Urinary System Functions

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Questions and Answers

What is the function of the mesangial cells in the renal corpuscle?

Forming the filtration slit pores

Providing structural support to the glomerular capillaries and regulating blood pressure (correct)

Filtering the blood

Secreting hormones that regulate electrolyte balance

What is the name of the capillary network that forms after the efferent arterioles in the cortex?

Glomerular capillaries

Peritubular capillaries (correct)

Vasa recta

Interlobar capillaries

What is the term for the elongated spaces between the interdigitating pedicles of podocytes?

Filtration slit pores (correct)

Fenestrae

Slit diaphragms

Capsular space

What is the function of the podocytes in the renal corpuscle?

To create the filtration apparatus of the kidney Signup and view all the answers

What is the term for the outer layer of the glomerular capsule?

Parietal layer Signup and view all the answers

What is the name of the arterioles that lead into a network of capillary loops known as glomerulus?

Afferent arterioles Signup and view all the answers

What is the term for the structure formed by the fusion of the basal lamina from both the endothelial cells of the capillary and podocytes?

Glomerular basement membrane Signup and view all the answers

What is the function of the proximal convoluted tubule?

Reabsorption and secretion within the nephron Signup and view all the answers

What is the term for the bundle of capillary loops that penetrate deep into the medulla?

Vasa recta Signup and view all the answers

What is the function of the slit diaphragms in the renal corpuscle?

To regulate the passage of substances during filtration Signup and view all the answers

What is the primary role of the urinary system?

Ensuring optimal blood properties Signup and view all the answers

Which of the following is NOT a function of the kidneys?

Stimulation of immune response Signup and view all the answers

What is the role of the kidneys in maintaining acid-base balance?

They excrete hydrogen ions and reabsorb bicarbonate Signup and view all the answers

What is the function of renin?

To increase blood pressure Signup and view all the answers

What is the role of the kidneys in vitamin D metabolism?

They convert vitamin D to its active form Signup and view all the answers

What is the role of the kidneys during starvation or periods of fasting?

To synthesize glucose from amino acids Signup and view all the answers

What is the function of the ureters?

To release urine from the kidneys Signup and view all the answers

What is the thin layer that covers the kidneys?

A thin fibrous layer Signup and view all the answers

What is the hilum?

Where nerves enter and the ureter exits Signup and view all the answers

What is the role of the urinary system in regulating electrolyte balance?

To regulate electrolyte levels for cell functioning Signup and view all the answers

What type of cells are found in the renal cortex?

Fibroblast-like cells and macrophages Signup and view all the answers

What is the primary function of the proximal convoluted tubule?

Reabsorption of a majority of the filtrate Signup and view all the answers

What is the main function of the descending limb of the loop of Henle?

Reabsorption of water Signup and view all the answers

What type of tissue surrounds the renal pelvis and calyces?

Adipose tissue Signup and view all the answers

What is the name of the space within Bowman's capsule where the initial filtrate is collected?

Bowman's space Signup and view all the answers

What is the function of the collecting duct?

Concentration of the urine and reabsorption of water Signup and view all the answers

What are the two types of cells found in the renal medulla?

Myofibroblasts and fibroblasts Signup and view all the answers

What is the function of the distal convoluted tubule?

Reabsorption of ions and water Signup and view all the answers

What is the main function of tubular secretion?

Elimination of additional wastes and maintenance of acid-base balance Signup and view all the answers

What is the term for the tip of each renal pyramid that projects into a minor calyx?

Renal papilla Signup and view all the answers

What is the primary function of the distal convoluted tubule?

Regulated reabsorption influenced by aldosterone Signup and view all the answers

What type of epithelium lines the mucosa of the ureters?

Transitional epithelium Signup and view all the answers

What is the function of the detrusor muscle in the bladder?

Propelling urine through peristaltic contractions Signup and view all the answers

What is the role of umbrella cells in the urothelium?

Protecting underlying cells from urine's hypertonicity Signup and view all the answers

What is the structure of the urethra in females?

Initially lined with transitional epithelium, transitioning to nonkeratinized stratified squamous epithelium Signup and view all the answers

What is the function of the loop of Henle?

Reabsorption of essential substances Signup and view all the answers

What is the name of the specialized junctions and membrane structures found in umbrella cells?

Uroplakins Signup and view all the answers

What is the function of the muscularis layer in the ureters?

Propelling urine through peristaltic contractions Signup and view all the answers

What is the name of the muscle that surrounds the middle part of the urethra in both sexes?

