Ch 25 Urinary System

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What are the layers of surrounding supportive tissue of the kidney?

renal fascia, perirenal fat capsule, fibrous capsule


Describe the renal fascia layer of the surrounding supportive tissue of kidney

anchoring outer layer of dense fibrous connective tissue


Describe perirenal fat capsule layer of the surrounding supportive tissue of kidney

fatty cushion


Describe fibrous capsule layer of the surrounding supportive tissue of kidney

prevents spread of infection of kidney


three parts of the internal anatomy of the kidney?

renal cortex, renal medulla, renal pelvis


Describe the renal cortex

granular appearing superficial region


describe renal medulla

composed of cone-shaped renal pyramids

-pyramids separated by renal columns (inward extensions of cortical tissue)


describe pelvis

funnel-shaped tube continuous with ureter


define papilla

tip of pyramid-releases urine into minor calyx


define lobe of kidney

renal pyramid and its surrounding cortical tissue and about 8 per kidney


Minor calyces

drain pyramids at papillae


define major calyces

-collect urine from minor calyces

-empty urine into renal pelvis


What is the order of urine flow?

renal pyramid-minor calyx-major calyx-renal pelvis-ureter


define pyelitis

infection of renal pelvis and calyces



-infection/inflammation of entire kidney

-normally-successfully treated with antibiotics (Cipro, Augmentin)


Describe the blood and nerve supply in the kidney

-kidneys cleanse blood and adjust its composition-rich blood supply

-renal arteries deliver about 1/4 of cardiac output to kidneys each minute

-nerve supply via sympathetic fibers from renal plexus



-structural and functional units that form urine

-more than 1 million per kidney

-two main parts:renal corpuscle and renal tubule


two parts of renal corpuscle?

glomerulus and glomerular capsule (Bowman's capsule)



-a tuft of capillaries

-fenestrated endothelium-highly porous-allows filtrate formation

-(parts of renal corpuscle)


Glomerular capsule (Bowman's capsule)

-(part of renal corpuscle)

-cup-shaped hollow structure surrounding glomerulus

-parietal layer-simple squamous epithelium

-visceral layer-branching epithelial podocytes

-foot processes that cling to basement membrane

-filtration slits between foot processes allow filtrate to enter


Describe the three parts of the renal tubule

-Proximal convoluted tubule (proximal-closest to renal corpuscle)

-nephron loop (between descending limb and ascending limb)

-distal convoluted tubule (distal-farthest from renal corpuscle)


The PCT part of the renal tubule?

-cuboidal cells

-dense microvilli (brush border increases surface area)

-large mitochondria

-functions in reabsorption and secretion



The nephron loop part of the renal tubule?

-descending and ascending limbs

-descending thin limb-simple squamous epithelium

-ascending thick limb-cuboidal to columnar cells

-recovers water and NaCl


Describe the DCT part of the renal tubule?

-cuboidal cells with very few microvilli


-function more in secretion than reabsorption


What are the two cell types in COLLECTING DUCTS

principal cells and intercalated cells


describe the principal cells (part of collecting ducts)

-sparse, short microvilli

-maintain water and Na+ balance


describe the intercalated cells (part of collecting ducts)

-cuboidal, abundant microvilli

-A and B: both help maintain acid-base balance of blood


Describe the functions of the collecting ducts?

-receive filtrate from many nephrons

-run through medullary pyramids-striped appearance

-fuse together to deliver urine through papillae into minor calyces


What are the classes of nephrons?

1) cortical nephrons

-85% of nephrons

-almost entirely in cortex

2) juxtamedullary nephrons

- long nephron loops down into medulla

-important in production of concentrated urine


Nephron capillary beds:

Renal tubules associated with two capillary beds:

-glomerulus-produces filtrate

-peritubular capillaries-reclaims most of filtrate


nephron capillary beds:

Juxtamedullary nephrons:

-vasa recta-instead of peritubular capillaries


Nephron capillary beds:


-specialized for filtraton

-different from other capillary beds- fed and drained by arteriole

-afferent arteriole-glomerulus- efferent arteriole

-blood pressure in glomerulus high because

-afferent arterioles larger in diameter than efferent arterioles

-arterioles are high-resistance vessels


Nephron capillary beds:

