act as a filter

what is the purpose of selective reabsorption?

to retain things like glucose, water and salt, but get rid of all the urea from the body

what happens in the proximal convoluted tubule

al of the glucose, amino acids, vitamins and hormones are moved back into the blood via active transport. NaCl is also actively transported out, and water follows down the concentration gradient.

how is the proximal convoluted tubule adapted for its function?

many microvilli, increasing surface area | lots of mitochondria to keep active transport going

how do substances get back into the blood after they've been removed from the nephron?

diffuse into the capillaries down steep concentration gradients that are maintained by good blood supply.

what mechanism does the loop of Henle use?

Countercurrent multiplier

Describe the process of the descending limb of the loop of Henle

water goes from the limb to the tissue fluid via osmosis, creating a very negative water potential inside the descending limb. It is also impermeable to NaCl, meaning they cannot diffuse out, furthering this effect.

describe the process of the ascending limb of the loop of Henle

The ascending limb is very permeable to NaCl, so they diffuse out, increasing the water potential. Further up the limb, they are also actively transported out. Importantly, the ascending limb is impermeable to water, meaning the tissue fluid around the nephron has a very low water potential, and the fluid leaving the loop of Henle is very dilute.

Where are salt and water levels 'fine-tuned' via active transport, in response to the bodies needs

The distal convoluted tubule

where is the concentration and volume of water mostly decided?

The collecting duct

why is osmoregulation important?

Because water potential of the blood must be maintained, due to things like osmotic pressure

describe how ADH works

released from pituitary gland and carried in blood to collecting duct. Binds to receptors on the cell membrane and triggers formation of cAMP (secondary messenger). Vesicles containing aquaporins fuse with cell surface membrane on edge of cell in contact with tissue fluid Aquaporins are channel proteins that increase permeability to water water moves out of the collecting duct and is reabsorbed into the tissue fluid/blood via osmosis More/less ADH = More/less water reabsorbed

what detects a change in water potential?

osmoreceptors in the hypothalamus. These are sensitive to inorganic ions in the blood