13. Excretion in Humans + 15. Drugs Flashcards
What is a difference between plants and humans in terms of the removal of waste products?
Unlike plants, humans have organs which are specialised for the removal of certain excretory products
What are 3 examples of organs which are vital for excretion?
lungs
kidney
liver
What do the lungs mainly excrete?
carbon dioxide
Why are lungs a part of the excretory system?
The lungs excrete CO2 (a waste product of aerobic respiration) during exhalation
What do the kidneys mainly excrete?
excess water, salts and urea
Why are kidneys a part of the excretory system?
The kidneys excrete excess water, excess salts and urea (formed in the liver from excess amino acids) by producing urine
Excretion definition
Excretion is the removal of the waste substances of metabolic reactions (the chemical reactions that take place inside cells), toxic materials and substances in excess of requirements
Why must carbon dioxide be excreted?
Carbon dioxide must be excreted as it dissolves in water easily to form an acidic solution which can lower the pH of cells
This can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions
What substances are toxic to the body?
For this reason, too much carbon dioxide in the body is toxic
Urea is also toxic to the body in higher concentrations and so must be excreted
What happens to many digested food molecules once absorbed?
Many digested food molecules absorbed into the blood in the small intestine are carried to the liver for assimilation (when food molecules are converted to other molecules that the body needs)
What is an example for the use of amino acids?
Amino acids, which are used to build proteins such as fibrinogen, a protein found in blood plasma that is important in blood clotting
- What happens to excess amino acids and why?
Excess amino acids absorbed in the blood that are not needed to make proteins cannot be stored, so they are broken down in a process called deamination
- What plays a key role in deamination?
ENZYMES in the liver split up the amino acid molecules
- During deamination, what happens to the carbon present in the amino acids?
The part of the molecule which contains carbon is turned into glycogen and stored
- During deamination, what happens to the nitrogen present in the amino acids?
The other part, which contains nitrogen, is turned into ammonia, which is highly toxic, and so is immediately converted into urea, which is less toxic
- What happens to the urea after deamination?
The urea dissolves in the blood and is taken to the kidney to be excreted
A small amount is also excreted in sweat
- What is a brief summary of deamination?
In deamination, the nitrogen-containing amino group is removed and converted into ammonia and then urea to be excreted
What is the difference between excretion and egestion? Give definitions
Excretion is the removal from the body of waste products of metabolic reactions, toxic substances and substances in excess of requirements.
Egestion is the expulsion of undigested food waste from the anus.
What are the 4 main structures involved in the urinary system?
Kidney
Ureter
Bladder
Urethra
Kidney definition
two bean-shaped organs that filter the blood
ureter defintion
Tube connecting the kidney to the bladder
Bladder definition
Organ that stores urine (excess water, salts and urea) as it is produced by the kidney
urethra definition
Tube that connects the bladder to the exterior,; where urine is released
What are two different factors to examine when looking at changes in urine?
The colour and quantity of urine produced in the body can change quickly
What are large quantities of urine associated with?
Large quantities of urine are usually pale yellow in colour because it contains a lot of water and so the urea is less concentrated
What are small quantities of urine associated with?
Small quantities of urine are usually darker yellow / orange in colour because it contains little water and so the urea is more concentrated
What are three factors which affect the concentration of urine?
water intake
temperature
exercise
How does water intake affect urine?
the more fluids drunk, the more water will be removed from the body and so a large quantity of pale yellow, dilute urine will be produced
How does temperature affect urine?
the higher the temperature the more water is lost in sweat and so less will appear in urine, meaning a smaller quantity of dark yellow, concentrated urine will be produced
How does exercise affect urine?
the more exercise done, the more water is lost in sweat and so less will appear in urine, meaning a smaller quantity of dark yellow, concentrated urine will be produced
Where are the kidneys located?
The kidneys are located in the back of the abdomen
What are the two important functions of the kidney?
