1
Q
What is metabolism?
A
All of the chemical reactions that happen in your cells
2
Q
What does metabolism produce?
A
Waste products
3
Q
What are some examples of waste products produced by metabolism?
A
Carbon dioxide
Nitrogenous waste
Urea
4
Q
What is excretion?
A
The removal of waste products of metabolism from the body
5
Q
What does excretion help with?
A
Maintaining homeostasis by keeping levels of certain substances in the body constant. It also maintains normal metabolism
6
Q
What and where is the liver?
A
It is a large organ in the abdomen
7
Q
What is the hepatic vein?
A
This takes deoxygenated blood away from the liver
8
Q
What is the hepatic artery?
A
This supplies the liver with oxygenated blood from the heart, so the liver has a good supply of oxygen for respiration
9
Q
What is the hepatic portal vein?
A
Brings blood from the duodenum and ileum (small intestine) to the liver, making it low in oxygen but rich in nutrients
10
Q
What is the bile duct?
A
Take bile to the gall bladder to be stored
11
Q
What is bile?
A
A substance produced by the liver to emulisfy fats
12
Q
What is the liver made up of?
A
Liver lobules
13
Q
What are liver lobules?
A
Cylindrical structures made of cells called hepatocytes that are arranged in rows which radiate out from the centre. Each lobule has a central veins which connects to the hepatic vein. Many branches on the hepatic artery, hepatic portal vein and bile duct are also connected to each lobule. Each lobule is separated by connective tissue
14
Q
How are the hepatic artery and hepatic portal vein connected to the central vein?
A
By capillaries called sinusoids
15
Q
What are sinusoids lined with?
A
Hepatocytes
16
Q
What do hepatocytes do?
A
Extract oxygen from blood flowing past hepatocytes. They also extract various metabolites and poisons. They then break down these substances into less harmful substances. These are then released back into the blood. This blood then runs to the cell tral vein. The central veins from all lobules connect to form the hepatic vein
17
Q
What are Kupffer cells?
A
These are cells which are also attached to the walls of sinusoids. They remove bacteria and break down old red blood cells
18
Q
What do hepatocytes produce?
A
Bile. They then secrete it into tubes called bile canaliculi. These tubes then drain into the bile ducts. All these ducts then connect up and leave the liver.
19
Q
What are the tubes that bile is secreted into?
A
Bile canaliculi
20
Q
What does liver tissue look like under a microscope?
A
Before examining, the sample must be stained. The large white circle will be the central vein. The smaller white spaces are sinusoids. The cells radiating out of the central veins are hepatocytes and the red dots are nuclei
21
Q
Why is there an incomplete layer of endothelial cells lining the sinusoids?
A
So nlood is able to reach the hepatocytes
22
Q
What is the livers functions?
A
1) Excreting amino acids
2) Detoxification
( alcohol, paracetamol, insulin)
3) Glucogen storage
23
Q
Why can excess amino acids not be stored?
A
Because they have nitrogen in their amino groups, and nitrogenous cannot usually be stores by the body, meaning they must be broken down.
24
Q
Describe how amino acids are broken down by the liver
A
1) The nitrogen containing amino groups are removed, forming ammonia and organic acids. This process is called deamination
2) The organic acids can be respire to give ATP or converted to carbohydrates and stored as glycogen
3) The ammonia is too toxic to be directly excreted, so is is combined with CO2 in the ornithine cycle to create urea and water
4) Urea is excreted into the blood. The kidneys then filter out the urea as urine
25
What is deamination?
The process of removing the nitrogen containing amino groups from excess amino acids
26
What is the amino group
NH2
27
What is the formula for ammonia?
NH3
28
What does the ornithine cycle do?
Convert ammonia into water and urea by adding carbon dioxide to it
29
What is detoxification?
It is a function of the liver. It is breaking down harmful substances into less harmful compounds that can then be excreted from the body
30
Explain alcohol detoxification
Alcohol is a toxic substance which can damage cells. It is broken down in the liver into ethonal, which is then broken down into acetic acid or ethanol, into ethanoate. This is then either respire or stored as fatty acids. Excess alcohol over a long period of time can lead to cirrhosis of the liver
31
What is cirrhosis of the liver?
When the cells of the liver die and scar tissue blocks blood floe
32
What does excess paracetamol cause?
