Human Anatomy CH 24 Flashcards
What are the 3 main functions of the kidneys?
- Maintain the chemical consistency of blood
- Filter many liters of fluid from blood
- Send toxins, metabolic wastes, and excess water out of body
What are the 3 main waste products? What can they be generalized as?
Nitrogenous compounds
1. Urea
2. Uric acid
3. Creatinine
What organ is red-brown in color?
Kidneys
Where are the kidneys located? It is lateral to which vertebrae?
Retroperitoneally (behind peritoneum); lateral to T12-L3
What are the length, width, and height of the kidney?
12 cm tall, 6 cm wide, 3 cm thick
What is the concave surface of the kidney where vessels and nerves enter and exit?
Hilum
What is the capsule that surrounds the kidneys called? What is its function?
Fibrous Capsule
Inhibits spread of infections
What kind of tissue is the Fibrous Capsule made out of?
Dense connective tissue
What is external to the renal capsule?
Perirenal fat capsule
What is external to the perirenal fat capsule? What does this contain?
Renal fascia; contains fat
What is the superficial region of the kidney with a granular appearance?
Renal cortex
What is the renal medulla consisted of?
Cone-shaped renal pyramids
What 2 things compose the renal pelvis?
- Major calices
- Minor calices
What arteries branch into the segmental arteries? The segmental arteries branch into what arteries? What arteries branches off from the previous arteries?
Renal artery —> segmental arteries —> interlobar arteries —> arcuate arteries
Where is the nerve supply for the kidneys?
Renal plexus
What is the renal plexus? What is it an offshoot of?
Network of autonomic fibers that is an offshoot of the celiac plexus
The renal plexus is supplied by ____________ fibers from which 2 nerves?
Sympathetic fibers
1. Lowest thoracic splanchnic nerve
2. First lumbar splanchnic nerve
What is the functional unit of the kidney called? How many are present in each kidney?
Nephron
Over 1 million nephrons present in each kidney
What happens in filtration?
Filtrate of blood leaves kidney capillaries
What happens in resorption?
Most nutrients, water, and essential ions are reclaimed
What happens in secretion?
Active process of removing undesireable molecules
What 2 structures is a Nephron composed of?
- Renal tubule
- Renal corpuscle
What is the first part of the nephron called?
Renal corpuscle
What is the fenestrated tuft of capillaries within the Nephron called?
Glomerulus
What 2 layers makes up the Glomerular (Bowman’s) Capsule? What are these layers consisted of?
HINT: One of them is asking for tissue type
- Parietal layer - simple squamous epithelium
- Visceral layer - consists of podocytes
Where does the filtration membrane lie?
Lies between blood in glomerulus and capsular space
What 3 layers does the filtration membrane consist of? Where does each one lie?
- Filtration slits between foot processes of podocytes - Innermost
- Basement membrane - Middle
- Fenestrated endothelium of the capillary - Outermost
The basement membrane and slit diaphragm hold back what?
Most proteins
The basement membrane and slit diaphragm allows passage of what 5 substances?
- Water
- Ions
- Glucose
- Amino Acids
- Urea
Filtrate proceeds to what from the glomerulus?
Renal tubules
What tubule connects (comes before) the nephron loop?
Proximal convoluted tubule
The nephron loop connects to what 4 parts? Name them in order
- Descending limb
- Descending thin limb (DTL)
- Ascending thin limb (ATL)
- Thick ascending limb (TAL)
The distal convoluted tubule connects (comes before) what?
Collecting ducts
What 2 functions does the collecting ducts have?
- Receives urine from several nephrons
- Plays important role in conserving body fluids
What gland secretes ADH? What does the secretion of ADH help with?
Posterior pituitary gland
Increases permeability of collecting ducts and distal convoluted tubules to water
What are the 2 classes of nephrons? What percentage of nephron does each one respectively make up?
- Cortical nephrons - 85% of nephrons
- Juxtamedullary nephrons - 15% of nephrons
What is the function of the juxtamedullary nephrons?
Contributes to kidney’s ability to concentrate urine
What 2 capillary beds do nephrons closely associate with?
- Glomeruli
- Peritubular capillaries/vasa recta
What are capillary beds called in cortical nephrons? What are they called in juxtamedullary nephrons?
- Cortical nephrons - Peritubular capillaries
- Juxtamedullary nephrons - Vasa recta
What is the main function of Glomeruli? How much fluid does it produce at what rate? What percentage of it is then resorbed by tubules?
Produces filtrate that becomes urine at a rate of 1 liter every 8 minutes. 99% is resorbed by tubules
Glomeruli is fed and drained by which 2 arterioles?
