Chapter 10.4 Kidneys and Homeostasis Flashcards
What role do the kidneys play in homeostasis?
They maintain the water-salt balance in the body, they regulate the pH of the blood
The liver produces?
Urea, the primary nitrogenous end product of humans, which is excreted by the kidneys
If the liver is a swage treatment plans, the tubules of the kidneys are like?
The trucks that take the sludge, prepared waste, away from the town (body)
What is metabolic waste removal necessary for?
For maintaining homeostasis
What must the blood be constantly cleanses of?
The nitrogenous wastes, end products of metabolism
The liver produces urea and muscles make?
Creatinine
The urine producing kidneys, are responsible for the excretion of?
Nitrogenous wastes
Most of the water found in the filtrate is reabsorbed into the?
Blood before urine leaves the body
All parts of a nephron and the collecting duct participate in the?
Reabsorption of water
What always precedes the reabsorption of water?
The reabsorption of salt
Water is returned to the body by a process of?
Osmosis
Where does water pass during the process of reabsorption
During the process of reabsorption, water passes through water channels, called aquaporins, within a plasma membrane protein
What are present in the renal cortex?
- The proximal convoluted tubule
- Distal convoluted tubule
- The cortical portion of the collecting ducts
Most of the water (65%) that enters the glomerular capsule is reabsorbed from?
The nephron into the blood at the proximal convoluted tubule
Na+ is actively reabsorbed and what follows passively?
CI-
Aquaporins are always open and water is?
Reabsorbed osmotically into the blood
What regulates the reabsorption of sodium and water in the distal convoluted tubule?
Hormones
A hormone secreted by the adrenal glands, which sit atop the kidneys
Aldosterone
This hormone promotes ion exchange at the distal convoluted tubule
Aldosterone
The release of aldosterone is set into motion by the?
Kidneys
What is the juxtaglomerular apparatus?
A region of contact between the afferent arteriole and the distal convoluted tubule
When blood volume falls too low for filtration to occur what happens?
The juxtaglomerular apparatus can respond to the decrease by secreting the renin
Describe the enzyme renin
An enzyme that ultimately leads to secretion of aldosterone by the adrenal glands
Antidiuretic hormone (ADH) is produced by
The hypothalamus and secreted by the posterior pituitary according to the osmolarity of the blood
If our intake of water has been low, what is secreted by the posterior pituitary?
ADH
Water moves from the distal convoluted tubule and the collecting duct into?
Blood
What is atrial natriuretic hormone (ANH)
A hormone secreted by the atria of the heart when cardiac cells are stretched due to increased blood volume
ANH inhibits the secretion of?
Renin by the juxtaglomerular apparatus and the secretion of aldosterone by the adrenal glands
What is dependent on the work of the medullary portions of the nephron (loop of the nephron) and the collecting ducts?
The ability of humans to regulate the tonicity of their urine
What is the long loop of the nephron made up of?
It is made up of a descending limb and an ascending limb
What passively diffuses out of the lower portion of the ascending limb?
Salt
Any remaining salt of the ascending limb gets actively transported from?
The thick upper portion of the limb into the tissue of the outer medulla
Concentration of salt after is passes the ascending limb is greater in?
The direction of the inner medulla
What has a higher concentration of solutes
The inner medulla
What leaves the descending limb?
Water leaves the descending limb along its entire length via a countercurrent mechanism because of the osmotic gradient within the medulla
What limb does not absorb water and why?
The ascending limb because it has no aquaporins, is job is to help establish the solute concentration gradient
When water is reabsorbed where is it returned?
To the cardiovascular system
Where does water diffuse?
Water diffuses from the entire length of the collecting duct into the blood if aquaporins are open, as they are if ADH is present
What happens when ADH is present?
More water is reabsorbed (blood volume and pressure rise) and a decreased amount of urine results
ADH fine-tunes what?
The tonicity of urine according to the needs of the body
Without adequate blood pressure what happens
Exchange across capillary walls cannot take place, nor is glomerular filtration possible in the kidneys
What happens when sodium ions Na+ concentration falls too low?
Blood pressure falls and the renin-aldosterone sequence begins. Then the kidneys increase Na+ reabsorption, conserving as much as possible
What are diuretics
Chemicals that increase the flow of urine
What causes diuretic
Drinking alcohol because it inhibits the secretion of ADH
Is caffeine a diuretic?
Yes, because it increases the glomerular filtration rate and decreases the tubular reabsorption of sodium ions (Na+)
If the blood pH rises above 7.45, a person is said to have
Alkalosis
If the blood pH decreases below 7.35, a person is said to have
Acidosis
What is a buffer?
A chemical or a combination of chemicals that take up excess hydrogen ions (H+) or excess hydroxide ions (OH-)
Only the kidneys can get rid of
A wide range of acidic and basic substances
What organ can be used for reabsorbing bicarbonate ions and excreting hydrogen ions as needed to maintain the normal pH of the blood
The kidneys
Where is ammonia produced?
In tubule cells by the deamination of amino acids
Aside from producing renin, the kidneys assist the?
Endocrine system and also the cardiovascular system by producing erythropoietin
What is erythropoietin used for?
Used to stimulate red bone marrow production in patients in renal failure or recovering from chemo
How do the kidneys assist the skeletal, nervous, and muscular systems?
By helping to regulate the amount of calcium ions in the blood
