Anatomy 2 Exam 3

What are the organs of the urinary system?

kidneys, ureters, urinary bladder, urethra

Why is the right kidney lower than the left?

crowded by the liver

What is the function of the ureters?

transport urine from the kidneys to the bladder

Where is urine made?

kidneys

What is the function of the urethra?

transports urine out of body

What kind of muscle makes up the urinary bladder?

smooth collapsible muscle

What is the function of the urinary bladder?

temporarily stores urine

How many openings does the bladder have?

3 (2 from ureters, 1 for urethra)

What is the trigone?

• Smooth triangular area outlined by the openings for the ureters and the urethra.

• two from ureters

• one to the urethra

What is the detrusor muscle?

smooth muscle in wall of bladder

What type of tissue is the mucosa in the bladder comprised of?

transitional epithelium

What is the function of the internal urethral sphincter?

blocks urine flow from the bladder

Is the muscle control of the internal urethral sphincter voluntary or involuntary?

involuntary

What is the function of the external urethral sphincter?

allows for urine flow from the urethra outside of the body

Is the muslce control of the external urethral sphincter voluntary or involuntary?

voluntary

Why do we create urine?

to remove waste products from the blood

renal hilum

medial opening for entry/exit of artery, vein, and ureter

Path of Blood Flow to and from the Kidney

Aorta --> Renal Artery --> Afferent Arteriole --> Glomerulus --> Efferent Arteriole --> Peritubular Capillaries --> Renal Vein --> Inferior Vena Cava

What are nephrons responsible for?

1. production of filtrate; 2. reabsorption of organic nutrients, water, ions

What are the two main parts of a nephron?

renal corpuscle and renal tubule

What is the renal corpuscle comprised of?

glomerulus and glomerulus capsule

What is the function of the renal corpuscle?

filter blood

What is the renal tubule?

a duct that leads away from the glomerular capsule and ends at the tip of the medullary pyramid

What are the two types of nephrons?

cortical and juxtamedullary

What is the vasa recta?

the capillary networks that supply blood to the medulla, only found in juxtamedullary nephrons

podocytes

• cells that surround the glomerular capillaries that create a layer of filtration

• when pressure is high → fluid and small solutes flow into glomerular capsule as filtrate

What is the function of the afferent arteriole?

brings blood to the glomerulus

What is the function of the efferent arteriole?

carries blood away from the glomerulus

What is tubular reabsorption?

• the process that moves solutes and water out of the filtrate and back into the bloodstream

• reclaiming (reabsorbing) useful substances: water, glucose, amino acids, and ions

• some is passive, most is active

• mostly occurs in the Proximal convoluted tubule

What is tubular secretion?

• The movement of materials from peritubular capillaries into the renal tubules

• secreted substances: K+, H+, Cl-, creatinine, and penicillin

• materials left in the renal tubule then move toward ureter

• active transport within the renal tubules that is very selective and only chooses specific substances that are harmful/waste products and directs its flow to the tubules from the peritubular capillaries. 

What substances does the peritubular capillaries reabsorb?

water, glucose, amino acids, ions

What substances does the peritubular capillaries secrete?

potassium, hydrogen ions, choline, creatine, penicillin

What is the function of the collecting duct?

• receives urine from nephrons and delivers urine into the calyces and renal pelvis

• runs through medullary pyramids

• ADH, Aldosterone, and atrial natriuretic peptide are hormones that mainly act on this

What is the excretion rate?

(filtration rate + secretion rate) - reabsorption rate

What does cloudy urine indicate?

urinary tract infection

What is the composition of urine?

95% water and 5% solutes

urochrome

The pigment that gives urine its characteristic yellow color

Where does urochrome come from?

breakdown of hemoglobin

What is the pH of urine?

Slightly acidic (~pH 6, with a range of 4.5 to 8.0)

What causes a lower pH in urine?

more acidic diet (protein, whole wheat)

What causes a higher pH in urine?

alkaline diet (vegetarian)

What makes up the solutes in urine?

urea, uric acid, creatine

renal calculi

kidney stones; crystal aggregations, usually of calcium oxalate but sometimes of calcium phosphate

How do you treat renal calculi?

shock wave lithotripsy since it is non-invasive, pain treatment

What solutes are NOT normally found in urine?

glucose, blood proteins, amino acids, red blood cells, hemoglobin, white blood cells, bile

osmolality

• concentration of molecules per weight of water

• reflects ability to cause osmosis

• number of solute particles in 1 kg of H2O

• maintained at 280-300 mOsm

countercurrent mechanism

Occurs when fluid flows in opposite directions in two adjacent segments of the same tube

countercurrent multiplier

• interaction of filtrate flow in ascending/descending limbs of nephron loops

• establishes osmotic gradient

• dependent on nephron loop

countercurrent exchanger

blood flow in ascending/descending limbs of vasa recta

What is the descending limb permeable to?

water ONLY (no way to transport Na+, Cl- or K+)

What is the ascending limb permeable to?

