HOMEOSTASIS AND EXCERTION Flashcards
Maintaining constant conditions in the body. maintaining a constant internal environment
homeostasis
removal from the body of the waste products of the metapolism
excretion
Watery solution of salts, glucose and other solutes. surrounds all the cells of the body forming a pathway for the transfer of nutrients between the blood and the cells.
tissue fluid
Salts in urine or in the blood are present as ……….
ions
Na+, K+, Cl+ NH4+…..
How the tissue fluid is formed?
by leakage from blood capillaries.
Why is Homeostasis important?
because cells will only function properly if they are bathed in a tissue fluid which provides them with their optimum conditions.
sort the following urine substance from highest amount to lowest
urea
ammonia
other nitrogenous waste
sodium
potassium
phosphate
urea
sodium
phosphate
other nitrogenous waste
potassium
ammonia
True or false
all animals have to excrete a nitrogenous waste product
True
How urea is formed in the body?
Urea is produced in the liver
It is produced from excess amino acids
If more protein is eaten than is required, the excess cannot be stored in the body
However, the amino acids within the protein can still provide useful energy
amino acids in broken down into carbohydrate (stored in liver as glycogen), and ammonia. Ammonia is combined with carbon dioxide to form urea. passes into the bloodsttream and filtered out by the kidney
Many excretory products are formed in humans, with two in particular (…………………and ……………) being formed in much greater quantities than others
Many excretory products are formed in humans, with two in particular (carbon dioxide and urea) being formed in much greater quantities than others
Urea is produced in the ………….
liver
Water content (of an individual cell or of the body fluids of an organism)
Temperature
pH
Blood pressure
Blood glucose concentration
Two examples of homeostasis in humans include the ………… and the control of ……………..
Two examples of homeostasis in humans include the control of body temperature and the control of body water content
Why the waste products are dangerous?
- waste products can have toxic effects if they are allowed to reach high concentrations
- Carbon dioxide 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
- tissue fluids can become more concentrated due to higher amounts of waste products, and cells will loose water by osmosis and become dehydrated.
- if the tissue fluid is too dilute the cells will swell up with water.
Organs of Excretion are………..
Kidneys
Skin
Lungs
•Metabolic waste is any waste that has been made from a ……………
•Metabolic waste is any waste that has been made from a chemical reaction e.g. carbon dioxide from respiration.
•Excretion occurs in all living things.
Can you think of an example in plants?
In photosynthesis plants release
oxygen
The kidneys remove …..from the blood.
The skin removes …………and …….. by sweating
The lungs remove ………… from the blood.
The kidneys remove urea from the blood.
The skin removes water and salt by sweating
The lungs remove carbon dioxide from the blood.
label the following diagram
State the function of each
Renal Vein
Renal Artery
Bladder
Urethra
Ureter
Kidney
Renal Vein : removes cleaned blood from the kidney
Renal Artery: carries blood with high concentration of urea
Bladder: Stores urine
Urethra: removes urine from the body
Ureter: Carries urine to the bladder
Kidney: filters urea and other waste chemicals out of the blood
label the diagram
urea formula
CH₄N₂O
label the diagram
explain the processes of ultrafiltration
Small vessels in the glomerulus create a resistance to flow and this creates pressure. The pressure created causes smaller molecules to leave the blood. These smaller molecules include: Water, minerals, glucose and urea
•explain the processes of selective reabsorption
Describe how a healthy kidney produces urine.
Protein is not found in the urine of a healthy person.
Explain why.
Haemoglobin is not found in the urine of a healthy person, but haemoglobin can be
found in the urine of a person with haemolytic anaemia.
Explain why.
label the diagram
comes from the aorta and delivers oxygenated blood to the kidney
renal artery
delivers the deoxygenated blood from the kidney to the vena cava
renal vein
blood delivered from the kidney to the vena cava is
oxygenated
deoxygenated
deoxygenated
aorta delivers blood to the kidney
is the blood
oxygenated or deoxygenated ?
oxygenated
tube carrying urine from the kidney to the bladder
ureter
main nutrogenous excretory product of mammals
urea
tube carrying urine from the bladder to the outside of the body
urethra
The functional unit of the kidney
nephron
two important functions of the kidneys
- They regulate the water content of the blood
- They excrete the toxic waste products of metabolism such as urea
nephrons are blood vessels
true / false
false
they are microscopic tubes
structure consisting of a hollow cup of cells at the start of a kidney tubule. the site of ultrafiltration
Bowman’s capsule
fluid that passes through the Bowman’s capsule at the start of a kidney tubule
glomerular filtrate
ball of capillaries surrounded by the Bowman’s capsule at the start of a kidney tubule
glomerulus
filtration of the blood taking place in the Bowman’s capsule of kidney tubule, where the filter separates different-sized molecules under pressure
ultrafiltration
u-shaped part in the middle of a kidney tubule. Involved in concentrating the fluid in the tubule.
