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Biology, Module 5 OCR > 5.1.1-2 Communication and homeostasis > Flashcards

5.1.1-2 Communication and homeostasis Flashcards

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1
Q

Describe the structure of the urinary system (6)

A
  • Kidneys: main organ responsible for Osmoregulation and filters out nitrogenous waste.
  • Ureter: takes urine to the bladder
  • Bladder: stores urine
  • Urethra: where urine exists out the body
  • Renal artery: brings waste blood to kidneys from abdominal aorta
  • Renal vein: takes clean blood away from kidneys to inferior vena cava
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2
Q

Describe the structure of the kidney

A
  • Cortex: outer layer with dense network of capillaries. Filtration takes place here
  • Medulla: usually very hypertonic and contains the collecting ducts for the tubules
  • Pelvis: where urine is collected before entering ureter
  • Nephrons: tubules responsible for the filtration of blood
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3
Q

Describe the structure and function of the nephron

A
  • Glomerus: + Bowman’s capsule: contains a network of capillaries where ultrafiltration takes place and big molecules are filtered out.
  • proximal convoluted tubes: First point of reabsorption of water and organic molecules
  • loop of Henle-contains a very high solute concentration and is countercurrent to Na and Cl.
  • Distel convoluted tube- ADH acts on the walls permeability for Osmoregulation. Ion balance and pH is also controlled.
  • collecting duct- where urine passes before the pelvis. Osmoregulation using ADH.
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4
Q

What are the six main types of cell signalling?

A
  • Contact dependant
  • Paracrine
  • Autocrine
  • Endocrine
  • Synaptic
  • Gap Junction signalling
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5
Q

Gap junction signalling

A
  • Type of cell signalling where there is a gap between the membrane of adjacent cells
  • No receptors are present so signalling molecules travel inbetween membranes
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6
Q

Contact dependant

A
  • Type of cell signalling where the target cell and signalling cell are in close proximity
  • Signalling cell sends out molecules that binds to receptions on target cell
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7
Q

Paracrine cell signalling

A

-signalling molecules are sent within a close proximity but are not contact dependant

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8
Q

Endotherm

A

Animals that rely on internal metabolic reactions to generate heat and maintain a constant core temperature

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9
Q

Advantages and disadvantages of endothermy

A

Advantages:

  • Can survive a wide range of environments due to adaptations that allow a core temperature to be maintained

Disadvantages:

  • Metabolic rate is much higher than ectotherms so more food is needed to be consumed
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10
Q

Advantages and disadvantages of ectothermy

A

Advantages:

  • Metabolic rates are low so less food is needed to be consumed

Disadvantages:

  • Less active in colder areas as enzymes are not in optimum conditions
  • relies on behavioural methods to control temperature
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11
Q

Ectotherms

A

Animals that are reliant on their environment to maintain a core temperature

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12
Q

Vasodilation

A
  • Physiological response to hot temperatures
  • Blood vessels (especially arterioles) widen which increases blood flow and decreases blood pressure
  • More blood flow at the surface of the skin cools the blood by convection
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13
Q

How is heat generated/ transferred? (4)

A
  • Conduction: Heat molecules from one source is transferred to another
  • Convection: movement of fluid. Hot air rises while cool air condenses
  • Radiations: placing a vacuum between heat source and component being heated (eg the sun and Earth)
  • Metabolic processes(respiration)
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14
Q

Vasoconstriction

A
  • Physiological reaction to low temperature
  • Arterioles especially constrict so that they are further away from the surface of the skin: this allows warm blood to be kept below surface
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15
Q

Sweating

A
  • Physiological response to hot temperatures

- Evaporation of water from the sweat gland releases energy as it does so, therefore cooling the body

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16
Q

Raised body hair

A
  • Physiological reaction to cold temperature
  • Erector pili muscles contract (piloerection) which lifts hair follicle
  • this raised hair forms an insulating layer which traps heat
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17
Q

Main functions of the liver (4)

A
  • Carbohydrate metabolism: conversion and storage of glucose
  • Deamination of amino acids:
    Removal of amine group to covert into ammonia then urea
  • Detoxification:
    Breaking down of toxins into less harmful products
  • Transamination:
    Conversion of one amino acid to another
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18
Q

Structure of the liver (7)

A
  • Hepatic artery
  • Hepatic portal vein
  • Hepatocytes
  • Hepatic vein
  • Sinusoids
  • Kupffer cells
  • Canaliculi
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19
Q

Hepatocytes (7)

A
  • Liver cells that make of most of the mass of the live and are responsible for the metabolic functions:

Deamination
Detoxification
Carbohydrate metabolism

  • Contains a large nuclei:
    Active DNA transcription due to a lot of protein production
  • Abundant Golgi apparatus:
    Mass amount of proteins are being packaged and modified.
  • Abundant Mitochondria:
    Due to very active cell metabolism, high amounts of ATP is needed for cell reactions
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20
Q

Hepatic vein

A

Takes deoxygenated blood and detoxified products away from the liver toward the vena cava

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21
Q

Hepatic artery

A

Brings oxygenated blood to the liver

22
Q

Hepatic portal vein

A

Brings products of digestion and metabolism from the intestines to the liver

23
Q

Sinusoids

A

Conjunction where the blood from the hepatic portal vein and hepatic artery meet.

