Chapter 5: Communication, Homeostasis, Excretion - Kidney (complete) Flashcards
Revise structure and function of the kidney
Define excretion
Removal of metabolic waste from the body - products of chemical reactions
What are excreted substances and what are the organs responsible?
Urea and Carbon dioxide - Lungs and kidneys
What is carbonic acid and how is it made?
Alters PH of blood and interferes with cellular processes - made by dissociation of carbon dioxide
What’s the Ornithine cycle?
Liver deaminates excess amino acids, forming ammonia - ammonia converted to urea (less toxic and less soluble) to be excreted
What’s the formula equation for the conversion of ammonia to urea?
2NH3 + CO2 -> CO(NH2)2 + H2O
Where is the glomerulus located in the kidney?
In the Nephron (the functional unit of the kidney)
What does the fibrous capsule do?
Protects the kidney
What is the medulla in the kidney made up of?
Segments called pyramids
How are podocytes adapted for their function?
foot like projections - allow filtration
How have the cells of the PCT adapted for their function?
Microvilli and mitochondria - increase surface area
What does it mean if glucose appears in the urine?
Diabetes type 1 - the glomerulus filters more than the PCT can reabsorb
OR
damage to the kidney
What is the process of Ultrafiltration into the Bowman’s capsule?
1) Blood enters glomerulus via afferent arteriole - build up of pressure in capillaries that make up glomerulus
2) Increase in hydrostatic pressure is enough to force into lumen of Bowman’s capsule
What does PCT stand for and what process occurs within it?
Proximal convoluted tubule: selective reabsorption
What’s the concentration of RBC and WBC in the glomerular filtrate and why?
0 because the membrane has tiny pores for smaller substances
What is found in glomerular filtrate?
Water, urea, glucose, ions, amino acids
How is glucose reabsorbed in the PCT?
Initially by passive diffusion, then active transport ensures all glucose is reabsorbed - needs cotransporter molecules and sodium
What does the loop of henle do?
Creates a high concentration of salts in the medulla so water can be reabsorbed from the collecting duct and produce hypertonic or concentrated urine
In the Nephron, what is the order that the filtrate goes through?
afferent arteriole, Bowman’s capsule, glomerulus, PCT, Loop of henle, distal tubule, collecting duct
Compare the structure of the descending and ascending limbs
Descending: Narrow thin walls, highly permeable to water
Ascending: Wider thick walls, impermeable to water
Describe the loop of henle process
Na+ and Cl- ions pumped out, lowers water potential of medulla - draws water out of descending limb as ascending limb reaches minimum water potential (at the bottom), filtrate flows up ascending limb - filtrates water potential increases as ions pumped out
What happens in the distal convoluted tubule?
Na+ actively pumped out and k+ actively pumped in, this fine tunes the PH of blood by selective reabsorption of some minerals and is connected to the collecting duct
What are two causes of kidney failure?
- High blood pressure - damage epithelial cells and basement membrane
- Polycystic kidney disease - healthy tissue replaced by fluid filled cysts - put pressure on the kidney
What are two symptoms of kidney failure?
- Protein in urine - damage to the basement membrane allowed large protein molecules to pass through
- Blood in the urine - shows that the filter is damaged
What are 4 effects of kidney failure?
loss of electrolyte balance - no excess ions, osmotic balances, weakened bones due to loss of calcium, build up of urea
How do you measure kidney function?
Glomerular filtration rate- rate at which blood is filtered: Creatinine level will increase if there is a problem
5 things to consider when measuring kidney function
Age, sex, ethnicity, diet, exercise
What is osmoregulation?
The maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.
NEGATIVE FEEDBACK: how do the osmoreceptors and effectors work in osmoregulation?
Osmoreceptors in hypothalamus monitor the water content of blood
Effectors = alter production of ADH
What does ADH do?
stops diuresis when the blood-water concentration is low - effects permeability of collecting duct
What type of hormone is ADH and where does it travel to be stored?
Peptide hormone, from hypothalamus to be stored in the posterior pituitary gland
When is ADH released?
If water-blood content too low
What is the name of the hormone released by pregnant women in their urine?
Human chorionic gonadotrophin (HCG)
