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Flashcards in Urinary Deck (53):

kidney location

in the abdominal cavity against the dorsal body wall


kidney function

2. maintains water/electrolyte/acid-base homeostasis
3. excretes metabolic wastes
4. filters the blood


ureters function and location

1. tubules that carry urine form the kidneys to the bladder
2. under the parietal peritoneum
3. tunnels through the bladder wall entering near its base


bladder function

holds urine


urethra function

1. carries urine from the bladder to the exterior


kidney medulla

1. Inner region of the kidney interior
2. Contains pyramids


kidney cortex

1. Outer regions of the kidney interior
2. Contains nephrons
3. Contains renal corpuscles and medullary rays


kidney capsule

1. Exterior of kidney
2. Contains tough outer layer of collagen fibers and inner layer with looser tissue and fibroblasts.
3. Outside covered by thick layer of fat


renal pelvis

1. within the medulla
2. branches into calyces which connect to the renal papillae
3. collects urine


structure of the nephron

- renal corpuscle
- proximal convoluted tube
- distal convoluted tube


function unit of the kidney



what happens in the renal corpuscle



what happen in the renal tubules

1. Fluid returned to the blood stream and adjustments in ion content are made


What are the three main nephron functions



where does filtration occur

renal corpuscle


where does reabsorption occur

proximal convoluted tubule
henles loop


where does secretion occur

distal convoluted tubule


bowmans capsule

1. Thin layer of epithelium which surrounds the glomerulus



1. Capillary bed within the renal corpuscle


renal corpuscle

1. Site of filtration
2. Contains glomerulus and bowman’s capsule
3. Distinguishing characteristic of the cortex


describe pressure filtration

i. Blood enters the glomerulus through afferent arteriole and leaves through efferent arterioles. The afferent are larger than the efferent. The capillaries are fenestrated. The size different between the afferent and efferent arteriole creates a pressure which forces liquid and small molecules out of the fenestrated capillaries and into the space of the bowman’s capsule.


what are the components of the glomerular filter

-fenestrated capillaries
-podocytes secondary processes
- the basement membrane of the capillary epithelium and podocytes


describe fenestrated capillaries

1. thin endothelium with large pores – fenestrations allow molecules to pass through without allowing RBCs and WBCs through


describe podocytes

1. create the inner epithelium of bowman’s capsule that covers the capillaries of the glomerulus – surround the capillaries to create a glomerular filter


primary processes of podocytes

are cytoplasmic extensions which wrap around the capillary and each ends with secondary processes


secondary processes of podocytes

part of the glomerular filter


functions of the glomerular filter

iv. functions of the filter is to allow most liquid and small molecules to pass into Bowman's capsule while retaining blood cells and large molecules (such as proteins).


What is the pathway of filtrate?

1. Filtrate leaves the bowman's capsule into the proximal convoluted tubules where it is reabsorbed. Glucose, amino acids, ions, and water are reabsorbed and returned to surrounding capillaries.
2. It then moves to Henle's loop to be further concentrated.
3. From there it moves to the distal convoluted tubule where blood pH and ion concentrations are fine tuned.


How are ion concentration and blood pH fine tuned in the distal convoluted tubule

Surrounding capillaries secrete hydrogen ions into the filtrate if the pH is too high and absorb Na from the filtrate to return it to the blood if Na concentrations are too high


Proximal tube

- work horse
- reabsorbs 65% of filtrate
- cuboidal epithelium that is than the epithelium of the distal tubule
- thick brush border with long microvilli


Brush border of the proximal tubule

Reflects function to absorb glucose, amino acids, ions, and water from the filtrate and return them to surrounding capillaries


Microvilli of the proximal tubule

1. on the brush border
2. Contain large amount of mitochondria
- The absorption of glucose and amino acids requires energy
- Absorbed nutrient diffuse through epithelial cells, cross the basement membrane, and enter nearby capillary of the capillary plexus


