TAYLOR ANP II Exam 4

Intrinsic controls of glomerular filtration rate

Manages filtration rates during normal day activities to prevent quick dehydration

(myogenic and tubuloglomerular feedback)

Extrinsic controls of glomerular filtration rate

sympathetic; activate during stress which causes AFFerent arteriole constriction

during the extrinsic controls when afferent constriction occurs, what happens?

decreased filtration, and activation of renin-angiotensin-aldosterone

where is renin-angiotensin-aldosterone activated?

through zona glomerulosa stimulation

under normal control (renal blood vessels)

remain wide open for max filtration

how does sympathetic release effect renal filtration

the release of norepi. & epi. during stress cause afferent arterioles to constrict

how does the constriction of afferent arterioles effect renal blood filtration

constriction causes a decrease in filtration due to a reduction of blood flow to glomerular capillary beds

what does decreased filtration trigger

renin release and therefore catalyzation angTENSIN --> angTENSIN I --> angTEN II

what effect does angTENSIN II have within the kidneys

it acts on zona glomerulosa in adrenal cortex to release aldosterone

how is blood flow chnaged during extreme stress

sympathetic sys diverts (temporarily) blood away from kidneys to prioritize other functions

two primary internal regulation systems

myogenic mechanism and tubuloglomerular feedback

what is the myogenic mechanism

an intrinsic, fast-acting vascular response where the smooth muscle of the afferent arteriole constricts

What is the tubuloglomerular feedback mechanism?

backup to myogenic mechanism response to increased blood pressure.

how much filtrate is produced daily

180 liters; 40-50 gallons

how much of that 180 L of filtrate becomes urine?

1.5 liters

which three membranes are required for reabsorption

luminal, basolateral, capillary Endothelium

what substances are reabsorbed in reabsorption?

Na+, K+, Ca+, Mg2+, all organic nutrients, and water.

what is the main site of reabsorption in the kidneys, and what percentage?

proximal convoluted tubule; reabsorbs roughly 65% of Na+ and H20, plus ion and small proteins and nutrients

The Loop oh Henle: descending limb

reabsorbs water

The LOOP of Henle: ascending limb

reabsorbs Na+, K+, and Cl-

What is sodium transport

always active and drives reabsorption of other solutes and water.

collecting ducts

normally impermeable to water and produce diluted urine by default

what allows collecting ducts to become permeable to water, and what is the purpose of this happening?

ADH; water conservation

Distal convoluted tubule and collecting ducts reabsorption depends on?

Hormones: PTH (calcium), ADH (h20), Aldosterone/ANP (Na+)

How does tubular secretion move? Which sequence

peritubular capillaries BACK into filtrate for elimination

what does filtrate contain

everything in plasma EXCEPT for large proteins and cells

why are large proteins and cells not able to be in filtrate

due to fenestrated epithelium, filtration slits and (-) charged BM

primary method for removing K+ ions from filtrate

Tubular secretion via concentration gradient between Sodium and Potassium

What does the tubular elemination secretion pathway provide

Allows a backdoor pathway for substances bound to plasma proteins to exit (cannot enter filtration by normal means)

Urine flow pathway

collecting tubules --> renal papillae --> major and minor calyces --> renal pelvis --> paired ureters --> retroperitoneal bladder

what type of tissue are paired ureters composed of

transitional epithelium and smooth muscle and protective fiborous

What is the trigone in the urinary bladder?

smooth triangular area outlined by openings for ureters and urethra

paired ureters location and function

insert below urinary bladder and close off, leading to INC bladder Psi, this prevents backflow.

How do ureters contract, whats the purpose of this contraction?

sequentially (perstaltic-like waves); moves urine into bladder

what does it mean when the bladder is retroperitoneal?

it is outside the peritoneal cavity, against the body wall

what is the normal bladder volume, what is its limit?

about 0.5 L normally and maximally around 1 L

bladder mucosal layer contains what tissue, for what purpose

transitional epithelium for stretch accomidation

bladder muscularis layer contains what muscle(s)? what are the purposes?

Longitudinal, circular, and diagonal; purpose is to wring out urine to prevent infection and retention

Male vs female urethra length

males have longer urethras than females

Male urethra is divided into what 5 parts? three sections and two sphincters

Sections:

- Prostatic (through prostate)

- membranous (urogenital diaphragm)

- spongy (free penis portion)

Sphincters:

- internal (involuntary)

- External (Voluntary/learned)

who does the bladder send impulses brain to trigger spinal reflexes?

