Urinary

Organs of Urinary system?

Kidneys, Ureters, Bladder, Urethra

functions of kidney?

produce renin (maintains blood pressure), produce erythropoietin (stimulate RBC production), convert Vitamin D to active form

Waste products in urine?

nitrogenous wastes, toxins, drugs, excess ions

how much blood through kidney?

1/4 of total blood supply every minute

What is the functional unit of kidney?

Nephrons - Renal Corpuscle & Renal Tubule

What is in Renal corpuscle?

Glomerulus surrounded by Glomerular (Bowman's) capsule

Where is filtration done in kidney?

Glomerulus. Specifically the Podocytes - Filtration Slits formed by Foot processes

Sudivision of Renal Tubule? From the Bowman's capsule...

1. Proximal Convoluted Tubule (PCT) 2. Nephron loop (loop of Henle) 3. Distal Convoluted tubule (DCT)

2 nephrons locations?

Cortical (entirely in cortex), Juxtamedullary (cortex-medulla junction)

Which nephron location has most nephrons?

cortical

2 capilary beds associated with each nephron?

Glomerulus (Filtration) & Pertubular (absorption)

blood supply/drainage of glomerulus?

Afferent arteriole - feeds glomerulus...Efferent arteriole - drains (CHECK THIS... slide 22)

What does the efferent arteriole drain to?

carry FILTERED blood to Pertibular Capillary beds

Function of Pertibular capillary beds?

low-pressure -> adapted for absorption instead of filtration... receives solutes/water

How is urine formed? (3 events)

1. Glomerular filtration. 2. Tubular reabsorption. 3. Tubular secretion

What solutes are filtered at the Glomerulus?

Proteins and blood... too big to pass through

What is "filtrate"?

the filtered fluid post glomerulus, leaves kidney via renal tubule

Key requirement for filtration to occur?

maintained systemic blood pressure... if too low, filtrate cannot be formed through glomerulus capillary beds

What substances are absorbed through tubular?

water, glucose, amino acids, ions

where does most reabsorption occur?

proximal convoluted tubule (PCT)

is reabsorption passive?

Most is active, requiring ATP

What is Tubular secretion?

reabsorption in reverse. Some materials (H&K ions, creatinine) move from peritubular capillaries into renal tubules TO BE ELIMINATED IN FILTRATE..Materials left in renal tubule move toward ureter

Function of tubular secretion?

eliminate substances not already in filtrate, remove drugs/excess ions, maintaining pH of blood

3 Main Renal processes?

Glomerular filtration, Tubular reabsorption, Tubular Secretion (slide 31)

What type of products are poorly reabsorbed in renal system?

Nitrogenous wastes - Urea, Uric acid, Creatinine

What products tend to remain in filtrate and excreted in urine?

Nitrogneous wastes - Urea, Uric acid, Creatinine

What is Urea?

end product of protein breakdown

Uric Acid results from what?

results from nucleic acid metabolism

What is Creatinine?

associated with creatinine metabolism in muscles

How much urine is produced in typical 24 hours?

1-1.8 Liters

Differences between Urine and filtrate?

Filtrate contains everything blood plasma does (except proteins), Urine iswaste material

Solutes found in Urine?

Nitrogenous wastes, ammonia, bicarbonate ions, Na&K ions

Solutes NOT found in Urine?

glucose, blood proteins, RBC's, hemoglobin, WBC's (pus), bile

Factors that facilitate urine transport in ureters?

Peristalsis and gravity

Volume of bladder?

200 mL

What is micturition?

Taking the piss, yeh?

What controls release of urine?

internal and external urethral sphincties

How do I know I gotta pee?

Bladder stretch receptors transmit impulses to sacral region of spinal cord, impulses return to bladder via pelvic sphlnachnic nerves to cause bladder contractions. When contractions strong enough, urine forced past internal sphincty --> I GOTTA PEE

Which urethral sphincty is involuntary?

Internal. Urine forced past this sphincty tells me I gotta pee

How is micturition voluntarily delayed?

external sphincty

3 factors on blood composition?

Diet, Cellular metabolism, urine output

4 kindey roles in maintaining blood composition?

1. Excreting nitrogenous wastes. 2. Maintaining water balance of the blood. 3. Maintaining electrolyte balance of blood. 4. maintaining blod pH

Water composition in humans?

females -50%, males - 60%, babies - 75%, elderly - 45%

Where is water stored? (3 fluids)

1. Intracellular fluid (ICF) - accounts for 2/3 body fluid. 2. Extracellular fluid (ECF). 3. Plasma (3L of total water)

What fluid links internal/external environments?

Blood Plasma

Driving force for water intake? (i.e. what structure tells us we’re thirsty?)

thirst mechanism (osmoreceptors) in hypothalamus

What is the thirst mechanism?

Osmoreceptors in hypothalamus react to small changes in plasma solute concentration. Dry mouth also

Sources of water output?

lungs ("insensible"), perspiration, shit-n-piss

Hormone responsible for water/electrolyte reabsorption in kidneys?

Antidiuretic hormone (ADH)

What does Antidiuretic hormone do?

prevents excessive water loss in urine, increases water reabsorption, targets kidney's collecting ducts

Hormone responsible for blood composition/volume by kidney?

Aldosterone.... "Water follows salt"

What causes water to move between compartments?

electrolyte concentration... "water follows salt"

What triggers Aldosterone release?

Renin-angiotensin mechanism, controlled by juxtaglomerular (JG) apparatus of renal tubules

What is renin-angiotensin mechanism?

JG apparatus stimulated by low BP, renin released into blood. Renin produces angiotensin II -> causes vasoconstriction and aldosterone release ---> INCREASE BP and BLOOD VOLUME

Neutral Blood pH?

7.35-7.45

What is alkalosis?

Blood pH above 7.45

What is acidosis?

Blood pH below 7.35 (physiologically between 7-7.35)

What structure is most important for pH balance?

Kidney... then blood buffers and respiration

Blood buffers?

Acids are proton donors... Bases are proton acceptors

3 main blood buffer systems?

Bicarbonate, Phosphate, Protein

How does Bicarbonate buffer system work?

carbonic acid (H2CO3) & sodium bicarbonate (NaHCO3)... NaHCO3is weak base -> reacts with strong acid to produce salt (NACl)... H2CO3 is weak acid that react to strong bases to create water and weak base (NaHCO3)

How does respiratory mechanism affect blood pH?

changes to manage CO2 levels --> which manages Carbonic acid (H2CO3) levels

Renal mechanism of high blood pH?

Bicarbonate ions excreted... H ions retained in kidney tubules

Renal mechanism of low blood pH?

Bicarbonate ions reabsorbed... H ions secreted

Typical Urine pH?

4.5 - 8