1
Q
What is excretion?
A
The process by which toxic waste products of metabolism and substances in excess of requirement are removed from the body
Excretion is crucial for maintaining homeostasis.
2
Q
How do the lungs participate in excretion?
A
By excreting the waste product carbon dioxide through gas exchange and exhalation
This process is vital for respiratory function.
3
Q
What do the kidneys produce that is related to excretion?
A
Urine that contains the waste product urea in solution
Urea is a key nitrogenous waste product.
4
Q
Why is excretion important in maintaining metabolism?
A
Because metabolic waste can have serious negative consequences on the body if allowed to accumulate
Accumulated waste can affect enzyme efficiency.
5
Q
What types of metabolic waste do mammals produce?
A
- Carbon dioxide
- Nitrogenous waste (ammonia, urea, uric acid)
- Bile pigments (produced during the breakdown of haemoglobin)
Mammals have high metabolic rates, leading to increased waste production.
6
Q
How is carbon dioxide produced in the body?
A
From the decarboxylation of respiratory substrates
This process occurs during cellular respiration.
7
Q
What is ammonia produced from?
A
The deamination of excess amino acids
Ammonia is highly toxic and must be excreted efficiently.
8
Q
What can happen if carbon dioxide and ammonia are not excreted properly?
A
They can accumulate and change the cytoplasm and body fluid pH, causing enzymes to work less efficiently
pH changes can disrupt cellular functions.
9
Q
Which organ is key in producing excretory substances?
A
The liver
The liver plays a central role in detoxification and waste processing.
10
Q
What is the primary function of the liver?
A
The liver is involved with the breakdown of toxic substances and the production of excretory waste.
11
Q
How does the liver receive oxygenated blood?
A
Oxygenated blood from the heart is carried to the liver via the hepatic artery.
12
Q
What is the role of the hepatic portal vein?
A
The hepatic portal vein carries blood from the digestive system to the liver, allowing it to absorb and metabolise nutrients.
13
Q
How does deoxygenated blood exit the liver?
A
Deoxygenated blood exits the liver in the hepatic vein and flows back to the heart.
14
Q
What is the function of the gall bladder?
A
The gall bladder stores bile and releases it into the duodenum via the bile duct.
15
Q
What does bile contain?
A
Bile contains bile salts for lipid digestion and bile pigments from the breakdown of haemoglobin.
16
Q
What are hepatocytes?
A
Hepatocytes are the main cells of the liver that carry out almost all its functions.
17
Q
How are liver cells organized?
A
Liver cells are arranged into structures known as lobules.
18
Q
What supplies blood to each lobule?
A
Each lobule is supplied with blood by branches of the hepatic artery and the hepatic portal vein.
19
Q
What are sinusoids?
A
Sinusoids are wide capillaries within each lobule where blood from the hepatic artery and portal vein mixes.
20
Q
What occurs in the sinusoids?
A
Blood within the sinusoid exchanges substances with nearby hepatocytes, allowing them to perform liver functions.
21
Q
How does blood drain from each lobule?
A
Each lobule is connected to a branch of the hepatic vein that drains blood away into the main hepatic vein.
22
Q
What are the main functions of the liver?
A
The main functions of the liver include storage of glycogen, formation of urea, and detoxification.
23
Q
What process converts glucose into glycogen in the liver?
A
The process that converts glucose into glycogen is known as glycogenesis.
24
Q
What triggers glycogenesis in the liver?
A
Insulin triggers glycogenesis after the pancreas detects an increase in blood glucose concentration.
25
Where is glycogen stored in the liver?
Glycogen is stored inside hepatocytes.
26
What is formed during the breakdown of protein in the liver?
During the breakdown of protein, amino acids are formed and transported to the liver via the hepatic portal vein
27
What two-step process is involved in processing excess amino acids in the liver?
The two-step process involves deamination and the ornithine cycle.
28
What happens during deamination?
During deamination, the amino group (NH2) is removed from each amino acid, NH2 and H+ combine forming ammonia (NH3).
29
What can the remaining part of the amino acid after deamination be converted into?