• impermeable to water

• transport of Na+, CL-, and K+

What is the normal osmolality range before entering the nephron loop?

300 mOsm

What is the normal osmolality range going down the nephron loop in the countercurrent multiplier?

300 - 1200 mOsm

What is the normal osmolality range going up the nephron loop in the countercurrent multiplier?

1200 - 200 mOsm

What is the normal osmolality range in the vasa recta descending limb in the countercurrent exchanger?

200 - 1200 mOsm

What is the normal osmolality range in the vasa recta ascending limb in the countercurrent exchanger?

1200 - 300 mOsm

What happens during the countercurrent multiplier?

salts from the filtrate are removed, causing water to leave as well

What happens during the countercurrent exchanger?

water and salts are added into the blood from the filtrate

What three things is blood composition dependent on?

diet, cellular metabolism, urine output

What are the four roles kidneys have in maintaining blood composition?

• excretion of wastes

• maintaining water balance of the blood

• maintaining electrolyte balance of the blood

• ensuring proper blood pH

What are the three sources of water intake?

beverages, foods, and metabolism

What are the four sources of water loss?

feces, sweat, insensible loss, and urine

What are aquaporins and what do they do?

integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane.

What is ADH?

• Anti-diuretic hormone - it controls the concentration of urine and is released into the bloodstream by the posterior pituitary gland

• from neurosecretory cells originating in hypothalamus

• reabsorbs water → less urine

diuresis

process of urine production

diuretic

promotes the production of urine

antidiuretic

Substance that inhibits urine formation.

ex: reabsorption of water; aquaporins

What triggers the release of ADH?

high plasma osmolarity, low blood pressure, decreased blood volume

What happens when osmolality increases?

the hypothalamus stimulates thirst and ADH is released

What happens when osmolality decreases?

thirst is not stimulated and ADH is inhibited

What is aldosterone and what does it do?

• Steroid hormone secreted from adrenal cortex

• Causes distal convoluted tubules to reabsorb sodium ions and water at the expense of losing potassium ions

• keeps Na+ → water follows → high bp → less urine

What triggers aldosterone to be released?

Angiotensin II

Angiotensin II

• vasoconstrictor

• increases mean arterial pressure

• BP → Renin release from kidneys → Cleaves → angiotensinogen → Angiotensin

atrial natriuretic peptide

• released in response to atrial stretch and prompts excretion of salt and water

• releases Na+ and water → more urine

Where is atrial natriuretic peptide released?

atrium in response to stretch of the wall

What acids and bases are produced by the body?

phosphoric acid, lactic acid, fatty acid, carbonic acid, ammonia

What are the three lines of defense for maintaining blood pH?

buffering of hydrogen ions, respiratory compensation, renal compensation

What are buffers?

molecules that react to prevent dramatic changes in hydrogen ion concentrations

What are the three major chemical buffer systems?

Bicarbonate buffer system

Phosphate buffer system

Protein buffer system

What buffer is found in eyrthrocytes?

hemoglobin

What is the Bohr effect?

oxygen binds to hemoglobin which leads to hydrogen ions being released

Hypoventilation will ____ pH

decrease

Hyperventilation will ___ pH

increase

What happens during renal compensation from respiratory acidosis?

increase in H+ secretion and increase HCO3- reabsorption and synthesis

What happens during renal compensation from respiratory alkalosis?

decrease in H+ secretion and decrease HCO3- reabsorption and synthesis

What is metabolic acidosis?

An accumulation of acids as a byproduct of metabolism leading to a decrease in pH

How do the kidneys respond to metabolic acidosis?

respiratory: increase ventilation to decrease CO2

renal: increase H+ secretion, HCO3- reabsorption, and synthesis of a new bicrabonate

What is metabolic alkalosis?

elevation of HCO3- usually caused by an excessive loss of metabolic acids

How do the kidneys respond to metabolic alkalosis?

respiratory: decrease ventilation to increase CO2

renal: decrease in H+ secretion, HCO3- reabsorption, and decrease in the synthesis of new bicarbonate

What is the primary sex organ in males?

testes

What is the primary sex organ in females?

ovaries

What are gametes?

sex cells (sperm and egg)

What sex hormones do testes produce?

testosterone

What sex hormones do the ovaries produce?

estrogen and progesterone

What are the accessory reproductive organs for males?

ducts, glands, and external genitalia

Where are the testes located?

scrotum

Where is sperm produced?

testes

Delivery of Sperm

epididymis, ductus deferens, ejaculatory duct, urethra

What is the scrotum?

Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity, contains the pair of testes

Why are the testes cooler than the rest of the body?

lower temperature is necessary for sperm production