11. Animal Physiology : 11.3 Kidneys Flashcards
What do metabolic processes produce?
Waste, breakdown of products of protein digestion
Detoxification products from your liver
Metabolic waste products
List three main forms of excreted nitrogenous waste in animals.
Urea
Uric acid
Ammonia
What happens to ammonia in humans and marine animals?
- In humans, ammonia is immediately converted into urea
- Fish and aquatic invertebrates have mechanisms that allow the fast disposal of ammonia before it builds up in body tissues
Is uric acid soluble in water?
No
What is an advantage of uric acid?
The process of converting ammonia to uric acid requires a lot of energy but it conserves water.
How can animals be classified as osmoredulators or osmoconformers?
Depending on the strategies used to achieve water balance
Define osmoregulator.
Organisms that are able to keep or regulate the solute concentration of their body fluids above or below that of their external environment.
- Have the ability to control the osmolarity of tissues with narrow limits
- Changes in environment does not have effect on them
Define osmoconformers.
Marine organisms that actively or passively maintain an internal environment that is isosmotic to their external environment.
- Cannot regulate the solutes of their body fluids at a concentration
- solute concentration of their body fluid is the same as the solute concentration of the external medium in which the organisms live
What are the causes of over-hydration?
Causes of over hydration:
- When the normal balance of electrolytes in body exceeds limit
- Diseases that encourage water accumulation in the body
List the consequences of overhydration.
Consequences:
- Swelling up of body cells
- Swollen cells in brain lead to intracranial pressure
- As the pressure increases, the blood flow to the brain can be interrupted, leading to dysfunction in the central nervous system, seizures, coma or even death
- Nausea
- Vomiting
- Changes in mental state
- Muscle weakness or cramps
- Unconsciousness
What is dehydration caused by?
Caused by: Vigorous exercise Intense diarrhoea Vomiting Fever Excessive sweating Not taking in enough fluids
List the consequences of dehydration.
Consequences of dehydration:
- Dark urine : more urobilin or urochrome
- More elastic skin
- Heart rate and breathing rate increases
- Blood pressure decreases because there is a decrease in blood volume
- Affect the ability to sweat and may cause damage to brain
- Death
What is the role of kidneys in removing nitrogenous wastes?
- Filter your blood to rid of nitrogenous waste
- Regulate osmolarity
- Produce urine
List removed compounds in blood that is going out.
Removed compounds in blood: drugs, salt, water, toxins and nitrogenous wastes
How does blood flow through the kidney?
Blood goes in through renal artery and goes out through renal vein, so concentrations higher in artery than in vein
What is the blood going in consists of?
High concentrations of : Drugs Salt Oxygen Water Toxins glucose
What is the blood going out consists of?
High concentrations of :
Carbon dioxide
URINE
Define a nephron.
A long tube which starts at the bowman’s capsule and ends at the collecting duct, which drains in the renal pelvis.
What is the structure and function of a bowman’s capsule?
Highly porous wall which collects the filtrate
What is the structure and function of a glomerulus?
Knot-like capillary bed where high-pressure ultrafiltration takes place.
What is the structure and function of a proximal convoluted tubule?
Twisted section of the nephron where water, nutrients and salts are reabsorbed back into the blood; contains many mitochondria and microvilli
What is the structure and function of a loop of henle?
Hairpin shaped tube with a descending and ascending limb; water and salt reabsorption takes place here
What is the structure and function of a distal convoluted tubule?
Another twisted section of the nephron, where water and salts are reabsorbed back into the blood; also contains many mitochondria and microvilli
What is the structure and function of a collecting duct?
A slightly wider tube that carries the filtrate to the renal pelvis
What is the structure and function of a afferent arteriole?
Brings blood from the renal artery
What is the structure and function of a efferent arteriole?
A narrow blood vessel that restricts blood flow, which helps to generate the pressure needed for filtration
What is the structure and function of a vasa recta?
