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Hormonal Communication Flashcards

1
Q

What are the four main types of communication in the body?

A

Endocrine
Nervous
Autocrine
Paracrine

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2
Q

What are the two main types of communication in body? (I know I said there were four before, but these are the biggies)

A

Endocrine Nervous

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3
Q

What is the mechanism of action for nervous communication?

A

Action potentials

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4
Q

What is the afferent branch?

A

Signal direction towards the brain

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5
Q

What is autocrine communication?

A

Variety of agents released by cells have effect on cell itself

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6
Q

What is paracrine communication?

A

Hormones released locally rather than directly into the blood

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7
Q

What are the three roles of a control center in the body? Name two control centers, and what they control

A

Determine set reference point of chemical levels
Analyses signals from afferent branch
Determines appropriate response
Hypothalamus involved in endocrine control.
Medulla involved in cardiovascular and respiratory.

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8
Q

What is a receptor used for?

A

To detect stimuli, such as changes in environment

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9
Q

Name three examples of receptors

A

Chemo, pressure and temperature

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10
Q

What is an effector?

A

An agent that controls change

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11
Q

What is the pathway from control center once response has been decided?

A

Control –> Efferent nervous pathway –> Effector

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12
Q

What does loss of efferent pathway use do in paraplegic patients?

A

Sweat glands cannot be controlled, so reduces ability of paraplegic patients to lose heat

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13
Q

What is negative feedback, and how common is it?

A

Effectors oppose stimulus

Occurs in most homeostatic control systems

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14
Q

What are the two advantages of negative feedback?

A

Give stability to control systemsAllow a point to be controlled within fine limits

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15
Q

What is hunting behaviour and what is it indicative of?

A

Occurs in negative feedback when levels overshoot set points several times before rest. Indicative of dynamic equilibrium.

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16
Q

What is positive feedback?

A

Stimulus produces a response which increases its effect

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17
Q

How fast is the change caused by positive feedback?

A

Rapid

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18
Q

Give two examples of positive feedback in the body

A

Ovulation and blood clotting cascade

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19
Q

Give two examples of negative feedback in body

A

Hyperglycaemia stimulates insulin releaseBody water homeostasis

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20
Q

Where is biological clock situated in body? (think chasm)

A

Suprachiasmaic nucleus in hypothaamus

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21
Q

Give three examples of biological rhythmns

A

Cortisol levels vary throughout the day. Peak at 7 am and trough at 7 pm. So, blood cortisol levels should be measured at same time each day.
Menstrual cycle varies over month. Woman’s core body temperature varies during cycle and can be used as a marker of ovulation.
Melatonin released from pineal gland in response to light and dark

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22
Q

What do you have to do when measuring cortisol levels in patients and why?

A

Take measurement same part of day, varies throughout day (peaking at 7 am, troughing at 7pm)

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23
Q

How many litres of water in normal healthy 70KG male?

A

42

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24
Q

How many litres of blood in heathy 70 kg male?