They regulate the water content of the blood (vital for maintaining blood pressure)
They excrete the toxic waste products of metabolism (such as urea) and substances in excess of requirements (such as salts)
What does each kidney contain?
Each kidney contains around a million tiny structures called nephrons, also known as kidney tubules or renal tubules
What are examples of waste substances that need to be removed from the blood?
urea
excess hormones
excess water
uric acid
excess salt/ions e.g Na+ or Cl-
ammonia
Where does the nephron start?
The nephrons start in the cortex of the kidney
Where does the nephron loop down into? (where is it’s main body located?)
loop down into the medulla and back up to the cortex
Where do the contents of the nephron drain into?
The contents of the nephrons drain into the innermost part of the kidney and the urine collects there
Where does the collected urine flow to?
it flows into the ureter to be carried to the bladder for storage
- What is the first process which takes place in the nephron?
Ultrafiltration
- What is the glomerulus and where is it located?
Ultrafiltration
Arterioles branch off the renal artery and lead to each nephron, where they form a knot of capillaries (the glomerulus) sitting inside the cup-shaped Bowman’s capsule
- What happens to the capillaries as they get further into the glomerulus and what does this do?
Ultrafiltration
The capillaries get narrower as they get further into the glomerulus which increases the pressure on the blood moving through them (which is already at high pressure because it is coming directly from the renal artery which is connected to the aorta)
- What does this high pressure do?
Ultrafiltration
This eventually causes the smaller molecules being carried in the blood to be forced out of the capillaries and into the Bowman’s capsule, where they form what is known as the filtrate
This process is known as ultrafiltration
- What substances are forced out the capillaries?
Ultrafiltration
The substances forced out of the capillaries are: glucose, water, urea, salts
These compose the filtrate
- What happens to the useful substances forced out the capillaries?
Ultrafiltration
Some of these are useful and will be reabsorbed back into the blood further down the nephron
Where is water reabsorbed at? (in the nephron)
loop of henle and collecting duct
Where are salts reabsorbed at? (in the nephron)
loop of henle
Where is glucose reabsorbed at? (in the nephron)
proximal (first) convoluted tubule
Where is urea reabsorbed at? (in the nephron)
NOT REABSORBED
- What is the second process that takes place in the nephron?
Selective reabsorption
- What is the first substance to be reabsorbed and where is it reabsorbed?
Reabsorption of Glucose
After the glomerular filtrate enters the Bowman’s Capsule, glucose is the first substance to be reabsorbed at the proximal (first) convoluted tubule
- By what process is glucose reabsorbed?
Reabsorption of Glucose
This takes place by active transport
- How is the nephron adapted for reabsorption of glucose?
Reabsorption of Glucose
The nephron is adapted for this by having many mitochondria to provide energy for the active transport of glucose molecules
- Can reabsorption of glucose take place anywhere? Why?
Reabsorption of Glucose
NO
Reabsorption of glucose cannot take place anywhere else in the nephron as the gates that facilitate the active transport of glucose are only found in the proximal convoluted tubule
- What is the difference of the glucose reabsorption in a normal / diabetic person’s body?
Reabsorption of Glucose
In a person with a normal blood glucose level, there are enough gates present to remove all of the glucose from the filtrate back into the blood
People with diabetes cannot control their blood glucose levels and they are often very high, meaning that not all of the glucose filtered out can be reabsorbed into the blood in the proximal convoluted tubule
- In a diabetic person, where does this excess glucose end up?
Reabsorption of Glucose
As there is nowhere else for the glucose to be reabsorbed, it continues in the filtrate and ends up in urine
- What check might a doctor do to test if a person is diabetic?
Reabsorption of Glucose
one of the first tests a doctor may do to check if someone is diabetic is to test their urine for the presence of glucose
- By what process are salts and water reabsorbed and where?
Reabsorption of water and salts
As the filtrate drips through the Loop of Henle necessary salts are reabsorbed back into the blood by diffusion
As salts are reabsorbed back into the blood, water follows by osmosis
- Apart from the loop of Henle, where is the water reabsorbed?