An unbranched capillary shaped like the loop of Henle, with the descending limb bringing blood deep into the medulla.
What are podocytes? What does it do?
- cells of the inner wall of bowman’s capsule
- have many extensions that fold around blood capillary forming a network of filtration silts that hold back the blood cells during ultrafiltration with the help of a glomerular basement membrane.
Where do ultrafiltration occur at?
Fenestrations that are covered on the outside by a basement membrane of glycoproteins
Define ultrafiltration.
A process that is driven by the high pressure in the capillaries.
How do ultrafiltration occur?
- fenestrations allow blood to flow out
- basement membrane acts like a sieve during the process and stop blood cells and large proteins
What determines unusual high capillary presssure?
Short, large diameter afferent arterioles conveying blood at high arterial pressure directly to the glomerular capillaries
What are the three aspects of the reabsorption process?
SUMMARIES
What happens in the descending loop of henle?
- water moves out into medullary interstitial fluid by osmosis
- permeable to sodium ions
- osmolarity of filtrate increase as water lost
What occurs in the ascending loop of henle?
- impermeable to water but permeable for Na+
- moves out of filtrate into medullary interstitial fluid
- salts remain near loop to help maintain concentration gradient
- absorption of Na+ into vasa recta by active transport
- less concentrated fluid leaves
What happens in the concentration gradient in the medulla?
- Maintained by the vasa recta countercurrent exchange
- No direct exchange between the filtrate and the blood and the substances pass through the interstitial region of the medulla
What makes the medullary fluid hypertonic?
as Na+ are pumped out of the ascending loop of Henle, the interstitial fluid in the medulla becomes hypertonic
How does length correlate with the need for water conservation in animals?
Animals living in the desert have longer loops of Henle = more water reabsorption
What does the antidiuretic hormone do?
Increases the permeability of these structures to water, more water absorbed and decreased solute concentration
Secreted by the posterior lobe of the pituitary gland.
What are aquaporins and what is their function?
- Membrane proteins that form water channels allowing water to pass through the cell membrane
- The insertion of aquaporins to the membrane makes the membrane permeable to water.
- Water moves through the channels.
- Then passes into the circulation across the basolateral membrane
What are the causes of kidney failure?
Causes of kidney failure:
Diabetes
Hypertension
Untreated urinary tract infections
Explain the treatment of kidney failure by haemodialysis.
Haemodialysis: a process that uses dialysis tubing to remove wastes from the blood and to restore proper balance of electrolytes in the blood and eliminate extra fluid from the body.
During haemodialysis, blood cells, proteins and other important molecules remain in your blood because they are too big to pass through the membrane. Smaller waste products in the blood, such as urea, creatinine, potassium and extra fluid, pass through the membrane and are washed away in the dialysate.
What is urine analysed for ?
Used to detect drug abuse
Kidney failure
Diabetes
Kidney function
What do the urine tests indicate?
- tests presence of cells and range of compounds
- each indicate a particular disorder of kidney
Give three examples of how urine tests indicate a particular disorder of the kidney.
- too much glucose = diabetes
- Presence of blood or leukocytes may indicates an infection or a kidney tumour.
- Too much protein = ultrafiltration process may be failing , indication of advanced and prolonged hypertension
What is the haemolymph?
a fluid that combines the characteristics of blood and interstitial fluid. Their internal organs are bathed in this liquid.
What is the solution to insects lacking a closed circulatory system?
The haemolymph needs to be cleansed but insects lack a closed circulatory system that could cleanse the circulating haemolymph.
So they have tubules that branch off from their hind gut
What do the tubules that branch off from the hind gut of insects do?
- Absorb solutes, water, waste from the surrounding haemolymph
- Carries out osmoregulation and removal of nitrogenous wastes
- Hind gut reabsorbs water and minerals
- Convert ammonia to uric acid and it is the semi-solid in their faeces
Explain how ADH controls reabsorption of water in the collecting duct.
IDK GOSH
