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A LEVEL BIOLOGY > Chapter 15 > Flashcards

Chapter 15 Flashcards

Homeostasis

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1
Q

What is homeostasis

A

Homeostasis is the maintenance of a stable equilibrium in the conditions in the body

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2
Q

What is negative feedback

Example

A

Negative feedback is a feedback system where a change is detected and effectors work to reverse that change and restore normal conditions
Eg water balance

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3
Q

What is positive feedback

A

A change is detected and effectors are stimulated to reinforce the change and increase the response
Eg in childbirth the head presses against the Fergus stimulating oxytocin which stimulates the cervix to contact pushing the head harder which continues until birth

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4
Q

What is an ectotherm

A

An animal which uses thier surroundings to warm thier bodies

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5
Q

Give some examples of behavioural responses to homeostasis in ectotherms

A 
Basking in the sun
pressing body into warm surfaces 
contracting muscles to increase heat from metabolic reactions 
Seeking shade 
Burrowing
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6
Q

Give some examples of physiological responses for homeostasis in ectotherms

A

Colour as dark colours absorbe more radiation than white ones
altering heart rate to increase or decrease metabolic rate

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7
Q

What is an endotherm

A

An endotherm is an animal that rely on their metabolic process to warm their bodies

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8
Q

Give an example of how endotherms cool down

A

Vasdilation- arterioles at the skin surface dilate and the arterialvenous shunt vessels constrict forcing blood to the surface to increase radiation

Increased sweating as evaporation causes heat loss

reduced insulation-erector pilli muscles relaxed flattening hair/feathers to prevent trapping insulated air

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9
Q

Give some examples of how endotherms warm up

A

Vasoconstriction- arterioles at the surface constrict and arterialvenous shunt vessels dilate reducing blood flow to the surface and radiation

Decreased sweating- which reduces evaporation and heat loss

raising hair/ feathers- erector pilli muscles contract pulling hair/feathers erect trapping insulating air

shivering- rapid involuntary contraction and relaxation of muscles to create metabolic heat

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10
Q

What different types of heat receptors are there

A

Thermoreceptors in the hypothalamus detect change in internal temperature
Peripheral temperature receptors detect external temperature

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11
Q

What is excretion

A

Excretion is the removal of waste products of metabolism from the body

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12
Q

What are the main metabolic waste products

A

Carbon dioxide ball pigments and nitrogenous waste (urea)

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13
Q

Draw a diagram of the liver

A

Should include hepatic vein, hepatic artery, inferior venva cava, gallbladder and hepatic portal vein

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14
Q

Draw a diagram of of a liver lobule

A

Should include branch of hepatic artery branch of hepatic portal vein and branch of bile duct

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15
Q

Draw a diagram of the structure of a lobule

A

Should include central vein, sinusoid, kupffer cells, hepatocytes, branch of hepatic artery branch of hepatic portal vein, branch of bile duct

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16
Q

What is the function of the liver in the storage of glycogen

A

when blood glucose levels rise insulin is produced which stimulates the hepatocytes in the liver lobules to convert glucose to glycogen in the liver similarly when blood glucose level falls glucagon stimulates the hepatocyte to convert stored glycogen into glucose

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17
Q

What is the function of the liver in deamination

A

The body cannot store excess amino acids so the hepatocyte in the liver the amino group into ammonia and organic acids organic acids can be respired or converted and stored but the ammonia is too toxic so it is converted to urea in the ornithine cycle

Ornathine cycle:
Ammonia and CO2 make carbamoyl phosphate
Carbamoyl phosphate and ornathine make citrulline
Citrulline and asparic acid make arginine
Arganine makes ornathine and urea

18
Q

What is the function of the liver in detoxification

A

For example for alcohol hepatocyte contain the enzyme alcohol dehydrogenase which breaks down ethanol to ethanal
another example is cath sites contain catalase which breaks down hydrogen peroxide into oxygen and water

19
Q

Which parts of which when examining liver tissue under the microscope

A

Large white circle is the central vein and lobule
Red parts with small nuclei are hepatocytes
White parts are sinusoids

20
Q

Draw a diagram of the kidney

A

Should include cortex, medulla, capsule, nephron, pelvis, renal vein, renal artery, and ureter

21
Q

Draw a diagram of a kidney nephron

A

Shoukd include afferent arterial, bowman’s capsule ,efferent arteriole, proximal convoluted tubule, loop of henle, convoluted tubule, collecting duct and capillary network

22
Q

Give an outline of the functions of the nephron

A

1) blood flows in through the renal artery into the afferent arteriole in the cortex
2) the splits into the glomerulus where ultrafiltration takes place
3) the filtrate then flows along the proximal convoluted tubule which are covered in microvilli for surface area and mitochondria for ATP in active transport
4) here reabsorption takes place
5) the filtrate then flows into the loop of henle where selective reabsorption takes place
6) the filtrate then flows through the distal convoluted tubule and the collecting duct where water content is maintained through reabsorption

23
Q

What is ultrafiltration

A

The afferent arteriole which the blood comes in through is smaller in diameter than the efferent arteriole which take that away this means the blood is under high pressure in the glomerulus and forces small molecules and liquid out of the bowman’s capsule through a wall of a capillary endothelium, basement membrane, and a layer of podocytes

