A&P Test 4

Where does filtration occur

Renal corpuscle (glomerulus/bowman’s capsule)

What happens after passing through the renal corpuscle (glomerulus/bowman’s capsule)

The filtered fluid forms urine and passes through the renal tubules (proximal convuluted→loop of henle →distal convuluted

What is the function of the proximal convoluted tubule?

reabsorption of water, sodium ions, and bicarbonate ions

reabsorbs 60-70% of filtrate volume produced in renal corpuscle

Where does the urine go after the renal tubules?

To the renal pelvis (kidney)

Where does urine go after the kidneys?

Ureters→Urinary Bladder →Urethra

What order does urine pass through?

Glomerulus and renal corpuscle →Renal tubules →Renal pelvis →Ureters →Urinary bladder →Urethra

Components of renal corpuscle

Spherical structure consisting of glomerular (Bowman’s) capsule and the glomerulus (capillary network)

Function of renal corpuscle

Filtration

Blood pressure forces water and small solutes across membrane into capsular space

Organ of the urinary system performs the most excretory function

The kidney

Function of the distal convoluted tubule

reabsorb water, sodium, calcium ions

actively secretes undesirable substances (ions, acids, drugs, toxins)

transports sodium and chloride out of tubular fluid, back into peritubular capillaries

Flow of blood into the glomerulus

Afferent arteriole

Flow of blood out of the glomerulus

Efferent arteriole

Flow of blood into the kidney entire pathway

renal artery → segmental artery → interlobar artery →arcuate arteries →cortical radiate/interlobular artery →afferent arterioles →glomerular capillaries →efferent arterioles →peritubular capillaries →venules →cortical radial/interlobular veins →arcuate veins →interlobar veins →renal vein

Flow of blood out of the kidney

renal vein

Flow of blood into the kidney

Renal artery

Countercurrent exchange

Vasa recta returns reabsorbed solutes and water to general circulation

Peritubular capillaries

receive blood from efferent arterioles

What drives glomerular filtration

hydrostatic pressure and colloid osmotic pressure

Glomerular filtration rate (GFR)

Amount of filtrate kidneys produce each minute

Components of juxtaglomerular complex

Macula densa

Juxtaglomerular cells

Extraglomerular mesangial cells

Macula densa

Function as chemoreceptors or baroreceptors

Juxtaglomerular cells

Function as baroceptors and secrete renin

Extraglomerular mesangial cells

Located between afferent and efferent arterioles

Provide feedback control

Order of structures of renal corpuscle to pass through during filtration

capillary endothelium, dense layer, filtration slit, capsular space

Specialized cells in visceral layer of renal corpuscle

podocytes

Organs of the urinary system

Kidneys, urinary tract

Function of kidneys

produces urine

function of urinary system

excretion, elimination, homeostatic regulation

Epithelium in ureters and bladder

transitional epithelium

Micturition

process of eliminating urine

urine voiding complex

involves spinal reflexes and pontine micturition center

Function of pontine storage center and micturition

when bladder contains 200 mL of urine, urge to urinate

Stretch receptors send impulses to pontine micturition center, initiating sacral spinal reflexes

Detrusor contracts

Internal and external urethral sphincters relax

Trigone of bladder

funnel

triangular area bounded by openings of ureter and entrance to urethra

Temporary storage of urine

urinary bladder

Formula for NFP

NHP - BCOP = NFP

Blood colloid osmotic pressure (BCOP)

Osmotic pressure resulting from suspended proteins in blood

Net filtration pressure (NFP)

average pressure forcing water and dissolved substances

out of glomerular capillaries and into the capsular spaces

Colloid osmotic pressure

Pressure due to materials in solution

On each side of capillary walls

Net hydrostatic pressure (NHP)

GHP - CsHP = NHP

Filtration pressure of the glomerulus

balance between hydrostatic pressure and colloid osmotic pressure

Pressure that drives filtration in a nephron

glomerular hydrostatic pressure

glomerular hydrostatic pressure (GHP)

pushes water and solutes through the filtration membrane into bowman’s capsule (filtrate)

Function of decending nephron loop

reabsorption of water (freely permeable to water NOT other solutes)

reabsorbs sodium and chloride from tubular fluid

Function of ascending nephron loop

removal of sodium and chloride ions from tubular fluid

medullary concentration gradient

Majority of nephrons in the kidney

Cortical nephrons with short loop of henle

Functional unit of kidney

nephron

Most abundant organic waste removed with urine

Urea

Role of aldosterone with sodium in the renal corpuscle

Increased aldosterone secretion by adrenal glands increases Na+ retention

Causes body to retain water in blood, increasing blood volume and arterial pressure

