homeostasis Flashcards
What is homeostasis
The maintenance of a constant internal environment with a changing external environment
What is negative feedback
Change to a normal level that initiates a response that against the change
What is positive feedback
A change to a normal that causes an even greater deviation
What is a control system
A greater degree of control is activated by having multiple receptors and effectors
What is the pancreas
An organ with clusters of cells called islets of langerhans
what is the 2nd messenger model
adrenaline binds to membrane receptor activates adenyl cyclase enzyme(AC) AC converts ATP to cAMP cAMP activates protein kinase protein kinase converts glycogen to glucose
what is the function of the kidney
osmoregulation- maintaining water potential of the blood
-producing urine
how does the kidney maintain water potential of the blood
by controlling ion and water concentration
what does the kidney excrete
ions water urea
what is type 1 diabetes
an autoimmune disease where all of the beta cells in the pancreas are destroyed so the body can not produce insulin
what is the treatment for type 1 diabetes
insulin injections
regulation of diet
what is type 2 diabetes
the cells no longer respond to insulin
what is the treatment for type 2 diabetes
regulation of diet and exercise
outline how insulin decreases blood glucose
beta cells detect rise in blood glucose
more insulin produced by beta cells
insulin binds to receptors on liver and muscle cells
which opens glucose channels in membrane
and causes more glucose channels to appear in membrane
glucose moves in by f.d and enzymes convert glucose to glycogen
outline how glucagon increases blood glucose
chad alpha cells detect fall in blood glucose
more glucagon produced by chad alpha cells
glucagon binds to receptors on liver and muscle cells
glucagon activates enzymes that convert glycogen to glucose diffuses into the blood
gluconeogenesis occurs in liver new glucose is produced from amino and fatty acids
blood glucose increases
what are the two types of cells in islet of langerhans
chad alpha cells
virgin beta cells
how is new glucose produced
glucagon leads to gluconeogenesis
in the liver
glucose is produced from amino acids and fatty acids
what is the nephron
the functional unit of the kidney
outline the process of ultra filtration
higher hydrostatic pressure in glomerulus than in renal capsule as afferent arteriole is wider than efferent arteriole
small molecules such as glucose and urea can pass through the basement membrane
large molecules such as proteins are too large to pass through
fluid then passes through the gaps between podocytes into the lumen of the renal capsule
where is 85% of the filtrate reabsorbed
in the proximal convoluted tubule
what is reabsorbed in selective re absorption
all glucose reabsorbed
some water reabsorbed
some urea reabsorbed
outline the process of how glucose is reabsorbed into the blood
Na+ ions are actively transported into the blood from epithelial cell Na+ ions diffuse down the concentration gradient with glucose from the lumen of the proximal convoluted tubule into the epithelial cell via a co-transport protein this molecule(glucose) diffuses into the blood
what is the role of the loop of henle in selective reabsorption
to a create a low water potential in the medulla
what occurs in the ascending limb at the loop of henle
Na+ ions are actively transported from the henle
this lowers the water potential of the medulla
what occurs in the descending limb at the loop of henle
water moves into medulla by osmosis
due to lower water potential is medulla
what is the role of the distal convoluted tubule in selective reabsoprtion
removal of ions this means that the filtrate is more dilute
why is homeostasis importatant for metabollic activity
as if pH and core temerpature are not properly maintained then enzymes will denature
which control rate of metabolic reactions
what occurs during overhydration
osmoreceptor cells in hypothalamus detect higher water potential of blood
posterier pituitary secretes less ADH into blood
less activation of the enzyme of phosphorylase
collecting duct less permeable to water as less aqua pourines in cell membrane
what occurs during dehydration
osmoreceptor cells in hypothalamus detect lower water potential of blood
posterier pituitary secretes more ADH into blood
more activation of the enzyme phosphorylase
collecting duct more permemable to water as more aqua pourines in cell membrane