The remaining part can enter the Krebs cycle, be converted to glucose, or be converted to glycogen or fat for storage.
30
What is the ornithine cycle?
The ornithine cycle is the process where ammonia is converted into urea.
31
What is produced during the ornithine cycle?
One molecule of urea is produced from one molecule of carbon dioxide and two amino groups.
32
How is urea transported after its formation in the liver?
Urea diffuses through the phospholipid bilayer of hepatocytes and is transported to the kidneys dissolved in blood plasma.
33
What is detoxification in the liver?
Detoxification is the breakdown of substances that are not needed or are toxic.
34
What substances undergo detoxification in the liver?
Substances include alcohol, hydrogen peroxide, lactate, and medicinal drugs.
35
What happens to alcohol in the liver?
Alcohol is converted into ethanal by the enzyme alcohol dehydrogenase inside hepatocytes.
36
What condition can continuous alcohol detoxification lead to?
Continuous alcohol detoxification can lead to fatty liver and eventually cirrhosis.
37
What are the two main functions of the kidneys?
The kidneys are responsible for osmoregulation and excretion.
38
What is the role of the kidneys as an osmoregulatory organ?
They regulate the water content of the blood, which is vital for maintaining blood pressure.
39
What is the role of the kidneys as an excretory organ?
They excrete toxic waste products of metabolism, such as urea, and substances in excess, such as salts.
40
What surrounds the kidney?
The kidney is surrounded by a tough outer layer known as the fibrous capsule.
41
What are the three main areas of the kidney?
The three main areas are the cortex, medulla, and renal pelvis.
42
What does the cortex of the kidney contain?
The cortex contains the glomerulus, Bowman’s capsule, proximal convoluted tubule, and distal convoluted tubule of the nephrons.
43
What does the medulla of the kidney contain?
The medulla contains the loop of Henle and collecting duct of the nephrons.
44
What is the renal pelvis?
The renal pelvis is where the ureter joins the kidney.
45
What are nephrons?
Nephrons are tiny tubes within each kidney and are the functional units responsible for urine formation.
46
What is located within the Bowman’s capsule of each nephron?
Each Bowman’s capsule contains a structure known as the glomerulus.
47
How is blood supplied to the glomerulus?
Each glomerulus is supplied with blood by an afferent arteriole, which carries blood from the renal artery.
48
What happens to blood after it flows through the glomerulus?
The capillaries of the glomerulus rejoin to form an efferent arteriole.
49
Where does blood flow after the efferent arteriole?
Blood flows into a network of capillaries that run closely alongside the rest of the nephron.
50
Where does blood eventually flow after the nephron capillaries?
Blood from these capillaries eventually flows into the renal vein.
51
What is the functional unit of the kidney?
The nephron is the functional unit of the kidney; nephrons are responsible for the formation of urine.
52
What are the two stages of urine formation in the kidneys?
The two stages of urine formation are ultrafiltration and selective reabsorption.
53
What occurs during ultrafiltration?
Small molecules are filtered out of the blood and into the Bowman's capsule of the kidney nephron, forming glomerular filtrate.
54
What happens during selective reabsorption?
Useful molecules are taken back from the filtrate and returned to the blood; after reabsorption is complete, the remaining filtrate forms the urine.
55
How does urine flow after formation?
Urine flows out of the kidneys, along the ureters and into the bladder, where it is temporarily stored.
56
What is the glomerulus?
The glomerulus is a knot of capillaries formed by arterioles branching off the renal artery, located inside the Bowman’s capsule.
57
What causes high blood pressure in the glomerulus?
The afferent arteriole entering the glomerulus is wider than the efferent arteriole leaving it, resulting in high blood pressure within the glomerulus.
58
What substances pass out of the capillaries to form glomerular filtrate?
The main substances are amino acids, water, glucose, urea, and inorganic ions (mainly Na+, K+, and Cl-).
59
What remains in the blood during ultrafiltration?
Blood cells and large proteins remain in the blood as they are too large to pass through the holes in the capillary endothelial cells.
60
What are the layers separating blood in the glomerular capillaries from the Bowman’s capsule?