- Afferent glomerular arteriole
- Efferent glomerular arteriole
Efferent arteriole has a _______ diameter than afferent arteriole
smaller
What arises from the efferent arterioles draining cortical glomeruli?
Peritubular capillaries
The peritubular capillaries are specifically adapted for? What are some features for this adaptation?
- Adapted for absorption
- Low pressure, porous capillaries
Are all molecules secreted by nephrons into urine from the peritubular capillaries?
Yes
What continues from the efferent arterioles of juxtamedullary nephrons?
Vasa recta
What are vasa recta?
Thin-walled looping vessels
Where do the vasa recta descend to?
Medulla
What mechanism is the vasa recta part of?
Part of kidney’s urine concentrating mechanism
What is the Juxtaglomerular Complex?
Area of specialized contact between terminal end of the ascending limb and afferent arteriole
What is the function of the Juxtaglomerular Complex?
Regulating blood pressure
What are granular cells?
Modified smooth muscle cells
Granular cells contain what hormone? When is it secreted?
Renin is secreted in response to falling blood pressure in afferent arteriole
What is the end of the nephron loop called?
Macula Densa
Where is the Macula Densa located adjacent to?
Adjacent to granular cells
What is the macular densa made out of? (Tissue)
Tall, closely packed epithelial cells
What are the 2 main functions of the macula densa? The secreted hormone initiates what mechanism?
- Monitor solute concentration in the filtrate
- Signals granular cells to secrete renin which activates renin-angiotensin mechanism
What cells interact with the macula densa and granular cells? What is its function?
Extraglomerular mesangial cells help regulate blood pressure
What cells are located around the base of the glomerulus? What do they do within the glomerulus?
Mesangial cells regulate blood flow within the glomerulus
What organ carries urine from the kidneys to the urinary bladder?
Ureters
The oblique part of the ureter does what?
Oblique entry into bladder prevents backflow of urine
What 3 layers is the ureter made out of?
- Mucosa
- Muscularis Externa
- Adventita
What type of tissue is the mucosa of the ureter made out of?
Transitional Epithelium
The Muscularis Externa of the ureter has what 2 layers?
- Inner longitudinal layer
- Outer circular layer
What kind of tissue makes up the Adventitia of the ureter?
Fibroelastic connective tissue
What is the urinary bladder? What is its function?
Collapsible muscular sac
Stores and expels urine
What is a full bladder like and where is it located? What is an empty bladder like/where is it located?
Full bladder - Spherical - expands into the abdominal cavity
Empty bladder - lies entirely within the pelvis
What is the closed remnant of the allantois called?
Urachus
What is located directly inferior to the bladder and only in males? What does it surround?
Prostate; surrounds the urethra
The urinary bladder is composed of what 3 layers? What type of tissue are they composed of?
- Mucosa - transitional epithelium
- Thick muscular layer called detrusor
- Fibrous adventita
What are the 3 types of epithelium tissue that makes up the urethra? Where is each one located?
- Transitional epithelium - at proximal end near bladder
- Stratified and pseudostratified columnar - mid urethra in males
- Stratified squamous epithelium - at distal end near urethral opening
What kind of muscle is the internal urethral sphincter made out of?
Involuntary smooth muscle
What are the 2 ‘functions’ of the external urethral sphincter
- Voluntarily inhibits urination
- Relaxes when one urinates
How many cm is the urethra in females? In males?
Females: 3-4 cm
Males: 20 cm
What 3 regions of the urethra are only present in males? What does each one pass through?
- Prostatic urethra - passes through the prostate gland
- Intermediate part of urethra - through urogenital diaphragm
- Spongy (penile) urethra - passes through length of penis
What disorder is more common in females and causes a burning sensation during micturition?
Urinary tract infection (UTI)
What is another name for kidney stones?
Renal calculi
Bladder cancer consists of what percentage of cancers?
3%
Kidney cancer arises from what?
Epithelial cells of uriniferous tubules
The embryo develops what 3 pairs of kidneys?
- Pronephros
- Mesonephros
- Metanephros
Which pair of kidneys is the only one to persist to become the adult kidneys?
Metanephros
What is the name of the kidney that produces urine in the fetal stage? At what month does it produce urine?
Metanephric kidney produces urine by fetal month 3
The metanephros/metanephric kidney contributes to the volume of _________?
amniotic fluid
As the kidney and bladder function declines with advancing age, what 5 things occur?
- Nephrons decrease in size and number
- Tubules are less efficient at secretion and resorption
- Filtration declines
- Recognition of desire to urinate is delayed
- Loss of muscle tone in the bladder