Loop of Henle
middle part of the kidney containing blood vessels, loops of Henle and collecting duct.
medulla of kidney
99% of the glomerular filtrate is reabsorbed back into the blood
True/ False
True
outer part of the kidney containing kidney tubules and blood vessels
cortex of kidney
membrane in the wall of the Bowman’s capsule that acts as a molecular filter during ultrafiltration in the kidney
basement membrane
a process taking place in a kidney tubule whereby different amounts of substances are absorbed from the filtrate into the blood.
selective reabsoption
desert animals are able to conserve water in their bodies explain why.
desert animals have many long loops os Henle in the kidneys. Loops of Henle are responsible to make more concentrated urin by having more water to be reabsorbed into the blood.
and the longer the loops of Henle the more concentrated urin the animal will have preserving more water in the body.
funnel-like part of the kidney leading to the ureter
pelvis of kidney
Nephrons start in the ….. of the kidney, loop down into the …..and back up to the …..
The contents of the nephrons drain into the ….. and the urine collects there before it flows into the …..to be carried to the …..for storage
Nephrons start in the cortex of the kidney, loop down into the medulla and back up to the cortex
The contents of the nephrons drain into the renal pelvis and the urine collects there before it flows into the ureter to be carried to the bladder for storage
Where does the water get reabsorbed in the kidney?
Loop of Henle and the collecting duct
Where do salts get reabsorbed?
loop of Henle
Lungs excretory products
Co2 and H2o
Urea is _____.
The product of the metabolism of amino acids
Ultrafiltration is
The movement of small molecules (salt, water, urea) from the blood into the kidney under pressure
Why kidney must absorb some of the molecules
For the process of respiration
afferent arteriole
carries blood to the glomerulus
efferent arteriole
carries blood away from the glomerulus
Process of removing waste products when kidneys aren’t fully functioning
dialysis
All filtered then all reabsorbed for respiration
Glucose
Not filtered due to large complex molecules
Proteins
All filtered and most in urine as toxic
Urea
Area where ureter joins kidney
Pelvis
. Urine is carried from the kidneys to the bladder by two thin tubes called:
Ureters
Tubulars
Capillaries
urethra
Ureters
. Identify Letter A
Bowman’s Capsule
Afferent Arteriole
Efferent Arteriole
Glomerulus
Bowman’s capsule
Identify Letter D
Glomerulus
identify letter J
Distal Convoluted Tubule
Collecting Duct
Peritubular Capillaries
Proximal Convoluted Tubule
collecting duct
Identify Letter H
Ureter
Renal Capsule
Renal Coretx
Renal Medulla
Renal Medulla
In a normal human, which substance should be 100% reabsorbed, meaning that it should not be present in the urine
answer choices
glucose
salt
water
urea
glucose
To enter the Bowman’s capsule, fluid from the blood crosses (in the correct order)…
- epithelium of Bowman’s capsule, basement membrane, capillary endothelium
- capillary endothelium, epithelium of Bowman’s capsule, basement membrane
- arteriole endothelium, basement membrane, epithelium of Bowman’s capsule
- capillary endothelium, basement membrane, epithelium of Bowman’s capsule
An object which’s permeability changes to water due the response from ADH
the collecting tube
What are the left over substances after ultrafiltration
Red blood cells, white blood cells and proteins are too large to leave and they remain in the blood
What is the name given to the filtrate that is filtred out during ultrafiltration? And what percentage of the liquid is reabsorbed back into the blood?
The glomerular filtrate
99%
What is left in the distal convoluted tubule after the glomerular filtrate has passed through the proximal tubule and the Loop of Henle?
- Urea and slats in a concentrated solution
- Glucose
- water and salts
Urea and slats in a concentrated solution
What is the name of the type of absorption featured after ultrafiltration? and why is it called this?
Selective re-absorbtion because only water, glucose and some ions are reabsorbed
regulation of salt and water balance in the body
osmoregulation
What hormone is used to alter the water levels in the body?
ADH (Anti-Diuretic Hormone)
Describe the 3 stages of the process of osmoregulation?
Stage 1: Receptors in the hypothalamus detect changes in the concentration of water in the blood
Stage 2: If water levels decrease then ADH is released from the pituitary gland. However, if water levels increase then less ADH will be released.
Stage 3: ADH causes the collecting duct to become more permeable and therefore more water passes from the kidneys into the bloodstream.
Th reduction of ADH causes the kidneys to reabsorb less water as the collecting duct becomes less permeable to water and therefore more water exits into the urine
What 4 organs are involved in the urinary system?
