Urinary system Flashcards
What is the function of the Urinary system
The urinary system’s function is to filter blood and create urine as a waste by-product.
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 red blood cells
- perform the final synthesis step of vitamin D production
- providing the anatomical structures to store urine until the body is able to dispose.
Where does the Urinary systems ability to filter blood reside?
2 to 3 million tufts of specialized capillaries (the glomeruli) distributed equally between the two kidneys.
What is the first part of the nephron?
Bowman’s capsule – first part of the nephron where blood is initially filtered (to form filtrate).
Normal urine output volume:
1-2 litres/day
What does Oliguria mean?
Output of urine is below level may be caused by severe dehydration
What does Anuria mean?
The virtual absence of urine production.
What does Ployuria mean?
Excessive urine production, which may be due to diabetes mellitus or diabetes insipidus.
What is the minimum urine output volume?
500 mL/day
Location of the Kidneys:
kidneys lie on either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, well protected by muscle, fat, and ribs.
Describe the internal anatomy of the kidney:
- Outer region: renal cortex
- Inter region: medulla
- Renal columns: connective tissue extensions that radiate downward from the cortex through the medulla that divides the kidney into 6-8 lobes.
Describe the anatomy of the Ureters:
- ureters are approximately 30 cm long.
- inner mucosa is lined with transitional epithelium and scattered goblet cells that secrete protective mucus.
- longitudinal and circular smooth muscles that create the peristaltic contractions to move the urine into the bladder.
- loose adventitial layer composed of collagen and fat anchors the ureters between the parietal peritoneum and the posterior abdominal wall.
Describe the anatomy of the urinary bladder:
- partially retroperitoneal(outside the peritoneal cavity)
- peritoneal-covered “dome” projecting into the abdomen when the bladder is distended with urine
- interior surface is made of transitional cellular epithelium
- When empty, it resembles columnar epithelia, but when stretched, it “transitions” to a squamous appearance
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
- terminal portion is a non-keratinized, stratified squamous epithelium.
- In males there is pseudostratified columnar epithelium between two cell types.
Describe the anatomy of the nephron:
- functional unit of the kidney
- Afferent arteriole leads to renal corpuscle
- the afferent arterioles lead into a glomerulus
- Renal corpuscle consists of the glomerulus surrounded by Bowman’s capsule
- PCT
- loop od 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 Bowmans capsule:
- the parietal layer, is a 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 consists 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?
Increase water absorption, therefore decreasing the volume of urine output
What is aldosterone?
- released when Sodium concentration is low, causes sodium reabsorption, which causes water reabsorption, and this increase of water volume increases blood pressure.
What is parathyroid hormone?
- Maintains and controls calcium 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?
When ADH is present, the collecting duct becomes permeable to water.