It is a common painkiller broken down by the liver. Excess of it in the blood can lead to liver and kidney failure
33
What does excess insulin cause?
Insulin is a hormone broken down by the liver that controls blood glucose. Excess insulin can cause issues with blood sugar levels
34
Explain the livers role in glycogen storage
The liver converts excess glucose into glycogen via glycogenesis. The glycogen is then stored as granules in liver cells until glucose is needed for energy
35
How is glycogen stored in the liver?
Granules
36
Why are amino acids not excreted directly?
They still provide a good source of energy
37
Why does deamination occur in the mitachindria?
So ammonia doesn't come into contact with the cytoplasm. Also means organic acids can be used more easily in respiration
38
Why does the rate of flow in the hepatic vein show as more than the hepatic artery?
Because the hepatic vein takes blood from the hepatic artery and hepatic portal vein
39
What are the advantages of the ornithine cycle instead of linear pathways?
Less reactant is needed due to their ability to be regenerated
40
What is an explanation of the build up of fats in hepatocytes if binge drinkers?
Dehydrogenation of alcohol uses NAD which is also needed for fatty acid break down. Increased alcohol therefore means there isn't enough NAD to process fatty acids. Fats are therefore converted into lipids and stored in hepatocytes
41
Explain detoxification of hydrogen peroxide?
(H2O2). This is converted into oxygen and water. A peroxisome engulfs hydrogen peroxide. This artificially increases the conc of this enzyme in the area causing the reaction to happen fast
42
What side does the left kidney show as?
The right side. But it's still called the left kidney
43
What are the blood vessels that go into and out of the kidneys?
The renal artery and the renal vein
44
What is the tube that takes urine to the bladder?
Ureter. There is a left and right one
45
What is the urethra?
The tube going from the bladder
46
What is the cortex?
The lighter coloured outer reigon of the kidney
47
What is the renal capsule?
An outer membrane that protects the kidney
48
What is the medulla?
The darker inner part made up of loops of henlè, collecting ducts and blood vessels
49
What is the renal pelvis/calyx?
A hollow structure which connects to the ureter. The base of these are flower like and they are smaller hollow structures leading from the base of the renal pyramids called renal calyces (singular is calyx)
50
What is bowman's capsule?
It is a cup shaped structure which contains a mass of blood capillaries known as the glomerulus
51
What are the proximal convoluted tubules?
A series of loops surrounded by blood capillaries.
52
What are the loops of henlè
A long hair pink loop that extends from the cortex into the medulla, and back again. It has 2 limbs: ascending and descending
53
What are the distal convoluted tubules?
A series of loops (further away) that are surrounded by capillaries
54
What are collecting ducts?
Many distal convoluted tubules empty here. It becomes increasingly wide and opens into the pelvis/ calyx
55
Is the afferent or afferent arteriole first and how big are they?
The afferent arteriole is before Bowman's capsule. This is bigger than the efferent one.
56
What is the glomerulus?
A dense network of capillaries
57
What are peritubular capillaries?
Surrounded the proximal convoluted tubule, loop of henlè and distal convoluted tubule
58
Where is the bowman's capsule?
The cortex
59
Explain how the cortex would look under a light microscope
The bundle of capillaries (glomerulus) will be stained purple with a white "ring" around it. This is the bowman's capsule. The proximal tubules have a longer brush boarder, larger cells and fewer visible nuclei. Cytoplasm stains darkly and the lumen is small and irregular. The distal tubules have no brush boarder and smaller cells. They have more visible nuclei. Cytoplasm stains paler. They are surrounded by squamous epithelial cells
60
How will the medulla look under a light microscope?
Thick segments of loops of henle will be seen. They will stain white. The red dots will be capillaries
61
Where does ultrafiltratuon occur?
The bowman's capsule
62
What are nephrons?
The functioning units of the kidneys
63
Explain ultrafiltration
Blood is filtered under high pressure to produce filtrate. The hydrostatic pressure in the aterioles causes substances to be forced out of the capillaries into the renal capsule. Endothelial cells of capillaries have many pores, first allowing fluid to flow through. Surrounding the capillaries is the basement membrane, made of glycoproteins which acts as a molecular seive. This prevents red blood cells, platelets and large plasma proteins from passing into the renal capsule. Finally, a layer of cells called podocytes have finger like extensions that make slits in the epithelium and stops plasma proteins escaping
64
How is the hydrostatic pressure created in bowman's capsule?