Peritubular capillaries:

-low pressure, porous capillaries adapted for absorption of reclaimed water and solutes

-arise from efferent arterioles

-cling to adjacent


Nephron capillary beds:

Vasa recta:

-long, thin-walled vessels parallel to long nephron loops of juxtamedullary nephrons

-arise from efferent arterioles serving jutamedullary nephrons

-instead of pertiubular capillaries

-function in formation of concentrated urine


Juxtaglomerular complex (JGC)

-one per nehpron

-modified portions of

-distal portion of ascending limb of nephron loop

-afferent (sometimes efferent) arteriole

-important in regulation of rate of filtrate formation and blood pressure


Three cell populations of JGC?

macula densa

granular cells

extraglomerular mesangial cells


macula densa

-tall,closely packed cells of ascending limb

-chemoreceptors:sense NaCl content of filtrate


Granular cells (juxtaglomerular, or JG cells)

-enlarged, smooth muscle cells of arteriole

-secretory granules contain enzyme renin

-mechanoreceptors: sense blood pressure in afferent arteriole


extraglomerular mesangial cells

-between arteriole and tubule cells

-interconnected with gap junctions

-may pass signals between macula densa and granular cells


How much urine is processed and secreted daily?

180 liters processed daily--only 1.5 l of urine


what are the three process in urine formation and adjustment of blood composition?

1) glomerular filtration

2) tubular reabsorption

3) tubular secretion


mechanisms of urine formations?

kidneys filter entire plasma volume 60x per day

consume 20-25% oxygen used by body at rest


Define filtrate

(produced by glomerular filtration)

=blood plasma minus proteins



-<1% of original filtrate

-contains metabolic wastes and unneeded substances


1) glomerular filtration

-passive process=no metabolic energy required

-hydrostatic pressure forces fluids and solutes through filtration membrance


What is the filtration membrane?

porous membrane between blood and interior of glomerular capsule

-water, solutes smaller than plasma proteins pass

-normally no cells pass


What are the three layers of the filtration membrane?

-fenestrated endothelium of glomerular capillaries

-basement membrane

-foot processes of podocytes with filtration slits


What is allowed through the filtration membrane?

-allows molecules smaller than 3 nm to pass (water, glucose, AA, nitrogenous wastes)

-macromolecules "stuck" in filtration membrane engulfed by glomerular mesangial cells

-plasma proteins remain in blood-maintains colloid osmotic pressure-prevents loss of all water to capsular space

-proteins in filtrate indicate membrane problem


Pressures that affect filtration?

-outward pressures promote filtrate formation:

-hydrostatic pressure in glomerular capillaries=Glomerular blood pressure

-chief force pushing water, solutes out of blood

-quite high-55 mm Hg- because efferent arteriole is high resistance vessel with diameter smaller than afferent arteriole


Pressures that affect filtration?

-inward forces inhibiting filtrate formation:

-hydrostatic pressure in capsular space (HP_cs)

-pressure of filtrate in capsule-15 mm Hg

-colloid osmotic pressure in capillaries (OP_gc)

-pull of proteins in blood-30 mm Hg


Sum of forces (pressures that affect filtration)

---> Net filtration pressure

55 forcing out of blood-45 opposing=net outward force of 10 mm Hg


What is NFP responsible for?

-pressure responsible for filtrate formation (10 mm Hg)

-main controllable factor determining GFR

(slide 47 in part one has good visual)


What does a constant GFR allow for the kidneys?

a constant GFR allows kidneys to make filtrate and maintain extracellular homestasis


Goal of intrinsic controls?

maintain GFR in kidney


How does GFR affect systemic blood pressure?

-increased GFR causes increase urine output, this decreases blood pressure and vice versa


goal of extrinsic controls?

maintain systemic blood pressure


Describe Intrinsic controls?

(renal autoregulation)

-act locally within kidney to maintain GFR


Describe Extrinsic controls?