Kidney
Ureter
Bladder
Urethra
What 2 things happen to urea during it being excreted?
It is filtered out from the kidneys as it is toxic
Excreted as urine when mixed with water
Where is urea made? What is urea made from?What is it an example of?
Made in the liver and is made out of broken down excess amino-acids. It’s an example of nitrogenous waste
what is the difference between Excretion and Egestion
Excretion is he removal of metabolic waste product from the body.
Egestion is the removal of undigested solid waste (faeces) out of the anus
What is the function of the kindney’s in the urinary system?
They act as an excretory and homeostatic organ which filters unwanted substances out of the blood
Metabolic waste in animals:
CO2 and urea
CO₂, H₂O and urea
H2O and urea
CO₂, H₂O and urea
Metabolic waste in plants:
CO₂ and O₂
Where does urea come from?
Breaking down excess proteins
Liver has a role in excretion
True / False
True
liver breaks amino acids down into 2 parts, one is urea.
the volume of water reabsorbed depends on
A.The concentration of urine
B. the body’s water content
C. the temperature of the external environment
B. the body’s water content
what is Homeostasis?
The maintenance of a constant internal environment
What does the Proximal Convoluted Tubule in the Nephron do?
A.Selective reabsorbtion which reabsorbs some salts through diffusion, most water through osmosis and all glucose
B. Ultrafiltration which filters out small molecules from the blood
C. Hold back blood cells and large molecules such as proteins.
A. Facilitates Selective reabsorbtion which reabsorbs some salts through diffusion, most water through osmosis and all glucose
Why blood cells and protein molecules are not filtered during ultrafiltration?
ultrafiltraiton happens in nephrones through 3 layers ( capillary wall , wall of the Bowman’s capsule and the basement membrane) these layers act as a filter and doesn’t allow large cells such as red blood cells to pass through, and only water, ions, and small molecules such as glucose and urea are allowed to pass through making a fluid called glomerular filtrate.
basement membrane is made of cells
True /Flase
False
Ball of capillaries found in Bowman’s capsule
Glomerulus
The process that controls osmoregulation. If the water content gets too high or too low, this process will bring the water content back to normal.
Negative feedback
What type of blood vessels are found in the glomerulus?
capillaries
Oryx and humans can control water loss by making their urine very concentrated. Describe how this is done.
If the water content of the blood is too low, ADH is released from the pituitary gland into the bloodstream, causing the kidney to reabsorb more water, and produce a more concentrated, smaller volume of urine.
If water content too high, ADH is not produced, so less water is reabsorbed by kidney, producing a more dilute, larger volume of urine
Explain why the body does not excrete glucose and how this is achieved by the kidney.
glucose is needed for respiration and energy / ATP
this is achieved by a process called selective reabsorbtion which happens in the proximal convoluted tubule , it reabsorb glucose back into blood by active transport
How Glucose and Sodium ions get reabsorbed in the tubule?
A.by Diffusion
B. by Active transport
C. by filtration
B. Active transport
act as a fine molecular filter in the process of ultrafiltraiton
basement membrane
What causes smaller molecules being carried in the blood to be forced out of the capillaries and into the Bowman’s capsule?
small substances such as urea are forced out of the blood during filtration as a result of high-pressure mass flow, they don’t diffuse out of the blood.
why blood in the glomerulus is at high pressure?
- blood is coming to the kidney directly from the renal artery which is connected to the aorta and it is at high pressure already.
- The capillaries get narrower as they get further into the glomerulus which increases the pressure on the blood moving through them
what is the difference between the cells of the Bowman’s capsule , cells of glomerulus capillaries and the basement membrane?
Cells of the Bowman’s capsule and cells of glomerulus capillaries have gaps between them making them much more permeable. ( coarse filter)
basemenet membrane is not made of not cells and do not have gaps so they act as a fine molecular filter
Explain the stages of cxcretion in the nephron
stage 1: Unfiltered blood enters the kidney via the renal artery branching into smaller arteries .
stage 2: Artery leads to supplying the capillaries of the glomerulus and as pressure is high all substances forced into Bowman’s capsule through the capillary walls allowing water , ions, glucose and urea to pass through (glomerular filtrate) , large molecules such as proteins and blood cells to remain in the blood (ultrafiltration)
stage 3: proximal convoluted tubule reabsorbe all glucose by active transport (selective reabsorption)
stage 4: loop of Henle reabsorbs salts by diffusion and water by osmosis
stage 5: in the collecting duct further reabsorbtion of water by osmoregulation and adh
stage 6: several nephrones join up to form a collecting ducts where urine passes out into the pelvis then to the ureter which leads to bladder where fluid is stored for excretion finally urine moves via urethra outisde the body
Reabsorption of glucose is only found in only found in the proximal convoluted tubule and cannot take place anywhere else in the nephron
true / false
true
External question
why do you thing 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?
because people with diabetes have glucose levels often very high, meaning that not all of the glucose filtered out can be reabsorbed into the blood in the proximal convoluted tubule therefore it continues in the filtrate and ends up in the urine :)
samples were taken from the nephrone for analysis
what substances can you find in sample 3?