Because the diameter of afferent arteriole is larger than the efferent one
65
What is the filtrate after ultrafiltration?
Less concentrated than the blood (hypotonic)
66
What is in the filtrate after ultrafiltration?
Urea, excess salts, water, amino acids, etc
67
Describe the mechanism for reabsorption in the proximal convoluted tubule
1) Sodium ions are actively transported from the cells into the blood
2) This lowers the conc of na ions inside the cells. This causes na ions in the filtrate to diffuse down their concentration gradient into epithelial cells
3) These na ions move via co transporter proteins, which binds to other solutes e.g glucose and amino acids, which drags them into the cells as well
4) This creates a gradient, causing them to diffuse into the capillary via facilitated diffusion.
5) The increased conc of ions and glucose causes reduced water potential, so water moves into the PCT cell, then capillary via osmosis
6) Larger proteins are transported via pinocytosis. Lysosomes will fuse with vesicle and break down protein into amino acids.
68
What is the filtrate in comparison to bloom after reabsorption in the PCT?
Isotonic
69
What is the fluid which enters the renal capsule called?
The glomerular filtrate
70
What do reabsorbed susbstabces include after reabsorption in the PTC?
Water
Salts
Glucose
Amino acids
71
Describe the lining of the PCT tubule
It's composed of a single layer of epithelial cells. They have microvilli, which create the brush boarder. The cells have pinocytic vesicles. They basement membrane surrounds the peri tubular capillary
72
How are the epithelial cells of the PCT adapted
-Many microvilli to increase SA. This increases the rate of facilitated diffusion and therefore reabsorption
-Many co transporter proteins
-Many mitachondria for ATP for active transport
-Cells packed tightly together so no fluid can pass between cells
73
How are most solutes reabsorbed?
Facilitated diffusion
74
What mechanism does the loop of henlè have?
Countercurrent multiplier mechanism, which helps reabsorbed water back into the blood
75
Explain how the countercurrent multiplier mechanism work?
1) Near the top of the ascending limb, Na and Cl ions are actively pumped out onto the medulla. Water stays in the tubule which creates a low water potential in the medulla as there is a high conc of ions
2) Water potential is lower in the medulla than the descending limb so water moves out of the descending limb into the medulla by osmosis. This makes filtrate more concentrated. Water in the medulla is reabsorbed into the blood
3) near the bottom of the ascending limb na and cl will diffuse out into the medulla, further lowering water potential in the medulla
4) Some na and cl ions move back in via facilitated diffusion
5) when filtrate reaches the hair pin bend the conc of solutes in the filtrate is very high
6) This conc causes water to move out of the collecting ducts by osmosis. This is controlled by ADH as well
76
What is the ascending limb?
Impermeable to water. The thin limb is permeable to some solutes. The thick limb is used for active transport of na
77
What is the descending limb?
Highly permeable to water but not ions
78
Where is most water reabsorbed?
The PCT. The remainder is done in the loop of henle and collecting ducts
79
What does the loop of henle connect to?
The DCT in the cortex, then the collecting duct
80
What is the function of the loop of henle?
To increase the conc of solute in the medulla
81
What do different animals have?
Different lengths of their loop of henle
82
What does a longer loop of henle mean?
More water can be reabsorbed from the filtrate. This is useful for animals in hotter environments with little water available. This is because more ions can be pumped out
83
How is the gradient from the loop of henle used?
Water diffuses from the duct into the medulla to capillaries due to low water conc in the medulla. In this way urine from the collecting duct can be made as concentrated as the tissue fluid it has just passed through.
84
When does the body excrete hypertonic urine?
When the body needs to conserved water
85
When does the body excrete hypotonic urine?
When it needs to excrete excess water
86
What may cause a rise in solute potential in the blood?
-Eating salty food
-Lack of water intake
-Sweating
87
How is ADH produced?
Water potential of the blood is monitored by cells called osmoreceptors in the hypothalamus. They are stimulated when they loose water due to low water potential in the blood, causing them to shrink. This triggers neurosecretory cells in the hypothalomas to produce ADH. ADH passes along neurosecretory cells to the posterior love of the pituitary gland. It is then secreted into the blood.
