Exam 3 Lecture: Urinary System Organization Flashcards
Superficially, what is the role of the kidneys?
to clean the blood
How does the kidney clean the blood?
Via a two step process
What is the first step of the 2-step process the kidney goes though?
filtration of blood as it runs through the organ to produce an unfiltrate
What is the second step of the 2-step process the kidney goes through?
selective reabsorption of desired components from that filtrate and their return to the bloodstream
How does the kidney maintain the extracellular fluid?
by controlling how much of the filtrate returns to the blood stream and how much of the filtrate remains as urine
What is the most important think the kidney does?
it handles water and Na
What enzymes does the kidney release?
renin and EPO
What is the importance of renin?
an important hormone for normal renal function and maintenance of blood pressure
What is the importance of EPO?
important for red blood cell production amongst all other things
Where are the kidneys located?
dorsally and slightly posteriorly in the lumbar region on either side of the spinal column
What is the outer covering of the kidney and what is it composed of?
the capsule, collagen and some smooth muscle
What is the function of the capsule?
to provide structural integrity to the kidney, because there is almost no connective tissue in the kidney
What are the two layers of the kidney?
the cortex and the medulla
What is the appearance of the cortex?
darker and granular
True or false: the differences between the cortex and the medulla are only physical
false: they are also chemical
What is the functional unit of the kidney?
the nephron
In simple terms, what is the nephron?
an epithelial lined tube
What is the number of nephrons proportional to?
the size of the kidney; a larger kidney has more nephrons
What are the two classes of the nephron?
cortical or juxtamedullary
How do the two types of the nephron differ?
in their abilities to absorb various things and in the way they respond to some hormones
What are the little granular blobs/balls in the cortex?
the renal corpusles
What is the cortical labyrinth and where is it located?
mess of tubing that is composed of proximal and distal convoluted tubules; located in the cortex
What are the medullary rays and where are they located?
extensions of the cortex that project into the medulla containing proximal and distal straight tubules, and the collecting ducts
What is located in the outer medulla?
loops of henle, collecting ducts, and distal straight tubules
what is located in the inner medulla?
collecting ducts
What is the function of the renal corpuscle?
filtration
What is the first stage of renal physiology and where does it occur?
filtration: blood enters the kidney via the renal artery and gets sent out to renal corpuscles in the cortex
What occurs in the glomerulus?
blood gets squeezed through the walls of the capillaries for filtration
What is the function of the bowmans capsule?
to collect the filtrate excreted by the glomerulus
What is the renal corpuscle?
the bowmans capsule + the glomerulus
What is the vascular pole?
where the capillaries enter
What is the urinary pole?
where the proximal tubule leaves
How is blood supplied to the glomerulus?
by an afferent arteriole
How is blood drained from the glomerulus?
by the efferent arteriole
What helps generate high pressure in the glomerulus?
the stretchiness difference between the efferent and afferent arterioles
Which arteriole generates more resistance to blood flow?
the efferent
How does the distal straight tubule make contact with arterioles/glomerulus?
at the macula densa
What about the capillaries of the glomerulus allow blood to get filtered into the urinary space?
they are fenestrated
How are the capillaries of the glomerulus supported?
by the mesangial cells
What is the function of intraglomerular mesangial cells?
supportive cells that are also contractile and phagocytic
Where are intraglomerular mesangial cells located?
in the glomerulus
Where are extraglomerular mesangial cells located?
near the vascular pole
What are the extraglomerular mesangial cells important for?
the renin-angiotensin system
What is the visceral layer of the renal corpuscle?
the part of the bowmans capsule that touches the glomerulus; makes intimate contact with the capillaries
What is the parietal layer of the renal corpuscle?
the part of the capsule that is not touching the capillaries
What is the cell type of the parietal layer?
simple squamous epithelial cells
What is the cell type of the visceral layer?
podocytes
What is the function of podocytes?
they aid in glomerular filtration
What are pedicels?
finger like projections of podocytes that wrap around the capillaries of the glomerulus
What is the first stage of the filtration apparatus?
plasma is filtered through pores of capillary and fenestrated capillaries
What is the second step if the filtration apparatus?