There are two cell layers with a basement membrane in between: the endothelium of the capillary and the epithelium of the Bowman’s capsule.
61
What adaptations do proximal convoluted tubule epithelial cells have for reabsorption?
They have microvilli, co-transporter proteins, many mitochondria, and tightly packed cells.
62
How do microvilli aid reabsorption?
Microvilli increase the surface area for reabsorption.
63
What role do co-transporter proteins play in reabsorption?
Co-transporter proteins transport specific solutes (e.g., glucose or amino acids) across the luminal membrane.
64
How do mitochondria contribute to reabsorption in the proximal convoluted tubule?
Mitochondria provide energy for sodium-potassium (Na+/K+) pump proteins in the basal membranes of the cells.
65
What is the mechanism of sodium ion reabsorption?
Sodium ions are transported from the proximal convoluted tubule into surrounding tissues by active transport.
66
How do chloride ions follow sodium ions during reabsorption?
Chloride ions follow sodium ions by diffusion due to the electrical gradient created by sodium ion transport.
67
How are sugars and amino acids transported during reabsorption?
They are transported into surrounding tissues by co-transporter proteins that also transport sodium ions.
68
What happens to water during the reabsorption process?
Water leaves the proximal convoluted tubule by osmosis due to the lowered water potential in the surrounding tissues.
69
How does the loop of Henle contribute to reabsorption?
Sodium and chloride ions are pumped out of the filtrate in the ascending limb, lowering the water potential of the medulla.
70
What is the permeability of the ascending limb of the loop of Henle?
The ascending limb is impermeable to water, preventing water from leaving by osmosis.
71
What occurs in the descending limb of the loop of Henle?
Water moves out of the descending limb by osmosis due to the low water potential of the medulla.
72
How does the water potential change in the descending limb?
The water potential decreases as water is lost and ions are retained.
73
What enables the reabsorption of water from the collecting duct?
The low water potential in the medulla created by the ascending limb allows for the reabsorption of water from the collecting duct by osmosis.
74
What is osmoregulation?
The control of the water potential of body fluids.
75
Why is osmoregulation important?
It is a key part of homeostasis.
76
What are osmoreceptors?
Specialised sensory neurones that monitor the water potential of the blood.
77
Where are osmoreceptors located?
In the hypothalamus, an area of the brain.
78
What happens when osmoreceptors detect a decrease in blood water potential?
Nerve impulses are sent to the posterior pituitary gland.
79
What does the posterior pituitary gland release in response to nerve impulses?
Antidiuretic hormone (ADH).
80
What is the function of ADH?
It causes the kidneys to reabsorb more water.
81
How does ADH affect urine production?
It reduces the loss of water in the urine.
82
How is water reabsorbed in the kidneys?
By osmosis from the filtrate in the nephron.
83
Where does water reabsorption occur in the nephron?
As the filtrate passes through the collecting ducts.
84
What effect does ADH have on collecting duct cells?
It increases their permeability to water.
85
How does ADH increase permeability in collecting duct cells?
By increasing the number of aquaporins in the luminal membranes.
86
What happens to aquaporins when ADH binds to receptor proteins?
They become activated and cause vesicles to fuse with the luminal membranes.
87
What is the result of increased aquaporin activity?
Increased permeability of the membrane to water.
88
What happens to the filtrate as it travels along the collecting duct?
Water moves from the collecting duct into the tissue fluid and blood plasma.
89
What is the result of water loss from the filtrate?
The filtrate becomes more concentrated.
90
What type of urine is produced as a result of ADH activity?
A small volume of concentrated urine.
91
Where does urine flow after being produced in the kidneys?
Through the ureters and into the bladder.
92
What is kidney failure?
Kidney failure can occur in one or both kidneys due to various reasons, including blood loss, high blood pressure, diabetes, overuse of certain drugs, and certain infections.
93
What are the consequences of kidney failure?
Kidney failure leads to the retention of urea, water, salts, and various toxins, decreased glomerular filtration rate (GFR), and disrupted electrolyte balance.
94
What can excess potassium ions in the blood cause?
