The Urinary System Flashcards
Primary role is excretion of waste
Urinary system functions
Bean-shaped retroperitoneal organs
Kidneys
Kidneys are covered by 3 layers of tissue:
- Renal fascia (outer)
- Adipose capsule
- Renal capsule
Dense irregular CT binds kidney to abdominal wall
- Renal fascia (outer)
Mass of fatty tissue for protection
- Adipose capsule
Transparent sheet of dense irregular CT over kidney surface: serves as a barrier against trauma and maintains shape of organ
- Renal capsule
Kidney:
Ureter, renal arteries and vein located in indented ______ region
Hilus
Kidney have 2 main regions:
- cortex
2. medulla
Contains renal pyramids
Medulla
Functional unit is the ______
- are cortical (85%) and juxta-medullary nephrons (JMN) (15%)
Nephron
Nephron:
Consists of 2 parts:
- renal corpuscle
2. renal tubule
Formed by the glomerulus and the cup-like Bowman’s capsule
- renal corpuscle
Extends from the Bowman’s capsule as the proximal convoluted tubule, straightens to form the loop of Henle, and then becomes the distal convoluted tubule
- renal tubule
Renal tubules mainly have simple ______ epithelium (good for absorption/secretion)
Cuboidal
Many distal convoluted tubules open into a single:
collecting duct
Collecting ducts open into papillary ducts at the tip of a pyramid which drain into the:
minor calyx
Urine formed in the nephron drains into (pathway):
minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra
glomerulus → Bowman’s capsule → PCT → loop of Henle → DCT → collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra
Pathway of Urine Flow
_______ artery supplies blood to kidney (delivers ~1200 ml/min of blood flow through both kidneys)
Renal
Divides numerous times to give rise to:
Afferent arterioles
Each afferent arteriole supplies blood to 1 nephron forming a capillary tuft, the:
Glomerulus (ball-shaped)
Blood leaves the glomerulus by an:
Efferent arteriole
Efferent arteriole gives rise to:
Peritubular capillaries
Vasa recta
Found in cortex
Peritubular capillaries
Found in medulla
Vasa recta
______ vein drains venous blood from the kidneys
Renal
Urine formation consists of 3 processes:
- Glomerular Filtration
- Tubular Reabsorption
- Tubular Secretion
Process by which water and solute molecules in the blood plasma pass from the glomerulus into Bowman’s capsule forming the filtrate that enters the capsular space
Glomerular Filtration
Filter substances according to:
SIZE
______ water, glucose, amino acids, Na+, Cl- (and other ions), nitrogenous wastes (ammonia, urea, creatinine), fatty acids, electrolytes and vitamins
Filter
Most large anions, protein-bound minerals, hormones, cells and large proteins are ________ in the blood due to their large size
Retained
Filtration process is efficient because the:
Glomerulus is coiled and has a large ____________
Surface Area
Filtration process is efficient because the:
Filtration membrane between the glomerulus and Bowman’s capsule is:
Thin and porous
= glomerular endothelial cell pores + glomerular basement membrane + podocyte filtration slits of cells in inner wall of Bowman’s capsule
Filtration membrane
Filtration process is efficient because the:
Blood pressure in glomerulus is very high because the efferent arteriole is smaller in diameter than _____ arteriole
Afferent
This ↑ blood pressure to ___ mmHg (only 18 mmHg in other capillary beds)
55
Glomerular filtration depends on pressures that promote and _________ filtration
Oppose
We actually only produce 1-2 L of urine/day because the remaining 179 L of filtrate is reabsorbed. This means ___% of the filtrate gets reabsorbed!