Reabsorption of water and salts
Water is also reabsorbed from the collecting duct in different amounts depending on how much water the body needs at that time
Why may the kidney not function?
The kidneys might not work properly for several reasons, including accidents or disease
With how many kidneys can a person survive? Why?
Humans can survive with one functioning kidney, but if both are damaged then there will quickly be a build-up of toxic wastes in the body which will be fatal if not removed
What are two treatments for kidney failure?
dialysis or transplant
- What is the basic concept of dialysis?
This is an artificial method of filtering the blood to remove toxins and excess substances
- What are patients connected to and what does this do?
dialysis
Patients are connected to a dialysis machine which acts as an artificial kidney to remove most of the urea and restore/maintain the water and salt balance of the blood
- What is done once the patient is connected to a dialysis machine?
dialysis
Unfiltered blood is taken from an artery in the arm, pumped into the dialysis machine and then returned to a vein in the arm
- What is inside the machine and how are these things separated
dialysis
Inside the machine the blood and dialysis fluid are separated by a partially permeable membrane
- In what direction does the blood and dialysis fluid flow and why?
dialysis
the blood flows in the opposite direction to dialysis fluid, allowing exchange to occur between the two where a concentration gradient exists
- What does dialysis fluid contain? (3)
dialysis
a glucose concentration similar to a normal level in blood
a concentration of salts similar to a normal level in blood
no urea
- Why is it important that dialysis fluid doesn’t have any urea in it?
dialysis
As the dialysis fluid has no urea in it, there is a large concentration gradient – meaning that urea diffuses across the partially permeable membrane, from the blood to the dialysis fluid
- Why is it important that dialysis fluid has the same glucose concentration as in normal blood in it?
dialysis
As the dialysis fluid contains a glucose concentration equal to a normal blood sugar level, this prevents the net movement of glucose across the membrane as no concentration gradient exists
- Why is it important that dialysis fluid has the same salt concentration as in normal blood in it?
dialysis
As the dialysis fluid contains a salt concentration similar to the ideal blood concentration, movement of salts across the membrane only occurs where there is an imbalance (if the blood is too low in salts, they will diffuse into the blood; if the blood is too high in salts, they will diffuse out of the blood)
- What is done to the fluid in the dialysis machine?
dialysis
The fluid in the machine is continually refreshed so that concentration gradients are maintained between the dialysis fluids and the blood
- How often must dialysis be carried out?
dialysis
Dialysis may take 3-4 hours to complete and needs to be done several times a week to prevent damage to the body from the buildup of toxic substances in the blood
- What is added to the blood before dialysis is carried out?
dialysis
An anticoagulant is added to blood before it runs through the machine to prevent the blood from clotting and slowing the flow
What is an advantage of a kidney transplant?
Kidney transplants are a better long term solution to kidney failure than dialysis; however, there are several disadvantages to kidney transplants, including:
What are 3 disadvantages of kidney transplants?
Donors won’t have the same antigens on cell surfaces so there will be some immune response to the new kidney (risk of rejection is reduced – but not removed – by ‘tissue typing’ the donor and the recipient first)
This has to be suppressed by taking immunosuppressant drugs for the rest of their lives – these can have long term side effects and leave the patient vulnerable to infections
There are not enough donors to cope with demand
What are 4 advantages of kidney transplants?
the patient has much more freedom as they are not tied to having dialysis several times a week in one place
their diets can be much less restrictive than they are when on dialysis
use of dialysis machines is very expensive and so this cost is removed
a kidney transplant is a long-term solution whereas dialysis will only work for a limited time
Where is carbon dioxide excreted through?
Carbon dioxide is made by all cells during respiration and dissolves in blood plasma to form a weak acid which lowers the pH and can denature enzymes. Carbon dioxide is transported to the alveoli and excreted through the lungs.