-nervous and endocrine mechanisms that maintain blood pressure-can negatively affect kidney function

-take precedence over intrinsic controls if systemic BP <80 or > 180 mm Hg


What is the regulation of glomerular filtration controlled by?

-controlled via glomerular hydrostatic pressure

-if rises-> NFP rises -> GFR rise

-if falls by as little as 18% -> GFR =0


Two types of renal autoregulation (intrinsic controls)?

1) myogenic mechanism

2) tubuloglomerular feedback mechanism


Intrinisic controls: myogenic mechanism?

smooth muscle contracts when stretched

-increased BP-> muscle stretch-> constriction of afferent arterioles -> restricts blood flow into glomerulus (protects glomeruli from damaging high BP)

-decreased BP -> dilation of afferent arterioles

-both help maintain normal GFR despite normal fluctuations in BP


Intrinsic controls: tubuloglomerular feedback mechanism

-flow-dependent mechanism directed by macula densa cells-respond to filtrate NaCl concentration

-if GFR increases->filtrate flow rate increases-> decreased reabsorption time ->high filtrate NaCl levels-> constriction of afferent arteriole-> decreased NFP and GFR-> more time for NaCl reabsorption

-opposite for decreased GFR


Extrinsic controls: sympathetic nervous system?

-under normal conditions at rest

-renal blood vessels dilated

-renal autoregulation mechanisms prevail


Extrinsic controls: sympathetic nervous system:

If extracellular fluid volume extremely low (BP low)....

-norepinephrine released by sympathetic nervous system, epinephrine released by adrenal medulla

-systemic vasoconstriction -> increased blood pressure

-constriction of afferent arterioles->decreased GFR-> increased blood volume and pressure


Extrinsic controls: renin-angiotensin-aldosterone mechanism

What are the 3 pathways to renin release by granular cells?

1) direct stimulation of granular cells by sympathetic nervous sytem

2) stimulation by activated macula densa cells when filtrate NaCl concentration low

3) reduced stretch of granular cells


Extrinsic controls: other factors affecting GFR:

Kidneys release some chemicals that act as paracrines to affect renal arterior:

-adenosine (increased calcium-smooth muscle effects)

-prostaglandin E2-> increased GFR

-intrinsic angiotensin ii-> reinforces effects of hormonal angiotensin II->increased sodium


Step 2 reabsorption of nutrients, water, and ions?

-Na+ reabsorption by primary active transport provides energy and means for reabsorbing most other substances

-organic nutrients reabsorbed by secondary active transport

-co-transported with Na+

-glucose, AA, some ions, vitamins


Passive tubular reabsorption of water?

-movement of sodium and other solutes creates osmotic gradient for water

-water reabsorbed by osmosis, aided by water-filled pores called aquaporins



-always present in PCT-> obligatory water reabsorption

-aquaporins inserted in collecting ducts only if ADH present-> facultative water reabsorption

-solute concentration in filtrate increases as water reabsorbed->concentration gradients for solutes->

-fat soluble substances, some ions and urea, follow water into peritubular capillaries down concentration gradients

-> lipid-soluble drugs, environmental pollutants difficult to excrete


What is transport maximum?

it exits because transcellular transport systems specific and limited

-transport maximum for almost every reabsorbed substance

-reflects number of carriers in renal tubules available

-when carriers saturated, excess excreted in urine (hyperglycemia-high glucose levels exeed Tm and theres glucose in urine)


Reabsorptive capabilities of renal tubules and collecting ducts:


-site of most reabsorption

-all nutrients (glucose and AAs)

-65% of Na+ and water

-many ions

-all uric acid, 1/2 urea (later secreted back into filtrate)


Reabsorptive capabilities of renal tubules and collecting ducts:

Nephron loop....

-descending limb-H2O can leave/solutes cant

-ascending limb-H2O cant leave/solutes can


Reabsorptive capabilities of renal tubules and collecting ducts:

DCT and collecting duct...