Bladder has stretch receptors that become activated when urine comes in

Micturition center does what for sympathetic and parasympathetic systems

this center will increase parasympathetic activity and decrease sympathetic activity

what does activation of PNS and deactivation of SNS actually cause to happen within the body (micturition center)

detrusor muscle contracts, internal sphincter opens, inhibits somatic motor activity (opening external sphincter)

Storage center:

DEC PNS activity, STIMs SNS and somatic motor activity = inhibits micturition

Definition of micturition

emptying bladder = urine production

When does nerve control for storage center develop

between 2 and 3 years of age (some may be 4)

what does the development of this storage center depend on

nervous system maturing and physical ability to focus

When is potty training too early

before 15 months; it is physiologically inappropriate and potentially harmful

What are the two types of incontinence

stress and overflow

stress incontinence

occurs during heavy coughing, sneezing = small urine leakage

overflow incontinence

bladder is at max capacity and cant hold more; protective mechanism to prevent bladder rupture.

what does the body do during overflow

the body will automatically release urine to protect the bladder from rupturing

semi-bladders are bad, why?

half full can create rapid internal pressure during car accidents

How can anesthetic drugs affect urinary retention

muscles need time to regain control after exposure; catheters are standard to catch urine

How does diabetes insipidus cause overflow incontinence

ADH inhibition or lack of; damage to posterior pituitary neurons

Alcohols affect on urination

ADH function is inhibited; causes increase urination

Prostatic Hypertorphy has what effect on older men

it increases urine release

How many kidneys develop during first month of gestation

3 pairs (6 total)

by the 5th week of gestation, how many kidneys are left

one pair (2 total)

when does urine production begin

by the end of the 1st trimester

what is fetal urine cycling pathway?

it is unconcentrated and enters amniotic fluid for recycling

how does swallowing amniotic fluid effect the fetus

this stimulates GI tract development

fetus bladder complications

tiny bladders = limited space

ineffective kidneys (not very concentrated)

Potty training is

mastery of external (voluntary/learned) sphincter.

Kidney ____; ____ with age

efficiency; declines

horseshoe kidneys

1 in 400-500; fused kidneys

Hypospadias

male; urethral opening is not at tip of penis

Polycystic kidneys

improperly formed collection ducts create fluid-filled cysts, prevents proper urine drainage and INC infection risk, need kidney transplants

Diuretics enhance urine output through three distinct mechanisms

osmotic diuretics (unabsorbed substances glucose), ADH inhibitors (alcohol), sodium reabsorption inhibitors (caffeine)

Infant composition

73% body water due to low body fat and bone mass

Adult male composition

60% water

Adult female composition

50% due to differences in muscle mass to adipose tissue ratio

elderly body composition

around 45%

Why do men have higher water content than females? what are the %?

it is higer in males due to their skeletal muscle being 65% water while adipose tissue is around 20%

2/3 of body water is

(25L out of 40) INTRACELLULAR

1/3 of body water is

12L interstitial and 3L plasma

the body maintains equal osmotic pressures between....

intracellular, extracellular, and plasma components

60% of water intake

drinking fluids

30% of water intake

food consumption

10% of water intake

metabolic water; oxidative processes

60% of water output is

through urine

28% of water output is

lost through insensible losses

what are insensible losses of water

respiratory and skin moisture that serves no physiological purposes

8% of water output

is lost through sweat for cooling purposes

4% of water output

is lost through feces

How can water output percentages change

heat, humidity, diarrhea

Primary extracellular cation and anion

Na+ and Cl-

Primary intracellular cation and anion

K+ and Phosphate

where does bicarbonate ion come from? How much of co2 in plasma is bicarbonate ion?

Comes from carbon dioxide conversion; 70%

where is protein concentration highest and lowest

highest is intracellularly; lower is extracellularly (interstitial fluid)

osmotic pressures

determined by the amount of particles dissolved in a fluid

water movement

from lower (dilute) concentrations to higher

How do kidneys relate to osmotic pressure

they maintain balance in blood plasma and interstitial (extracellular) compartments

If Na+ blood [M] increases...what happens to water

fluid will move from interstitial space into the blood

how does fluid move relative to salt concentrations

downstream

Rising plasma osmolarity does what to the human body

increases thirst and decrease saliva production (dry mouth) AND triggers ADH release

water absorption in GI tract does what to blood

decreases plasma osmolarity = inhibition of thirst "quench"

Dehydration

water output is greater than water input (negative fluid balance)

causes of dehydration

extracellular fluid loss, exercise, water deprivation, diuretics (meds or caffeine), sweating, vomiting, diarrhea, bleeding, burns, tissue damage

extreme dehydration

hypovolemic shock, electrolyte imbalance, ADH release