5.1.4 Hormonal Communication Flashcards
what’s the difference between a hormone and a chemical mediator
hormones are released into the blood whereas mediators work locally
give an example of a hormone and a mediator
hormone- ADH
mediator- histamine
what hormone does the following produce: pituitary gland thyroid gland thymus adrenal gland pancreas ovaries testes
pituitary gland- FSH, LH, ADH thyroid gland- thyroxine thymus- thymosin adrenal gland- adrenaline pancreas- insulin, glucagon ovaries- oestrogen and progesterone testes- testosterone
define hormones
molecules secreted by endocrine glands into the blood, they will communicate with specific target tissues
define target tissues
cells that have specific complementary receptors on their plasma membranes to a specific hormone
define endocrine gland
ductless gland that secretes hormones directly into the blood
define exocrine gland
have ducts and secretes molecules into duct to transport it to where it needs to be used
describe the structure of target cells
have receptors with complementary shape to hormone from endocrine cell, binding often causes an enzyme to be activated
what are the two types of hormones give examples
steroid- testosterone and oestrogen
and non steroid - insulin n glucagon
describe steroid hormones
lipid soluble non- polar m molecules that can pass through the phospholipid bilayer of the plasma membrane
they bind to receptors inside the cell to form the hormnone- receptor complex and affect gene expression
describe non steroid hormones
hydrophilic and not lipid soluble so cannot pass through the bilayer
they bind to specific receptors on the surface of the plasma membrane and cause changes in the cell by activation of enzymes
what type of organ is the pancreas
both exocrine and endocrine
how is the pancreas exocrine
releases digestive enzymes into ducts
how is the pancreas endocrine
monitors blood glucose conc and secretes insulin and glucagon accordingly directly into the blood
what is the specific name for the endocrine part of the pancreas, what can this be divided into
the islets of langerhans
ALPHA CELLS- glucAgon
BETA CELLS- insulin
how does the structure and properties of alpha glucose relate to its function
forms hydrogen bonds with water so soluble
easily transported around organism
can move within the cell
transported across the bilayer as is small
bonds contain energy
can be hydrolysed to produce energy
how much glucose should we have in our blood
90mg per 100cm3
what are the two storage sites of glycogen
skeletal muscle liver cells (hepatocytes)
state the advantages to mammals of storing glucose as glycogen
glycogen is- insoluble so has no effect on the WP metabolically inactive compact highly branched
what happens if there is too much glucose
beta cells secrete insulin
insulin binds to receptors on hepatocytes/ skeletal muscle cells and triggers more glucose to be transported by facilitated diffusion into cells, insulin activates an enzyme to do the conversion of glucose into glycogen maintaining a steep diffusion gradient
in a process called gylcogenesis
what happens if there is too little glucose
alpha cells secrete glucagon
glucagon triggers the conversion of glycogen into glucose in a process known as glycogenolysis
what happens if glycogen stores run out
gluconeogenesis
the fats and amino acids are used as an energy source
what would happen if there was too much insulin
you would become hypoglycaemic
meaning glucose levels in blood very low
glucose is taken up by hepatocytes and skeletal muscle
glycogenesis
mitochondria have no glucose for respiration
no ATP for cells
death
how does glucagon increase blood glucose levels
the liver hydrolyses its glycogen store into glucose and releases It back into the bloodstream
this lowers the amount of glucose absorbed by the liver cells, more stays in the blood
gluconeogenesis
how do beta cells know how much insulin to produce
1) K+ ion channels open so potassium diffuses out maintiaining resting potential
2) glucose enters B cell when conc high, glucose enters by a transport protein
3) glucose is phosphorylated through glycolysis pathway into ATP
4) extra ATP closes the app sensitive k+ channels causing depolarisation
5) change in k+ conc changes potential difference to -30mv which opens the voltage gated ca2+ channels and ca2+ diffuses into the cell
6) calcium ions cause vesicles filled with insulin to fuse with the cell membrane and release insulin into the blood by exocytosis
what is the proper name for diabetes
diabetes mellitus
what’s the difference between hyperglycaemia and hypoglycaemia
hyper- dangerously high glucose levels
hypo- dangerously low glucose levels
what’s the difference between type 1 and type 2 diabetes
type 1: occurs at a young age autoimmune response immune system attacks b cells little insulin secreted often genetic but can Be caused by a virus TREATED: with injections of insulin
type 2: occurs at older age
glycoprotein receptors on liver and muscle cells no longer respond to insulin
liver and muscle cells do not take up enough glucose from the blood
linked to- obesity/ high sugar diet/lack of exercise/ excessive alcohol
TREATED: with a diet of low carb and sugar or drugs that stimulate insulin production
how is gm bacteria insulin produced
plasmid is removed from bacteria cell
dna fragment containing required gene that codes for insulin production is inserted into plasmid
it is then injected back into the bacteria cell which then replicates by binary fission
result: insulin producing bacteria
what are some advantages of gm bacteria insulin
- less likely to cause a allergic reaction
- can be mass produced
- dependable supply of insulin
- cheap production costs
- no ethical objections ( used to be pig insulin not anymore)
what is a potential cure for type 1 diabetes
stem cell treatment- permanent cure
beta cells are replaced with stem cells taken from bone marrow which protects from attack
name two hormones the adrenal medulla produces
adrenaline and noradrenaline
both are amino acid derivatives ( non-steroid)
both work in response to stress- increase heart rate increase breathing rate dilation of pupils
what four hormones do the adrenal cortex produce
cortisol- glucocorticoids- regulates blood pressure
corticosterone- glucocorticoids- regulate immune response
aldosterone- mineralocorticoids- control conc of na+ and k+ in blood
androgens- sex hormones
what’s the difference between the first and second messenger
first messenger- the hormone that transmits a signal around the body
second messenger- the chemical that transmits the signal inside the cell
describe the second messenger model
adrenaline first messenger binds to receptors
this activated enzyme adenyl cyclase which can convert many ATPs into many cAMP
cAMP 2nd messenger activated enzymes which leads to the hydrolysis of glycogen
CASCADE EFFECT
what does cAMP stand for
cyclic adenosine monophosphate ( 2nd messenger)