A. Protein , Glucose , sodium ions, urea
B. Protein , Glucose
C. sodium ions, urea
C. sodium ions, urea
ultrafiltration is the process happnes in nephrones in which small substances such as urea, water and glucose are diffused out of the blood
True / False
False
substances are forced out the blood as a result of high-pressure mass flow, they don’t diffuse out of the blood.
samples were taken from the nephrone for analysis
what substances can you find in sample 1?
A. Protein , Glucose , sodium ions, urea
B. Protein , Glucose
C. sodium ions, urea
A. Protein , Glucose , sodium ions, urea
samples were taken from the nephrone for analysis
what substances can you find in sample 2?
A. Protein , Glucose , sodium ions, urea
B. Protein , Glucose
C. Glucose , sodium ions, urea
C. Glucose , sodium ions, urea
what is the flow rate of sample 4 ? explain why?
100%
1%
50%
25%
1%
this is because 99% of the water has been reabsorbed.
samples were taken from the nephrone for analysis
what substances can you find in sample 4?
A. Protein , Glucose , sodium ions, urea
B. Protein , Glucose
C. sodium ions, urea
C. sodium ions, urea
samples were taken from the nephrone for analysis
comparing concentration of Na+ in both sample 1 and 4
A. Na+ in sample 1 is twice as concentrated as in smaple 4
B. Na+ in sample 4 is twice as concentrated as in smaple 1
C. Na+ is at the same concentration in both samples
B. Na+ in sample 4 is twice as concentrated as in smaple 1
comparing sample 1 and sample 2
A. all substances are at the same concentration in both samples
B. Protein concentration is zero at sample 2 and other substances are at the same concentration in both samples .
C. Protein concentraiton and glucose concentration is zero at sample 2 and other substances are at the same concentration in both samples.
B. Protein concentration is zero at sample 2 and other substances are at the same concentration in both samples .
The human kidney removes urea from the blood.
Name two other substances the kidney removes from the blood.
water
sodium ions
in the end of the first coiled tubule the urea concentration is
three times than the concentraiton in capsule space is it
True / False?
explain why
True
because water was reabsorbed
in sample 2 and 3 Na+ concentration is not chaged explain why
part of Na+ has been reabsorbed
How is the glomerulus adapted to its function?
The renal artery is highly branched in the glomerulus forming a knot of a very small capillaries and this provides a larger surface area for blood to flow in the kidney for filtration.
the capillaries become narrower in the glomerulus this builds up higher pressure necessary for ultra-filtration.
Explain why you are thirsty after exercise
excerecise causes loss of water in the sweat which changes the water potential of the blood . osmoreceptors are specialised cells that respond to changes in the water potential of the blood.
Stimulation of osmoreceptors can lead to secretion of the hormone ADH in the pituitary gland
- Permeability of membrane / cells (to water) is increased;
- More water absorbed from / leaves distal tubule / collecting duct;
- Smaller volume of urine is excreted.
- Urine becomes more concentrated.
- Osmoreceptors which cause the release of ADH also send impulses to the thirst centre of the brain to encourage the individual to drink more water!
write short description of action of ADH
and explain how this is an example of negaive feedback
If the water content of the blood is too low, ADH is released from the pituitary gland into the bloodstream, causing the kidney to reabsorb more water, and produce a more concentrated, smaller volume of urine.
If water content too high, ADH is not produced, so less water is reabsorbed by kidney, producing a more dilute, larger volume of urine.
give example of homeostatsis
control of body temperature and the control of body water content
how homeostasis is maintained
Negative feed-back loops
Explain how the kidney is adapted to its function
Adaptations for ultrafiltration
It has a permeable Bowman’s capsule that only allows substances such as water, glucose, urea and salt ions to pass through but prevents the passage of proteins and blood cells.
The renal artery is highly branched forming small capillaries in the glomerulus and this provides a larger surface area for blood to flow in the kidney for filtration.
the capillaries get narrowers in the glomerulus and this builds up higher pressure necessary for ultra-filtration.
Adaptations for reabsorption
Kidney tubules are long and coiled and this provides a larger surface area for reabsorption and more time is allowed for reabsorption of the useful substances. Also the first coiled tubule (proximal convoluted tubule) can allow reabsorption of glucose by active reabsorption and glucose is needed for the body respiration.
The loop of henle is U -shaped and this the efficient reabsorption of water and salts.
