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Semester 1 - Metabolism > Metabolism Session 7 - Introduction to the endocrine system and the endocrine pancreas > Flashcards

Metabolism Session 7 - Introduction to the endocrine system and the endocrine pancreas Flashcards

1
Q

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

Give four characteristics of control systems

A

Endocrine
Nervous
Autocrine
Paracrine

Communication
Control Center
Receptor
Effector

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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.
Medullar 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 systems

Allow 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 release

Body 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.
Menstral cycle varies over month. Womans 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
Q

What is an increase in blood osmolarity?

What happens when it is detected?

A

Increase in conc (not enough water)

Osmoreceptors in hypothalamus detect decrease in water potential (increased osmolarity)
ADH (vasopressin) is released from the posterior pituatry
Causes increase in permeability of collecting ducts to water, increasing reabsorption of water from the urine into the blood
Makes urine more concentrated

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26
Q

Where is ADH released from?

A

Posterior pituitary

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27
Q

What is ADH released in response to?

A

Increased blood osmolarity

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28
Q

What does ADH do?

A

Causes increase in permeability of collecting ducts in kidney to water, increasing reabsorption of water

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29
Q

What is a HORMONE?

A

Chemical messengers travel via blood stream

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30
Q

Afferent branch Hypothalamus  Anterior pituitary gland  Endocrine glands
What is missing?

A

Releasing factors

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31
Q

Outline Hypothalamic-Pituitary-Adrenal axis

A

Hypothalmus  Corticotrophin releasing hormone (CRH)  Anterior pituitary  Adrenocorticotrophic hormone  Adrenal cortex  Cortisol  Inhibits anterior pituitary

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32
Q

What are two factors which control hormone secretion?

A
  • Change in a variable regulated by a hormone

* Concentration of hormone itself or another hormone

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33
Q

Why do hormones bind with proteins in the blood?

A

Mostly not soluble enough to dissolve

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34
Q

Name two hormones which exhibit specific binding to proteins

A

Steroid and thyroid hormones

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35
Q

Give three reasons why hormones bind with protein carriers

A

•Increases solubility of hormone in plasma
•Increases half life of hormone
Serves as readily accessible reserve

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36
Q

Name four main types of hormone

PAGS

A

Polypeptide hormone
Glycoprotein hormones
Amino acid derivatives
Steroids

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37
Q

Why is the largest hormone group?

A

Polypeptide

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38
Q

What do polypeptide hormones consist of?

A

Short or long single chain(s) of amino acids

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39
Q

Give two types of polypeptide hormone

A

Insulin and Glucagon

also GSH and placental lactogen

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40
Q

What do glycoprotein hormones consist of?

A

Large two chained protein molecules with carbohydrate sidechains

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41
Q

Name two types of glycoproteins

A

LH, FSH and TSH

42
Q

What do amino acid derviatives consist of?

A

Small molecules synthesised from amino acids

43
Q

Name two types of amino acid derivatives

A

Adrenaline and thyroid hormones

44
Q

What are steroids derived from?

A

Cholesterol

45
Q

What do different steroid hormones differ in?

A

The number of carbons

46
Q

Give three examples of steroid hormones

A

Cortisol, testosterone, oestrogen, progesterone

47
Q

Name three hydrophillic hormone types

A

Polypeptide, Glycoprotein and adrenaline (amino acid derivative)

48
Q

Name two hydrophobic hormone types

A

Steroid and thyroid hormones

49
Q

What is the main variable which determines the effect of hormones on target cell?

A

Concentration of free or unbound hormone

50
Q

What two changes in concentration can have clinical consequences?

A

Defiency and excess

51
Q

Where are the receptors bound to by lipophillic hormones situated?

A

Inside cell (cytoplasmic/nuclear)

52
Q

What do hormones bind to

A

Specific, high affinity receptor

53
Q

Give examples of things which hormone binding to receptors may affect

A

Activity of enzyme or gene expression

54
Q

How long does a change in gene expression take to take effect?

A

Minutes-hours

55
Q

Give three factors which influence magnitude of hormonal response

A
  • Concentration of active hormone at target tissue
  • Receptor number
  • Affinity of receptor for hormone
  • Degree of signal amplification
56
Q

How is rate of secretion of hormones affected?

A

By blood concentration of hormones

57
Q

What is a trophic hormone?

A

One that controls the secretion of another hormone by targeting endocrine tissue

58
Q

Where are trophic hormones secreted?