-reabsorption hormonally regulated

-ADH-keep water in body, insert aquaporins

-Aldosterone-keep sodium (therefore water), increase BP

-ANP-get rid of Na+, decrease BP

-PTH-keep Ca2+


Step 3: tubular secretion

reabsorption in reverse-almost all in PCT

-selected substances

-K, H, NH4, creatinine, organic acids, and bases move from peritubular capillaries through tubule cells into filtrate

-substances synthesized in tubule cells also secreted-(HCO3-)

-disposes of substances (drugs) bound to plasma proteins

-eliminates undesirable substances passively reabsorbed (urea and uric acid)

-rids body of excess K+ (aldosterone effect)

-controls blood pH by altering amounts of H+ or HCO3- in urine


Regulation of urine concentration and volume?


-number of solute particles in 1 kg of H2O

-reflects ability to cause osmosis


osmolality of body fluids?

-expressed in milliosmols

-kidneys maintain osmolality of plasma at about 300 mOsm by regulating urine concentration and volume

-kidneys regulate with countercurrent mechanism


Countercurrent mechanism?

occurs when fluid flows in opposite direction in two adjacent segments of same tube with hair pin turn

-countercurrent multiplier

-countercurrent exchanger


countercurrent multiplier?

-interaction of filtrate flow in ascending/descending limbs of nephron loops of juxtamedullary nephrons


countercurrent exchanger?

-blood flow in ascending/descending limbs of vasa recta


Role of countercurrent mechanisms?

-establish and maintain osmotic gradient (300-1200) from renal cortex through medulla

-allows kidneys to vary urine concentration


Countercurrent exchanger??

-vasa recta preserves medullary gradient

-prevent rapid removal of salt from interstitial space

-remove reabsorbed

-water entering ascending vasa recta either from descending vasa recta either from descending vasa recta or reabsorbed from nephron loop and collecting duct->

-volume of blood at end of vasa recta greater than at beginning



-larger volume dilute urine

-ADH production decreased

-urine is about 100 mOsm

-if aldosterone present, additional ions removed-> about 50



-small volume concentrated urine

-maximal ADH released

-urine is about 1200 mOsm

-severe dehydration -99% water reabsorbed


Chemicals that enhance urinary output (diuresis)?

-ADH inhibitors (alcohol)

-Na+ reabsorption (H2) reabsorption) inhibitors (caffeine, drugs for hypertension or edema)

-loop diuretics inhibit medullary gradient formation (Lasix)

-osmotic diuretics- substance not reabsorbed so water remains in urine (high glucose of a diabetic)


Renal Clearance?

-volume of plasma kidneys clear of particular substance in given time

-renal clearance tests used to determine GFR

-to detect glomerular damage

-to follow progress of renal disease


Renal clearance equation?


c=renal clearance rate in ml/min

u=concentration of substance in urine in mg/ml

v= flow rate of urine formation in ml/min

p=concentration of same substance in plasma



-plant plysaccharide is standard used

-freely filtered neither reabsorbed nor seceted by kidneys and its renal clearance is 125 ml/min

-if C<125 substance reabsorbed

-if c=0, substance completely reabsorbed or not filtered

-if c=125 ml/min, no net reabsorption or secretion

-if c> 125 ml/min substance secreted (most drug metabolites)


Chronic renal disease?

GFR is <60 for three months (diabetes mellitus, hypertension)


Renal failure?

GFR is <15

-causes of uremia:ionic and hormonal imbalances, metabolic abnormalities, toxic molecule accumulation

-treated with hemodialysis or transplant


What is the pale to deep yellow color of urine from?

urochrome-pigment from hemoglobin breakdown


What should the smell of urine normally be?

-slightly aromatic when fresh

-it can develop ammonia odor upon standing from bacteria metabolize solutes


What is the pH of urine typically?

Specific gravity?

Chemical composition?

-slightly acidic (pH 6 with range of 4.5-8.0), acidic diet like protein and whole wheat decreased the pH and a alkaline diet like a vegetarian or from prolonged vomiting or UTIs causes the pH to increase

-specific gravity is 1.001 to 1.035

-95% water and 5% solutes


Nitrogenous wastes in urine?

-urea (from amino acid breakdown)-largest solute component

-uric acid (from nucleic acid metabolism)

-creatinine (metabolite of creatine phosphate)


Ureters start where?

