Please enable JavaScript.
Coggle requires JavaScript to display documents.
Control of body fluid and micturition, example, Enhance - Coggle Diagram
Control of body fluid and micturition
ECF HOMEOSTASIS
internal steadiness despite
external fluctuation
ICF (cells) is bathed by ECF.
So, keeping ECF properties stable lets the cells work normally
If no kidney disease
In acidemia → kidneys will produce acidic urine (decrease urine pH)
If ECF is hypotonic/hypoosmolal → kidneys will excrete more free water
(without solute) → more diluted urine
• In hypertension (high ECF volume = salt + water) or high salt intake →kidneys will produce larger urine volume (more salt (Na+) excreted with water)
PREDICTING URINE OUTPUT PER UNIT TIME
Total excreted osmole (mOsm) = urine volume (L) x urine osmolality (mOsm/L)
Urine volume (L) = total excreted osmole (mOsm)
urine osmolality (mOsm/L)
maximal concentrated urine we can produced → ≈ 1400mOsm/L → very small free water excreted Osmoles needed to excrete = 600 mOsm (metabolism) diet (e.g.400 mOsm) = 1000 mOsm per day Urine volume = 1000/1400 = 0.7 L = 700 ml/day
Sympathetic Nervous System and Renal ECF control
Mild – moderate sympathetic stimulation → little effect on
RBF & GFR but increase renal tubular reabsorption
Severe + persistent sympathetic stimulation (minutes –
hours) → reduce GFR
Parallel to effect of norepinephrine and epinephrine
Little influence in resting + healthy person
Renal Response to Change in ECF Volume
Change
Increased Na+ intake → Increased ECF volume
Pressure natriuresis &
pressure diuresis
Adjust tubular Na+ reabsorption → within 2-3 days
Other functions of the kidneys
Secretion, metabolism and excretion of hormone esp.
Vitamin D, kinin, renin
Gluconeogenesis (with liver) in prolonged fasting (produce
almost 20% of the liver’s glucose capacity)
Produce erythropoietin → RBC production from bone
marrow
PHYSIOLOGY OF
MICTURITION
Review the Anatomy of Urinary System
Anatomy of Structures Involved in Micturition
Bladder → body and neck(Trigone at posterior wall → links 2 ureters and a urethra)
Innervation of Ureters
Well supplied with sympathetic, parasympathetic nerves,
intramural plexus, pain nerve fibers
When a ureter becomes blocked (e.g., by a ureteral stone)
Intense reflex constriction + severe pain (from part of
afferent autonomic fibers)
Sympathetic reflex back to the kidney to constrict the renal arterioles = ureterorenal reflex → decreasing urine output to prevent excessive urine flow
Micturition
The process of bladder emptying after filling
Storage phase = progressive filling → until tension >
threshold level for micturition reflex
Voiding phase = emptying → micturition reflex (autonomic spinal cord reflex) → can be inhibited or facilitated by higher control (maybe voluntary)
Micturition (Stretch) Reflex
The reflex is self-regenerative before becoming fatigue. → initial contraction further activates the stretch receptors
Higher Level of Micturition Control by The Brain
Exert final control of micturition by tonic contraction of the external bladder sphincter and at bladder detrusor muscle tone to partially inhibit micturition reflex until a convenient time
Strong facilitative and inhibitory centers in the brain stem (mainly in the
pons and suprapontine centers)
Several cerebral cortex centers (mainly inhibitory but can also facilitate the
sacral micturition centers to help initiate a micturition reflex if desired)
example
Enhance