A

4.6

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25
What is an increase in blood osmolarity?What happens when it is detected?
Increase in conc (not enough water) Osmoreceptors in hypothalamus detect decrease in water potential (increased osmolarity) ADH (vasopressin) is released from the posterior pituitary Causes increase in permeability of collecting ducts to water, increasing reabsorption of water from the urine into the blood Makes urine more concentrated
26
Where is ADH released from?
Posterior pituitary
27
What is ADH released in response to?
Increased blood osmolarity
28
What does ADH do?
Causes increase in permeability of collecting ducts in kidney to water, increasing reabsorption of water
29
What is a HORMONE?
Chemical messengers travel via blood stream
30
Outline Hypothalamic-Pituitary-Adrenal axis
Hypothalmus  Corticotrophin releasing hormone (CRH)  Anterior pituitary  Adrenocorticotrophic hormone  Adrenal cortex  Cortisol  Inhibits anterior pituitary
31
What are two factors which control hormone secretion?
•Change in a variable regulated by a hormone •Concentration of hormone itself or another hormone
32
Why do hormones bind with proteins in the blood?
Mostly not soluble enough to dissolve
33
Name two hormones which exhibit specific binding to proteins
Steroid and thyroid hormones
34
Give three reasons why hormones bind with protein carriers
•Increases solubility of hormone in plasma •Increases half life of hormone Serves as readily accessible reserve
35
Name four main types of hormone(PAGS)
Polypeptide hormone Glycoprotein hormones Amino acid derivatives Steroids
36
Why is the largest hormone group?
Polypeptide
37
What do polypeptide hormones consist of?
Short or long single chain(s) of amino acids
38
Give two types of polypeptide hormone
Insulin and Glucagon(also GSH and placental lactogen)
39
What do glycoprotein hormones consist of?
Large two chained protein molecules with carbohydrate sidechains
40
Name two types of glycoproteins
LH, FSH and TSH
41
What do amino acid derviatives consist of?
Small molecules synthesised from amino acids
42
Name two types of amino acid derivatives
Adrenaline and thyroid hormones
43
What are steroids derived from?
Cholesterol
44
What do different steroid hormones differ in?
The number of carbons
45
Give three examples of steroid hormones
Cortisol, testosterone, oestrogen, progesterone
46
Name three hydrophillic hormone types
Polypeptide, Glycoprotein and adrenaline (amino acid derivative)
47
Name two hydrophobic hormone types
Steroid and thyroid hormones
48
What is the main variable which determines the effect of hormones on target cell?
Concentration of free or unbound hormone
49
What two changes in concentration can have clinical consequences?
Defiency and excess
50
Where are the receptors bound to by lipophillic hormones situated?
Inside cell (cytoplasmic/nuclear)
51
What do hormones bind to
Specific, high affinity receptor
52
Give examples of things which hormone binding to receptors may affect
Activity of enzyme or gene expression
53
How long does a change in gene expression take to take effect?
Minutes-hours
54
Give three factors which influence magnitude of hormonal response
Concentration of active hormone at target tissue Receptor number Affinity of receptor for hormone Degree of signal amplification
55
How is rate of secretion of hormones affected?
By blood concentration of hormones
56
What is a trophic hormone?
One that controls the secretion of another hormone by targeting endocrine tissue
57
Where are trophic hormones secreted?
Anterior pituitary
58
Name three hormones secreted by the anterior pituitary gland and their role
``` Thyroid Stimulating Hormone = Thyrotrophin (TSH) – affects thyroid gland Adrenocorticotrophic Hormone = Corticotrophin (ACTH) – affects adrenal gland Growth Hormone = Somatotrophin (GH) – affects metabolism Luteinizing Hormone (LH) = Affects ovary and testis function ```
59
Name a regulatory mechanism for trophic hormones
Negative feedback. | Increased hormone level causes suppression of stimulating hormone
60
Where do releasing or inhibiting hormones come from?
Nerve cells in the hypothalamus
61
How do releasing or inhibiting hormones travel to endocrine glands?
Specialised blood vessels known as hypophseal portal vessels
62
Name three releasing hormones and what they effect
Thyrotrophin Releasing Hormone (TRH) – stimulates TSH release Corticotrophin Releasing Hormone (CRH) – stimulates ATCH release Somatotrophin Releasing Hormones (SRH) – stimulates GH release
63
Where does inactivation of hormones occur?
Liver, kidney and sometimes in target tissues
64
How are steroid hormones inactivated?
Relatively small change in chemical structure which increases water solubility enabling them to be excreted from the body in urine or bile
65
How are protein hormones inactivated?
Undergo extensive chemical change and are degraded to amino acids, which are then reused.
66
What is the structure of insulin?
Two chains linked covalently by two disulphide bridges. Extra third disulphide bridge in alpha chain
67
Where is insulin secreted?
B cells of islets of langerhans
68
How is insulin stored?
In B cells as crystalline-zinc complex storage granules
69
What is the structure of glucagon?
Single chain polypeptide hormone, lacking disulphide bridge so has flexible 3D structure
70
How is insulin circulated?
Dissolve in the plasma and circulates as free hormon
71
When is Glucagon activated?
Upon binding to its receptor on surface of target cells
72
What are the three main target tissues of insulin?
Liver, Skeletal muscle and adipose tissue
73
What part of a cell does insulin react with?
Cell surface receptors
74
What does insulin stimulate to work?
Enzymes and proteins inside target cell
75
How does glucagon become an active molecule?
Post translational processing to produce biologically active molecule
76
What type of metabolism does insuline encourage?
Anabolic
77
What type of metabolism does glycogen encourage?
Catabolic
78
What three metabolic reactants do insulin and Glucagon influence?
Carbohydrate, lipid and amino acid metabolism
79
What are the function of insulin in the short term?
Removes absorbed nutrients from blood following a meal
80
What are the long term functions of insulin?
cell growth/cell division that relate to its ability to stimulate protein synthesis and DNA replication.
81
What is the name for a glucagon receptor?
G protein coupled receptor (GPCR)
82
What does binding to the GPCR receptor by glucagon do?
Causes adenylate cyclase to increase, which increases cyclic AMP in the cell
83
Effect of insulin on glucose transport into adipose tissue?
Increase
84
What affect does insulin have on glycogenolysis?
Decrease in insulinIncrease glucagon
85
What effect do insulin and glucagon have on gluconeogenesis?
Decrease insulinIncrease in glucagon
86
What effect do insulin and glucagon have on ketogenesis in the liver?
Decrease in insulinIncrease with Glucagon
87
What effect does insulin have on lipolysis?
Decrease in insulinIncrease in glucagon
88
What effect does insulin have on amino acid uptake in liver?
Increase
89
What are the major cell types in islets of langerhans, and what quantities do they exist in?
B - 75% - Insulin | A - 20% - Glucagon
90
Where is glucagon and insulin stored in a cell?
In a storage granule
91
What are the three main features of a cell specialised for protein synthesis?
More RER, well defined golgi, more mitochondria and system of microtubules and filaments
92
Where is proinsulin converted to insulin?
Golgi apparatus
93
Where is preproinsulin converted to proinsulin?
Endoplasmic reticulum
94
How does glucose move into B cells?
GR2 receptor
95
What does increase of glucose in cells cause an increase in?
ATP conc
96
What channels does increase in ATP inhibit and what effect does this have?
ATP sensitive potassium ion channelsDepolarises cell membrane
97
What enters through voltage gated channel after membranal depolarisation?
Calcium ions
98
What do calcium ions do in B cells?
Stimulate exocytosis of insulin
99
Define homeostasis
The control of an internal environment within set limits, dynamic equilibrium rather than fixed steady state.

1 - Metabolism (17 decks)

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