urinary system Flashcards
Describe the gross anatomy and functions of the kidney
The (2) kidneys’ function is to remove waste and excess substances from blood through urination. The kidneys’ primary function is to filter the blood to remove waste through filtration.
the anatomy of the kidney includes the renal cortex, renal medulla and papilla
the renal cortex is the outer layer of the kidney It contains the glomeruli, which are clusters of tiny blood vessels where blood filtration begins. The cortex also houses the renal corpuscles, consisting of Bowman’s capsule and the glomerulus and is responsible for the initial blood filtration.
beneath the renal cortex is the renal medulla , which consists of renal pyramids. Each renal pyramid has a series of tubules that collect the filtrate from the glomeruli and transport it toward the renal pelvis.
they are cone-shaped medullary
pyramids separated by renal
columns. The medullary pyramid and its
surrounding capsule makes up a Lobe
and the Papilla: is the tip of the pyramid;
releases urine into minor
calyx
- Describe the anatomy of a nephron.
Nephrons are the functional units of the kidneys there is approximately 1 million in each kidney. nephrons consist of a renal corpuscle and renal tubule which extends into the medulla. each nephron filters blood, reabsorbs essential substances and excretes waste products to form urine
Describe 3 processes regulated by the kidney: filtration, secretion and reabsorption and
where it occurs.
Glomerular filtration: movement of plasma across the filtration membrane in the Bowman capsule due to the pressure difference (blood-nephron) high pressure forces small molecules and water out of the glomerular capillaries and into Bowman capsule
Location: Filtration primarily occurs in the renal corpuscle, which is located in the renal cortex of the kidney.
tubular reabsorption: movement of substances from filtrate back into the bloodstream (returns glucose, amino acids, water and salt) (nephron-blood)
Location: Reabsorption occurs along the entire length of the renal tubules, including the proximal convoluted tubule, loop of Henle, and distal convoluted tubule, as well as the collecting ducts.
tubular secretion: substances are moved into the lumen of the nephron (blood-nephron)
Location: Secretion occurs along the renal tubules, particularly in the proximal convoluted tubule and distal convoluted tubule.
Process: Secretion is the process by which the nephrons actively transfer specific substances (e.g., hydrogen ions, potassium ions, and some drugs) from the blood in the peritubular capillaries into the renal tubules. This additional secretion allows the kidney to eliminate certain substances from the body by adding them to the filtrate, which will eventually become urine.
Describe the forces involved in glomerular filtration
Glomerular (hydrostatic) blood pressure is higher (55
mm Hg) than other capillaries
Colloid osmotic pressure: molecules that are not filtered
(e.g., plasma proteins) function to maintain osmotic
the pressure of the blood
Glomerular filtrate: fluid that passes through the
filtration membrane contains: water, glucose, urea, small
proteins, creatinine, ions etc..
99% of filtrate is reabsorbed; only about 1% becomes
urine
Explain the formation of dilute versus concentrated urine and how hormones regulate this.
dilute urine
Filtrate is diluted in the
ascending loop of Henle
In the absence of ADH,
dilute filtrate continues
into the renal pelvis as
dilute urine
Na+ and other ions may be
selectively removed in the
DCT and collecting duct,
decreasing osmolality
concentrated urine
Depends on the medullary
osmotic gradient and ADH
ADH triggers the reabsorption of
H2O in the collecting ducts
Facultative water reabsorption
occurs in the presence of
ADH so that 99% of H2O in
filtrate is reabsorbed
- Explain how the kidneys contribute to the long-term regulation of blood volume and blood
pressure, including the roles of the renin-angiotensin-aldosterone system
Filtration of Blood:
-Removes waste and excess substances.
-Renin-Angiotensin-Aldosterone System (RAAS):
Renin Release:
-Responds to low blood pressure.
-Converts angiotensinogen to angiotensin I.
Angiotensin II Effects:
-Causes vasoconstriction, increasing blood pressure.
-Stimulates aldosterone release.
Aldosterone Release:
-Increases sodium and water reabsorption in kidneys.
-Raises blood volume and pressure.
Regulation of Blood Volume:
-Adjusts water reabsorption/excretion in urine.
Regulation of Sodium Balance:
-Influences blood volume by adjusting sodium levels.
In summary, kidneys regulate blood volume/pressure through filtration, the RAAS, and direct control of water/sodium balance. RAAS involves renin, angiotensin II, and aldosterone, working to retain fluid and increase blood pressure
What are the roles of the Renin-Angiotensin-Aldosterone System (RAAS)?
Renin Release:
Responds to low blood pressure.
Converts angiotensinogen to angiotensin I.
Angiotensin II Effects:
Causes vasoconstriction, increasing blood pressure.
Stimulates aldosterone release.
Aldosterone Release:
Increases sodium and water reabsorption in kidneys.
Raises blood volume and pressure.
In summary, RAAS regulates blood pressure and volume through renin release, angiotensin II-mediated vasoconstriction, and aldosterone-induced sodium/water retention.