This combines raw material and increase oxygen concentration entering the liver.

24
Q

Kupffer cells

A

Act as the immunological defence for the liver by being macrophages that digest foreign material and debris

25
Q

Bile (2)

A

In terms of excretion:
It contains broken down haemoglobin (bilirubin) which is secreted into the Canaliculi

Then stored in the gallbladder

26
Q

What is excretion and how is it different from defecation?

A

Excretion is the removal of waste products from various metabolisms the body

Whereas defecation is the removal of undigested food, dead cells and bacteria from the body via the rectum

27
Q

Carbohydrate metabolism of the liver. (3)

A

As part of the homeostatic blood glucose control:

Hepatocytes convert glucose to glycogen to be stored when glucose levels are high

When glucose levels are low, then glycogen is converted back to glucose

28
Q

Deamination of amino acids (4)

A

The process of removing an amine group from amino acids as the body cannot store proteins/ amino acids

Excess amino acid is split:

The amino group combines with CO2 to dome urea which is filtered and excreted via the kidney

The rest molecule is used for respiration

29
Q

Ornithine cycle

A

This converts ammonia to urea using enzymes

30
Q

Detoxification processes in the liver (2)

A

Toxins are broken down to be less harmful

Hydrogen peroxide:
Broken down into water and oxygen using catalase enzyme.

Ethanol:
Breaks down into ethanal using alcohol dehydrogenase
Then breaks down ethanal into ethanoate which is used for fatty acids and respiration

31
Q

Liver cirrhosis

A

Liver damage where normal tissue is replaced with fibrous scar tissue

Causation:
Hepatitis C
Genetics
Excessive alcohol consumption

32
Q

Describe the effects of liver cirrhosis. (6)

A
  • Healthy liver tissue is replaced with scar tissue.
  • Hepatocytes are damaged and killed.
  • The causes the liver to shrink.
  • Metabolic processes are inhibited: no gluconeogenesis, deamination.
  • The damage is irreversible.
  • Build up of toxic substances like ammonia as detoxification does not occur.
33
Q

Positive feedback (2)

A

When any change in a parameter brings about an increase in that change

Eg during childbirth, oxytocin is constantly produced to stimulate contractions until he child is born

34
Q

Canaliculus

A

Tube that collects bile secreted by hepatocytes and transport it to the bile duct

35
Q

How can the ethanoate made from the detoxification of alcohol be metabolised?

A
  • Ethanoate is acetate which can bind with Coenzyme A to form acetyl CoA.
  • Acetyl CoA is used in the Kreb’s cycle.
  • This ultimately produces ATP.
36
Q

How are monoclonal antibodies produced?

A

Monoclonal antibodies are antibodies produced from clones of the same cell.

  1. hCG hormone is injected into a mouse which causes it to produce the right antibody.
  2. The B-cell that produces the antibody is extracted from the mouse’s spleen and fused with a myeloma cell.
  3. This cell divides rapidly to produce many monoclonal antibodies.
37
Q

Describe the stages in a pregnancy test.

A
  1. The wick of the pregnancy test is dipped in urine- This contains hCG is the woman is pregnant.
  2. The wick contains monoclonal antibodies which are attached to coloured beads.
  3. The antibodies bind to hCG to form a hCG/ antibody complex.
  4. Immobilised antibodies then bind to the hCG/antibody complex to form a coloured line.
  5. Excess mobile antibody bind to immobilised antibodies despite if the woman is pregnant of not- forms a second coloured line.
38
Q

Why is the urine useful for diagnosis?

A

Urine contains a breakdown of products from metabolic reactions.

Appearance of a new substance in the urine, this indicates an abnormality which could be a disease.

39
Q

How is the urine useful in testing for anabolic steroids?

A

The steroids are excreted in the urine.

Urine is vaporised and passed through a gas chromatogram and mass spectrometer.
This identifies the drug present.

40
Q

Urine and drug testing.

A

Many drugs can be tested as their metabolites are excreted through the urine.

Two samples of the urine is taken:
First sample is tested with monoclonal antibodies.
If that test is positive, then a gas chromatogram and mass spec is used to confirm the drug.

41
Q

Describe the mechanism of the loop of Henle.

A

The descending loop is permeable to water, but impermeable Na+ and Cl-:
Water moves out the tubule into the capillaries via osmosis.
Na+ and Cl- stay in the tubule so hypertonicity increases down the limb.

