Renal Physiology - Lymph and other body fluids Flashcards
- PB_BK_14 Lymphatic system - PB_BK_15 Special fluids especially cerebrospinal fluid: also pleural, pericardial and peritoneal fluids
How is pleural fluid produced, and what is its role?
A serous fluid produced by the pleural membrane covering the parietal and visceral pleurae
Lubricates the pleural layers, and maintains surface tension to facilitate negative pressure ventilation.
Has a pH of around 7.6, and low protein content. Mostly drained by bronchial venous circulation, but around 10% via lymphatic system
What causes a pleural effusion?
Fluid will leak into the pleural space if there is:
Increased capillary permeability
Increased hydrostatic pressure in the plasma
Decreased oncotic pressure in the plasma
Greater negative pressure in the pleural space
Can be transudative (Heart failure, cirrhosis, nephrotic syndrome) or exudative (Infection, cancer)
What is cardiac tamponade and why does it occur?
Serous fluid produced by pericardial membrane, usually 20-50ml, lubricating the parietal and visceral layers, and providing protection against blunt trauma.
If the volume of pericardial fluid increases rapidly, the stiff pericardial sac causes compression of the heart, preventing diastolic filling and reducing preload.
Causes are acute (trauma, infection, dissection, post-op bleeding) and chronic (pericarditis, cancer).
Typically described as causing Beck’s triad - muffled heart sounds, jugular venous distension, and hypotension.
Treatment is drainage of excess fluid.
What is lymph and what is its purpose?
An extracellular fluid.
Drains via the lymphatic system
Present everywhere aside from bone, spinal cord and brain.
Rudimentary capillaries with no basement membrane or valves
1mmHg prssure in the system, one way flow increased by external compression & arterial pulsation
Drains via thoracic duct on left, and lymphatic duct on the right into the subclavian veins.
Functions
Return of fluid and small amount of protein into the circulation
Maintains oncotic gradient between intravascular space and ECF
Fat digestion and transport in the GI tract (lymph forms the basis of chyle)
Lymphocytes and antibodies play role in immunity
How is intraocular fluid produced
Aqueous and vitreous humour
Plasma dialysate secreted by choroidal plexus at 0.08ml/hr
Passes through pupil into anterior chamber, draining via canal of Schlemm into venous system
Nutrition and oxygen for anterior chamber
Vitreous humour contains phagocytes
Which cells produce peritoneal fluid, and what is acites?
Peritoneal cells
Lubricates intestines to facilitate peristalsis
Ascites is a pathological accumulation of peritoneal fluid, associated with heart failure, malignancy or cirrhosis.
