Lecture 9: Urinary System Flashcards
Kidney general function
FILTER plasma constituents from blood, then selectively REABSORB water and useful constituents from filtrate, then EXCRETE the excess
kidney location
dorsal part of abdominal, on each side of aorta and vena cava, ventral to lumbar vertebrae
-in cows the LEFT kidney is pushed to the middle by the stomachs
Renal hilus
concave depression of kidney, where blood vessels and nerves enter ureter and lymphatics leave
Renal pelvis
expanded origin of the ureter within the kidney
- receives urine from the collecting tubules of the kidney
- not all species have a pelvis
Major calyces
openings from medulla to renal pelvis
Medulla
portion surrounding the renal pelvis
- striated appearance due to radially collection of tubules that form the renal pyramids
- medulla contains the loop of henle
Cortex
located on top of the medulla
- granular appearance due to many renal corpuscles/nephrons
- proximal and distal convoluted tubules are located in cortex
How much of total blood supply goes to kidneys?
about 1/4
Blood vessels supplying kidneys: arteries and afferet arterioles
two renal arteries enter the hilus and divide into a number of large branches, the arcuate arteries, and afferent arterioles, each of which branch to form capillary networks called GLOMERULUS
Arteriae rectae
capillary network surrounding the nephron, collecting tubules, and loop of henle
Efferent arterioles
-efferent arteriole leaves the glomerulus and forms the capillary network surrounding the nephron called ARTERIAE RECTAE
arcuate vessels
artery and vein that border the cortex and medulla
Nephron
functional part of the kidney
-includes the glomerulus, glomerular (Bowman’s) capsule, proximal and distal convoluted tubules
artery path:
interlobar arteries-arcuate arteries-interlobular arteries-afferent arterioles
Venous drainage pathway
venae rectae-arcuate veins-interlobar veins, and renal vein
lymph drains from kidney to the renal lymph nodes
Renal plexus
supply of sympathetic nerves connected to kidney
- follows blood vessels and terminate mainly at glomerular arterioles
- Vagus nerve may also supply
ureters
muscular tube that carries urine from the pelvis of kidney to the bladder
urinary bladder
hollow, muscular organ that varies in size depending on amount of urine
-as the bladder fills the walls become thinner, and most of the bladder is displaced up cranially toward the abdominal cavity, as it rests on the floor of the pelvis
bladder has a sphincter to…
control passage of urine into urethra at the neck of the bladder
pelvis, ureter, bladder, and urethra are all lined with what?
transitional epithelium
Micturition
expulsion of urine from the bladder
- a reflexive activity stimulated by distention/stretching of bladder
- voluntary control of the external sphincter around the neck of the bladder can prevent emptying reflex
Functions of the kidney
- excretion of waste products
- maintenance of homeostasis: the condition of internal environment including water balance, pH, osmotic pressure, electrolyte levels, and concentration of many plasma substances
glomerulus
network of capillaries (a tuft) at the beginning of the nephron, where filtration occurs
Glomerular capsule
the blind end of the tubule that surrounds the glomerulus
-visceral layer surrounds the capillaries, while the parietal layer is continuous with the proximal con. tube.
renal (malphighian) corpuscle, filtration part of nephron
part of the nephron. the complex of the glomerulus and the glomerular capsule
- where filtration of fluid from blood occurs
- approx. 100 times as much fluid passes through this filter as is eventually excreted
- blood pressure must be kept high to filter that quickly, which is ensured by capillaries being closer to an artery than a vein
Both arterioles control glomerular have smooth muscle in order to
control glomerular pressure
juxtaglomerular cells
present in afferent arterioles approaching glomerulus
- surrounded by a cuff of myoepithelial cells (act like both smooth muscle and epithelium)
- sites of RENIN production
myoepithelial cells
act like smooth muscle and epithelium
-surround the juxtaglomerular cells, which are the site of renin production
Stimulus of renin production
- fall in blood pressure in afferent arteriole
- decrease in plasma sodium concentration
- decrease in distal tubular osmolarity
- stimulation of sympathetic nerve fibers supplying afferent arterioles
Function of renin
-acts on globulin-angiotensinogen to produce angiotensin
angiotensin
- acts as a vasoconstrictor to increase blood pressure
- acts on adrenal gland to secrete ALDOSTERONE, which causes kidney to conserve sodium
aldosterone
increases sodium uptake from distal convoluted tuble and increased water uptake to increase blood pressure