What do the kidneys excrete?
Urea is produced in the liver during the deamination of excess amino acids and can denature enzymes. It is carried in the blood plasma from the liver to the kidneys where it is excreted in the urine, along with excess water and ions (substances in excess of requirements).
What is excretion?
The removal of the waste products of metabolism and substances in excess of requirements.
What is deamination?
The removal of the nitrogen-containing part of amino acids to form urea. The ammonia is carried to the kidneys in the blood and excreted in the urine as urea while the second part of the molecule is converted to carbohydrate or fat and used as a source of energy.
What is the role of the glomerulus?
The role of the glomerulus in the filtration from the blood of water, glucose, urea, and ions.
What is the role of the nephron?
The role of the nephron in the reabsorption of all of the glucose, some of the ions, and most of the water back into the blood.
Describe the formation of urine.
The formation of urine containing urea excess water and excess ions.
What is ultrafiltration?
Blood in the glomerulus is under high pressure and this forces substances out of the blood and is known as ultrafiltration.
From the substances forced out of the blood into the nephron, which ones are reabsorbed, and how are they reabsorbed along the nephron tubule (loop of Henle)?
All glucose is reabsorbed by diffusion and active transport, some water is reabsorbed by osmosis and some salts are reabsorbed by diffusion.
What is transported down the collecting duct to the ureter to be excreted?
Excess water, urea and excess salts.
What are the seven processes that take place in the nephron?
The blood is delivered to the glomerulus under high pressure by branches of the renal artery.
The blood is filtered by ultrafiltration and water, glucose, urea, and ions are forced into the renal capsule (proteins and blood cells are too big to be filtered).
In the first tubule of the nephron, all glucose, some ions, and some of the water are reabsorbed back into the blood.
The collecting tube further reabsorbed water by osmosis and returns it to the blood leaving concentrated urea in the urine.
The filtered blood is returned to the circulatory system by the renal vein.
Urea and excess ions are dissolved in excess water from the urine which is carried from the kidneys to the bladder in the ureter.
The urine is stored in the bladder and when the bladder is full, the urine is excreted out through the urethra.
Where is urea formed?
Urea is formed in the liver from excess amino acids.
What are the three main functions of the kidneys?
A
Controlling ion levels.
Excreting urea.
Osmoregulation.
Define osmoregulation.
Osmoregulation is the process by which organisms regulate the balance of water and salt in their bodies to maintain proper fluid balance and prevent dehydration or overhydration.
What are the main functions of the liver?
Makes bile to emulsify fats.
Stores glucose as glycogen.
Uses amino acids to make proteins e.g. fibrinogen.
Excess amino acids are deaminated.
Converts fatty acids and glycerol into fat or cholesterol.
Processes unwanted substances from the blood e.g. alcohol and poisons.
Generates heat to keep the body internal temperature at 37C.
What is the role of the liver?
Assimilation: uptake and use of nutrients by cells.
All the digested food molecules are absorbed into the capillaries of the villi and are transported to the liver by the hepatic portal vein.
What is excretion?
A
The removal of the waste substances of metabolic reactions, toxic materials and substances in excess of requirements.
What are excretory organs?
Lungs
Kidneys
liver
What is produced by the breakdown of respiration?
CO2
How is CO2 removed?
It is carried away by the blood and removed in the lungs.
Why must CO2 be removed?
It dissolves in water easily to form an acidic solution which can lower the pH of cells
What can an acidic atmosphere cause?
It can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions.
What happens to most of the food molecules absorbed into the blood?
They are carried to the liver for assimilation
What is assimilation?
When food molecules are converted to other molecules that the body needs.
What is fibrinogen needed for?
Blood clotting
What happens to excess amino acids?
They are broken down in a process called deamination
What does deamination involve?
The actions of enzymes to split up the amino acid molecules.
What happens to the part that contains carbon?
It is turned into glycogen and stored
What happens to the part that contains nitrogen?
