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Biology Hope > Liver and Excretion > Flashcards

Liver and Excretion Flashcards

1
Q

what is excretion

A

process by which toxic waste products of metabolism are removed from the body

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2
Q

what are examples of metabolic waste products

A

Carbon dioxide
- waste products of cellular respiration
- excreted from the lungs

Bile Pigments
- formed from the breakdown of haemoglobin from old red blood cells in the liver
- excreted in the bile from the live into the small intestine via the gall bladder and bile duct

Urea
- formed from the breakdown of excess amino acids by the liver
- excreted by the kidneys in the urine

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3
Q

what are the vessels in the liver

A
  • very rich blood supply
  • supplied with oxygenated blood by hepatic artery
  • blood removed by hepatic vein
  • hepatic portal vein supplies liver with products of digestion from duodenum
  • bile duct takes bile to the gall bladder
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4
Q

what is the structure of the liver

A
  • liver lobules known as hepatocytes
  • branches of the hepatic artery and hepatic portal vein supply each lobule with blood
  • sinusoids are wide capillaries that carry the blood, lined with endothelial tissues
  • each lobule connected to a branch of the hepatic vein that drains blood away from the lobule
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5
Q

what is the function of the liver

A
  • liver cells and hepatocytes have large nuclei, golgi apparatus, mitochondria
  • cells divide and replicate
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6
Q

how does the liver store glycogen

A
  • converts glucose into glycogen (glycogenesis) which helps to regulate blood glucose concentration
  • insulin triggers the process after it detects an increased blood glucose concentration
  • removes glucose molecules from the blood stream and decreased blood glucose to a normal range
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7
Q

how can the liver form urea and undergo deamination

A
  • amino group is removed with a hydrogen atom
  • combine to form ammonia and ammonium ions
  • ammonia is highly toxic so is converted to urea
  • ornithine cycle - 1 urea molecule is produced from 1 CO2 molecule and 2 amino groups
  • urea diffuses through the phospholipid bilayer of the membranes of the hepatocytes and transported to the kidneys
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8
Q

what is detoxification

A
  • breakdown of substances that are not needed or are toxic
  • lactate
  • alcohol
  • hormones
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9
Q

what are the kidneys

A

Osmoregulatory organ
- regulate water content of the blood- maintain blood pressure

Excretory organ
- excrete toxic waste products of metabolism and excess substances

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10
Q

what is the structure of the kidney

A

Renal artery - carries oxygenated blood to kidneys
Renal vein - carries deoxygenated blood away from the kidneys
Ureter - carries urine from the kidneys to the bladder
Bladder - stores urine temporarily
Urethra - releases urine outside of the body

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11
Q

what is the fibrous capsule

A
  • surrounds the kidney
    Cortex - glomerulus, bowman’s capsule, proximal convoluted tube, distal convoluted tube
    Medulla - loop of henele, collecting duct
    Renal pelvis - ureter joins kidney
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12
Q

what is a nephron

A

where urine is formed

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13
Q

how are the network of blood vessels arranged in the nephron

A
  • glomerulus within bowman’s capsule
  • glomerulus supplies by afferent arterioles
  • capillaries of glomerulus re-join to efferent arteriole
  • blood flows from the efferent arteriole into a capillary network
  • blood from capillaries flows into the renal vein
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14
Q

what is the process of ultrafiltration

A
  • blood from the renal artery enters arterioles in the cortex
  • arteriole splits into glomerulus - bowmans
  • afferent wider in diameter than efferent causing high blood pressure
  • high BP causes small molecules being carried into the blood to be forced out of the capillaries of the glomerulus into bowman’s capsule to form filtrate
  • blood in glomerulus is separated from the lumen of the Bowman’s by : endothelium of capillary, basement membrane, epithelium of Bowman’s capsule
  • blood passes through glomerular, gaps in podocytes and holes in endothelial cells allows dissolved substances into Bowman’s
  • glomerular filtrate in Bowman’s
  • red/ white blood cells, plasma remain in blood
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15
Q

what factors affect water potential in glomerulus and Bowman’s capsule

A

Pressure
- afferent wider creating high BP
- raises WP of blood plasma in glomerular above WP in capsule
- water moves down WP from blood plasma in glomerular to capsule