-they convey urine from kidneys to bladder and begin at L2 as continuation of renal pelvis

-enter base of bladder through posterior wall (as bladder pressure increases, distal ends of ureters close, preventing backflow of urine)


What are the three layers of ureter walls from inside to out?

Mucosa-transitional epithelium

Muscularis-smooth muscle sheets (contracts in response to stretch and propels urine into bladder)

Adventitia-outer fibrous connective tissue


Renal calculi?

-kidney stones in renal pelvis-crystallized calcium, magnesium, or uric acid salts

-large stones block ureter->pressure and pain

-may be due to chronic bacterial infection, urine retention, increased calcium in blood, increased pH of urine

-treatment-shock wave lithotripsy-noninvasive-shock waves shatter calculi


Describe the urinary bladder?

-muscular sac for temporary storage of urine

-on pelvic floor posterior to pubic symphyis

(on males-prostate inferior to bladder neck, females-anterior to vagina and uterus)

-openings for ureters and urethra

-trigone: smooth triangular area outlined by openings for ureters and urethra and infections tend to persist in this region


Describe the layers of the bladder wall:

-mucosa-transitional epithelial mucosa

-thick detrusor-three layers of smooth muscle

-fibrous adventitia (peritoneum on superior surface only)


Urinary bladder when empyting?

-it will collapse when empty-rugae appear

-expands and rises superiorly during filling without significant rise in internal pressure

-full bladder 12 cm long, holds about 500 ml (can hold twice that if necessary and can burst if overdistended)


What is the lining or the urethra?


-mostly pseudostratified columnar epithelium, except:

-transitional epithelium near bladder

-stratified squamous epithelium near external urethral orifice


internal urethral sphincter?

-involuntary (smooth muscle) at bladder-urethra junction

-contracts to open


external urethral sphincter?

voluntary (skeletal) muscle surrounding urethra as it passes through pelvic floor


female urethra?

-3-4 cm

-tightly bound to anterior vaginal wall

-external urethral orifice

-anterior to vaginal opening, posterior to clitoris


male urethra?

-carries semen and urine

-prostatic urethra (2.5 cm)-within prostate

-intermediate part of the urethra (membranous urethra) (2 cm)-passes through urogenital diaphragm from prostate to beginning of penis

-spongy urethra-(15 cm)-passes through penis; opens via external urethral orifice


name for voiding or urination?

three simultaneous events must occur?


-contraction of detrusor by ANS

-opening of internal urethral sphincter by ANS

-opening of external urethral sphincter by somatic nervous system


stress incontinence?

-increased intra-abdominal pressure forces urine through external sphincter


overflow incontinence?

urinary retention?

-urine dribbles when bladder overfills

-bladder unable to expel urine

-common after general anesthesia

-hypertrophy of prostate



Chaper 26-fluid, acid base

What is the body water content by gender?

-adult maes -60% water

-adult females _50% water (higher fat content, less skeletal muscle mass)

-water content declines to -45 % in old age


The total body water and different fluid compartments?

-total body water=40 L

1) intracellular fluid compartment: 25 L in cells

2) extracellular fluid compartment 15 L

-plasma 3 L

-interstitial fluid 12 L in spaces between cells

-other ECF: lymph, CSF, humors of the eye, synovial fluid, serous fluid, and GI secretion


composition of body fluids?

-water: the universal solvent

-solutes: electrolytes and nonelectrolytes

-Non: most are organic- do not dissociate in water (glucose, lipids, creatinine, and urea)

-electrolytes: dissociate into ions in water: (inorganic salts, all acids and bases, some proteins)

-most numerous solutes

-determine the chemical and physical reactions of fluids


Extracellular and intracellular fluids?

each fluid compartment has a distinctive pattern of electrolytes

-ECF: all similar, except higher protein content than plasma, major cation: Na+, major anion: Cl-

-ICF: low Na+ and Cl-, major cation: K+, major anion: HPO42-


Proteins and phospholipids and cholesterol and neutral fats make up the bulk of dissolved solutes, %?

