Kidney Flashcards
(62 cards)
What is deamination?
Surplus amino acids that are not used for protein synthesis cannot be stored in the body and are deaminated in the liver= the removal of the amino group to leave ammonia and pyruvic acid. The ammonia is converted to urea in the liver. The rest of the amino acid can be used in respiration as a source of energy or converted into fat and stored.
What is nitrogenous waste?
Waste products containing nitrogen, primarily formed from the breakdown of proteins and nucleic acids. The type an organism produces depends on the environment it inhabit. Some animals excrete their ammonia directly, others first convert it to less toxic wastes, such as urea or uric acid.
What is ammonia and what happens to it in different organisms?
Ammonia molecules are small, very toxic and soluble. Most aquatic animals excrete ammonia. In soft-bodied invertebrates, ammonia diffuses across the whole body surface into the surrounding water. In freshwater fish, most of the ammonia is lost as ammonium ions across the epithelium of the gills, with kidneys playing only a minor role in excretion of nitrogenous waste.
What is uric acid?
Thousands of times less soluble in water than either ammonia or urea and is excreted as a precipitate after nearly all the water has been reabsorbed from the urine. Land snails, insects, birds, and some reptiles excrete uric acid as the major nitrogenous waste. In birds and reptiles, the paste-like urine is eliminated along with faeces from the intestine.
What do animals do with Urea?
-Most terrestrial animals convert the ammonia to urea and excrete this.
-A terrestrial animal would have produced lots of urine to get rid of ammonia, because a compound so toxic could only be transported and excreted in a very dilute solution.
-Urea can be transported in a much more concentrated form because it is about 100,000 times less toxic than ammonia.
-Urea excretion enables the animal to sacrifice less water to discard it’s nitrogenous waste, an important adaptation for living on land.
What are the different types of nitrogenous waste?
Urea, uric acid, ammonia, creatinine.
Uric acid and urea represent two different adaptations that enable terrestrial animals to excrete nitrogenous waste with a minimal loss of water.
What is the structure of kidneys?
Each kidney contains approximately 1 million tiny tubules called nephrons. A nephron ( individual blood filtering unit) begins with a cup shaped structure called a Bowman’s capsule followed by the proximal concluded tubule (PCT) then loop of Henle which leads into the distal convoluted tubule (DCT) and finally joins to a collecting duct. Blood flowing through an afferent arterials which has branched from the renal artery forms a capillary network called the glomerulus within the bowman’s capsule.
What is homeostasis?
The maintenance of a constant internal environment by an organism.
It helps maintain optimal conditions for cellular reactions, and gives organisms independence from the external environment whilst still existing in it.
Describe homeostasis and kidney function:
- Stimulus produces change in variable.
- Change detected by receptors.
- Input: info sent along afferent pathway to control centre.
- Output: info sent along efferent pathway to effector.
- Response of effector feeds back to influence magnitude of stimulus and return variable to homeostasis.
What is homeostasis maintained by?
Maintained through a combination of nervous and hormonal mechanisms, often by negative feedback: whenever a factor moves away from the ideal/norm, a set of processes moves it back towards normal again.
What are hormones?
Molecules that are released by endocrine glands directly into the blood that travel to a target organ to produce an effect.
When is an endocrine gland?
A duct-less gland that secretes hormones directly into the blood.
What are the functions of the kidney?
-Filter the blood to remove nitrogenous metabolic waste to produce urine.
-Homeostatic function of osmoregulation (control of water and solute composition of body fluid (blood)).
What is an exocrine gland?
Secretes substances into a duct (=tube lined with epithelial cells and conveying secretion).
What is the nephron function?
-Blood in the vasa recta (a capillary network surrounding the loop of Henle) delivers nutrients and oxygen to the cells of nephrons.
-Carries waste and mineral ions reabsorbed from the kidneys.
Label human urinary system:
Answer in booklet.
Label the internal structure of a kidney:
Answer in booklet.
Label a nephron:
Answer in booklet.
How do you know if it’s a collecting duct on a microscope slide?
You can see the individual membranes.
How do you know if it’s a PCT on a microscope slide?
Have brush border.
How do you know if it’s a DCT on a microscope slide?
Has no brush border.
Why is the blood pressure in the capillaries high?
The efferent arteriole has a narrower lumen than the afferent arteriole so will cause an increase in pressure.
What is Ultrafiltration?
Filtering blood at high pressure, to remove urea. It happens in the glomerulus/Bowman’s capsule.
What materials pass into the Bowman’s capsule?
All small molecules, water, salts, amino acids, urea, glucose.
