hormonal communication Flashcards
1
Q
what is an endocrine gland
A
- group of cells
- specialised to secrete chemical (hormones)
- directly into the blood stream
- pancreas + adrenal glands
2
Q
pituitary gland
A
- growth hormone
- controls bones and muscles growth
- ADH
- increases water reabsorption in kidneys
- gonadotrophins
- control development of ovaries and testes
3
Q
thyroid
A
- thyroxine
- controls metabolism rate
- rate at which glucose is used up in respiration
- promotes growth
4
Q
adrenal gland (role)
A
- adrenaline
- increase heart/breathing rate
- raise blood sugar levels.
5
Q
testis
A
- testosterone
- control sperm production
- secondary sexual characteristics
6
Q
pineal gland
A
- melatonin
- affects reproductive development and daily cycles.
7
Q
thymus
A
- thymosin
- promotes production and maturation of WBC
8
Q
pancreas
A
- insulin
- glucose to glycogen
- glucagon
- glycogen into glucose
- in the liver
9
Q
ovary
A
- oestrogen
- controls ovulation
- secondary sexual characteristics
- progesterone
- prepares uterus lining for receiving an embryo
10
Q
what is an exocrine gland
A
- secrete hormones
- through ducts
- into organs
- or to the surface of the body
11
Q
steroid hormones
A
- lipid-soluble
- pass through lipid component of CM
- bind to steroid hormone receptors on CM
- hormone/receptor complex is formed
- complex can inhibit or facilitate the transcription of a gene
- E.g. oestrogen
12
Q
non-steroid hormones
A
- hydrophilic
- can’t pass directly through the cell membrane
- bind to specific receptor on surface of target cells membrane
- causes a cascade reaction mediated by secondary messengers
- E.g adrenaline
13
Q
compare the hormonal and nervous systems
A
- H: communication is by hormones
- N: communication by nervous impulses
- H: transmission by blood
- N: transmission by neurones
- H: slow transmission
- N: very rapid transmission
- H: widespread response
- N: localised response
14
Q
why is hormonal communication slow
A
- not released directly onto their target cells
- they aren’t broken down as quickly as NT so have a longer-lasting more widespread effect.
15
Q
where are the adrenal glands
A
- on top of each kidney
- cortex : outer region + produces hormones vital to life (cortisol and aldosterone)
- medulla : inner regions + produces non-vital hormones (adrenaline)
16
Q
Glucocorticoids
A
- adrenal cortex
- regulates metabolism
- control how fats, proteins and carbs are converted into energy
- regulates blood pressure
- cardiovascular responses to stress
- another gluc hormone = corticosterone
- works with cortisol
- both regulate immune responses
- suppress inflammatory reactions
- release of hormones controlled by hypothalamus.
17
Q
mineralocorticoids
A
- adrenal cortex
- aldosterone
- control blood pressure
- maintain balance of water and salt in blood and body fluids
- release is controlled by signals trigger by kidneys.
18
Q
androgens
A
- adrenal cortex
- small amounts of male/female sex hormones
- by ovaries/testis
- important for women after menopause.
19
Q
when are adrenal medulla hormones released
A
- when sympathetic NS stimulated
- body is stressed
20
Q
adrenaline
A
- adrenal medulla
- increases heart/breathing rate
- blood flows to brain and muscles
- rapidly increases BGC
- glycogen converted to glucose in the liver = glycogenolysis
21
Q
nor-adrenaline
A
- adrenal medulla
- works with adrenaline
- increases heart rate
- dilates pupils
- widens air passages in lungs
- narrows blood vessel near non-essential organs (inc blood pressure)
22
Q
function of the pancreas
A
Exocrine gland : producing and releasing enzymes into the duodenum via a duct
Endocrine glands : produce and releasing hormones into the blood.
23
Q
role of pancreas as an exocrine gland
A
- made up of exocrine glandular tissue
- produces digestive enzymes
- alkaline fluid : pancreatic juice
- enzymes + juice released into pancreatic duct and then to the duodenum (top of small I(
- amylase : starch into simple sugars
- protease : protein into amino acids
- lipase : lipids into FA and glycerol
24
Q
role of pancreas as an endocrine gland
A
- controls BGC
- small regions of endocrine tissue
- these are Islets Of Langerhans
- produce insulin and glucagon
- secrete them directly into the bloodstream.
25
endocrine tissue under microscope
- Islets of Langerhans
- lightly stained
- large, spherical clusters
26
exocrine tissue under microscope
- acini
- darker stained
- small clusters
27
Alpha IOL
- produce and secrete glucagon
| - larger and more than beta in IOL
28
Beta IOL
- produce and secrete insulin
29
reasons as to why BGC can increase
- Diet : when you eat carb-rich foods, the carb is broken down into glucose by DS. Glucose is absorbed by bloodstream and BGC rises
- Glycogenolysis : glycogen stored in liver and muscle cells is broken down into glucose which is absorbed into blood stream - inc BGC
- Gluconeogenesis - glucose is formed from non-carb sources : glycerol (from lipids) and amino acids in the liver form glucose. Released into blood stream and inc BGC.
