A&P Exam 2 (Urinary System)

Excludes Renal Physiology

Importance of the urinary system

excretory functions, maintain balance of water/salt, maintain balance between acids/bases (pH), and other metabolic functions

Major excretory organ of the urinary system

Kidneys

What things are regulated by the kidneys (4)

urea, creatinine, uric acid, and end products of hemoglobin breakdown

Urea

protein catabolism

Creatinine

muscle metabolism

Uric acid

nucleic acid metabolism

What functions of the urinary system are minute by minute?

maintenance of water/salt and acid/base balance

What other metabolic functions does the urinary system help with?

glycogenesis, activation of vitamin D, production of renin and erythropoietin

Renin

enzyme that helps regulate blood pressure

Erythropoietin

hormone that stimulates RBC production in bone marrow

What amount of water is added and taken away from the body daily?

2550ml

How is water added to the body?

ingestion (liquids/in food) and metabolically produced

How is water removed from the body?

insensible loss, sweat, in feces, and urine

Examples of insensible water loss

water lost through breathing or skin; NOT sweat

Kidneys location

superior lumbar region and retroperitoneal

Kidneys structure

adipose tissue capsule and tough renal fascia, surrounded by fibrous capsule

Function of adipose capsule and renal fascia for the kidneys

protects (cushions) and anchors kidneys in place

Function of fibrous capsule for the kidneys

anchor kidneys and prevents surrounding infections from spreading to them

Anorexia result on kidneys

breakdown of adipose capsule; kidney damage and urine backup

Ureters

slender tubes that extend from kidneys to urinary bladder; move urine through peristaltic contraction of muscular layers

Urinary bladder

hollow muscular sac just posterior to public symphysis

Function of the urinary bladder

store and expel urine (not by gravity)

Characteristics of the urinary bladder

very distensible (collapses when not full); has rugae; moderately full at 500ml, but can double that amount

Urethra structure and function

thin-walled tube from bladder to exterior that drains urine from bladder

Urethra in females

short and straight tube; more prone to urinary tract infections

Urethra in males

3 regions; long and curved tube; runs through prostate gland and has both urinary/reproductive function (carries semen and urine)

Cortex of the kidneys

bark, most superficial region

Medulla of the kidneys

inner core tissue composed of renal pyramids and columns

Renal pyramids

triangular masses that appear striped, houses collecting ducts

Collecting ducts

microscopic, parallel bundles of urine-collecting tubules

Renal columns

cortical tissue that surrounds renal pyramids

How many lobes (approx.) are in a kidney and what are they made up of?

about 8, pyramids and column pairs

Urine can be changed up to what point?

the end of the collecting duct/the minor calyx

What structures funnel urine from renal pyramids to the ureters?

minor calyx, major calyx, and renal pelvis

Nephron

structural and functional blood processing unit of the kidney; over 1 million per kidney

What makes up a nephron?

renal tubule and vascular component

What makes up a renal tubule (4)

glomerular (Bowman’s) capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule

Glomerular (Bowman’s) capsule

closed at one end, cup-shaped

What makes up the vascular component?

glomerulus and peritubular capillaries

Glomerulus

tuft of capillaries

What makes up a renal corpuscle?

glomerulus and glomerular (Bowman’s) capsule

Types of nephrons (2)

cortical and juxtamedullary

Cortical nephrons

represent 85% of nephrons; mostly in cortex; short loops of Henle that extend a short way into the medulla

Juxtamedullary nephrons

long loops of Henle; surrounded by vasa recta; key for concentrating urine

Blood supply to the nephron

aorta → segmental arteries → interlobar arteries → arcuate arteries → cortical radiate arterioles → afferent arterioles → glomerulus → efferent arteriole → peritubular capillaries

How does blood supply away from the nephron differ?

artery supply in reverse, except no segmental vein or efferent venules

Cortical radiate arterioles

supply cortical tissue, 90% of blood to kidneys

Functions of capillary beds of the nephron

production of filtrate and reabsorption

What is specialized for filtration and produces the filtrate?

the glomerulus

Structural differences that make the glomerulus specialized for the production of filtrate

fed/drained by 2 high resistance arterioles, afferent larger than efferent, large pores (fenestrations) in capillary walls

Increased diameter in the afferent has what function?

keeping the blood pressure in the glomerulus very high, fluid/solutes easily forced out of blood into glomerular capsule

What is specialized for reabsorption in the nephron?

peritubular capillaries

Peritubular capillaries

arise from efferent arteriole, wrap around adjacent renal tubule (proximal/distal), low-pressure and porous, secrete some substances into the renal tubule

Most of the filtrate (99%) is reabsorbed from tubule and returned to the blood (t/f)

true

The second capillary bed of the juxtamedullary nephrons tend to break up into peritubular capillaries (t/f)

false

Vasa recta

straight vessels formed instead of peritubular capillaries in juxtamedullary nephrons, surround tubules

The filtration membrane

allows free passage of water and solutes smaller than plasma proteins from blood into renal tubule

Three layers of the filtration membrane

fenestrations of endothelial cells, glomerular basement membrane, and podocytes

Fenestrations

allow all plasma components except blood cells

Basement membrane

restrict all but the smallest proteins, negatively charged to deter large anionic proteins

Podocytes

keep out other macromolecules that get through the basement layer, slit diaphragms

Where does filtrate switch to urine in the excretion of materials?

somewhere in the collecting duct

What structures only have blood in them?

glomerulus

What structures only have filtrate in them?

glomerular capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and beginning of collecting duct

What structures only urine in them?

end of collecting duct, minor/major calyx, renal pelvis, ureter, urinary bladder, and urethra

After filtrate has turned to urine, no more changes can be made (t/f)

true