·         Trace the flow of urine from creation to leaving the body.

Eliminating toxins, metabolic wastes, excess ions from blood

Regulation of blood volume and chemical makeup of the body

Maintaining balance between water and salts and acids and bases

Other functions: Producing renin (regulate bp and kid function)

Producing erythropoetin (rbc production)

metabolizing vitamin D to its active form

Covey urine from kidneys to bladder

Enter base of bladder through posterior wall

Strength and frequency of muscle contractions change with amount of urine present

Muscular sac for temporary storage of urine.

Trigone -smooth of triangular area outlined by openings for ureters and urethra

Layers of bladder well

1. Mucosa with transitional epithelium

2. Smooth muscle (3 layers)

3. Fibrous adventia 

Colappses when empty; rugae appear

Muscular tube

Lining epithelium is mostly pseudostratified columnar epithelium, except,

Transitional epithelium near bladder

Stratified squamous epithelium near external urethral orifice

1. Internal urethral spinchter

involuntary (smooth muscle) at bladder-urethra junction

contracts to open

2. external urethral spinchter

Voluntary (skeletal) muscle surounding urethra as it passes through pelvic floor

female is shorter. male is longer and carries semen and urine. 3 regions

prostatic urethra

membranous urethra

spongy urethra

Renal fascia - dense connective tissue; anchors kidney

Perirenal fat (adipose) capsule - cushioning

Fibrous capsule - prevents spread of infection to kidney

Rental cortex - granular, superficial region

Renal medulla - cone shaped medullary (renal) pyramids separated by renal columns

Renal Pelvis - funnel shaped tube within renal sinus

·         What are calyces & what is their function in urine collection?

The calyx is a portion of the human renal system, predominantly located in the kidney. The calyx is limited specifically to mammalian kidneys, and is part of the urinary collecting subsystem.

The calyx is the method by which urine is passed from the kidney to the bladder.

The structural and functional units of the kidneys that form urine.

1 million per kidney

2 main parts: glomerulus and renal tubule.

Processes in the kidney involve the interaction between incming blood and the tubular components of the kidneys (nephrons) where urine is processed

1. Glomerulus - afferent arteriole > glomerulus > efferent arteriole. it is specialized for filtration. Blood pressure is high in glomerulus

2. Peritubular capillaries

Low-pressure, porous capillaries adapted for absorption

What are the 2 major types of nephrons?

Cortical nephrons - 85% of nephrons; almost entirely in cortex (of kidneys)

Juxtamedullary nephrons - important in production of concentrated urine

Glomerulus - tufts of capillaries; filtration

Bowman's capsule - enlarged, cup-shaped capsule surrounding glomerulus - collects filtrate

Proximal convoluted tubule (pct) - tubular reabsorption

Loop of henle - Sodium (Na+) and water balance

Distal convoluted tubule (DCT) - tubular secretion

Glomerulus > proximal convoluted tubule (pct) > loop of henle > distant convoluted tubule (dct) > collecting ducts

collecting ducts - receive filtrate from many nephrons

principle cells of collecting ducts - help maintain water and salt balance

fuse together to deliver urine into minor calyces

Renal Artery - The blood vessel bringing blood to the kidney.

Renal Vein - The blood vessel draining the kidney.

Ureter - A duct leading from the kidney to the urinary bladder.

Urethra - A tube that releases urine from the body near the vagina in females and through the

penis in males; also serves in males as the exit tube for the reproductive system.

Renal Cortex - The outer portion of the vertebrate kidney.

Renal Medulla - The inner portion of the vertebrate kidney, beneath the renal cortex.

Nephron - The tubular excretory unit of the vertebrate kidney.

Glomerulus - A ball of capillaries surrounded by Bowman’s capsule in the nephron and serving as

the site of filtration in the vertebrate kidney.

Bowman’s capsule - A cup–shaped receptacle in the vertebrate kidney that is the initial,

expanded segment of the nephron where filtrate enters from the blood.

Proximal Tubule - In the vertebrate kidney, the portion of a nephron immediately downstream

from Bowman’s capsule that conveys and helps refine filtrate.

Loop of Henle - The long hairpin turn, with a descending and ascending limb, of the renal tubule

in the vertebrate kidney; functions in water and salt reabsorption.

Distal Tubule - In the vertebrate kidney, the portion of a nephron that helps refine filtrate and

empties it into a collecting duct.