Is removed and turned into ammonia
What happens to the ammonia produced?
Converted to urea which is less toxic
What happens to the urea?
It is dissolved in the blood and is taken to the kidney to be excreted as urine.
Where are the kidneys located?
Back of the abdomen
What functions does the kidney have?
Regulate water content in the blood
Excrete waste products of metabolism and substances of excess requirements
What is osmoregulation?
A
Regulate water content in the blood
What does the kidney tissue consist of?
Many capillaries and thousands of tiny tubules called renal tubules( nephrons) held together with connective tissue
What color is the cortex?
Dark outer region
What part is the medulla?
Lighter inner zone
What is the renal pelvis?
Where the ureter joins the kidney
Where is blood filtered and where is urine produced?
In the nephrons
Where does each nephron begin?
In the cortex of the kidney
Where do the tubules join up?
In the pelvis to join up with the ureter
Where does the ureter lead to?
To the bladder where urine is stored
What is the glomerlus?
Knot of capillaries that branch of the renal artery and lead to each nephron
Where does the glomerlus sit?
Inside a cup shaped structure called the Bowman’s capsule
What happens as the capillaries get narrower in the glomerulus?
Increase in the pressure on the blood
What does the pressure of the blood cause?
Causes small molecules including water and most substances dissolved in the blood to be squeezed out of the capillaries and into the Bowman’s capsule
What does the filtrate contain?
Water, salt, glucose and urea
Which molecules are too big to pass through?
protein molecules and blood cells
What is the first substance to be reabsorbed?
Glucose
Where is glucose reabsorbed?
In the proximal convoluted tubule.
How is glucose absorbed?
By active transport
What are nephrons surrounded by?
Capillaries where useful substances from filtrate are reabsorbed and passes into the blood
Where does the remaining filtrate continue?
through the hoop of henle
What happens at the loop of Henle?
Necessary salt and water are reabsorbed back into the blood by diffusion and osmosis.
What happens to the remaining liquid?
Continue through the distal convoluted tubule to the collecting duct where water is reabsorbed into the blood according to the body’s demand.
What is the ADH?
Anti diuretic hormone
What happens to the urine?
Flows out of the kidney through the ureter and into the bladder
What does the urine contain?
this contains urea and salts in water.
Where is water reabsorbed at?
Loop of Henle and collecting duct
Where is salts reabsorbed at?
Loop of Henle
Where is glucose reabsorbed at?
First convoluted tubule
What factors affect the volume and concentration of urine?
Water intake
temperature
Exercise
How does water intake affect the volume and concentration of urine change?
More fluids drunk means more water will be removed so a large quantity of urine is produced
How does temperature affect the volume and concentration of urine change?
The higher the temperature the more water is lost in sweat and so less will appear in urine
How does exercise affect the volume and concentration of urine change?
More exercise done the more water is lost in sweat and so less will appear in urine
Why is water and salt concentration controlled?
To keep the concentrations the same inside the cells as around them.
How does osmoregulation help the cells?
Protects the cells by stopping too much water from entering or leaving by osmosis.
How is water lost from the body?
Sweat
Water vapour from when we exhale
Why might a kidney not work?
Accident or disease
What are two treatments of kidney failure?
Dialysis
Kidney transplant
What is kidney dialysis?
This the artificial method of filtering the blood to remove toxins and excess substances
What does the dialysis machine act as?
An artificial kidney
What does the kidney dialysis machine do?
To remove most of the urea and maintain the water and salt balance of the blood
Where is the unfiltered blood taken from in dialysis?
Artery in the arm
Where is the filtered blood returned in dialysis?
In the vein
What are the blood and dialysis fluid separated by?
A partially permeable membrane
What does the dialysis fluid contain?
A glucose concentration similar to normal level in blood
A concentration of salts similar to a normal level in blood
No urea
What happens because the dialysis fluid has no urea in it?