30
how can BGC be decreased
- respiration : glucose used by cells to release energy for muscle cells to contract. The more intense physical activity, the more BGC decreases.
- Glycogenesis : Excess glucose converted to glycogen and stored in the liver.
31
role of insulin
- high BGC
- detected by beta cells
- secrete insulin directly into blood stream
- insulin binds to glycoprotein receptor
- tertiary structure of glucose transport protein channels change
- channels open
- glucose enters cell
- insulin activates enzymes to convert glucose to glycogen and fat
- increased cellular resp
- glycogenesis.
- insulin broken down by enzymes by cells in liver
- BGC returns to normal
- detected by beta cells
- when it falls below a set level, beta cells reduce insulin secretion
- negative feedback.
32
how does insulin lower BGC
- increases rate of glucose to fat conversion
- increases rate of glycogenesis
- increases respiratory rate of cells (need for glucose)
- increases rate of glucose absorption by cells (skeletal muscle cells)
- inhibits glucagon from alpha IOL
33
role of glucagon
- BGC is too low
- detected by alpha IOL
- glycogen secreted directly into bloodstream
- only liver and fat cells have glucagon receptors
- BGC increases by :
- glycogenolysis
- reducing absorption of glucose by liver cells
- gluconeogenesis
- BGC returns to normal
- detected by alpha cells
- when rises above a set level
- alpha cells reduce glycogen secretion
- negative feedback
34
control of insulin secretion
- at normal BGC, K+ channels in plasma membrane of beta cells are open
- K+ diffuses out of cells
- inside of cell = -70mV
- BGC rises
- glucose enters cell via glucose transporter
- glucose metabolised inside mitochondria
- ATP produced
- ATP binds to K+ channels
- K+ close
- channels are 'ATP sensitive'
- K+ no longer diffuse out
- CM depolarizes to -30mV
- depolarization causes VG Ca2+ to open
- Ca2+ diffuse in
- secretory vesicles release insulin by exocytosis.
35
Type 1 diabetes
- beta cells don't produce insulin
- no known cause, prevention or treatment
- Suggest that condition caused by autoimmune response where own immune system attacks the beta cells
- begins in childhood.
36
type 2 diabetes
- beta cells don't produce enough insulin or persons body cells don't respond properly to insulin
- due to glycoprotein insulin receptor on CM not working properly
- cells lose responsiveness to insulin
- don't take up enough glucose leaving it in the bloodstream
- risk increases with age
- result of excess body weight, physical inactivity.
37
symptons of diabetes
- high BGC
- glucose in urine
- excessive thirst + need to urinate
- weight loss
- blurred vision
- tiredness
38
Treatement for type 1
- regular insulin injection
- regularly test BGC (prick)
- analysed using machine, tells person BGC, person can work out does of insulin needed
- if injected with too much insulin - hypoglycaemia
39
treatment for type 2
- regulate carb intake through diet
- matching to exercise levels
- lose weight if overweight
- drugs can be used that stimulate insulin production / slow down the rate at which body absorbs glucose from intestine
- insulin injections.
40
adv of genetically modified insulin by bacteria
- pure form (less likely to cause allergic reactions)
- insulin produced in higher quantities
- cheaper
- overcomes religious/ethical reasons of using animal products.
41
use of stem cells in treating diabetes
- stem cells could be grown in beta cells
- beta cells implanted into the pancreas (with type 1)
- person could make insulin as normal
- if effective can cure type 1
- this means donor availability wouldn't be an issue (unlimited source of beta cells)
- reduce rejection likelihood because embryonic stem cells are unlikely to be rejected
- no longer have to inject with insulin
- limited knowledge : we don't know if the transplantation might induce tumours due to unlimited cell growth.
42
describe flight or fight response
- autonomic NS detects danger
- hypothalamus triggers sympathetic NS
- nervous impulse triggers release of hormones from adrenal medulla
- noradrenaline increases heart rate
- adrenaline causes glycogenolysis in liver cells
- BGC increases
- used for respiration
- provides ATP for muscle contraction
- pituitary gland stimulates the adrenal-cortical system by secreting ACTH
- hormones released from adrenal cortex that prepare body to deal with threat.
43
action of adrenaline
- non-steroid hormone
- binds to specific receptors on liver CM
- activates adenylyl cyclase
- activated enzyme coverts ATP to cAMP (S-messenger)
- increase in cAMP activates protein kinases
- these phosphorylate and activate other enzymes
- trigger conversion of glycogen into glucose