Collecting Duct - The location in the kidney where filtrate from renal tubules is collected; the

filtrate is now called urine.

Renal Pelvis - Funnel–shaped chamber that receives processed filtrate from the vertebrate

kidney’s collecting ducts and is drained by the ureter.

Cortical Nephrons - Nephrons located almost entirely in the renal cortex. These nephrons have a

reduced loop of Henle.

Juxtamedullary Nephrons - Nephrons with well–developed loops of Henle that extend deeply

into the renal medulla.

Afferent Arteriole - The blood vessel supplying a nephron.

Efferent Arteriole - The blood vessel draining a nephron.

Peritubular Capillaries - The network of tiny blood vessels that surrounds the proximal and distal

tubules in the kidney.

Vasa Recta - The capillary system that serves the loop of Henle.

Until the liquid reaches the renal pelvis, it is "glomerular filtrate," when it reaches the pelvis, it is called "urine"

filtrate is blood plasma minus proteins

urine contaisn metabolic wastes and uneeded substances. less than 1% filtrate.

·         What are the 3 steps in forming urine? Where does each occur?

1. Glomerular filtration - material passes from blood to tubules

location: glomerulus

2. tubular reabsorption - material passes back from tubules to blood

location: primarily in the proximal tubule

3. tubular secretion - material selectively transferred from blood to tubules

location: distal tubules

Glomerular hydrostatic pressure (HP g) - chief force pushing water and solutes out of glomerulus and into the capsule

55 mmHg

2 opposing forces that drive fluids back into glomerulus:

1. glomerular osmotic pressure - (30 mmHg)

2. Hydrostaric pressure of the capsule (15 mmHg)

 What characteristics make the glomerulus ideal for filtration?

What is GFR? What is the major limiting factor of GFR? Explain.

GFR is the amount of fluid filtered from the blood into the capsule each minute. Factors governing the filtration rate at the capillary beds are:

(1) total surface area available for filtration

            (2)        filtration membrane permeability

            (3)        net filtration pressure

GFR is directly proportional to net filtration pressure because the capillaries are exceptionally permeable and have a huge surface area. So therefore, net filtration pressure is the limiting factor. Normal GFR in both kidneys in adults is approximately 120 ml/min. A change in any of the pressures acting at the filtration membrane changes the NFP and thus the GFR. An increase in arterial blood pressure in the kidneys increases GFR, whereas dehydration inhibits filtrate formation.

What are macula densa cells? What do they do?

They are specialized cells in the walls od DCT (justaglomerular apparatus - JGA)

If filtrate is flowing too slow - they stimulate vasodilation of afferent arterioles

If filtrate is flowing too rapidly - it stimulates vasoconstriction

Slows blood flow to glomerulus; decreases gfr

·         In tubular reabsorption, substances are returned to the __________ from the ____________.

What substances in tubular reab moves actively?

glucose, amino acids, vitamins, most ions (na+)

most substances are transported with sodium on a carrier molecule.

Sodium movement (via active transport) establishes an osmotic gradient

water moves by osmosis out of filtrate and back into the blood

as water leaves, substances (in filtrate) follow their concentration gradients back into the blood

Loop of henle - descending limb: impermeable to Na+, but permeable to water

h2o reabsorbed

ascending - permeable to na+ but impermeable to water

na+, k+, Cl-

·         Explain the renin-angiotensin-aldosterone mechanism. What is its goal?

If mean arterial pressure (map) into kidney is too low, cells of juxtaglomerular apparatus (jga) secrete renin.

angiotensinogen (a plasma globulin)

renin > V

angiotensin I

angiotensin converting enzyme (ace) > V

angiotensin II

1. Constricts arteriolar smooth muscle, causing map to rise

2. stimulates reabsorption of Na+

Triggers adrenal cortex to release aldosterone

Aldosterone increases na+ reabsorption

3. Stimulates hypothalamus to release antidiuretic hormone (ADH) and activates thirst center

ADH - causes water to be retained

4. Constricts efferent arterioles, decreasing capillar hydrostatic pressure and increasing fluid reabsorption

5. Causes glomerular cells to contract, decreasing surface area available for filtration

·         If you wanted to create a more concentrated urine, what would your body do?

To form more concentrated urine, ADH causes the DCT and collecting ducts to be more permeable to water

Water can leave tubules and go into blood

blood volume increases

99% of h2O in filtrate is reabsorbed

 How does alcohol impact urine formation?

·         What are 2 ways you could check someone’s renal health?