A large concentration gradient is formed meaning the urea diffuses across the partially permeable membrane
What happens because the dialysis fluid has a glucose concentration equal to the normal sugar level?
No net movement of glucose
What happens because the dialysis fluid has a salt concentration equal to the blood?
No net movement
How long does dialysis take?
3- 4 Hours
What is added to the machine?
An anticoagulant is added to the blood to prevent the blood from clotting and slowing the flow.
What is kidney transplant?
Implanting a kidney from an organ donor into the patient’s body.
Benefits of kidney transplant
More freedom
Diets are less restrictive
use of dialysis machines is expensive
long term solution
Disadvantages to kidney transplants
Donors don’t have the same antigens on cell surfaces- organ rejection
You have to take immunosuppressant drugs which have side effects
Tissue typing can lead to long waits
There are not enough donors.
What does kidney dialysis remove?
Urea, ammonia, water
Where is the concentration of urine determined?
Medulla
Explain the function of the renal capsule
This is where ultrafiltration occurs. The high blood pressure assists molecules to diffuse into the glomerulus. Protein and blood cells are too big to go through but substances such as glucose are able to pass through
What is the renal capsule?
The glomerulus and Bowman’s capsule
Where does filtration occur?
In the glomerulus
Describe how urea is transported in the blood to the kidney
Dissolved in plasma
What does Bowman’s capsule do?
Collects the filtrate
Where does reabsorption take place?
In the proximal convoluted tubule
Where does reabsorption take place?
In the proximal convoluted tubule
How is the kidney adapted to do this?
blood is passed through at very high pressure
each kidney has many nephrons to filter substances
each kidney has a ureter to remove urine.
Process of ultrafiltration
The blood vessel entering the glomerulus is wider than the one leaving it which creates high pressure in the capillaries of the glomerulus. This forces small molecules into the spaces of the Bowmans capsule. (H2O, salt ions, urea, glucose, amino acids)
What happens in selective reabsorption?
Occurs in the first convoluted tubule. All glucose and amino acids are absorbed back into the blood as well as some water and salts.
What happens loop henle?
Water is reabsorbed. The longer the loop the more water reabsorbed by osmosis.
What effect does ADH have in the kidney?
The hypothalamus detects if the water level is too low. If it is ADH is released form the pituitary gland and travels in blood to the kidney, it makes the 2nd tubule and collecting duct more permeable to water so more water is reabsorbed into the blood and water level is restored. If water level is too high no ADH is released.
What is the role of the kidney?
To remove toxic waste (urea) from the body and regulates the water content of bloods
What does urine contain?
Water, urea and salts
Deamination
removal of nitrogen containing part of amino acids to form urea
excretory organs
lungs, liver, and kidneys
why is excretion important ?
urea and CO 2 are toxic materials, and must be expelled
Excretory products
● Carbon dioxide - is made during respiration. It is transported to the lungs in the blood plasma.Here, it diffuses out of the blood into the air in the alveoli and is breathed out
● Urea is made in the liver from excess amino acids. It is carried to the kidneys in the plasma
where it is filtered out and leaves the body dissolved in urine.
urine
Urea, excess water, and salts
urine is excrete by
kidneys
The volume and concentration of urine is affected by
Water intake, Temperature, Exercise
The liver carries out several functions as part of assimilation
● Stores glycogen (polysaccharide of glucose)
● Uses amino acids to make proteins, such as plasma proteins, e.g. fibrinogen
● Breaks down excess amino acids to urea (deamination)
● Converts fatty acids and glycerol into fat which is stored around the body
● Produces cholesterol from fats
The liver carries out several functions as part of assimilation
● Stores glycogen (polysaccharide of glucose)
● Uses amino acids to make proteins, such as plasma proteins, e.g. fibrinogen
● Breaks down excess amino acids to urea (deamination)
● Converts fatty acids and glycerol into fat which is stored around the body
● Produces cholesterol from fats
Roles of the liver
● Everything under assimilation
● Making bile
● Breaks down hormones after use
● Breaks down harmful substances such as alcohol
Amino acids that cannot be used in the body undergo
deamination .