A

Anterior pituitary

59
Q

Name three hormones secreted by the anterior pituitary gland and their role

A 
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
60
Q

Name a regulatory mechanism for trophic hormones

A

Inhibited by high level of hormone they cause the secretion of in the blood (Wen concentration of thyroid hormone gets too high, less TSH is secreted. Negative feedback)

61
Q

Where do releasing or inhibiting hormones come from?

A

Nerve cells in the hypothalamus

62
Q

How do releasing or inhibiting hormones travel to endocrine glands?

A

Specialised blood vessels known as hypophseal portal vessels

63
Q

Name three releasing hormones and what they effect

A

Thyrotrophin Releasing Hormone (TRH) – stimulates TSH release
Corticotrophin Releasing Hormone (CRH) – stimulates ATCH release
Somatotrophin Releasing Hormones (SRH) – stimulates GH release

64
Q

Where does inactivation of hormones occur?

A

Liver, kidney and sometimes in target tissues

65
Q

How are steroid hormones inactivated?

A

Relatively small change in chemical structure which increases water solubility enabling them to be excreted from the body in urine or bile

66
Q

How are protein hormones inactivated?

A

Undergo extensive chemical change and are degraded to amino acids, which are then reused.

67
Q

What is the structure of insulin?

A

Two chains linked covalently by two disulphide bridges. Extra third disulphide bridge in alpha chain

68
Q

Where is insulin secreted?

A

B cells of islets of langerhans

69
Q

How is insulin stored?

A

In B cells as crystalline-zinc complex storage granules

70
Q

What is the structure of glucagon?

A

Single chain polypeptide hormone, lacking disulphide bridge so has flexible 3D structure

71
Q

How is insulin circulated?

A

Dissolve in the plasma and circulates as free hormon

72
Q

When is Glucagon activated?

A

Upon binding to its receptor on surface of target cells

73
Q

What are the three main target tissues of insulin?

A

Liver, Skeletal muscle and adipose tissue

74
Q

What part of a cell does insulin react with?

A

Cell surface receptors

75
Q

What does insulin stimulate to work?

A

Enzymes and proteins inside target cell

76
Q

How does glucagon become an active molecule?

A

Post translational processing to produce biologically active molecule

77
Q

What type of metabolism does insuline encourage?

A

Anabolic

78
Q

What type of metabolism does glycogen encourage?

A

Catabolic

79
Q

What three metabolic reactants do insulin and Glucagon influence?

A

Carbohydrate, lipid and amino acid metabolism

80
Q

What are the function of insulin in the short term?

A

Removes absorbed nutrients from blood following a meal

81
Q

What are the long term functions of insulin?

A

cell growth/cell division that relate to its ability to stimulate protein synthesis and DNA replication.

82
Q

What is the name for a glucagon receptor?

A

G protein coupled receptor (GPCR)

83
Q

What does binding to the GPCR receptor by glucagon do?

A

Causes adenylate cyclase to increase, which increases cyclic AMP in the cell

84
Q

Effect of insulin on glucose transport into adipose tissue?

A

Increase

85
Q

What affect does insulin have on glycogenolysis?

A

Decrease in insulin

Increase glucagon

86
Q

What effect do insulin and glucagon have on gluconeogenesis?

A

Decrease insulin

Increase in glucagon

87
Q

What effect do insulin and glucagon have on ketogenesis in the liver?

A

Decrease in insulin

Increase with Glucagon

88
Q

What effect does insulin have on lipolysis?

A

Decrease in insulin

Increase in glucagon

89
Q

What effect does insulin have on amino acid uptake in liver?

A

Increase

90
Q

What are the major cell types in islets of langerhans, and what quantities do they exist in?

A

B - 75% - Insulin

A - 20% - Glucagon

91
Q

Where is glucagon and insulin stored in a cell?

A

In a storage granule

92
Q

What are the three main features of a cell specialised for protein synthesis?

A

More RER, well defined golgi, more mitochondria and system of microtubules and filaments

93
Q

Where is proinsulin converted to insulin?

A

Golgi apparatus

94
Q

Where is preproinsulin converted to proinsulin?

A

Endoplasmic reticulum

95
Q

How does glucose move into B cells?

A

GR2 receptor

96
Q

What does increase of glucose in cells cause an increase in?

A

ATP conc

97
Q

What channels does increase in ATP inhibit and what effect does this have?

A

ATP sensitive potassium ion channels

Depolarises cell membrane

98
Q

What enters through voltage gated channel after membranal depolarisation?

A

Calcium ions

99
Q

What do calcium ions do in B cells?

A

Stimulate exocytosis of insulin

100
Q

Define homeostasis

A

The control of an internal environment within set limits, dynamic equilibrium rather than fixed steady state.

Semester 1 - Metabolism (19 decks)

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