Fluid Compartments and Renal Overview

what are 4 things the kidneys regulate?

1. waste removal (through urine)

2. water regulation

3. ion regulation

4. acid-base balance

____% of the human body is water

60

blood is ___% plasma and ___% cells

60, 40

sodium is (low/high) in extracellular fluid while potassium is (low/high)

high, low

what is the total extracellular concentration of HCO₃⁻ in the body? what is the total osmolarity?

24 mM; 300 mOsm

what are 4 steps of estimating body fluid compartments by volume dilution?

1. select an appropriate indicator

2. inject a known volume of the indicator

3. allow the indictor to distribute evenly

4. take plasma sample and determine the indicator concentration

(t/f) an indicator must be able to be measured in a fluid samples and distribute evenly through the compartments by being metabolized and then being excreted

false; the indicator should not metabolize or be excreted

what are 2 indicators that will distribute to the total body water?

1. tritum (³H₂O)

2. antipyrine

which indicator will distribute to the extracellular fluid?

inulin

what 2 indicators will distribute to the plasma?

1. albumin

2. evan's blue

how can the total volume of plasma be calculated with an indicator? how can the total volume of blood be calculated?

Vplasma = ((volume of the indicator) * [indictor])/final concentration of the indicator in the body

Vblood = Vplasma / (1-0.4)

the renal arteries give rise to ______________ arteries which give rise to ______________ arteries

interlobular, arcuate

what is the function of the glomerulus in bowman's capsule?

plasma filtration

what is the function of the peritubular capillaries?

reabsorption from the nephron

what is the function of the afferent and efferent arterioles?

regulate the capillary hydrostatic pressure in the glomerulus

what is the filtration pressure of the arterioles? what is the reabsorption pressure of the peritubular capillaries?

60 mmHg; 13 mmHg

which component of the nephron does filtration take place?

bowman's capsule

which component of the nephron does bulk reabsorption?

proximal convoluted tubule

which component of the nephron produces an osmotic gradient?

loop of Henle

which component of the nephron fine-tunes reabsorption without water reabsorption?

distal convoluted tubule

which component of the nephron fine-tunes reabsorption with water reabsorption?

collecting tubule/duct

(t/f) most nephrons are cortical nephrons

true; 70-80% of nephrons are cortical nephrons

what is the purpose of a juxtamedullary nephron's long loop of Henle?

to produce an osmotic gradient that can concentrate urine

what are vasa recta?

capillary beds around the loops of henle of juxtamedullary nephrons

how does blood from the vasa recta regain water after descending into the medulla?

blood flow to the loop cells in the medulla cause water loss so the blood vessels will rise back into the cortex where it can regain the lost water

urine enters the bladder from the kidneys through the __________

ureters

(t/f) the bladder is a multi-unit of skeletal muscles

false; the bladder is a single unit of smooth muscle

what muscle will try to prevent micturition of the bladder?

the internal sphincter in the neck of the bladder

(t/f) the internal sphincter in the neck of the bladder is tonically contracted

true

(t/f) the external sphincter is made of smooth muscle and not under conscious control. where is it found?

false; the external sphincter is made of skeletal muscle and under conscious control

urethra

what does an increase in stretching of the bladder cause?

stimulates afferent fibers in the pelvic nerve which generates a reflex that causes the bladder to contract; this will lead to an increase in pressure which exceeds contracted strength of the internal sphincter causing urination

the contraction of the bladder is caused by (sympathetics/parasympathetics)

parasympathetics

the bladder is innervated by fibers in the (pelvic/pudendal) nerve while the external sphincter is innervated by fibers in the (pelvic/pudendal) nerve

pelvic, pudendal

consciously contracting and relaxing the (internal/external) sphincter is a learned process

external

(t/f) initiation of bladder emptying through an increase in pressure and a triggering of the micturition reflex can only done by the muscles of the bladder

false; abdominal muscles can contract to initiate bladder emptying by increasing pressure and triggering the micturition reflex

when the bladder contains _______-_______ mL, we get the urge to urinate. at the end of the urination, the bladder contains only 5-10 mL.

300-400

spinal damage, pudendal nerve damage, or pelvic nerve damage can result in urinary _______________

incontinence (the inability to control urine release)