Solute concentration
- plasma proteins stay in the blood
- solute concentration higher in blood plasma than capsule
- water moves down WP from capsule to glomerular

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16
Q

what is the process of selective reabsorption

A
  • filtrate flows along PCT through loop of henle along DCT
  • useful substances leave nephron tubules and enter capillary network
  • epithelium of PCT wall had microvilli to give large surface area for reabsorption
  • glucose, AA, vitamins, salts reabsorbed along PCT by active transport + facilitated diffusion
  • water enters blood by osmosis as WP of blood is lower than filtrate
  • water reabsorbed from loop of Henle, DCT and collecting duct
17
Q

what is the counter current mechanism

A
  • top of ascending limb Na and Cl pumped out of the medulla
  • ascending limb is impermeable to water
  • low WP in medulla due to high ion conc.
  • water moves out of descending limb into medulla via osmosis
  • filtrate more concentrated
    -water in medulla reabsorbed into blood
  • bottom of ascending limb Na and Cl ions diffuse out of the medulla and lowers WP
18
Q

What is osmoregulation

A
  • WP is measured and monitored by osmoreceptors in hypothalamus
  • osmoreceptors are stimulated by low WP the posterior pituitary gland releases ADH
  • ADH makes walls of DCT and collecting duct more permeable to water
19
Q

how do blood ADH levels rise when dehydrated

A
  • water content drops so does WP
  • detected by osmoreceptors
  • more ADH is released
  • more water reabsorbed into the blood via osmosis
  • small amount of highly concentrated urine produced
20
Q

how do blood ADH levels fall when hydrated

A
  • water content rises so does WP
  • detected by osmoreceptors
  • less ADH reduced
  • less water reabsorbed into blood via osmosis
  • large amount of dilute urine produced
21
Q

why is kidney failure bad

A
  • urea, salts, toxins are retained and not excreted
  • less blood is filtered by the glomerulus
  • build up of toxins in the blood
22
Q

what can a kidney infection cause

A
  • podocytes and tubules may be damaged
  • blood in urine
  • glucose in urine = diabetes
23
Q

what is haemodialysis

A
  • patients blood flows through a dialysis machine
  • blood flows on one side of a partially permeable membrane and dialysis on the other side
  • waste products, excess water, ions diffuse across the membrane into dialysis fluid removing them
  • blood cells, proteins are prevented from leaving
  • done by trained health professions, emotional support
  • causes fatigue, low blood pressure, blood clots, blood infections
24
Q

what is peritoneal dialysis

A
  • dialysis fluid through a tube that passes from the patients abdomen into abdominal cavity
  • waste products diffuse out into the fluid across the peritoneum
  • carried out at home, done by yourself
  • difficult, increased risk of infection
25
Q

how can urine be used to detect pregnancy

A
  • stick is used with application area containing monoclonal antibodies for hCG bound to a blue bead
  • urine applied any hCG binds to antibodies on the beads
  • urine moves up the test strip carrying beads
  • test strip has immobilised antibodies to hCG
  • if hcG is present the test strip turns blue
  • no HCG present beads pass through the test area without binding to anything
26
Q

how can urine be used to test for steroids

A
  • anabolic steroids build up muscle tissue
  • urine tested by chromatography / mass spectrometry
  • in gas chromatography the urine sample is vaporised through a column containing polymer
  • different substances move through at different speeds
  • substances in urine separate
  • mass spectrometer converts substances into ions and then mass/charge
  • results are analysed
27
Q

how is urine used to test for recreational drugs

A
  • test strips contain antibodies that the drug being tested for will bind to
  • sample of urine is applied to test strip
  • colour change occurs
  • first test shows positive result a sample of urine is sent for further testing

Biology Hope (26 decks)

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