5.1.4 Hormonal Communication

Question 1

what’s the difference between a hormone and a chemical mediator

Answer 1

hormones are released into the blood whereas mediators work locally

Question 2

give an example of a hormone and a mediator

Answer 2

hormone- ADH

mediator- histamine

Question 3

what hormone does the following produce:
pituitary gland
thyroid gland
thymus
adrenal gland
pancreas
ovaries
testes

Answer 3

pituitary gland- FSH, LH, ADH
thyroid gland- thyroxine
thymus- thymosin
adrenal gland- adrenaline
pancreas- insulin, glucagon
ovaries- oestrogen and progesterone
testes- testosterone

Question 4

define hormones

Answer 4

molecules secreted by endocrine glands into the blood, they will communicate with specific target tissues

Question 5

define target tissues

Answer 5

cells that have specific complementary receptors on their plasma membranes to a specific hormone

Question 6

define endocrine gland

Answer 6

ductless gland that secretes hormones directly into the blood

Question 7

define exocrine gland

Answer 7

have ducts and secretes molecules into duct to transport it to where it needs to be used

Question 8

describe the structure of target cells

Answer 8

have receptors with complementary shape to hormone from endocrine cell, binding often causes an enzyme to be activated

Question 9

what are the two types of hormones give examples

Answer 9

steroid- testosterone and oestrogen

and non steroid - insulin n glucagon

Question 10

describe steroid hormones

Answer 10

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

Question 11

describe non steroid hormones

Answer 11

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

Question 12

what type of organ is the pancreas

Answer 12

both exocrine and endocrine

Question 13

how is the pancreas exocrine

Answer 13

releases digestive enzymes into ducts

Question 14

how is the pancreas endocrine

Answer 14

monitors blood glucose conc and secretes insulin and glucagon accordingly directly into the blood

Question 15

what is the specific name for the endocrine part of the pancreas, what can this be divided into

Answer 15

the islets of langerhans
ALPHA CELLS- glucAgon
BETA CELLS- insulin

Question 16

how does the structure and properties of alpha glucose relate to its function

Answer 16

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

Question 17

how much glucose should we have in our blood

Answer 17

90mg per 100cm3

Question 18

what are the two storage sites of glycogen

Answer 18

skeletal muscle 
liver cells (hepatocytes)

Question 19

state the advantages to mammals of storing glucose as glycogen

Answer 19

glycogen is- 
insoluble so has no effect on the WP
metabolically inactive
compact
highly branched

Question 20

what happens if there is too much glucose

Answer 20

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

Question 21

what happens if there is too little glucose

Answer 21

alpha cells secrete glucagon

glucagon triggers the conversion of glycogen into glucose in a process known as glycogenolysis

Question 22

what happens if glycogen stores run out

Answer 22

gluconeogenesis

the fats and amino acids are used as an energy source

Question 23

what would happen if there was too much insulin

Answer 23

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

Question 24

how does glucagon increase blood glucose levels

Answer 24

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

Question 25

how do beta cells know how much insulin to produce

Answer 25

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

Question 26

what is the proper name for diabetes

Answer 26

diabetes mellitus

Question 27

what’s the difference between hyperglycaemia and hypoglycaemia

Answer 27

hyper- dangerously high glucose levels

hypo- dangerously low glucose levels

Question 28

what’s the difference between type 1 and type 2 diabetes

Answer 28

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

Question 29

how is gm bacteria insulin produced

Answer 29

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

Question 30

what are some advantages of gm bacteria insulin

Answer 30

• 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)

Question 31

what is a potential cure for type 1 diabetes

Answer 31

stem cell treatment- permanent cure

beta cells are replaced with stem cells taken from bone marrow which protects from attack

Question 32

name two hormones the adrenal medulla produces

Answer 32

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

Question 33

what four hormones do the adrenal cortex produce

Answer 33

cortisol- glucocorticoids- regulates blood pressure
corticosterone- glucocorticoids- regulate immune response
aldosterone- mineralocorticoids- control conc of na+ and k+ in blood
androgens- sex hormones

Question 34

what’s the difference between the first and second messenger

Answer 34

first messenger- the hormone that transmits a signal around the body
second messenger- the chemical that transmits the signal inside the cell

Question 35

describe the second messenger model

Answer 35

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

Question 36

what does cAMP stand for

Answer 36

cyclic adenosine monophosphate ( 2nd messenger)