99%
A selective process that removes substances from the filtrate and returns them to the blood
Tubular Reabsorption
Majority of water and solute reabsorption (Na+, K+, Ca+2, HCO3-, HPO4-, Cl-) from the filtrate occurs in the:
Proximal Convoluted Tubule
All ______ and _______ _____ are reabsorbed by facilitated diffusion and co-transport
Glucose; amino acids
_____ is reabsorbed by diffusion
Urea
Small proteins are reabsorbed by:
Pinocytosis
- a selective process which removes substances from the blood and adds them to the filtrate
- occurs mainly in the proximal and distal convoluted tubules
- dispose of unwanted substances such as urea, uric acid, bile salts, ammonia and creatinine
Tubular Secretion
Secretion of H+ (if blood pH ↓) and HCO3- (if blood pH ↑) serves to regulate _____ of the blood
pH
Hormones regulate ______ reabsorption and secretion
Tubular
Hormones that regulate kidney functions:
- Antidiuretic Hormone (ADH)
- Renin – Angiotensin System
- Aldosterone
Made by neurons in hypothalamus and stored in posterior pituitary gland
Antidiuretic Hormone (ADH)
ADH released from the posterior pituitary if solute concentration in blood __________
Blood volume _________
Increases; decreases
ADH increases the permeability of the distal convoluted tubules and collecting ducts so more water is ________
- result → less urine volume and urine is more concentrated
Reabsorbed
2 cell types in DCT + collecting ducts
1) Principle cells (most abundant)
2) Intercalated cells
Receptors for ADH and aldosterone (from adrenal gland)
- involved in salt/water balance
Principle cells
Most abundant cells in DCT + collecting ducts
Principle cells
The ____________ cells reabsorb K+ and secrete H+
Involved in acid/base balance for homeostasis of blood pH
Intercalated cells
ADH induces tubule cells in DCT/collecting ducts to synthesize _______ (water-channel proteins) and install them in the plasma membrane – more water passes through epithelial cell into blood
Aquaporins
In the absence of Antidiuretic hormone (ADH), DCT (distal convoluted tubule) and collecting ducts are _________ to water
- result → large volume of dilute urine
Impermeable
_______ inhibits ADH production more alcohol you drink → produce less ADH → DCT and collecting ducts remain impermeable to water → have to urinate more frequently as you need to expel an ↑ volume of dilute urine
Ethanol
Are modified smooth muscle cells of the afferent arteriole lying next to the DCT
Juxtaglomerular (JG) cells
Renin – Angiotensin System:
Stimulated by a decrease in BP
JG cells secrete the enzyme _____
Renin
Renin begins a series of steps that convert angiotensinogen to the active form of:
Angiotensin II
- potent vasoconstrictor
- stimulates adrenal cortex to release aldosterone
- stimulates posterior pituitary to release ADH
- stimulates the thirst center in hypothalamus so drink more water
Angiotensin II
Hormone released by the adrenal gland cortex
Acts on the DCT to increase Na+, Cl- and water reabsorption
Increases K+ tubular secretion
Aldosterone
Hormone released by the adrenal gland cortex in response to Angiotensin II
A decrease in [Na+] or an increase in [K+] in blood plasma
Aldosterone
Transport urine from the renal pelvis of the kidney to the posterior wall of the bladder (about 25 cm long)
Inner layer consists of transitional epithelium
Middle muscularis has an inner circular and outer longitudinal layer of smooth muscle
Ureters
Ureters inner layer consists of:
Transitional epithelium
Ureters middle muscularis has an inner circular and outer longitudinal layer of:
Smooth muscle
_______ waves of the smooth muscle (initiated by stretching of ureter due to urine) move urine through the ureters
Peristaltic
_______ pressure and gravity aid urine movement
Hydrostatic
Distensible sac that functions in the temporary storage of urine
Urinary bladder
Average capacity of the bladder is 500 ml to a maximum of _______ ml
700-800
Urinary bladder lined with transitional epithelium with ____
Rugae
Urinary bladder muscularis layer is called the _______________ - consists of 3 layers of smooth muscle
Detrusor muscle
Urinary bladder contains an internal urethral sphincter of smooth muscle at the opening to the:
Urethra
Leads from the floor of the bladder to the exterior
Urethra
In females, the urethra is ___ cm long and opens anterior to the vagina
4
In males, the urethra is about ___ cm long
20
In males, the urethra is about 20 cm long and has 3 regions:
Prostatic urethra
Membranous (Intermediate) urethra
Spongy urethra
_______ urethra (2.5 cm through prostate gland)
Prostatic
_______ urethra (through muscular floor of pelvic cavity)
Intermediate
_______ urethra (passes through penis)
Spongy