24
Q

What is reabsorption in the proximal convoluted tubule

A

in the proximal convoluted tubule or glucose amino acids vitamins and hormones are reabsorbed back into the blood by active transport
around 85% of salt is also moved back into the blood by active transport and it’s followes passively by water through osmosis

25
Q

What is selective reabsorption in the loop of henle

A

1) at the top of the ascending limb sodium and chloride ions are actively pumped out the ascending limb is impermeable so water cannot follow which creates a low water potential in the medulla
2) this causes water to move out of the descending limb into the medulla by osmosis where it is reabsorbed into the blood
3) the descending limb is impermeable to ions making the filtrate concentrated as they cannot follow the water
4) when the filtrate reaches the bottom of the ascending limb here the ions can diffuse out into the medulla
5) this lowers the water potential of the medulla
6) this causes water to move out of the distal convoluted tubule and collecting duct into the medulla where it is reabsorbed into the blood

26
Q

What is reabsorption in the loop of henle an example of

A

A countercurrent multiplier system

27
Q

How do you do a kidney dissection

A

Remove the protective layer of fat from around the kidney
Slice the kidney open by making a small cuts along one side
Observe the cortex medulla renal pyramids renal pelvis renal artery renal vein and ureter
add a drop of hydrogen peroxide to examine the nephron which can be seen more clearly under the microscope

28
Q

What happens when water is in short supply

A

Water content drops and is detected by osmoreceptors in the hypothalamus
the post area pituitary gland is stimulated to release more ADH into the blood
ADH binds to receptors on the collecting ducts and distilled convoluted tubule triggering cyclic AMP
cAMP causes vesicles to fuse with the cells lining and inserts protein-based water channels which makes it more permeable to water

29
Q

What happens when there is an excess of water

A

Water content rises and detected by the osmoreceptors in the hypothalamus
the post area pituitary gland releases less ADH making the distal convoluted tubule and collecting duct less permeable

30
Q

What is kidney failure caused by

A

Kidney infection information can damage cells

High blood pressure can damage glomeruli

31
Q

What are the problems with kidney failure

A

A buildup of toxic urea a loss of electrolyte balance a buildup of fluid causing swelling and anaemia

32
Q

How can you determine whether someone has kidney failure

A

Blood in the urine protein in the urine of normal glomerular filtrate rate
glomerular filtrate rate can be measured through measuring creatinine levels which is a breakdown product of muscles

33
Q

What is haemodialysis

A

Haemodialysis uses a dialysis machine plus leaves the body through an artery into the machine past partially permeable membrane filled with dialysis fluid is fluid contains normal levels of glucose, normal levels of ions and no idea

34
Q

What is peritoneal dialysis

A

peritoneal dialysis is when dialysis fluid is introduced into the abdomen via catheter and is left for hours before being drained

35
Q

What are the advantages and disadvantages of a kidney transplant

A

A kidney must be found of the same blood and tissue type
due to immune responses the patient must take immune suppressants for the rest of their life
However it is cheaper than dialysis long time convenient and improved quality of life

36
Q

How can urine be used to test pregnancy

A

The wick is soaked in urine
it contains monoclonal antibodies which will bind to the hCG in the urine if the woman is pregnant to create hCG antibody complex
the removes up the strip until it reaches a window with immobilized monoclonal antibodies which will form a pattern if the woman is pregnant
it will continue to a second window with immobilized monoclonal antibodies that will bind to the other antibodies with or without hCG to indicate the test is working

37
Q

How can urine be used to test for steroids

A

Anabolic steroids they tested with a gas chromatography and mass spectroscopy sample is vaporized and passed along the tube who’s lining absorb the gases and creates a chromatogram to indicate presence

38
Q

How can urine be used to test for drugs

A

drugs are tested for using test strips which contain antibodies the drug being tested for will bind to and present a colour change

39
Q

Why do we need communication systems in homeostasis

A

Sensory detect changes in stimulus eg temperature, pH, water balance, concentration of urea, ions
This is transmitted to the brain
A motor neurone transmits a response to an effector

39
Q

What is selective reabsorption in the loop of henle

A

1) at the top of the ascending limb sodium and chloride ions are actively pumped out the ascending limb is impermeable so water cannot follow which creates a low water potential in the medulla
2) this causes water to move out of the descending limb into the medulla by osmosis where it is reabsorbed into the blood
3) the descending limb is impermeable to ions making the filtrate concentrated as they cannot follow the water
4) when the filtrate reaches the bottom of the ascending limb here the ions can diffuse out into the medulla
5) this lowers the water potential of the medulla
6) this causes water to move out of the distal convoluted tubule and collecting duct into the medulla where it is reabsorbed into the blood

40
Q

Why do we need communication systems in homeostasis

A

To coordinate a response sensory receptors detect a change in stimulus and transmitted to the brain via a sensory neuron brain coordinates a response and a motoneuron sends a signal to the effector to carry out the change

A LEVEL BIOLOGY (18 decks)

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