5.4: Hormones Flashcards
Where in the pancreatic cell insulin molecules are synthesised?
RER
Outline the events that occur after the synthesis of an insulin molecule until it is ready to be secreted from the pancreatic cell:
Transported to Golgi; modified/ processed in Golgi; packaged into Golgi vesicles; vesicles transported towards plasma membrane; detail of modification
(splitting / recombining, polypeptide); role of cytoskeleton; use of ATP (in context of, modification / movement)
Describe the events leading to secretion of insulin from beta cell:
Glucose is phosphorylated/ respired/ metabolised to produce ATP (glucokinase); ATP blocks/closes K+ channels ; K+ build up (inside cell); (voltage-gated) Ca2+ channels open Ca2+ enter (cell by diffusion); (more) Ca2+ resulting in movement of vesicles to membrane/ exocytosis
Why does insulin secretion continue even when there is no further glucose intake:
(Continues to be secreted) as long as blood glucose conc higher than normal; (sufficient) ATP is still present so K+ channels remain closed; exocytosis still being triggered by Ca2+ (continues until Ca removed)
Describe how negative feedback is used to control blood glucose concentration:
1) beta cells/ alpha cells/ receptors detect change in bgc;
2) if higher gc, beta cells release insulin;
3) (increased) absorption of glucose by liver/ muscle/ effector;
4) enters through glucose transport proteins (in cell surface membrane);
5) glucose converted to glycogen/ glycogenesis;
6) increased (use of glucose in) respiration: ATP production;
7) if lower gc, alpha cells release glucagon;
8) (increased) conversion of glycogen to glucose/ glycogenolysis;
9) (increased) conversion of other compounds, (amino acid/ lipids), to glucose/ gluconeogenesis;
10) glucose leaves cell by facilitated diffusion/ through glucose channels
Define homeostasis:
Maintaining (relatively) stable internal environment within (narrow) limits/ range; even though environment is changing
Describe the changes that take place to make sure that the blood glucose concentration does not fall to a dangerous level:
Fall detected by pancreas; fall inhibits insulin secretion; stimulates secretion of glucagon (by alpha cells); into blood; binds to receptors on hepatocytes; glycogenolysis; gluconeogenesis; glucose into blood stream
Endocrine gland:
Ductless gland; secretes hormones; (directly) into the blood
Exocrine gland:
Enzymes/ pancreatic juice/ HCO3-; amylase/ trypsin/ chymotrypsin/ lipase/ carboxylpeptidase; into duct
Explain the advantages of using GM in treatment of diabetes:
Insulin produced by, microorganisms/ bacteria; cheaper source of insulin/ more reliable supple/ large scale production; more rapid response; less chance of immune/ allergic response; better for people who have developed a tolerance for animal insulin; acceptable to people who have ethical objections; vegetarians; no risk of infection/ contamination
After long periods of fasting, explain how the liver can still produce glucose by the process of gluconeogenesis:
Deamination of amino acids; pyruvate/ carbon skeleton; triose phosphate/ TP; condensation/ increasing no of C atoms
OR
Breakdown of lipid/ triglyceride; glycerol; TP; condensation
Describe how glucagon is involved in the regulation of blood glucose concentration in a healthy person: June 14 3dii 5mks
The alpha cells in the IoL detect low bgc and secrete glucagon in the blood; leads to glycogenolysis; gluconeogenesis; conversion of triglycerides to (free) fatty acids/ lipolysis/ increased use of fatty acids in respiration; glucagon inhibits insulin secretion; negative feedback;
What might happen if liver did not break down insulin:
Bcg would fall too low/ below normal; glucose would continue to be taken up by cells -> low bcg/ store too much glucose as glycogen; mitochondria can’t relapse enough energy/ ATP; coma/ death
How is type 1 diabetes caused:
Unable to produce sufficient/ effective insulin; beta cells not functioning correctly/ damaged/ attacked; by immune system/ antibodies/ autoimmune disease; triggered by virus/ environmental factor