External urethral sphincter of skeletal muscle (_______ control over urination) located lower down urethra
Voluntary
Process of voiding urine (urination)
Micturition
When bladder contains about _______ ml of urine, stretch receptors in the wall are stimulated
200-400
Micturition:
Transmit nerve impulses to ______ region of the spinal cord
Sacral
Micturition:
Relayed to:
Pons and cerebrum
When a conscious effort is made to urinate, impulses from pons cause contraction of ______ muscle and relaxation of the internal and external sphincters
Detrusor
Results from the breakdown of creatine phosphate in skeletal muscle
It is the nitrogenous waste product from the normal breakdown of muscle tissue and will be removed by the kidneys
CREATININE
Most CREATININE is filtered into the Bowman’s capsule during _______ filtration
Glomerular
Any remaining CREATININE will be secreted into the filtrate of the Proximal ______ ______
Convoluted Tubule
It is ________ (the breakdown product of creatine) that is secreted into the filtrate if it was missed being filtered during glomerular filtration
Your body does not need this nitrogenous waste product
CREATININE
Most CREATININE will be filtered and the rest will be secreted into the ____________ ___________ ________
Proximal Convoluted Tubule
Plasma CREATININE can be used as a measure of _______ function
Kidney
Plasma CREATININE level remains steady because the rate of _______ in urine should equal its discharge from muscle fibers
Excretion
So an increase in plasma CREATININE indicates ______ kidney function because it is not being eliminated by the kidneys like it should be
Poor
The urinary system removes nitrogenous wastes:
Urea, ammonia, creatinine
The urinary system regulates water content of ECF & ICF to maintain a constant osmolarity of ___M
0.3
The urinary system _______ plasma Na+, K+, Ca+2, phosphate and other ions (excrete excess ions)
Regulates
The urinary system regulates blood ___ (excrete H+ & conserve HCO3-)
pH
The urinary system produces _________ (endocrine: stimulates RBC production)
Erythropoietin
The urinary system releases enzyme _____ which activates hormonal mechanisms that control BP
Renin
The urinary system consists of 6 organs:
2 kidneys, 2 ureters, 1 urinary badder, 1 urethra
3 layers of tissue in kidney (from outer to inner):
Renal fascia
Adipose capsule
Renal capsule
Outer region of kidney:
Renal cortex
Inner region of kidney:
Renal Medulla
Have long loops of Henle that extend to the tip of the renal pyramids
- maintain a salt gradient in medulla that helps the body conserve water
Juxta-medullary nephrons (JMN)
Glomerulus + Bowman’s Capsule =
Renal Corpuscle
Each ________ arteriole supplies blood to 1 nephron forming a capillary tuft, the glomerulus (ball shaped)
Afferent
Blood leaves the glomerulus by an _______ arteriole
Efferent
Drains venous blood from the kidneys
Renal vein
Has a coiled and large surface area
Glomerulus
Glomerular endothelial cell pores + glomerular basement membrane + podocyte filtration slits of cells in inner wall of Bowman’s capsule =
Filtration membrane
Na+ goes first through _____ and _____ processes
Active; passive
2 routes of reabsorption for Na+
- Trancellular route
2. Paracellular route
ACTIVE process, substances pass through cytoplasm of tubule cell & then use Na+/K+ pump
Trancellular route
PASSIVE process, substances pass between tubule cells
Paracellular route
Males carry both ______ and ______ in urethra
That is where they open to the external enviroment
Sperm; urine
Glomerular filtration rate (GFR) remains fairly ___________
Constant
If too high, fluid flows through tubules too fast; unable to reabsorb water & solutes = results in:
Dehydration and electrolyte depletion
If too low, fluid flows too slow; body starts to reabsorb _______ that should be eliminated
Wastes
Can adjust _____ by changing glomerular blood pressure (GBHP) through renal autoregulation, neural regulation and various hormonal controls
GFR
The kidneys are stimulated to produce renin by a decrease in _______________
Blood pressure
The adrenal glands are located:
Atop the kidneys
The renal corpuscle is made up of:
Bowman’s capsule and glomerulus
The vasa recta supplies the:
Loop of Henle
Removal of nitrogenous wastes
Regulation of blood pH
Production of a hormone needed for red blood cell production
Functions of the urinary system
The transcellular route of Na+ reabsorption is a ________ process.
ACTIVE
Damage to the renal medulla would interfere first with the functioning of the:
Collecting ducts
Urine is carried from the kidneys to the urinary bladder by the:
Ureters
The muscularis layer of the urinary bladder is called the ________ muscle.
Detrusor
The tissue that binds the kidney to the abdominal wall is the:
Renal fascia