88
Describe what ADH does
1) ADH travels in the bloodstream. They then bind to receptors on the plasma membrane of the DCT and collecting duct.
2) A series of enzyme controlled reactions is activated ending either the activation of phosphorylase
3) This causes vesicles containing prices of membrane and aquamarine to fuse with the membrane
4) Water moves through channels down the conc gradient into the medulla and blood.
5) ADH also increases permeability of the collecting duct to urea which passes into the medulla, further decreasing the water potential of the mefulla
89
What do osmoreceptors stimulate?
A thirst reflex
90
What happens when the blood water context is too low (dehydration)
-Water content in blood drops
-Detected by osmoreceptors in hypothalomas
-Posterior gland stimulated to release more ADH into blood
-DCT and collecting ducts are more permeable to water
-Small amount of highly concentrated urine is produced and less water is lost
91
What may a fall in solute concentration of the blood be caused by?
Drinking lots of water
Low intake of ions
92
What is ADH?
Anti-diuretic hormone
93
What does diuresis mean?
Increased volume of urine
94
Describe the composition of urine?
It is a fluid more concentrated than blood, which contains waste products
95
What happens at the distal convoluted tubule?
This can reabsorbed mineral ions to maintain the balance of mineral ions in the blood. The conc of na is monitored and if it falls below a set point the cortex of the adrenal glands secrete aldrosterone which switches on genes that produce carrier proteins for na. These pump na out of the filtrate so it can be reabsorbed back into the blood stream
96
How do the kidneys regulate pH?
By excreting hydrogen and hydrogen carbonate ions into the urine
97
What is acute kidney injury?
This is also called acute renal failure and is more commonly reversible. It is usually caused by an event leading to kindey malfunction
98
What is chronic kidney failure?
This is where both kidneys have been irreversibly damaged. The chemical waste products and toxins therefore build up
99
What is kidney failure?
When the kidneys can't carry out their normal functions.
100
How can kidney failure be detected?
By measuring the glomerular filtrate rate (GFR) This works out how many millimetres of liquid your kidneys are able to filter a minute
101
What should the GFR of healthy kidneys be?
90 cm³min
102
What are possible causes of kidney disease?
-Bacterial infection of the pelvis or surrounding tissue
-Nephritis, inflammation of the glomerulus or in general. This damages cells and interferes with filtering or reabsorption
-High blood pressure, which damages the golmeruli
-Diabetes mellitus which leads to overworking
-Atherosclerosis leading to reduced blood supply to the kidney
103
What are the problems that arise from kidney failure?
-Waste products build up in the blood. E.g urea causes weight loss and vomiting
-Fluid starts to accumulate in tissues as the kidneys cannot remove excess water, causing swelling
-The balance of electrolytes becomes unbalanced. Blood may become too acidic. Imbalance of calcium and phosphate can lead to brittle bones. Salt build up may cause water retention, and changes in ph. Potassium ions cause cramping, tiredness and muscle weakness.
-Long term failure can lead to anemia which is lack of haemoglobin in the blood
104
What happens with sodium in the body?
It is either excreted or conserved depending on levels in the body. An inability to do this may lead to disorientation, muscle twitches and increased blood pressure
105
What do potassium ions cause as the conc in the blood increases due to kidney failure?
May interfere with impulses from the sinoatrial node which may lead to arrhythmia and cardiac arrest
106
What is renal dialysis?
Where a patients blood is filtered. One method of this is haemodialysis
107
What does dialysis mean?
To separate small and large molecules using a partially permeable membrane
108
Explain haemodialysis
This method involves passing a patients blood through a dialysis machine. The blood flows on one side of a partially permeable membrane and the dialysis fluid on the other side. They flow in opposite directions to maintain a steep.concentration gradient to increase rate of diffusion.
109
What is the dialysis fluid called in haemodialysis?
Dialysate. This doesn't contain any urea, and a similar conc of other products to normal blood levels
110
What is peritoneal dialysis?
Where a catheter is placed into the abdominal cavity and dialysate is pumped into the space. Urea and toxins will diffuse from the blood into the dialysis fluid. This is then exchanged, and oumped out around 4 times a day and new fluid is put back in. Excess and waste diffuses from capillaries and accross the peritoneum into the fluid. The disadvantages is that its more likely risks to infection and an operation must occur before hand, in order the place the tube from outside to their abdominal cavity
111
What mechanism does haemodialysis use?