The ascending loop is impermeable to water but permeable to Na+ and Cl-:
Na+ and Cl- move out of the tubule via diffusion, using a concentration gradient.
The higher ascending loop: Na+ and Cl- is actively pumped out. This increases hypertonicity in the tissue fluid of the medulla.

This allows a lot of water available at the distal convoluted tubule where osmoregulation can take place.

42
Q

Describe the mechanism of ADH in osmoregulation.

A

Osmoregulators in the hypothalamus detect a change in water potential of the blood.

When this is low, more ADH is secreted from the posterior pituitary gland, into the blood, where it travels to the walls of the collecting duct in the kidneys.

ADH binds to complementary receptors on the plasma membrane which triggers the formation of cAMP:

Vesicles containing aquaporins in the collecting duct fuse with the membrane connecting to tissue fluid in medulla.

This allows the collecting duct to be more permeable to water. Water moves of of tubules into tissue fluid in medulla, via osmosis.

43
Q

Describe the principles of homeostasis (4)

A

Sequence of events that occur as a result of responding to a stimulus.

  1. Stimulus is detected by a receptor: cell, tissue or organ that can detect changes in an environment.
  2. Receptors act as transducers: convert stimulus into another form of energy- electrical impulse.
  3. A series of cell signalling occurs as the neuronal system relays messages to the coordinating centre, (input).
  4. The coordinating centre sends a message to the effector (output), to initiate a response.
44
Q

Describe the need for multicellular organism to react to the external environment. (3)

A

As the external environment changes it can place stress on the organism.

For the organism to remain active and survive, the changes in the environment must be monitored.

The organism must change its behaviour or physiology to reduce the stress.

The environmental change acts as a stimulus and the behaviour and physiological reaction is a response.

45
Q

Describe the need for multicellular organism to react to the internal environment.

A

As cells undergo various metabolic activities they use up substances and produce products.
Some of these products are unwanted or toxic and diffuse out of the cells.
The build up of waste and toxins in the internal environment acts as a stimulus to cause the removal of the waste so cells can survive.

46
Q

What can appear in the urine as a result of kidney failure? (2)

A

Large plasma proteins: Filtration is not happening properly due to either damage to:
Basement membrane
Podocytes

Blood: Red blood cells have not been filtered out of the filtrate and is passed in the urine.

47
Q

Describe the effects of kidney failure. (4)

A

Build up of toxic urea: Kidney not able to remove urea efficiently.

Anaemia: kidneys produce erythropoietin which stimulates the production of red blood cells. Kidney damage prevents this process.

Loss of electrolyte balance: sodium, calcium and chloride ions are not excreted properly. This causes osmotic imbalance in tissues.

Weakened bones: Calcium and phosphate ions lost, bones are not maintained.

48
Q

Describe the process of haemodialysis as a treatment for kidney failure. (6)

A

The blood is filtered artificially outside the body using a dialysis machine.

Blood flows out of the body via an artery, into the dialysis machine. Anticoagulants like heparin are given to prevent blood clotting.

Blood is passed through a partially permeable membrane and flows countercurrent to the movement of dialysis fluid.

The dialysis fluid has the same concentration of sugar and some mineral ions, so they do not leave the blood.

Waste products like urea and other mineral ions flow out of the blood through the membrane by diffusion. They are removed by the dialysis fluid.

Clean blood is taken back into the body via a vein.

49
Q

Describe the process of peritoneal dialysis as a treatment for kidney failure.

A

This involves using the natural membrane inside the body: peritoneum in the abdomen.

Dialysis fluid is inserted in the body via a catheter.

Waste products move out of the blood, into the tissue fluid and diffuse across the peritoneal membrane into the dialysis fluid.

The dialysis fluid removes the waste products and us discarded.

50
Q

Describe the problems with dialysis as a treatment for kidney failure.

A

Very time consuming: Patients are on dialysis for hours and do so several times a week.

Expensive: In haemodialysis new membranes are always used and so is costly.

Risk of infection: Constant insertion of foreign needles.

Diet has to be monitored very closely.

51
Q

Describe the process of getting a kidney transplant as a treatment for kidney failure. (6)

A

This is a more ‘permanent’ method for treating kidney failure. However the transplant lasts for an average of 10-15 years.

Healthy kidney(s) are donated from a donor that has a very closely related tissue match to the recipient

The kidney is inserted by matching the arteries and veins and linking the ureter to the bladder.

HOWEVER:
There is a risk of rejection due to the recipient’s body not recognising the antigens on the donor’s kidney.

Recipient has to be on immunosuppressants for life in order to avoid rejection- This can lead to susceptibility to infection.

The availability of donors is low compared to those on the waiting list as people are not signing up to be donors.

52
Q

Homeostasis definition.

A

Maintenance of a constant internal environment.

Biology, Module 5 OCR (7 decks)

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