Excretory Flashcards
What are the three main functions of the kidneys
- Remove wastes
- Balance blood pH
3a. Maintain water balance
3b. Blood pressure
How many kidneys does the body have
What are they made up of
2
1 million nephrons
What are some wastes removed by the kidney?
How is uric acid formed?
What is the process it is formed in called?
Urea and uric wastes from the blood
Uric acid is formed from the breakdown of DNA
Urea I’d formed in a process called deamination
Where does deamination occur?
What is it
Liver
The conversion of amino acids in the blood to carbohydrates (urea is produced)
What are the steps to deamination
- NH3 is removed from amino acids
2. 2 NH3 + CO2 = urea
What is the build up of uric acid called?
Gout
How do the kidneys maintain pH balance
CO2 from peritubular capillaries + H2O in cells lining the nephron = carbonic acid
Carbonic acid breaks apart to make H+ and HCO3
What happens if the blood is too acidic
H+ is excreted in the urine and HCO3- is reabsorbed back to the blood …buffering the blood
What happens when the blood is too basic
HCO3- is excreted in the urine and H+ is reabsorbed back to the blood
How much water moves though the kidneys in one day?
How is 2L of water lost per day
How much water is reabsorbed
180L
Perspiration, exhaling, urine
178L
What happens of 1% water loss
5%
10%
1- thirst
5- pain and collapse
10- death
What two hormones regulate water concentration in the blood
Antidiuretic hormone (ADH) Aldosterone
What does ADH do
Where is it stored
Targets the distal tubule of the nephrons and collects dust
It increases H2O reabsorption into the bloodstream
Stored in posterior pituitary gland
What dies water lost in the body cause?
Causes water to move from tissues into the bloodstream
Osmoreceptors in the hypothalamus detect low osmotic(water) pressure
How does the hypothalamus respond to loss of H2O
Triggers thirst, send nerve message to the pituitary to stimulate the release of ADH
ADH travels in blood and targets the nephron
What is the effect of ADH on the nephron
ADH causes the distal tubule and collecting duct to become permeable to H2O
The kidneys reabsorb more H2O
A more concentrated urine is produced
What factors affect ADH
What happens when the release of ADH is inhibited
Cold-weather, caffeine, and alcohol all inhibit the release of ADH
Reabsorption of water can’t take place and urine volume is increased
What do the kidneys help regulate
Blood pressure
Where is aldosterone produced and what does it do
Produced and secreted by the adrenal glands
Targets the ascending loop of Henle, distal tubule, and collecting duct. Also increases the amount of sodium reabsorption… Therefore increasing the reabsorption of water, this increases blood pressure
What is low blood pressure detected by
Osmo receptors in the juxtaglomerular apparatus
What do cells in the juxtaglomerular apparatus release and what does it do
Renmin which converts angiotensinogen to angiotensin
What is angiotensinogen
What does it do
A plasma proteins secreted by the liver
Constricts blood vessels and causes aldosterone to be released from the adrenal glands
What do renal arteries do
what do renal veins do
Supply kidneys with oxygenated unfiltered blood
Remove deoxygenated filtered blood
What do kidneys do
How many layers are there and what are they
Filter wastes from the blood
Three layers
Cortex is outer layer of connective tissue
Medulla is inner layer which contains the nephrons
Pelvis is hollow chamber joining kidney to ureter
What are ureters
Two tubes through which filtered wastes from the kidneys passes through to reach the bladder
What is the bladder? How much can it hold? What happens when it reaches 400 mL
Storage for urine
200 mL of urine
At 400 mL stretch receptors signal the brain that it’s time to go
How does urine leave the bladder
Through the urethra
Sphincter muscles relax and urine is avoided
Why are women more susceptible to bladder infections
The urethra is shorter in women
What are nephrons
What do afferent arterials do
Functional units of the kidney
Supply the nephrons with the blood and branch into the capillary bed called the glomerulus
What does blood leaving the glomerulus do
Passes through the efferent arterioles, travels to the peritubular capillaries, goes to the venule, and then to the renal vein
What is the glomerulus surrounded by
The Bowmans capsule
What does the Bowmans capsule taper into
The proximal tubule
What does the proximal tubule Connect to? What does that connect to
Of Henle
Distal tubule
What does the distal tubule empty into
Where do those merge
Collecting duct
Renal pelvis
What are the three steps in the formation of urine
Filtration, reabsorption, secretion
What is the filtration process? Reabsorption? Secretion?
The movement of fluid from the blood (glomerulus) into the Bowmans capsule
Movement of essential solutes and water from the nephron back to the blood
Transport of materials from the blood into the distal tubule of the nephron
Where does filtration occur
How is filtration rate affected
What are the steps
Glomerulus
High pressure = High filtration rate
Blood enters nephron through afferent arterial
Blood enters glomerulus
Proteins, blood cells, and platelets are too large to filter through glomerulus and move into the efferent arterial
Plasma passes through glomerulus into Bowmans capsule
Where does most reabsorption occur
Where else does it occur
How long does it occur
Proximal tubule
Loop of Henle and distal tubule
Until threshold level is reached
In reabsorption, does active or passive transport occur?
Both
What are the steps to reabsorption
Glomerular filtrate travels through the proximal tubule
As the glomerular filtrate travels, water and ions are reabsorbed back into the bloodstream
This maintains water and ion balance
Where does secretion occur? Is it active or passive transport
Distal tubule, active transport
What is the composition of urine
What is the average pH of urine
Water, urea, uric acid, trace amino acids, electrolytes, excess vitamins and minerals
4 to 5
How can many kidney disorders be diagnosed
By analyzing a blood and urine sample
What is diabetes mellitus caused by, what is the result, what are the symptoms
Inadequate insulin secretion from islet cells
High glucose levels in blood, which causes less reabsorption of water
Large volumes of sugary urine are avoided
What is diabetes insipidus caused by, what is the result, what are the symptoms
Caused by destruction of hypothalamus cells, resulting in no ADH being released
Symptoms are that large volumes of dilute urine are voided
What is a cause of brights disease and what is the result
What are symptoms
Hypertension
Blood vessels in glomerulus become destroyed, making glomerulus permeable to plasma proteins
Symptoms are that you void large volumes of urine which contain proteins or blood cells
What are kidney stones caused by
Precipitation of mineral solutes from the blood
What is lithotripsy
Using shockwaves to break up kidney stones which can then be voided
What is dialysis
What types are there
Needed for people whose kidneys no longer function
Hemodialysis and paratonial dialysis
What is hemodialysis
A dialysis machine mimics the action of the nephron
The only function that a dialysis machine can’t do is active transport
Blood is pumped through a series of tubes and one of these tubes into the machine and is bathed in dialysis fluid
Dialysis tubing is semi-permeable so large solutes will pass through but small solutes can
