5.1.4) Hormonal Communication Flashcards
1
Q
What is the ENDOCRINE SYSTEM
A
- communication system
- that uses hormones…
- released by glands
- and is transported in the blood
2
Q
What is a GLAND
A
- group of specialised cells that produce and secrete chemicals (hormones or enzymes)
- 2 types of glands (endocrine and exocrine)
3
Q
Endocrine Gland
A
Chemical: hormones
Secreted into: bloodstream (transported in plasma)
Example gland: Thyroid, Adrenal, Pancreas
Example chemicals: Adrenaline, Thyroxine, Insulin, Glucagon
4
Q
What are the 2 types of glands?
A
- Exocrine (enzymes secreted in duct ie// salivary gland)
- Endocrine (hormones secreted into the bloodstream and transported by plasma ie// adrenaline, thyroxine, insulin, glucagon)
5
Q
Example of exocrine gland:
A
salivary gland
6
Q
Example of endocrine gland:
A
Thyroid gland/Adrenal/Pancreas
7
Q
What is a hormone
A
chemical messenger that travels around the body in the bloodstream
8
Q
How do hormones function
A
Diffuse out of blood and bind to complementary receptors…
- on the cell surface membrane of the target cells
- in the cytoplasm of target cells
…to stimulate a response
9
Q
Hormone of ADRENAL GLAND
A
ADRENALINE
10
Q
Hormone of TESTES
A
TESTOSTERONE
11
Q
Hormone of OVARY
A
OESTROGEN
12
Q
Hormone of THYROID GLAND
A
TYROSINE
13
Q
Hormone of PITUITARY GLAND
A
- ANTI-DURETIC HORMONE
- GROWTH HORMONES
- GONADOTROPHINS (LH + FSH for example)
14
Q
Hormone of THYMUS
A
THYMOSIN
15
Q
Hormone of PANCREAS
A
INSULIN
GLUCAGON
16
Q
Hormone of PINEAL GLAND
A
MELATONIN
17
Q
Life expectancy of hormones…
A
short life in body…
- broken down by enzymes in blood/cell (often in liver)
- excreted in urine
Insulin: 10-15 minutes
Adrenaline 1-3 minutes
18
Q
What makes an organ a target organ?
A
- Having the complementary receptor to the specific hormone on the Cell Surface Membrane/ Cytoplasm of target cell/organ.
19
Q
Advantages of having target organs
A
- different messages can be sent simultaneously ∴ causing specific responses
- can vary strength of response by altering hormone concentration.
20
Q
2 Types of hormones:
A
STEROID: hydrophobic/lipid soluble ∴ can pass through cell surface membrane
NON-STEROID: hydrophilic ∴ non-polar and cannot pass through CSM, instead binds to receptors on the CSM of target cell, which then triggers cascade reaction mediated by ‘secondary messengers’
21
Q
Where does a steroid hormone bind to?
A
- it binds to the ‘steroid hormone receptor’ found either in cytoplasm of cell or nucleus of target cell
- forms ‘hormone-receptor complex’ that can act as a transcription factor (which can be used to facilitate or inhibit transcription of specific gene
- examples: oestrogen, progesterone, testosterone
22
Q
Mechanism of Action for STEROID HORMONES:
A
- steroid hormones are lipid soluble ∴ pass through the phospholipid bilayer
- bind to steroid hormone receptors in cytoplasm or nucleus
- forms ‘hormone receptor complex’ (HRC)
- HRC acts as transcription factor (∴ can bind to DNA and alter transcription of specific genes)
- Specific proteins synthesised at ribosome and undergo their function
23
Q
Where are adrenal glands found?
A
2 small glands found on top of kidneys
24
Q
Structure of adrenal gland
A
2 distinct parts,
- inner = medulla (produces non-essential hormones)
- outer = cortex (produces essential hormones)
surrounded by capsule
25
hormones produced in adrenal medulla...
NON-ESSENTIAL
adrenaline and noradrenaline work together in response to stress
- adrenaline
(increases heart rate; raises blood glucose conc. by converting glycogen --> glucose [glycogenolysis in liver cells])
- noradrenaline
(increases heart rate; widens air passage in lungs; dilation of pupils; narrowing of BV in non-essential organs --> increased BP)
26
Function of adrenaline
- increase heart rate
- raise blood glucose conc. (by converting glycogen to glucose[glycogenolysis in liver cells])
27
Function of noradrenaline
works with adrenaline in response to stress
-increase heart rate
- widening of pupils
- widening of air passage in lungs
- narrowing of blood vessels in non-essential organs to increase BP
28
hormones produced in adrenal cortex...