Distal convoluted tubule

- site of secretion
- fine tunes the blood pH and ion concentrations
- shorter cuboidal epithelium with sparse, short microvilli
- secrete hydrogen ions from surrounding capillaries into the filtrate, lowering the blood pH if too high
- can absorb sodium from the filtrate and return it to the blood


justaglomerular apparatus structure/location

1. formed by adjacent regions of the distal convoluted tubule and afferent arteriole of the glomerulus


juxtaglomerular apparatus function

sense and regulate blood pressure by sensing sodium ion concentration and secreting renin when low sodium concentrations detected which leads to blood vessel constriction and elevation of blood pressure



1. contractile, connective tissue made of modified pericytes that holds capillaries of the glomerulus together
2. can change the diameter of the capillaries in response to circulating hormones


capillary plexus

1. surrounds all parts of the renal tubule
2. network of capillaries from branching efferent glomerular arteriole
3. contains blood from which much of the liquid and organic molucules have been removed by filtration
4. reabsorbs much of the filtrate passing through the tubule returning water and nutrients to the blood stream


vasa recta

1. U-shaped path around the henle’s loop – part of the capillary plexus
2. Capillary loops
3. Parallel to henle’s loop
4. Absorb water removed from filtrate in the thin limb
5. Thin walls


thin limb

1. Thin squamous epithelium
2. Descending
3. Permeable to water
4. Water is pulled from the filtrate into the surrounding tissue by the high osmotic force created by the thick limb
5. part of the loop of henle


thick limb

1. Simple cuboidal
2. Ascending
3. Impermeable to water
4. Pumps sodium ions, followed by chloride, from the filtrate into the surrounding tissue creating a high salt concentration and osmotic gradient within the medulla
5. Requires mitochondria to actively pump out the Na ions
6. part of the loop of henle


collecting tubules

1. Reabsorb water when stimulated by ADH which is taken up by the vasa recta and returned to the blood stream
2. Impermeable to water unless stimulated by ADH


what hormone is essential for the modification of filtrate after it has left the distal tubule?

ADH - antidiuretic hormone


How does ADH work

a. ADH secreted when body needs to conserve water, making the walls of the collecting tubules permeable to water and decreasing total urine production


collecting ducts

1. Collect urine
2. Do not further modify the urine


Ducts of bellini

i. Large collecting ducts lined with columnar epithelium
ii. Run to the tips of renal papillae where the urine enters a calyx space



1. An empty space lined with transitional epithelium
2. Upper end of the ureter


where is transitional epithelium found

i. Transitional epithelium is found in the urethra, inner layer of the ureter and the outer layer of the bladder


How does transitional epithelium function?

ii. allows expansion – stretch and relax without losing integrity
1. when relaxed – stratified with cuboidal/columnar cells
2. when stretched – cells become squamous making it thinner


Describe the transitional epithelium of the bladder. What is unique about it?

1. Contains dome cells where have thickened plaques with their surface plasma membrane which resist damage from acidity and toxic chemicals of the urine
2. Forms impenetrable barrier to toxic wastes in the urine
3. Prevents water from diffusion from the underlying tissue into the hypertonic urine within


major tissues of the ureter

i. Folded mucosa with lamina propria rich in collagen fibers
ii. Smooth muscle with inner longitudinal and out circular layer arranged in spirals. Additional outer longitudinal layer in lower third.
iii. Adventitia containing connective tissue and blood vessels surrounds
iv. Inner surface of transitional epithelium



- spherical organ that can expand to hold large volumes of urine
- highly folded mucosa when empty which flattens when full
- 3 layers of smooth muscle
- connective tissue containing elastin and collagen for elasticity of the wall
- sphincter of circular muscle fibers
mucosa the same as the ureter


Describe the muscle of the bladder

3 layers
- outer longitudinal
- inner longitudinal
- central region of oblique and circular fibers


How does the urethra of a male differ from that of a female?

i. Is longer in males
ii. In females leads directly from bladder to external opening in anterior of vagina
iii. Male leads from bladder through the prostate gland and runs through the penis before opening to the exterior at the penis tip