Urinary System: Anatomy Review
Name the organs in the urinary system:
The kidneys are retroperitoneal (behind the peritoneum), lying against the dorsal body wall in the upper abdomen.
The adrenal gland sits atop the kidneys. Blood vessels enter and leave the kidney at the renal cortex.
The functional units of the kidney are the nephrons. They are called renal pyramids if they are located mainly in the cortex. They are called renal pyramids if they are located in both the cortex and the medulla.
Blood enters the kidney through the hilus artery. The artery branches into smaller and smaller arteries and arterioles. Complete the sequence below:
______________ arteriole ______________ capillaries ______________ arteriole ______________ capillaries and vasa recta
Complete the sequence below showing all parts of the nephron:
Glomerular (Bowman’s) capsule proximal convoluted tubule loop of henle (both descending and ascending limb) distal convoluted tubule collecting duct (both cortical and medullary sections)
The renal corpuscle consists of two parts: glomerular capillaries and the Bownan’s capsule. A portion of the plasma is filtered into the capsular space due to the hydrostatic pressure of the blood.
The filtration membrane consists of fenestrated capillary endothelium, porous basementmembrane, and the photocyte (which contain filtration slits).
This filtration membrane permits (large or small) molecules to be filtered.
Proximal tubule: The simple cuboidal cells of the proximal tubule are called brush border cells because they contain numerous microvilli. The microvilli increase the surface area for reabsorption.
The proximal tubule cells are highly permeable to water and many solutes. The tight junctions permit the movement of water between the cells.
Loop of Henle: The thin descending limb of the loop of Henle is highly permeable to water but not to solutes.
The thick ascending limb of the loop of Henle is highly permeable to ___________________ but not to ___________________.
The thick ascending limb of the loop of Henle runs back between the afferent and efferent arterioles as they enter and leave the glomerular (Bowman’s) capsule. The juxtaglomerular apparatus consists of the macular densa cells of the tubule and the granular (modified smooth muscle) cells of the afferent arteriole.
Granulerutal cells serve as baroreceptors sensitive to blood pressure within the arteriole.
Macular densa cells monitor and respond to changes in the osmolarity (or electrolyte composition) of the filtrate in the tubule.
After the juxtaglomerular apparatus, the tubule becomes the distal tubule, which merges with the cortical collecting duct. The cortical collecting duct contains two functional types of cells:
Principal cells—hormones regulate their permeability to water and solutes.
Intercalated cells—secrete hydrogen ions for acid-base regulation.
The medullary collecting duct is composed of principal cells.
Their permeability to urea and water is hormonally regulated.
Urinary System: Glomerular Filtration
What force drives filtration at the glomerulus? Blood pressure
Glomerular filtration is a process of bulk flow driven by the hydrostatic pressure of the blood.
Common components of the filtrate are divided into four categories on the CD program. These include: 1. water
3. notrogenous waste
4. organic molecules
Blood pressure in the glomerulus is about 60 mmHg.
What two pressures oppose filtration and what are their values? 1. hydrostatic 15mmHg
2. osmotic 28mm Hg
What is the normal net filtration pressure? 17 mmHg
With a glomerular filtration rate of 125 ml/min, how much plasma would be filtered per day? 180L In 24 hours? _____
In an exercising individual the afferent arteriole will (dilate or constrict) to avoid excess fluid loss....
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