-90% in plasma

-60% in IF

-97% in ICF


What is fluid movement among compartments regulated by?

regulated by osmotic and hydrostatic pressures

-HP forces filtrate out of capillaries

-colloid osmotic pressure pulls filtrate back in

water moves freely by osmosis

ion fluxes require active transport or channels

change in solute concentration of any compartment leads to net water flow


Water balance and ECF osmolality?

water intake=water output=2.5 L/day


Regulation of water intake?

-thirst mechanism is the driving force for water intake

-hypothalamic thirst center osmoreceptors stimulated by

-decreased plasma osmolalituy of 2-3%

-angiotensin II or baroreceptor input

-dry mouth

-substantial decrease in blood volume or pressure


Influence of ADH on regulation of water output?

-water reabsorption in collecting ducts is proportional to ADH release

-decrease ADH-> dilute urine and decreased volume of body fluids

-increase ADH-> concentrated urine

-hypothalamic osmoreceptors trigger or inhibit ADH

-other factors: large changes in blood volume or pressure (fever, sweating, vomiting, diarrhea, blood loss, traumatic burns)



-atypical accumulation of IF-> tissue swelling, may impair blood circulation

-anything that increased flow of fluid out of blood or hinders its return

-increase BP

-increased capillary permeability (usually due to inflammatory chemicals)

-incompetent venous valves, localized blood vessel blockage

-congestive heart failure, hypertension, increased blood volume


Importance of salts:

-controlling fluid movements


-membrane permeability


Central role of sodium?

-most abundant cation in the ECF

-sodium salts in the ECF contribute 280 mOsm of the total 300 mOsm ECF solute concentration

-Na+ leaks into cells and is pumped out against its electrochemical gradient

-changes in plasma sodium levels affect

-plasma volume, BP

-ICF and IF volumes

-renal acid-base control mechanisms are coupled to sodium ion transport


Regulation of Sodium Balance: Aldosterone

-Na+ reabsorption

-65% is reabsorbed in the proximal tubules

-25% is reclaimed in the loops of Henle

-aldosterone-> active reabsorption of remaining Na+

-water follows Na+ if ADH is present


Regulation of Sodium Balance: ANP

-released by atrial cells in response to stretch (increase BP)


-decreases blood pressure and blood volume:

-decrease ADH, renin, and aldosterone production

-increase excretion of Na+ and water

-promotes vasodilation directly and also by decreasing production of angiotensin II


Influence of estrogens, progesterone, glucocorticoids on sodium reabsorption?

-estrogens: increased NaCl reabsorption (like aldosterone)

-H2O retention during menstrual cycles and pregnancy

-progesterone: decrease reabsorption (blocks aldosterone)-promotes Na+ and H2O loss

-glucocorticoids: increase Na+ reabsorption and promote edema



alert the brain of increased in blood volume and pressure

-sympathetic nervous system impulses to the kidneys decline

-afferent arterioles dilate

-GFR increases

-Na+ and water output increase


Importance of potassium:

affects RMP in neurons and muscle cells (especially cardiac muscle)

-Increase ECT (K+) -> decrease RMP-> depolarization -> reduced excitability

-decrease ECF (K+)-> hyperpolarization and nonresponsiveness


Regulation of potassium balance?

-K+ balance is controlled in the cortical collecting ducts by changing the amount of potassium secreted into filtrate

-high K+ content of ECF favors secretion of K+


Regulation of Potassium balance:

Influence of aldosterone:

-stimulates K+ secretion (and Na+ reabsorption)

-increased K+ in the adrenal cortex causes

-release of aldosterone

-potassium secretion


Ca2+ in ECF is important for:

-neuromuscular excitability

-blood clotting

-cell membrane permeabilitiy




what is calcium balance controlled by?

hypocalcemia- increases excitability and muscle tetany

hypercalcemia-inhibits neurons and muscle cells, may cause heart arrhythmias

-calcium balance is controlled by parathyroid hormone (PTH) and calcitonin


Influence of PTH?

