Hormonal Communications Flashcards
What is Glycogenolysis
When there is a decrease in B-G Conc. thus alpha cells secrete insulin
1.Glucagon binds to receptors on memb. of liver cells
2.Activates G Protein -> activates adenylyl cyclase
3. Adenylyl cyclase catalyses conversion of ATP to 2nd messenger (cAMP)
4.cAMP binds to protein kinase A and activates it which activates glucose phosphorylation enzymes which catalyse breakdown of Glycogen to Glucose
cAMP initiates enzyme cascade
cascade amplifies original signal of glucagon resulting in release of release of glucose in liver cells
What are 3 functions of adrenaline
Increase glycogenolysis
Increase heart rate
Increase B-P Conc.
What are the 2 parts of adrenal glands
Outer part - Cortex
Inner part - Medulla
Where are steroids secreted?
Adrenal glands in the cortex reigon
2 similarities of plant and animal cell signalling
Hormone binds to receptor
Causes cascade of reactions
How does body respond to Low B-G conc.
alpha cells secrete glucagon in Islet of Langerhran in Pancreas
Glucagon catalysed conversion of glycogen into glucose
Trigluycerides turn into fatty acids
Negative feedback inhibits secretion of glucagon
Glucagon REDUCES secretion of insulin
What is difference. between Endocrine and Exocrine system
Endrocrine —> Contain alpha cells which secrete glucagon and beta cells which secrete insulin. Contains Islet of Langerhan in pancreas which control B-G conc.
Exocrine —> Enzymes released into ducts, triggered by hormonal stimulations.
Pancreatic stimulations into small intestine
Contains: amylase + trypsin
How can adrenaline cause different effects in target tissues
Different tissues have different adrenaline receptors
cAMP / Second Messenger may be different
What is First and Second Messenger
First - Sends message from endorctine to receptor
Second - Sends message from receptor to different parts of the cell
What is meant by homeostasis
Regulation of internal body environment even though environment is changing
Process of secretion of insulin?
K+ channels open and K+ enters cell. Causes Memb. pontetinal to go to -70mV. Glucose enters via facilitated diffusion and becomes phosphorylase’s and metabolised to produce ATP. Memb. potential goes to -30mV. ATP blocks K+ Channel and change in Memb. Potential causes Ca2+ channels to open. Ca2+ DIFFUSES into cell causing bristle to move and fuse with plasma membrane and insulin is released via exocytosis
How does -ve feedback affect low B-G conc.
Receptors detect change in B-G conc. -> B cells secrete insulin. Increased uptake of glucose by effector cells. More glucose used in respiration
What happens at Low B-G conc.?
Change detected by receptors. Alpha cells secrete glucagon. Glucagon binds onto receptors in liver cells. Activated G protein which activated adenyl cyclades which catalysed conversion of AMP to cAMP. cAMP binds to protein Kinsde A enzymes activated them. activated glucose phosphorylation enzymes and catalysed conversion of glycogen into gkucose
What happens in cortex
Contains steroid hormones ( Aldosterone) which regulates levels of salt and h20
Contaisn cortisol which is the primary stress hormone which regulates metabolsism of glucose to release usuable energy
What happens in Medulla
Produces adrenaline which prepars body for “fight or flight response”