The kidneys are part of the
urinary system
Blood enters the kidneys through the
renal arteries .
kidney tubules
Inside each kidney is a complex
network of filtering units
The function of the kidney tubules
filter
the blood, remove waste chemicals, and
determine how much water is excreted.
The filtering is carried out in the
cortex
The waste chemicals and excess water are
removed from the body in the urine
which flows from the kidneys down the ureter and is stored in the bladder .
Once inside the kidney, the renal artery branches many times to give
arterioles.
features pf glomerulus
high blood pressure
glomerulus function
ultra filtration
purpose of the proximal convoluted tubule (PCT)
PCT selectively absorbs glucose through active transport, all the needed salts through diffusion, and water by osmosis
purpose of the loop of Henle
absorbs water ( osmosis )
purpose of the digital convoluted tubule ( DCT)
absorbs sodium and potassium ions (Na+,K+)
metabolic wastes
carbon dioxide, uric acid
excess of substances
water
toxic substances
alcohol or nicotine
renal artery con. of urine
highest
renal vein con. of glucose
lowest
urine travels by
peristalisis
Adaptations of cells in the wall of the tubule include:
● Microvilli that increase S.A for absorption
● Plenty of mitochondria provide energy for
active transport
what causes the pressure that causes the blood to be filtered
The blood vessel entering the glomerulus is wider than the one leaving it, so there must be more blood entering the glomerulus than there is leaving it. This causes pressure to increase inside the glomerulus.
Adaptations of cells in the wall of the tubule include:
● Microvilli that increase S.A for absorption
● Plenty of mitochondria provide energy for
active transport
What is a drug?
A drug as any substance taken into the body that modifies or affects chemical reactions in the body
Describe the use of antibiotics for the treatment of bacterial infections.
They slow down the reproduction of bacteria so that the body’s own immune system can destroy them. Antibiotics act on bacteria by preventing cell wall formation, leading to the breakdown of the cell wall and the leakage of cell contents.
NOTE - Antibiotics kill bacteria but not viruses because viruses are not cells.
The use of antibiotics is increasing, antibiotics should not be used unnecessarily and a course of treatment must be completed. What happens if this doesn’t happen?
If not, some of the bacteria population recovers and developed strains of bacteria that are resistant to the antibiotics. If this happens the effectiveness of the antibiotic is reduced and new antibiotics need to be developed.
drug
any substance taken into the body that modifies or affects chemical reactions in the body.
Antibiotics
group of chemicals made by microorganisms that are used to kill pathogens or stop
their growth. These are prescribed by doctors or vets to cure human and animal diseases caused by bacteria or fungi.
Every antibiotic works in one of these two ways:
● A bactericidal antibiotic kills the bacteria by inhibiting the production of peptidoglycan.
➟The cell walls are now weak and burst due to osmotic pressure
● A bacteriostatic stops the bacteria from multiplying
how do bacteria develop resistance against antibiotics
This is formed by natural
selection over time as these bacteria develop a mutation. The
The development of resistant bacteria can be
minimized by:
● Prescribing antibiotics only when necessary
● Ensuring that people complete their courses
● Not overusing with animals
Antibiotics do not work against
viruses. Viruses are not cells, which means they do not carry out their metabolism but rely entirely on the cells of their host. To control viruses we would have to inhibit our metabolism, and this is not possible.
powerful depressant drugs
examples are alcohol and heroin
-The drugs greatly reduce one’s reaction
time and self-control
what happens when someone is addicted to depressant drugs
When someone is addicted to a drug, the body gets used to the drug, and it
causes pain. Addicts have to take more to reduce the pain. This is how tolerance is developed, and more needs to be taken each time to reduce the pain
mode of transmission for HIV
and Hepatitis.
sharing of needles
Social implications once addicted
● The addict only thinks about his/her next dose
● becomes difficult to keep a job
● Addicts shun friends and family and hang out only with other addicts
● Crime
● Road accidents
A user who stops taking heroin experiences
withdrawal symptoms
withdrawal symptoms
which include sleeplessness, hallucinations, cramps, sweating, vomiting, and nausea. Many drug addicts go through rehabilitation which is often the only way to overcome the habit.
