THE URINARY:
Urinary system notes: text notes pages 1-4; all of diagram note packet
• “Filtrate” = filtered plasma that exits blood at glomerulus
(fenestrated capillaries) in nephrons (functional units of kidneys)
◦ **Filtrate becomes urine
◦ “Filtrate” in nephrons is mostly H2O with glucose, amino
acids, and various ions, metabolic wastes BUT NO blood cells
& NO proteins (normally)
• Kidney location = between last 2 false (floating ribs) and crest of
ilium (between T-12 and L-3 vertebrae)
◦ Kidneys are very posterior — “paraspinal” — near spinal
column
• Hilus = entrance into the kidney and lungs; means an “entrance”
◦ The medial central region of each kidney contains an entry
and exit for the follow vessels (called the hilus) —
‣ Ureter
‣ Renal artery and vein
‣ Lymphatic Vessels
‣ Nerve fibers (sympathetic)
Kidney Anatomy: page 5 diagram notes
• Renal = “kidney”
• 1. Renal capsule = equivalent to a visceral pericardium; the outer
external connective tissue covering/layer of the kidney
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• 2. Cortex = outer region of internal kidney; lighter tissue; contains
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the structural and functional unit of the kidney —> the “nephron”;
contains most of the nephrons (about 1 million nephrons —
microscopic units — in each kidney)
◦ Nephrons are mostly in the cortex and do the work of the
kidneys
‣ They form the urine from blood which flows through
specialized capillaries called glomerulus and is filtered
through a structure called the Bowman’s capsule.
• 3. Medulla = also called renal medulla; triangular area; darker
tissue; middle internal region of kidney; contains the collecting tubules; contains the “pyramids” (or renal
pyramids)
◦ *Region
• 4. Pyramids = part of the renal medulla; also called renal pyramids; “cone like things” in kidneys; formed by
“collecting ducts” which collect the urine from nephrons
◦ *Structure in medulla
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5. Minor calyx = tube that comes down and carries urine from the bottom of every pyramid (2 of these)
6. Major calyx = formed by 2 minor calyx; all major calyx combined/merged together form renal pelvis
7. Renal pelvis = becomes the ureter; this is formed by all major calyx combing together
8. Ureter = carries urine to urinary bladder
A representative nephron: in diagram notes & text notes
• Corpuscle = little body
• Parts and functions:
◦ Collecting duct = white tubes down the middle
◦ Nephrons = 3 green tubes (microscopic in real life)
◦ Renal corpuscle = glomerulus (capillary bed) &
Bowman’s capsule (surrounds glomerulus & collects the
filtrate)
‣ Function: production of filtrate cooled by
“Bowman’s capsule”
◦ Proximal convoluted tubule = “proximal” — close
to glomerulus; convoluted — “twisted and turned”; this
transports the filtrate from the Bowman’s capsule
‣ Function: major site of reabsorption
• Reabsorption (to take back in) of water nutrients (glucose and amino acids) and ions
• During reabsorption (at proximal convoluted tubule), H2O, nutrients, and ions are returned to
blood by way of “peritubular capillaries” that surround the tubules of the nephron
◦ Distal convoluted tubule & collecting duct (part of pyramid) = both have variable of reabsorption of
water and ions
‣ Function: reabsorption under control of ADH and Aldosterone hormones
• ADH (antidiuretic hormone) stimulates reabsorption of H2O from filtrate resulting in less urine
production
• Aldosterone stimulates reabsorption of sodium ions (Na+) from the filtrate (and urine) resulting
in less Na+ in urine
Renal corpuscle: page 8-9 diagram notes
• JGA — Juxtaglomerular apparatus = group of cells of afferent arterioles (delivers unfiltered blood to the
glomerulus) and the cells of the distal convoluted tubule
◦ Cells of JGA produce a substance called “RENIN” in response to low blood pressure and essentially low
blood fluid volume [page 9 diagram]
‣ During blood loss OR dehydration, diarrhea (lose a lot of water)
◦ Renin enters the systemic blood —> at the liver, renin stimulates production of “angiotensin 1” which is an
inactive hormone [Angiotensin 1 enters the systemic blood — from liver]
‣ At the lungs, angiotensin 1 (inactive hormone) is converted to an active hormone “angiotensin
2” [Angiotensin 2 stimulates secretion of aldosterone and ADH; it also stimulates systemic
“vasoconstriction” (gets smaller) resulting in increased systemic blood pressure
‣ *Angiotensin 2 is very powerful vasoconstrictor
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