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What are the functions of the Urinary System?
- 1. Excretion of metabolic waste
- 2. Regulation of fluid & electrolyte balance
- 3. Regulation of blood acidity (pH)
- 4. Regulation of blood volume & blood pressure by the enzyme Renin (kidney)
- 5. Production of Erythropoietin hormone that stimulate bone marrow for RBC formation
- 6. Activation of Vitamin D to Calcitriol that stimulate intestinal absorption of Calcium
What is the only functional part of the Urinary system?
- The 2 kidneys are the only functional part.
- 2 Ureters are tubes
- Urinary bladder is a holding bowl
- Urethra is a tube
What covers the kidney?
What is the outer region of the kidney?
What is the inner region of the kidney with the renal pyramids?
What is the apex or renal tip of the renal pyramid?
What is the cortical tissue between the renal pyramids?
What part recieves urine from the renal papilla?
What collects urine from two or more minor calyces?
What collects urine from all major calyces?
What carries urine from renal pelvis to bladder?
What is the Nephron?
Microscopic filtering unit of the kidneys that consist of a renal corpuscle and renal tubules
What percent of nephrons are found in the renal cortex?
85% and they are called Cortical Nephrons
What percent of nephrons are found in the renal pyramids?
15% and they are called juxtamedullary nephrons or medullary nephrons
What is the renal corpuscle made up of?
- Loops of capillaries called glomerulus
- Double layered bowman's capsule surrounds glomerulus
What are the renal tubules?
- Proximal convoluted tubule - connects to bowman's capsule
- Loop of Henle - with descending and ascending limbs
- Distal convoluted tubule - is distal part of nephron
- Collecting duct - connects to several DCT's
What are the 4 processes required for urine formation?
- 1. Filtration from glomerulus capillaries blood into Bowman's capsular space to form filtrate
- 2. Tubular Reabsorption from filtrate into blood
- 3. Tubular Secretion from blood into filtrate
- 4. Excretion of the final product as urine
High glomerular capillary blood pressure of ?mmHg forces water and dissolved solutes through the glomerular capillary wall into bowman's capsular space to form initial filtrate?
What is the ?mmHg (pressure) in normal capillaries?
What is filtered into Bowman's capsule?
Only water and dissolved solutes
What is not allowed into Bowman's Capsule?
No plasma proteins or blood cells are filtered
What does filtrate consist of?
- Waste products such as urea and uric acid that must be eliminated in the urine.
- Useful substances such as water, organic nutrients and electrolytes that must be kept
What is the term and abbreviation for the amount of blood flow thru the kidneys in one minute?
Renal Blood Flow (RBF)
What is the term and the abbreviation for the amount of filtrate formed by kindeys in one minute?
Glomerular Filtrate Rate (GFR)
What % of renal blood becomes filtrate? What % of renal blood passes again and again.....?
- 10% becomes filtrate
- 90% cycles again and again
What controls the regulation of GFR?
- Regulation is by controlling glomerular blood flow.
- Dialation of afferent (arrive) arteriole and constriction of efferent (exit) arteriole increase GFR
- Constriction of the afferent (arrive) arteriole and dilation of the efferent (exit) arteriole decreases GFR
Dialation of afferent (arrive) arteriole and constriction of efferent (exit) arteriole does what to the Glomerular Filtration Rate or GFR?
Constriction of the afferent (arrive) arteriole and dilation of the efferent (exit) arteriole does what to the Glomerular Filtration Rate or GFR?
What are the three regulations of the Glomerular Filtration Rate or GFR?
- 1. Autoregulation - Regulation of the GFR by the kidneys themselves
- 2. Neural Regulation - Autonomic Nervous System (ANS) affects GFR
- 3. Hormonal Regulation - Hormones indirectly affect GFR.
- *Done by controlling glomerular blood flow
What is most of the filtrate moved from the nephron tubules back into?
- Capillaries blood
- (peritubular capillaries)
In tubular reabsorption water is absorbed by osmosis and solutes are reabsorbed by what 4 ways?
- 1. Diffusion - Increased concentration to decreased concentration
- 2. Active Trasport - cell uses ATP energy to perform work
- 3. Co-transport - molecule hooks to ATP and hitchhikes
- 4. Pinocytosis - cell eating
Where does most of the reabsorption take place?
Proximal Convoluted Tubule (PCT)
How much filtrate is formed each day?
How much urine is eliminated each day?
How much fluid is reabsorbed each day?
How much H2O is reabsorbed in the PCT?
How much H2O is reabsorbed in descending limb of Henle?
How much H2O is reabsorbed in the ascending limb of Henle?
How much H2O is reabsorbed in the Distal Convoluted Tubule or DCT?
How much H2O is reabsorbed in the collecting ducts or CD?
What solutes move from the blood of the peritubular capillaries into the filtrate?
Potassium, ammonium, hydrogen, and bicarbonate ions are secreted into filtrate
Urine is composed of 2 things. Name them and their percents.
- 95% water
- 5% dissolved solutes
What does tubular secretion balance?
regulates acid-base balance and electrolyte concentration
What are the 5% of dissolved solutes that are eliminated?
- Excess electrolytes - sodium, calcium, potassium
- Urea - by protein metabolism (toxic)
- Creatinine - by muscle melabolism (toxic)
- Uric Acid - by nucleic acids metabolism (poisonous & causes gout)
What is released when decreased body water trigger the hypothalamus? From what gland?
Antidiuretic hormone from the posterior pituitary gland
What does ADH do to the cells of the distal convoluted tubule and the collecting duct?
makes the cells more permeable to water and increase water reabsorption back into the capillary blood
ADH makes urine dark yellow and ....?
With optimum body water what gland stops secreting what hormone?
hypothalamus stops secreting ADH
With urine dilution the distal convoluted tubule and collecting duct become less permeable to water and causes what?
less water reabsorption
More water stays in the filtrate causing urine to be what color and volume?
large volume of pale yellow dilute urine
What is obligatory urine volume?
The minimum urine volume that MUST be excreted by the kidneys to get rid of metabolic waste and excess ions = 0.5 L/day
The body of the urinary bladder is covered by a sheet of smooth muscle called what?
- Detrusor muscle
The two ureters enter the bladder at the uppermost angles of the what? (which open into the neck)
What do the detrusor smooth muscle fibers form?
- Internal urethral sphincter (in the neck)
The skeletal muscle fibers form the external urethral sphincter which in under conscious control of what nerve?
What is micturation?
Micturation is the act of emptying the urinary baldder
The sensory stretch receptors in the urinary bladder are from what system?
S.N.S. - Sympathetic Nervous System
The pelvic nerve and spinal cord signals come from what system?
P.N.S. Parasympathetic Nervous System
Inhibitation or facilitation of the bladder is done by conscious control of what?