-bones are the largest reservoir for Ca2+ and phophates

-PTH increases calcium levels by targeting bones, kidneys, and small intestine (indirectly through vitamin D)

-calcium reabsorption and phosphate excretion go hand in hand

-normally 75% of filtered phosphates are actively reabsorbed in the PCT

-PTH inhibits this by decreasing the Tm


Regulation of Anions:


-Cl- is the major anion in the ECF

-helps maintain the osmotic pressure of the blood

-99% of Cl- reabsorbed under normal pH conditions


Normal pH of body fluids?

arterial blood: pH 7.4

venous blood and IF fluid: pH 7.35

ICF: pH 7.0

Alkalosis or alkalemia: arterial blood pH>7.45

acidosis or academia: arterial pH <7.35


H+ in acid base balance:

-Most is produced____

-concentration of H+ is regulated sequentially by:

most is produced by metabolism

1)chemical buffer systems: rapid, first line of defense

2) brain stem respiratory centers: act within 1-3 min

3) renal mechanisms: most potent, but require hours to days for pH changes


Whats a chemical buffer?

-system of one or more compounds that act to resist pH changes when strong acid or base is added

1) bicarbonate buffer system-ECF

2) phosphate buffer system- urine, ICF

3) protein buffer system-plentiful and powerful

amphoteric-weak acid or weak base

hemoglobin-protein that acts as buffer


function of respiratory and renal systems:

act more slowly than chemical buffer systems

have more capacity than chemical buffer systems


respiratory regulation of H+:

hypercapnia activates medullary chemoreceptors

rising plasma H+ activates peripheral chemoreceptors

-more CO2 is removed from the blood

-H+ concentration is reduced


The effect of alkalosis on the respiratory center?

-alkalosis depresses the respiratory center

-respiratory rate and depth decrease

-H+ concentration increase


respiratory system impairments?

hypoventilation-respiratory acidosis

hyperventilation-respiratory alkalosis


How does the chemical buffers eliminate excess acids or bases from the body?

-chemical buffers cannot eliminate excess acids or bases from the body

-lungs eliminate volatile carbonic acid by eliminating CO2

-kidneys eliminate other fixed metabolic acids (phosphoric, uric, and lactic acids and ketones) and prevent metabolic acidosis


most important renal mechanisms?

conserving (reabsorbing) or generating new HCO3-

excreting HCO3-


Renal mechanisms of acid base balance?

-generating or reabsorbing one HCO3- is the same as losing one H+

-excreting one HCO3- is the same s gaining one H+

-renal regulation of acid-base balance depends on secretion of H+

-H+ secretion occurs in the PCT and collecting duct


Bicarbonate ion secretion?

when the body is in alkalosis,

-secrete HCO3-

-reclaim H+ and acidify the blood


Whats the most important indicator of adequacy of respiratory function?

Pco2 level (normal level is 35-45)

-pco2 above 45-respiratory acidosis

most common cause of acid-base imbalances, due to decrease in ventilation or gas exchange, characterized by falling blood pH and rising Pco2


Respiratory alkalosis?

-Pco2 below 35 mm Hg

a common result of hyperventilation due to stress or pain


what are metabolic acidosis and alkalosis indicated by?

abnormal HCO3- levels


Causes of metabolic acidosis?

-ingestion of too much alcohol (-> acetic acid)

-excessive loss of HCO3- (persistent diarrhea)

-accumulation of lactic acid, shock, ketosis in diabetic crisis, starvation, and kidney failure


what is metabolic alkalosis indicated by?

-indicated by rising blood pH and HCO3-

-caused by vomiting of the acid contents of the stomach or by intake of excess base (antacids)


Effects of a too low or high pH?

-blood pH below 7-> depression of CNS-> coma->death

-blood pH above 7.8-> excitation of nervous system-> muscle tetany, extreme nervousness, convulsions, respiratory arrest


respiratory and renal compensations?

