Urinary System (Q4, P3) Flashcards
Main Functions of the Urinary System
- Maintain the chemical consistency of the blood
- Filter many liters of fluid from blood
- Send toxins, metabolic wastes, and excess water out of the body
Secondary Functions of the Urinary System
- Regulates blood volume and blood pressure
- Regulates pH
- Eliminates urea
- Controls electrolytes and metabolites
Organs of the Urinary System
- 2 Kidneys
- 2 Ureters
- 1 Urinary Bladder
- 1 Urethra
Location of Kidneys
- Located retroperitoneally: behind the peritoneum
- Lateral to T12-L3 vertebrae
Size of the Average Kidney
- 12 cm tall (4.7 in)
- 6 cm wide (2.4 in)
- 3 cm thick (1.2 in)
Hilus of the Kidneys (Hilum of 1 Kidney)
- an indentation in the surface of a kidney where blood vessels, ducts, nerve fibers, etc. enter or leave it.
- found on the concave surface of the kidney
Renal Capsule
The fibrous connective tissue that surrounds each kidney.
Renal Cortex
the outer layer of the kidney
Renal Pyramids
- kidney tissues that are shaped like cones
- found in the medulla
Renal Pelvis
- The area at the center of the kidney.
- Urine collects here and is funneled into the ureter, the tube that connects the kidney to the bladder.
Renal Plexus
complex network of nerves in the kidneys
Nephron
- the functional units of the kidney.
- composed of the renal corpuscle and renal tubules
- Each kidney has millions of nephrons
Renal Corpuscle
- the blood-filtering component of the nephron of the kidney.
- Composed of a Glomerulus
and Glomerular/Bowman’s Capsule
Glomerulus
- network of small capillaries known as a tuft, located at the beginning of a nephron in the kidney
- where waste products are filtered from the blood.
- Capillaries are fenestrated-little openings that increase permeability
Bowman’s Capsule
- a cup-like sac at the beginning of the tubular component of a nephron in the kidney that performs the first step in the filtration of blood to form urine.
- A glomerulus is enclosed in the sac.
- Fluids from blood in the glomerulus are collected in the Bowman’s capsule.
Renal Tubules
- long pipe like structure containing the tubular fluid filtered through the glomerulus.
- After passing through the renal tubule, the filtrate continues to the collecting duct system
- Composed of the proximal convoluted tubule, Loop of Henle, and the distal convoluted tubule
Proximal Convoluted Tubule
- the segment of the nephron in kidneys which begins from the renal pole of the Bowman’s capsule to the beginning of loop of Henle. (in the renal cortex)
- lined by simple cuboidal epithelium with brush borders which help to increase the area of absorption
- responsible for the reabsorption and secretion of some water and some salts.
Loop of Henle
- Long U-shaped portion of the renal tubule that conducts urine within each nephron of the kidney
- helps concentrate filtrate
Distal Convoluted Tubule
- portion of kidney nephron between the loop of Henle and the collecting tubule.
- reabsorbs some water and some salts
Collecting Ducts/Tubules
The last part of a long, twisting tube that receives urine from the distal convoluted tubules
Mechanisms of Urine Production
- Filtration
- Reabsorption
- Secretion
Filtration
Filtrate of blood leaves kidney capillaries
Reabsorption
most nutrients, water, and essential ions are reclaimed
Secretion
Active process of removing undesirable molecules
Flow of Urine through the Renal Structures
Renal Corpuscle (Glomerulus
and Glomerular/Bowman’s Capsule)
Proximal Convoluted Tubule
Loop of Henle
Distal Convoluted Tubule
Collecting Ducts
Papillary Ducts
Minor Calices
Major Calices
Renal Pelvis
Ureters
Bladder
Urethra
Ureters
- Carry urine from the kidneys into the urinary bladder
- oblique entry into bladder prevents backflow of urine
Urinary Bladder
- A collapsible muscular sac
- Stores and expels urine
Shape of the Full Bladder
- Spherical
- Bladder expands into the abdominal cavity
Shape of the Empty Bladder
Lies entirely within the pelvis
Urethra
the hollow tube that lets urine leave the body
- Epithelium
- composed of the internal urethral sphincter and the external urethral sphincter
Internal Urethral Sphincter
- Involuntary smooth muscle
- regulates involuntary control of urine flow from the bladder to the urethra
External Urethral Sphincter
- voluntarily inhibits urination
- provides voluntary control of urine flow from the bladder to the urethra
External Urethral Orifice
the external opening (or meatus) of the urethra.
Length of Urethra in Females
3–4 cm
Length of Urethra in Males
- 20 cm in length
- Three regions: prostatic, membranous, spongy/penile
Prostatic urethra
- Passes through the prostate gland
- first portion of the male urethra
Membranous Urethra
Through the urogenital diaphram
Spongy/Penile Urethra
Passes through the length of the penis
Renal Medulla
Medial layer of the kidney