- glucocorticoids 'glucose + cortex + steroids'
(regulates metabolism; regulates BP; stimulates production of glucose from breakdown of glycogen; cortisol and corticosterone work together to regulate immune response and suppress inflammatory response)
- mineralocorticoids (eg. aldosterone)
(helps control BP; maintains Na+ and K+ ions in blood ∴ maintains water and salt conc in blood/ bodily fluids)
- androgens (eg. testosterone)
(male and female hormones, that are released in small amounts)
29
which hormones produced by the adrenal cortex work together to regulate immune response and suppress inflammatory response?
cortisol and corticosterone
30
Function of mineralocorticoids
- help control BP
- maintains Na+ and K+ ions in blood ∴ maintains balance of water and salt conc in blood and bodily fluids
31
Function of glucocorticoids
- regulates metabolism
- regulates BP and CV function in response to stress
- stimulates production of glucose from breakdown of glycogen
- cortisol and corticosterone work together to regulate immune response and suppress inflammatory response
32
What happens in 'flight or fight response'
[secondary messenger model]
- triggers liver cells to convert glycogen into glucose (process known as glycogenolysis)
- more glucose in bloodstream will mean more respiration can occur and more ATP produced, available for muscle contraction [Animal Response]
33
Secondary messenger model of adrenaline response
- CASCADE EFFECT
adrenaline = 1st messenger
cAMP= 2nd messenger
- adrenaline approaches receptor on cell surface membrane of liver cell
- adrenaline fuses with receptor ∴ activates the enzyme within membrane (adenylyl cyclase)
- activated enzyme converts ATP to cAMP (cyclic AMP)
- cAMP acts as secondary messenger and activates other enzymes (protein kineases phosphorylate and activate other enzymes) that convert glycogen into glucose [glycogenolysis at liver cells]
34
what is special about the pancreas
uses both EXO and ENDO crine system
35
Pancreas exocrine gland
produces enzymes [amylase, protease, lipase etc. in pancreatic juice] and releases them through pancreatic duct into the duodenum (top part of small intestine)
36
Pancreas endocrine gland
produces hormones [insulin and glucagon (both are peptide/non-steroid hormones)] and releases them into the blood
37
Pancreatic endocrine cells
Islets of Langerhans (cells responsible for producing insulin and glucagon)
38
Pancreatic exocrine cells
- Acinar cells (secrete digestive enzymes)
- duct cells (secrete aqueous NaHCO3 solution/sodium hydrogen carbonate)
39
alpha cells produce + secrete
glucagon
40
beta cells produce + secrete
insulin
41
alpha cells are _______ than beta cells
larger
42
beta cells are more _______ than alpha cells
abundant/greater number of them
43
Function of pancreatic duct
tube that collects all secretions from exocrine glands, transporting them to the small intestine (duodenum)
44
Function of Islets of Langerhans
small patches of tissue in pancreas that have endocrine function
45
Function of α cells
produce and secrete glucagon (hormones that causes blood glucose levels to rise)
detect decrease in BGL
46
Function of β cells
produce and secrete insulin (hormone that causes blood glucose levels to fall)
detect increase in BGL
47
Function of insulin
hormones that causes blood glucose levels to fall
48
Function of glucagon
hormone that causes blood glucose level to rise
49
Histology of islets of Langerhans...
Appearance: lightly stained
Shape: spherical clusters, large
tissue type: endocrine
function: detect blood glucose level and produce and secrete hormones to control it
50
Histology of pancreatic acini (singular: acinus)
Appearance: darker stained
Shape: small, berry-like clusters
Tissue type: exocrine pancreas
function: produce and secrete digestive enzymes [protease, lipase, amylase] into the small intestine [duodenum] through the pancreatic duct
51
Which hormones involved in controlling BGL
insulin and glucagon
52
How does insulin work?
- insulin binds to GLYCOPROTEIN RECEPTOR, and changes tertiary structure of glucose transport protein channels [this allows more glucose to enter the cell and leave the bloodstream]
53
Where is insulin broken down?
Liver by enzymes ∴ constantly need to be secreted
54
insulin produced by....
beta cells in islets of langerhans
55
beta cells detect...
increase in blood glucose conc
56
receptor and effector of insulin
beta cells
57
Function of insulin
lower blood glucose concentration level
58
How does insulin lower blood glucose concentration? [5]
- ↑ rate of absorption of glucose by cells
- ↑ respiratory rate of cells
- ↑rate of glycogenesis
- ↑rate of glucose to fat and glycogen
- inhibits release of glucagon from alpha cells
59
Receptor and effector of glucagon...
alpha cells in islets of langerhans
60
glucagon produced by...
alpha cells
61
alpha cells detect...
decrease in blood glucose conc
62
where are insulin receptors found?