Plasma is filtered b the basal lamina of the visceral layer
What are the layers of the basal lamina?
2 layers of lamina rara that sandwich the lamina densa within
What is the lamina densa made of?
collagen
What is the 3rd stage of the filtration apparatus?
plasma is filtered by slit diaphragm, a protein sheet full of holes secreted by podocytes
What is the structure of proximal tubules?
cuboidal epithelium, microvilli on the lumen, large basolaterally located nuclei and lots of mitochondria
What is the function of proximal tubules?
absorption using an active process
What is the structure of distal tubules?
low cuboidal, more oval apical nuclei, few microvilli, few mitochondria, lumen is not as fuzzy
What is the function of distal tubules?
reabsorption, but not as powerful as the proximal tubule
What are distal tubules impermeable to?
H20 and urea
What are the regions of the collecting ducts?
cortical, medullary, and papillary
What cell types are in the cortical collecting ducts?
principle and intercalated
What is located in principle cortical collecting duct cells?
mitochondria and microvili
What is are the types of intercalated cells?
type A and type B
What is the function of type a intercalated cells?
excrete H+ and reabsorb HCO3-; also reabsorb K+
What is the function of type b intercalated cells?
Excrete HCO3- and reabsorb H+
What type of cells are located in the outer medulla collecting ducts?
principle cells and intercalated cells
What type of cells are located in the inner medulla collecting ducts?
principle cells only
What cells are located in the papillary collecting ducts?
principle cells
Is water permeable in the collecting ducts?
no, it is only permeable when ADH is present
What is the structure of collecting ducts?
cuboidal epithelium, large nucleus with a halo around it, diminished brush border
What is the structure of the loops of Henle?
simple squamous and few mitochondria, bulging nuclei; have an ascending and descending limb
What is the function of descending limb?
permeable to H2O but impermeable to Na+
What is the function of the ascending limb?
not really permeable to H2O but permeable to Na+
What is the function of the juxtaglomerular aparatus?
in charge of altering GFR
What is the macula densa?
a specialized group of cuboidal cells on the wall of the distal tubule
Where is the macula densa located?
at the junction of the straight and convoluted distal tubule
What is the structure of the macula densa?
densely packed tall cells with no basal lamina
What does the lack of basal lamina in the macula densa allow?
direct contact between the extraglomerular mesangial cells and justaglomerular cells
What do extraglomerular mesangial cells receive a signal from?
the macula densa and pass it on to the juxtaglomerular cells
What are juxtaglomerular cells?
specialized smooth muscle cells full of renin inclusions
What is the function of the ureter?
convey urine from the kidney to the bladder via peristalsis
What type of epithelium is the ureter lined with?
transitional epithelium
What is the function of the transitional epithelium?
protection and distension
What does the lamina propria in the ureter do?
provides a layer of separation from the harmful osmotically active acidic urine and the underlying tissues
What are the muscle layers in the ureter?
an inner longitudinal layer of smooth muscle and an outer longitudinal layer of smooth muscle
What is the outermost layer of the ureter?
tunica adventitia
What type of epithelium is in the bladder?
transitional epithelium
What is the layer directly adjacent to the transitional epithelium of the bladder?
2 lamina propria layers - for an osmotic barrier
What are the muscle layers of the bladder?
a inner longitudinal layer, a middle circle layer, and a outer longitudinal layer
What are the muscle layers of the bladder called?
the detrusor muscle
What does the middle circular muscle layer form
?
the internal sphincter muscle
What type of muscle is the external sphincter?
the skeletal muscle
What is the function of the urethra?
convey urine from the bladder during voiding
What type of epithelium is in the urethra?
transitional
What is directly adjacent to the epithelial layer of the urethra?
a large lamina propria where muscous glanda are occasionally present
What is the mucous gland in the lamina propria of the urethra called?
glands of littre
What are the muscle layers of the urethra?
the inner circular layer and the outer longitudinal layer
