Urinary System Flashcards
(78 cards)
7 purposes of the Urinary System:
- Cleansing the blood and ridding the body of wastes
- Regulation of pH
- Regulation of blood pressure
- Regulating the concentration of solutes in the blood
- Determining the concentration of RBC
- Performs the final synthesis step of Vitamin D production
- Providing the anatomical structures to store urine until the body is able to dispose of it
Where does the urinary system’s ability to filter blood reside?
2-3 million tufts of specialized capillaries (glomeruli) distributed between the two kidneys
What is the first part of the nephron?
The glomerulus
Normal urine output volume:
1-2 liters/day
What is the minimum urine output volume, what is it called when the body produces less than this, and what can cause this?
-500mL/day
-oliguria
-severe dehydration or renal disease
Name the virtual absence of urine and the excessive production of urine:
-anuria
-polyuria
Location of the kidneys:
Either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall
Describe the internal anatomy of the kidney:
-Outer region: renal cortex
-Inner region: medulla
-Renal columns: connective tissue extensions from the cortex to the medulla that divides the kidney into 6-8 lobes
Describe the anatomy of the ureters:
- approximately 30 cm long
-the inner mucosa is lined with transitional stratified epithelium and scattered goblet cells that secrete mucus
-longitudinal and circular smooth muscles create the peristaltic contractions that move the urine into the bladder
-a loose layer of collagen and fat anchors the ureters between the parietal peritoneum and the posterior abdomen wall
Describe the anatomy of the urinary bladder:
-partially retroperitoneal (outside the peritoneal cavity)
-the peritoneal covered dome projects into the abdomen when distended with urine
-interior surface is made of transitional cellular epithelium; when empty it resembles columnar epithelia, when distended it resembles squamous epithelia
Describe the anatomy of the urethra:
-transports urine from the bladder to the outside of the body
-the proximal urethra is lined by transitional epithelium
-the terminal portion is stratified non-keratinized squamous epithelium
-in males, there is pseudostratified columnar between the other two types
-the distal urethra is colonized by bacteria/fungi/viruses which render urine unsterile
Describe the anatomy of Nephrons:
-Functional unit of the kidney
-afferent arteriole leads to renal corpuscle
-renal corpuscle consists of the glomerulus surrounded by Bowman’s capsule
-PCT
-loop of henle
-DCT
-collecting duct
What tissue type lines the vasculature of the glomerulus and Bowman’s capsule?
Simple squamous epithelial
Where are all renal corpuscles, PCTs, and DCTs found?
Renal Cortex
Describe the microanatomy of Bowman’s capsule:
-parietal layer is composed of simple squamous epithelium
-visceral layer (over the glomerulus) consists of podocytes, which extend pedicels to cover the glomerular capillaries
Describe the anatomy and function of the PCT:
-composed of simple cuboidal epithelial cells with microvilli
-the microvilli increase surface area for reabsorption and secretion
-these cells actively transport ions across their membranes
Describe the anatomy and function of the loop of Henle:
-descending thick portion consists of simple cuboidal epithelium:
-permeable to water, impermeable to ions
-hypertonic, therefore absorbs water
-ascending thick portion consists of simple cuboidal epithelium
-impermeable to water, permeable to ions
-descending and ascending thin portions consist of simple squamous epithelium
Describe the anatomy and function of the DCT:
-formed by simple cuboidal epithelium
-fewer microvilli
-cells pump against conc. gradient, although less mitochondria than PCT
-sensitive to endocrine hormones:
-anti-diuretic hormone
-aldosterone
-parathyroid hormone
What is anti-diuretic hormone?
-increases H2O absorption, therefore decreasing the volume of urine output
What is aldosterone?
-released when Na conc. is low, causes Na reabsorption, which causes water reabsorption, and this increase of water volume increases blood pressure
What is parathyroid hormone?
-maintains/controls Ca concentration
Describe the anatomy and function of the collecting ducts:
-sensitive to hormones
-each duct collects from several nephrons
-lined with simple squamous epithelium
What happens when collecting ducts are stimulated by ADH?
-cells will insert aquaporin channel proteins into their membranes, allowing water to pass from the duct lumen into the interstitial spaces to be recovered by the vasa recta
-this allows for the recovery of large amounts of water
What happens in the absence of ADH?
-aquaporin channel proteins are not inserted, resulting in the excretion of the water
-results in very dilute urine
