Lecture 27. Fundamentals of Cardiovascular and Renal Physiology Flashcards
What type of capillaries do lymph vessels have ?
Blind ending
Where do large lymph vessels empty into ?
The subclavian vein
What do valves prevent ?
Backflow
What are the major functions of lymph vessels ?
- Tissue drainage
- Return leaked plasma proteins
- Absorption of digested fat
- Defence
How is leaked fluid returned to cardiovascular system /
Via the lymphatic system
What is an oedema ?
Build up of fluid in the interstitium/tissue
What are some ways oedema may occur ?
- Reduced plasma proteins
- Increased capillary permeability
- Increased venous pressure
- Lymph blockage
How may plasma proteins be reduced ?
- Loss in urine - kidney disease
- Reduced synthesis - liver disease
- Dietary
How may capillary permeability be increased ?
Inflammation and allergic responses
How may venous pressure be increased ?
- Uterine compression during pregnancy
2. Aeroplane flight - decompression and immobility
How may lymph blockage occur ?
- Damage during surgery
2. Parasitic infection
What does osmoregulation do ?
Balances the uptake and loss of water and solutes
What is plasma composition regulated by ?
Kidneys
What is urine ?
Filtered plasma
How does the renal system produce urine ?
By refining a filtrate derived from plasma
What are the steps of osmoregulation ?
- Filtration
- Reabsorption
- Secretion
- Excretion
In osmoregulation, what is filtration ?
Filtering of plasma
In osmoregulation, what is reabsorption ?
Reclaiming of valuable solutes
In osmoregulation, what is secretion ?
Adding nonessential solutes and wastes to the filtrate
In osmoregulation, what is excretion ?
Processed filtrate containing nitrogenous wastes is released from the body
What does filtrate produced in Bowman’s capsule contain ?
Salts, glucose, amino acids, vitamins, nitrogenous wastes
What happens in the proximal tubule ?
- Reabsorption of ions, water and nutrients takes place
2. Materials to be excreted become concentrated and some toxic materials are secreted into the filtrate
How are molecules transported from the filtrate into the interstitial fluid and then capillaries ?
Actively and passively
What happens in the descending limb loop of henle ?
Water is reabsorbed through channels and the filtrate becomes more concentrated
What are the channels with which water is reabsorbed from formed by ?
Aquaporins
What is the reabsorption of water in the descending limb of the loop of henle driven by ?
The high osmolarity of the interstitial fluid which is hyperosmotic to the filtrate
What happens in the ascending limb of the loop of henle ?
Salt but not water is able to diffuse from the tubule into the interstitial fluid, causing the filtrate to become increasingly dilute
What is the function of the distal tubule ?
Regulates the potassium ions and sodium chloride concentrations of body fluids
What is the function of the collecting duct ?
- Carries filtrate through the medulla to the renal pelvis.
- Reabsorption of solutes and water
What is urine hyperosmotic to ?
Body fluids
What manages the osmoregulatory functions of the mammalian kidney ?
A combination of nervous and hormonal controls
What is another name for anti-diuretic hormone ?
Vasopressin
What do ADH bind to ?
Membrane receptors on collecting duct cells
What does the binding of ADH to receptors initiate ?
A signal cascade leading to insertion of aquaporin proteins into the membrane lining the collecting duct
What does the increase in water recapture reduce ?
Urine volume
What do osmoreceptor cells in the hypothalamus monitor ?
Blood osmolarity and regulate release of ADH from the posterior pituitary
What happens when osmolarity rises above its set point ?
ADH release into the bloodstream increases
What happens when ADH drops below a set point ?
Causes a reduction in ADH secretion
What generates thirst ?
Specific neurons of hypothalamus
What is normal blood osmolarity ?
285-295 mOsm/L
What is a major contributor to blood pressure ?
Blood volume
What regulates blood pressure via neuronal and hormonal control ?
Cardiovascular and renal systems