The liver is the organ that breaks down
alcohol and other toxic substances
Excessive alcohol consumption can cause liver damage such as :
● Cirrhosis - the permanent scarring of liver tissue
● Alcoholic hepatitis - inflammation
● Stomach ulcers
● Heart disease
● Brain damage
Nicotine
a drug that reacts with nerve cells at synapses. It is a stimulant . Nicotine makes the heart
beat faster and narrows the arterioles, which increases blood pressure.
Tar
the sticky black material that collects in the lung as smoke cools. It irritates the airways and
stimulates them to produce more mucus. Cilia are damaged, and mucus remains in the airways, therefore narrowing them. Chemicals in tar are carcinogenic
Carbon monoxide (CO)
poisonous gas which combines with hemoglobin, reducing the volume of
oxygen that blood can carry by around 10%.
Diseases caused by smoking
Chronic obstructive pulmonary disease (COPD) is the term given for several lung diseases such as bronchitis and emphysema.
Bronchitis
Accumulation of mucus, which contains dust and dirt (including pathogens) in the bronchi allows bacteria to replicate. The body sends phagocytes to the bronchi. Large amounts of phlegm are produced which people attempt to cough up. This condition is known as chronic bronchitis.
Emphysema
When bacteria, tar, and particles reach the alveoli, phagocytic WBCs digest a pathway through the wall to get them. Eventually, the walls of the alveoli are weakened so they break down and burst. This reduces the surface area for gas exchange. This condition is known as emphysema
Lung cancer
Carcinogens in tar promote changes in DNA cells on the lining of the airways. The cells grow and divide uncontrollably, eventually becoming a tumor. If undiscovered, it may occupy a large area of the lung, blocking airways and blood vessels. The tumor may break off and spread to other organs. Graphs that show deaths from lung diseases show that the increased popularity of smoking has led to lung cancer,
while other diseases have been reduced due to improvements in medical care.
Heart disease
Tobacco smoke increases the chances of fat build-up in the arteries of the heart. The chances of CHD are also increased.
anabolic steroids
similar to the male sex hormone testosterone. They work by mimicking the protein-building effects of the hormone.
anabolic steroids cause
● Muscle growth
● Increased strength
● Increases endurance
Long-term effects of anabolic steroids include:
● In men
○ Aggression
○ Impotence
○ Baldness
○ Kidney and liver damage
○ Development of breasts
● In women
○ Male features
○ Facial and body hair
○ Irregular periods
Carbon dioxide is excreted through
The lungs
The kidneys excrete
urea and excess
water and ions
The function of the glomerulus is
ultrafiltration from the blood of water, glucose, urea and
ions.
The function of the nephron
reabsorption of all the glucose, some of the ions and
most of the water back into the blood.
Urine contains
urea, excess water and excess ions.
Role of liver
the assimilation of amino acids by converting them to proteins.
Urea is formed in the
liver from excess amino acids.
Deamination
removal of the nitrogen-containing part of amino acids to form urea
Urea is toxic
it can lower the pH of the body and denature the enzyme. Denaturing
of enzyme might lead to death of the individual therefore excretion of urea is
important.
Drug
any substance taken into the body that modifies or affects chemical reactions
in the body
Antibiotics are used to
treat bacterial infections.
Some bacteria are resistant to antibiotics which
the effectiveness of
antibiotics.
Antibiotics kill bacteria but do not affect
viruses
If antibiotics are taken only when essential they can
limit the development of resistant bacteria.