-if acid-base imbalance is due to malfunction of a physiological buffer system, the other one compensates

-respiratory system attempts to correct metabolic acid-base imbalances

-kidneys attempt to correct respiratory acid-base imbalances



gestation period:

conceptus: developing offspring

gestation period:

-last menstrual period until birth

-approx. 280 days



intrauterine insemination

-sperm is directly inserted into the uterus at the time of ovulation


in vitro fertilization (IVF)

ICSI-intracytoplasmic sperm injection

eggs are gathered and combined with sperm in a lab and the resulting embryos are transplanted into the uterus

a single sperm is injected straight into a single egg in the laboratory and the resulting embryo is transplanted into the uterus


0-3 months -first trimester

Month 1: amniotic sac and placenta form, primitive face forms with large dark circles for eyes, mouth and lower jaw and throat are developing, blood cells are taking shape, and circulation will begin

Month 2: facial features continue to develop, ears begin to develop, tiny buds that eventually grow into arms and legs are forming, fingers and toes and eyes are also forming in the second month, digestive tract and sensory organs begin to develop, bone starts to replace cartilage, embryo begins to move, 1 inch long, weighs about 1/3 ounce and 1/3 of the baby is made up of its head, about size of kidney bean

Month 3: baby has arms, hands, fingers, feet, and toes, can open and close its fists and mouth, fingernails and toenails are beginning to develop, external ears are formed, beginnings of teeth are forming, reproductive organs develop, circulatory and urinary systems are working and liver produces bile, 3-4 inches long, weighs about 1 ounce


4-6 months: second trimester

month 4: finger and toes well defined and developed, eyelids and eyebrows and eyelashes, nails, and hair are formed, can such thumb, yawn, stretch and make faces, about 6 inches long

Month 5: about 10 inches long, weighs approx. 1/2 to 1 pound, hair begins to grow on the head, skin is covered with white coating

Month 6: about 12 inches long, weighs approx. 2 lbs, skin is reddish in color and wrinkled, eyes begin to open


7-9 months-> third trimester

-month 7: fetus is about 36 cm long, weighs anywhere from 2-4 lbs, skin is red/wrinkled, lungs are still undeveloped, hearing is fully developed and they respond to stimuli

Month 8: baby is 46 cm, weighs about 5 lbs, continues to develop body fat reserves, brain develops rapidly, hear develops into its final shape, central neural, endocrine, and immune systems still developing, skin is smooth and unwrinkled, baby can see and hear

Month 9: baby is 18-20 inches, weighs about 7 lbs, lungs are almost fully developed, genitalia fully formed, meconium begins gathering in intestines, has moved down to pelvis, head is facing down towards birth canal


labor stages?

dilation, expulsion, placental


dilation stage of labor:

-from beginning onset until cervix is fully dilated 10 cm

-weak but regular contractions

-15-30 mins apart and lasts 10-30 seconds

-as labor progresses, contractions become more painful and rapid (cervix softens, thins and dilates)

-the amnion ruptures releasing amniotic fluid and the water breaks


expulsion stage:

-from full dilation to delivery

-strong contractions- every 2-3 minutes lasting about 1 minute

-urge to push/bear down with AB muscles

-crowning (head distends the vulva)


Placental stage:

-delivery of placenta and attatched fetal membranes

-within 30 minutes of birth

-strong contractions occur due to cutting off placenta and limiting bleeding

-placental pieces must come out to prevent continued uterine bleeding (postpartum bleeding)


Involution of the Uterus?


immediately after birth is about the size of a softball, fundus descends 1 cm each day

lochia: rubra-dark red for 3-4 days

serosa-pinkish brown for 4-10 days

alba-whitish yellow-10-28 days


involution of the vagina and perineum?

-vagina takes 6-10 weeks for involution of the vagina to be complete

-perineum is swollen and bruised, is episiotomy is performed it takes 4-6 months to heal,


Cardiac changes during birth?

hypervolemia during pregnancy increases blood volume by 30-45% which allows for substantial blood loss during birth (500 mL vag delivery, 1000 ml C-section)

returns to normal values after 6-12 weeks


endocrine system and resumption of ovulation/menstration...

-levels of placenta hormones such as estrogens, progesterone, and human placental lactogen decline fairly rapidly

-HCG is present for 3-4 weeks

non nursing mothers resume menstruation 7-9 weeks after childbirth



sudden changes in hormone levels after delivering a baby can trigger depression

about 10% of new moms develop PPD, but might be higher