External sphincter of striated muscle Signup and view all the answers

What is the normal volume of urine stored in the bladder of an average adult?

400-600 mL Signup and view all the answers

Study Notes

Urinary System Components

The urinary system consists of:
- 2 kidneys
- 2 ureters
- Bladder
- Urethra

Kidney Functions

Regulate the balance between water and electrolytes and the acid-base balance
Excrete metabolic wastes along with excess water and electrolytes in urine
Excrete bioactive substances including drugs
Secrete renin
Secrete erythropoietin (in the proximal convoluted tubule)
Convert vitamin D (in the proximal convoluted tubule)
Maintain pH levels and regulate blood pressure
Perform glycogenesis during starvation or periods

Kidney Structure

Each kidney has a hilum, where nerves enter and the ureter exits
The kidneys are covered by a thin fibrous layer
The outer layer consists of fibroblasts and collagen fibers
The inner layer is made of myofibroblasts that resist volume and pressure
Inside the hilum, the upper end of the ureter expands and becomes the renal pelvis
The renal pelvis divides into two or three major calyces, which then turn into minor calyces
The area surrounding the renal pelvis and calyces has adipose tissue
The parenchyma (functional tissue) of the kidney is divided into renal cortex and renal medulla
The renal cortex is an outer darker region containing renal corpuscles and tubules
The renal medulla is the inner region consisting mostly of aligned linear tubules and ducts

Nephron Structure and Functions

Nephrons are functional units that filter blood and form urine
Each nephron consists of a corpuscle and a long renal tubule
The renal corpuscle contains a glomerulus and Bowman's capsule
The glomerulus is a tuft of capillaries where blood filtration begins
Bowman's capsule collects the filtrate from the blood
The renal tubule is divided into several segments, each with specific functions in processing the filtrate
The proximal convoluted tubule (PCT) reabsorbs a majority of the filtrate
The loop of Henle is a U-shaped structure with descending and ascending limbs
The distal convoluted tubule (DCT) continues to reabsorb ions and water, under the influence of hormones
The collecting duct receives filtrate from multiple nephrons and reabsorbs water and concentrates the urine

Blood Flow in the Kidneys

The renal arteries transport oxygenated blood from the heart and aorta to the kidneys for filtration
The renal veins transport filtered deoxygenated blood from the kidneys to the heart
The renal arteries enter each kidney at the hilum and divide into segmental arteries
The segmental arteries branch into interlobar arteries, which extend from the renal pyramids to the corticomedullary junction

Renal Corpuscle

The renal corpuscle contains a glomerulus surrounded by a epithelial capsule called the glomerular capsule
The visceral layer is made of stellate epithelium called podocytes
The podocytes have primary processes that extend and curve around the glomerular capillaries
The filtration apparatus is made of podocytes and capillary endothelial cells
The filtration slit pores and slit diaphragms regulate the passage of substances during filtration

Proximal Convoluted Tubule (PCT)

The PCT reabsorbs a majority of the filtrate, including water, ions, and nutrients
The PCT cells are highly specialized for their role in reabsorption and secretion within the nephron
The PCT has a dense brush border, abundant mitochondria, and extensive membrane invaginations

Loop of Henle

The loop of Henle is a U-shaped structure with descending and ascending limbs
The thin descending limb and thin ascending limb have simple squamous epithelium and organelles
The thick ascending limb has simple cuboidal epithelium and many mitochondria

Distal Convoluted Tubule (DCT)

The DCT performs regulated reabsorption while influenced by the hormone aldosterone from the adrenal glands
The DCT cells are smaller and flatter compared to those in the PCT

Ureters

The ureters are muscular tubes that transport urine from the renal pelvis of the kidneys to the urinary bladder
The ureters have three layers: mucosa, muscularis, and adventitia
The ureters move urine towards the bladder via peristaltic contractions and prevent backflow into the kidneys as the bladder fills

Urinary Bladder

The bladder is a hollow organ with a highly expandable wall consisting of mucosa, muscularis, and adventitia
The bladder stores urine (400-600 mL in an average adult) and expels it during micturition

Urothelium (Transitional Epithelium)

Found in the renal pelvis, ureters, bladder, and parts of the urethra
Consists of basal cells, intermediate cells, and umbrella cells
Protects underlying tissues from the toxic effects of urine and allows the bladder to stretch and contract

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Description

This quiz covers the key components and functions of the urinary system, including its role in regulating balance, excretion, and secretion of various substances.