Excess potassium ions can lead to abdominal cramps, tiredness, muscle weakness, and even paralysis.
95
What happens if potassium ion concentrations continue to increase?
Increased potassium concentrations may decrease the frequency of impulses from the sinoatrial node, potentially leading to arrhythmia and cardiac arrest.
96
What role does sodium play in the body?
Sodium is important for neuromuscular function, fluid balance, and acid/base balance.
97
What can a build-up of sodium cause?
A build-up of sodium can cause disorientation, muscle spasms, higher blood pressure, and general weakness.
98
What are the two forms of treatment for kidney failure?
The two forms of treatment are renal dialysis and kidney transplant.
99
What is renal dialysis?
Renal dialysis is a treatment that removes toxins and excess substances from the blood using diffusion via a dialysis membrane.
100
What is haemodialysis?
Haemodialysis is a type of renal dialysis where a machine acts as an artificial kidney to filter the blood.
101
How does the dialysis machine work?
The dialysis machine uses partially permeable membranes to separate the patient's blood from the dialysis fluid, allowing for the removal of urea and the maintenance of necessary substances.
102
What is the role of heparin in renal dialysis?
Heparin is added to the blood as an anticoagulant to prevent the formation of blood clots.
103
What are the disadvantages of renal dialysis?
Dialysis imposes heavy restrictions on patients, requiring regular hospital visits and careful dietary control.
104
What is a kidney transplant?
A kidney transplant involves replacing non-functioning kidneys with a functioning kidney from a compatible donor.
105
What are the challenges of kidney transplants?
Challenges include the need for a compatible donor, potential immune response to the new kidney, and the requirement for lifelong immunosuppressant medication.
106
What are the advantages of kidney transplants over dialysis?
Kidney transplants offer more freedom, less restrictive diets, and eliminate the high costs associated with dialysis.
107
What is the most common urine test?
The most common urine test is to look for 'sugar' (glucose) in the urine.
108
What should happen to glucose in the glomerular filtrate?
All the glucose in the glomerular filtrate should be reabsorbed by the proximal convoluted tubule (PCT).
109
What does the presence of glucose in urine suggest?
The presence of glucose in urine suggests that there is something wrong with the person's homeostatic control of glucose.
110
What are ketones and when are they produced?
Ketones, such as acetone and acetoacetate, are produced by the metabolism of people who have diabetes.
111
What does the presence of ketones in urine or blood indicate?
The presence of ketones suggests the person has diabetes mellitus.
112
What does protein in urine indicate?
The presence of protein in urine suggests that the person's blood pressure may be too high, or it may indicate a kidney infection or an issue with blood filtration.
113
What do positive tests for nitrate ions in urine indicate?
Positive tests for nitrate ions in urine indicate a bacterial infection in the urinary tract.
114
How are urine samples used in pregnancy testing?
Urine samples are used in pregnancy testing to detect human chorionic gonadotropin (hCG), a hormone produced during pregnancy.
115
What is the source of antibodies in pregnancy testing sticks?
The antibodies in the testing sticks originate from a single clone of B lymphocyte cells that produce the same antibody specific to hCG.
116
What is tested for in urine samples regarding anabolic steroids?
Urine samples can be used to test for anabolic steroids, which athletes are regularly tested for.
117
How are anabolic steroids detected in urine?
Anabolic steroids are detected in urine via gas chromatography or mass spectrometry.
Biology
flashcards
Decks in class (19)
# Cards
-
5.1 - Communication And Homeostasis66
-
5.2 - Excretion117
-
5.4 - hormonal Comunictaion71
-
4.2 - Biodiversity154
-
4.3 - classification And Evolution139
-
4.1 - Communicable Diseases224
-
Photosynthesis70
-
The Nervous System87
-
DCPIP practical20
-
Practical Terminolgy6
-
Animal Responses93
-
Respiration56
-
Pracical - Investigating The Rate Of Respiration13
-
Practical - Repsirometer6
-
Plant Response43
-
Excretion - The Rest Is In Your Notes30
-
Biodeiversity 233
-
Statistics In Biology9
-
Vaccinations0