- virtually on all cell surface membranes except RBC
- mostly found on liver and muscle cell surface membranes
63
where are glucagon receptors found?
liver and fat cell surface membranes
64
Function of glucagon
raise blood glucose level
65
How does glucagon raise BGL [3]
- ↑ glycogenolysis (conversion of glycogen into glucose)
- ↑ gluconeogensis (coversion of AA and glycerol (which is derived from lipids) into glucose in liver cells)
- ↓ rate of absorption of glucose by liver cells
66
glycogenesis
production of glycogen
when BGL too high (detected by beta cells) glucose converted into glycogen
- glycogen stored in liver
67
glycogenolysis
breakdown of glycogen
when BGL too low (detected by alpha cells) glycogen broken down into glucose
- released into bloodstream
- increase BGL
68
gluconeogenesis
production of glucose from NON-CARB SOURCES
glycerol and AA converted to glucose by liver cells
- formed glucose release into bloodstream
- increase in BGL
69
Release of insulin [steps]
//this occurs in beta cell
1. glucose enters beta cell by glucose transporter protein channel
2. glucose metabolised at mitochondrion
- produces ATP
3. ATP binds to K+ ion channels
- these channels known as ATP-sensitive channels bcos. close when ATP binds to it
- channel closes
- p.d reduced to -30mV
4. Depolarisation causes Ca2+ voltage-gated channels to open
- influx of Ca2+ ions into cell
5. Influx of Ca2+ ions causes exocytosis of secretory vesicles containing insulin.
70
Resting p.d of cells
-70mV
71
Problem of T1
beta cells don't produce insulin
72
Problem of T2
beta cells don't produce ENOUGH insulin
cells no longer respond to insulin
73
T1 Treatment
regular injections of insulin (is insulin dependent)
74
T2 Treatment [3]
- drugs to stimulate insulin production
- drugs to slow down rate of glucose absorption by intestine
- insulin injections
75
Advantages of medically produced insulin [4]
- production costs cheaper
- human insulin less likely to cause allergic reaction
- easier to produce at a larger scale
- religious or ethical concerns are overcome
76
Where is the cardiovascular centre in the brain?
Medulla Oblongata
77
myogenic
initiates its own contraction
78
which motor neurone increases heart rate
accelerator nerve, through the SYMPATHETIC NS
79
which motor neurone decreases heart rate
vagus nerve, through the PARASYMPATHETIC NS
80
Where are baroreceptors found
- carotid arteries
- aorta
- vena cava
81
Where does blood in carotid arteries lead to?
brain
82
Where are chemoreceptors found?
- carotid arteries
- aorta
- medulla
83
what do baroreceptors detect?
increase and decrease in BLOOD PRESSURE
84
what do chemoreceptors detect?
low and high pH
85
What happens when BP is too high?
1. baroreceptors detect BP is too high
2. impulses sent to medulla oblongata
3. impulse sent along parasympathetic neurones (vagus nerve) to SAN
4. SAN decreases heart rate back to normal
86
What happens when BP is too low?
1. baroreceptors detect BP is too low
2. impulses sent to medulla oblongata
3. impulse sent along sympathetic neurones (accelerator nerve) to SAN
4. SAN increases heart rate back to normal
87
What happens to pH when CO2 conc increases?
more CO2 means more carbonic acid formed in blood ∴ more acidic ∴ lower pH
88
What happens when pH too high?
1. chemoreceptors detect pH too high
2. reduced frequency of impulses sent to medulla oblongata
3. reduces frequency of impulses sent along sympathetic NS to SAN
4. SAN decreases heart rate back to normal, pH increases back to normal
89
When might pH get low?
When CO2 levels increase
During increased metabolic activity (muscular activity like exercise)...more CO2 produced from tissues from increased respiration....more CO2 = more carbonic acid = more acidic = lower pH
90
When might pH get high?
When CO2 levels in blood decreases
91
What happens when pH gets too low?
1. chemoreceptors detect pH too low
2. increased frequency of impulse sent to medulla oblongata
3. increased frequency of impulse sent to SAN via sympathetic neurones (accelerator)
4. SAN increases heart rate
5. increased blood flow removes CO2 faster
6. CO2 levels return to normal and so does pH
92
How does adrenaline cause an increased heart rate (clue: SAN)
1. adrenaline binds to receptors on the CSM of SAN cells
2. adenylyl cyclase converts ATP into cAMP
- cAMP acts as secondary messenger
3. results in depolarisation of SAN cell membrane
4. increased freq of SAN impulses
5. increased heart rate and cardiac output
93
Equation for cardiac output (cm3min-1)...
heart rate (bpm) x stroke volume (cm3)
94
Purpose: heart rate increase
pump more oxygenated blood around the body
95
Purpose: pupils dilate
maximise light for better vision
96
Purpose: arterioles in skin constrict
more blood to brain, heart, major muscle groups and muscles for ventilation
97
Purpose: blood glucose levels increase
more ATP produced and energy available for muscle constriction
98
Purpose: smooth muscle of airways relaxes
larger lumen = allows more O2 to enter lungs
99
Purpose: non-essential systems shut down
all E directed to emergency functions
100
Purpose: difficulty focusing on small tasks
brain solely focused on where threat is coming from