A countercurrent mechanism
112
What are the disadvantages of haemodialysis?
-Patients can feel unwell between sessions as products begin building up again
-Inconvenient
-Expencive long term
113
What are the advantages of haemodialysis?
Can keep someone alive until a transplant is available
Less risky than surgery
114
What is a kidney transplant?
Where a new kidney is implanted into a patients body to replace a damaged one.
115
What are the advantages of kidney transplant?
Convenient
Has to be from the same blood group from a live donor, or same tissue type from a dead donor.
Heavier risk of infection
Must stay on immunosuppresants
116
What is hCG?
Human chorionic gonadotropin. It is a hormone found in the urine of pregnant woman. It is secreted hy an embryo as soon as its implanted in the uterine lining.
117
Explain the testing steps for pregnancy
1) A stick is used with an application area that contains monoclonal antibodies for hCG bound to a blue coloured bead. Monoclonal antibodies are all identical to each other
2) When urine is applied, any hCG will bind to the antibody on the beads
3) The urine moves uo the test strip, carrying the beads with it.
4) The test strip has antibodies to hCG stuck in place.
5) If there is any hCG present, the test strip turns blue because hCG attacked to the beads bind to the immobilised antibodies which concentrates the blue beads
6) If no hCG is present the beads will pass through the test area so it won't be blue
118
What are anabolic steroids?
Drugs that build up muscle tissue
119
What is an example of an anabolic steroid?
Testosterone
120
How are steroids removed from the blood?
Via urine
121
How is blood tested for steroids?
Gas chromatography/ mass spectrometry
122
Explain how steroids are tested
In gas chromatography the urine sample is vaporised and passed through a column containing a polymer. Different substances move through the column at different rates so the substances in the urine sample separate out.
Once the substances separate, a mass spectrometry convertes them into ions, then separates the ions depending on their mass and charge. The results are the analysed by a computer and by comparing them with a known sample we can tell what is in the urine
123
The contents of what structure would give a brick red colour when using the benedicts test
Bowman's capsule
124
Why is blood pressure in the glomerular capillaries higher than normal capillaries?
Because the afferent arteriole is much thinker than the efferent one. This causes higher pressure. Pressure is built up to acheive filtration
125
What does RMM stand for?
Relatove molecular mass
126
Describe ways how gluconeogenesis occurs
-The deamination of amino acids removes the amino groups into pyruvate. Triose phosphate. Condensation reaction increases the C atoms
-Break down of lipids into glycerol. Triose phosphate. Condensation increases C atoms
127
Why does glucose not appear in the urine but urea does?
Both filtered by the kidney. They are both small molecules. Glucose is reabsorbed by active uptake via cotransporter proteins. Some glucose is used in active processes in the kidney. Some urea reabsorbed by diffusion
128
What is the abdominal cavity lined with?
Membrane called the peritoneum
129
What is the renal hilum?
An indent in the kidney
130
What is the adipose tissue?
The tissue covering the beginning of the blood vessels at the kidney
131
What are renal pyramids?
Cone shaped structures in the medulla. They appear stripy as they contain straight sections of nephron
132
What are renal collums?
These are in between renal pyramids
133
What property of hCG means it can be detected in the urine?
Has a molecular mass of less that 69000
Biology OCR
flashcards
Decks in class (25)
# Cards
-
Cell Structure And Microscopy51
-
Biological Molecules97
-
Nucleotides And Nuclaic Acids32
-
Enzymes35
-
Biological Membranes36
-
Cell Division And Organisation41
-
Exchange And Transport55
-
Transport In Animals66
-
Transport In Plants46
-
Disease And The Immune System71
-
Biodiversity59
-
Classification And Evolution77
-
Ecosystems80
-
Populations And Sustainability45
-
Neurology124
-
Homeostasis And Hormonal Control83
-
Plant Responses And Hormones79
-
Excretion133
-
Photosynthesis75
-
Respirstion56
-
Cellular Contril53
-
Patterns Of Inheritance58
-
Evolution ^31
-
Manipulating Genomes97
-
Cloning And Biotechnology57
