2 Flashcards
What are the 3 types of extracellular fluid?
Plasma, interstitial, lymph fluid
What rate does the renal system filter blood at?
150-200L a day
How much salt is filtered by the kidney?
1.5kg
What do kidneys do?
Remove soluble substances, recapture useful substances
What are the general functions of the renal systems?
Produce and expel urine, gluconeogenesis, regulate the volume and composition of the extracellular fluid, produce hormones
What hormones are produced by the renal systems?
Renin (an enzyme), erythropoietin, 1,25-dihydroxyvitamin D
How does the renin system control the volume and composition of the extracellular fluid?
- Control pH
- blood volume
- blood pressure
- osmolality
- ion balance
What is osmolality?
The amount of solute per kg of solvent
What is osmolarity?
A volume of solvent
What does erythropoietin do?
Stimulate production of RBCs
What does vitamin D do?
It is important for absorption of calcium ions
What do the paired kidneys form?
A filtrate of the blood (extracellular fluid) that is modified by reabsorption and secretion
Where does urine move through?
Moves along the ureters to the bladder
What is Potter’s syndrome?
When a baby is born without kidneys - the baby dies shortly after birth
Which kidney is lower?
The right is lower than the left
Why is the right kidney lower?
Because of the liver
Describe the ureters.
Approximately 25cm long with thick muscular walls which can contract from the kidneys, they have flaps
What do flaps on the ureters do?
They let urine flow into the bladder and prevent back-flow of urine into the kidneys
What is the detrusor muscle?
Smooth muscle which remains relaxed to store urine
What does the urethra do?
Remove fluid from the body
What does the urethral sphincter do?
Seal the urethra
Describe the urethral sphincter.
Striated skeletal muscle - voluntary control
What is micturition controlled by?
Both branches of the ANS (sympathetic via adrenoceptors and parasympathetic via cholinergic receptors)
Give an example of primary active transport.
Sodium potassium pump
What is secondary active transport?
Use of an electrochemical gradient across a plasma membrane as its energy source (usually sodium) - the movement of an ion down its electrochemical gradient coupled with transport of another molecule against its concentration gradient
What is co-transport?
When solutes move in the same direction
What is counter transport?
Occurs when solutes move in the opposite direction
What do aquaporins do?
Allow water to cross the cell membrane
What is the largest gland in the body?
The hepatic system
Where does the hepatic system lie?
Under the diaphragm, within the rib cage in the upper right quadrant of the abdomen
What is the liver bound by?
A fibrous connective tissue called Glisson’s capsule
Does the liver contain nerve endings and why?
Yes so when it becomes enlarged, it sends signals to experience pain
Describe the vascular supply of the hepatic system.
Dual supply
What does the hepatic artery do?
Bring nutrient poor/oxygen rich blood to the liver (25%)
What does the hepatic portal vein do?
Bring nutrient rich and oxygen poor blood to the liver
What occurs at sinusoids?
Mixing of oxygenated and deoxygenated blood
How much cardiac output does the liver receive?
30%
How much blood volume does the liver receive?
10-15% but can be adjusted to suit demand
Describe the glandular functions of the liver.
It is an endocrine gland and secretes into the circulation and it is an exocrine gland and secretes substances via a duct into the gut
Give examples of hormones secreted by the hepatic system (endocrine)?
Insulin-like growth factor, angiotensinogen, thrombopoietin and hepcidin
What does insulin-like growth factor do?
Insulin-like effects regulate cell growth and development
What does angiotensinogen do?
Vasoconstriction and release of aldosterone (increased sodium reabsorption) from adrenal cortex
What does thrombopoietin do?
Stimulate megakaryocytic to produce platelets
What does hepcidin do?
Inhibit intestinal iron absorption and iron release by macrophages
What are the examples of the exocrine functions of the hepatic system?
Bile is the exocrine secretion of the liver
How much bile is secreted a day?
600-1000ml
Where is bile stored?
In the gallbladder
Describe bile.
Yellow/green in colour and alkaline
What is bile composed of?
Bile salts, phospholipids, bile pigments and electrolytes
What are bile salts derived from?
Cholesterol
What is an example of a bile pigment?
Bilirubin
What is the carbohydrate metabolic function of the hepatic system?
- Glycogenesis (synthesis of glycogen)
- glycogenolysis (breakdown of glycogen)
- gluconeogenesis (synthesis of glucose from non-carbohydrate substrates)
What is the fat metabolic function of the hepatic system?
Oxidising triglycerides and synthesis of lipoprotein, fatty acids, triglycerides, cholesterol and phospholipids
What is the protein metabolic function of the hepatic system?
Synthesis of non-essential amino acids, deamination and transamination of amino acids, synthesis of urea from ammonia, synthesis of clotting factors and synthesis (of angiotensinogen and albumin)
What does the hepatic system store?
Glycogen, iron and fat soluble vitamins (A, D, B12, E and K)
Describe the excretion of the hepatic system.
Waste products from RBCs via bile, cholesterol, hormones and drugs