Explain what is meant by the term hormone:
Can be steroids/ peptides/ amides; released in minute quantities; from endocrine glands; travels in blood; affects target organs; by binding to protein receptor sites on membranes
Treatment for type 1 diabetes:
Insulin injections; insulin pump therapy: permanent needle in skin; islet cell transplant (stem cells)
Describe the different ways in which the pancreas acts as both an endocrine and an exocrine gland:
endocrine:
H1 hormone(s) released directly into blood ;
H2 beta / β , cells , secrete / produce / release , insulin ;
H3 alpha / α , cells , secrete / produce / release , glucagon ;
H4 islet / and , cells , detect / monitor ,
blood glucose concentration ;
exocrine:
E1 fluid / juice / secretion / enzymes , released into duct ;
E2 (release triggered by) nervous / hormonal , stimulation ;
E3 pancreatic secretions into ,
gut / small intestine / duodenum ;
E4 alkaline / pH 8 / (sodium) hydrogen carbonate ;
E5 containing 2 named enzyme(s) ;
State two advantages of treating Type 1 diabetes by using insulin that has been produced by genetically modified bacteria rather than insulin that has been extracted from pigs:
idea of plentiful / dependable , supply ;
2 cheap ;
3 not cruel to pigs / more ethical ;
4 no religious objections / can be used by vegetarians ;
5 reliable , quality / standard ;
6 (exact match to) human insulin / no allergic reaction ;
Factors that increase risk of type 2 diabetes:
Ageing (>40); genetic; more common in males; obese; ethnic groups; high intake of processed food/ high GI food/ sugars; lack of physical activity; high BP; excessive alcohol intake
Secondary messenger for insulin:
Tyrosine kinase (causes phosphorylation of inactive enzymes to activate them to catalyse fusion of vesicles containing glucose transporter proteins into membrane)
Secondary messenger for glucagon:
Adenyl cyclase
A potential treatment for Type 1 diabetes is the use of stem cells. State an advantage of this form of treatment compared to treatment using insulin.
1 (has the potential to) cure / do more than manage ,
the condition ;
2 long term effect / permanent /
no need for repeated treatments ;
e.g. no need to restrict diet
2 e.g. no need to inject insulin (regularly)
Name the part of the adrenal gland that releases aldosterone. [F214 jan 13 6ci]
cortex;
Suggest and explain what effect the action of aldosterone will have on the secretion of ADH. (2mks) [F214 jan 13 q6cii]
water potential of, plasma/ blood , will , decrease/ become more negative ; [concentration of Na+ in, plasma / blood, will increase]
(ADH secretion) will increase;
Glycogenolysis
[f214 Jan 11 q5aii]
Hydrolysis
Protein kinase/ (activates) glycogen phosphorylase kinase OR glycogen phosphorylase (stimulates conversion of glycogen) OR inhibition of glycogen synthase (preventing glucose conversion to glycogen)
70.Treated rats were given a glucose meal and the concentration of blood glucose measured immediately and at intervals for eight hours. The results of this investigation are shown in the figure below.
With reference to the figure, discuss the possible benefits and problems of using this gene therapy in the treatment of diabetes in humans, rather than taking insulin.
70.benefits
avoids injections / pain of injections / children’s fear of injections;
mimics normal pancreatic behaviour;
more stable homeostasis / reduced highs and lows in blood sugar;
less chance, hypoglycaemia / hyperglycaemia;
less restriction on lifestyle;
no need to measure blood sugar;
AVP;max 3
problems
rejection;
cells could lodge elsewhere;
may take longer to act;
AVP; e.g. rat data may not be applicable to humans,
transgene may have unforeseen effectmax 3max 4
3 differences between in the ways in which plant and mammalian hormones operate: f215 June 13
1 (M) made in endocrine glands versus
(P) made in many plant tissues ;
2 (M) move in blood versus
(P) move, in xylem / in phloem / from cell to cell ;
3 (M) act on, a few / specific / target, tissues versus
(P) act on most tissues / can act in cells where produced ;
4 (M) act more rapidly ; ORA