Distal tubule and collecting duct

hypokalemia

Role of ADH

Increases rate of osmotic water movement

DCT and collecting system permeable to water

effects of ADH on thirst

stimulates thirst

movement of chloride at thick ascending limb of nephron loop

removal of chloride ions from tubular fluid into interstitial fluid

movement of hydrogen ion at PCT process

sodium ions enter tubular cells by countertransport for hydrogen ions

sodium transporters

primary active

cotransport

facilitated

glucose transporter

cotransporter

simple diffusion

diffusion without a helper protein

facilitated diffusion

diffusion using a helper protein

active transport

movement of substances against concentration gradient

from low to high concentration

requires energy

osmosis

movement of water molecules from an area of high concentration to an area of low concentration across a semipermeable membrane

PCT

decending limb of nephron loop

cotransport

secondary active transport

movement of one moledule down its concentration gradient is coupled with the movement of another molecule against its concentration gradient

countertransport

antiport

mediate net transfer of solute across cell membrane in direction against electrochemical potential gradient of solute

effects of aging on urinary system

nephrolithiasis (formation of calculi)

decrease in number of functional nephrons

reduction in GFR

reduced sensitivity to ADH

problems with urinary reflexes

components of extracellular fluid (ECF)

interstitial fluid of tissues and plasma of blood, ions

Exchange site between the 2 main subdivisions of ECF

capillaries

Percentage of water in adult female

50%

Percentage of water in adult male

60%

How much water is lost and gained each day on average

Lose and gain about 2500 mL

Lose: urine, feces, insensible and sensible perspiration, fever

pH of ECF

7.35-7.45

pH of acidosis

blood pH <7.35

pH of alkalosis

blood pH >7.45

Principle ions of ECF

Cation: Na+

Anion: Cl-

Principle ions of ICF

Cation: K+

Anion: PO43- (phosphate)

What is intracellular fluid and where is it found (ICF)

fluid inside cells (cytosol)

potassium, magnesium, phosphate ions

negatively charged proteins

Primary source of water gains/losses

Gains: digestive

Losses: Urinary

What is extracellular fluid (ECF)

Lymph, CSF, synovial fluid, serious fluids, aqueous humor, perilymph, endolymph,

Ions: sodium, chloride, bicarbonate

affects homeostatic mechanisms that monitor body fluid composition

Where is ECF found

outside of cells in the body: blood plasma, intersitial fluid

percentage of total body water in ICF

percentage of total body water in ECF

33% of total body water

Plasma volume- 25%

Interstitial volume- 75%

Buffer

dissolved compounds that stabilize pH of solution by adding or removing H+

Regulation of acid-bade balance

Respiratory compensation

Renal compensation

Electrolyte

ions released through breakdown of inorganic compounds

can conduct electrical current in solution across cell membranes

Imbalance of this electrolyte can cause the most dangerous problems

K+

Sign and cause of respiratory alkalosis

Sign: High blood pH due to hypocapnia

Cause: Hyperventilation

Respiratory alkolosis

pH >7.45 (alkalemia)

Kidneys retain more hydrogen ions

Respiratory acidosis

pH <7.35 (acidemia)

Respiratory system cannot eliminate all CO2 generated by peripheral tissues

Sign and cause of respiratory acidosis

Sign: Low blood pH due to hypercapnia

Cause: Hypoventilation

How does angiotensin II elevate ECF volume

renin-angiotensin-aldosterone system activates

water and Na+ losses are reduced

Water and Na+ gains are increased

ECF volume increases

Drinking pure water during strenuous exercise can lead to this condition

hyponatremia

Hormone that affects blood osmolarity the most

ADH

Uncontrolled diabetes mellitus can lead to this type of metabolic acid-base disorder

ketoacidosis

Hypercalcemia

Ca2+ concentration in ECF >5.3 mEq/L

caused by hyperparathyroidism, malignant cancers, excessive calcium or vitamin D supplementation

Hypocalcemia

Ca2+ concentration in ECF is <4.3 mEq/L

Caused by hypoparathyroidism, vitamin D deficiency, chronic renal failure

Hypokalemia

deficiency of K+ in bloodstream

Hyperkalemia

elevated level of K+ in bloodstream

Hypernatremia

Due to dehydration

Na+ concentration of ECF >145 mEq/L

Hyponatremia

Due to hyperhydration

Na+ concentration of ECF <135 mEq/L

Hypercapnia

High blood PCO2 (partial pressure of carbon dioxide)

Hypocapnia

Low blood PCO2 (partial pressure of carbon dioxide)

organs responsible for maintaining acid-base balance

lungs and kidneys

Role of natriuretic peptides and heart chamber volume of blood

released by cardiac muscles in response to abnormal stretching of heart walls

Role of PTH and calcium ions

Ca2+ gained by absorption at digestive tract, reabsorption in kidneys

Both stimulated by PTH and calcitriol (raises blood calcium levels)

Role of carbonic acid bicarbonate buffer system (ECF)

limits pH changes caused by metabolic and fixed acids

affected by respiratory compensation