Diabetes and Endocrine Introduction Flashcards by Peter Savage

What are paracrine chemicals?

Act local to the site of synthesis and do not travel?

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What are autocrine chemicals?

Act in/on the same cell that synthesises it?

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What are exocrine chemicals?

Released from exocrine glands via ducts to the external environment including the GI tract

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What is the effect of an exocrine chemical on a cell without the respective receptor?

No response

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What is a neurotransmitter?

Chemical released by a neurone which acts locally within the synaptic cleft

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What is the neuroendocrine system?

Nerves releasing hormones into the blood to the target cells

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How is the adrenal medulla activated?

Sympathetic NS

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What are the target tissues of insulin?

Skeletal/adipose tissue

Liver

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What is the response of skeletal muscle/adipose tissue to insulin?

Increased glucose uptake

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What is the response of the liver to insulin?

Increased Glycogenesis

Decreased gluconeogenesis

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The pineal gland produces what hormones?

Melatonin

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The hypothalamus produces what hormones?

Trophic hormones

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The posterior pituitary produces what hormones?

Oxytocin

Vasopressin (ADH)

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The anterior pituitary produces what hormones?

Prolactin
HGH
ACTH
TSH
Follicle stimulating hormone
Luteinizing hormone

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The thyroid gland produces what hormones?

Trilodothyronine and thyroxine

Calcitonin

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The parathyroid gland produces what hormones?

Parathyroid hormone

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The thymus gland produces what hormones?

Thymosin

Thymopoeitin

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The heart produces what hormone?

Atrial natriuretic peptide

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The liver produces what hormone?

Angiotensinogen

Insulin-like growth factors

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The adrenal cortex produces what?

Aldosterone
Cortisol
Androgens

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The adrenal medulla produces what hormones?

Epinephrine

Norepinephrine

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The pancreas produces what hormones?

Insulin
Glucagon
Somatostatin
Pancreatic polypeptide

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The kidney produces what hormone?

Erythropoeitin

Vitamin D3

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The testes produce what hormone?

Androgens

Inhibin

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The ovaries produce what hormone?

Estrogen Progesterone Inhibin Relaxin (pregnancy)

What are the 6 features of an endocrine hormone?

``` Produces by cell or group of cells Secreted from cells --> blood Transported in blood to distal targets Effective at very low concentrations Act by binding to receptors Actions terminated by feedback ```

What are the classifications of endocrine hormones?

Peptide/protein Amine Steroid

What are peptide hormones?

Composed by chains of amino acids

What are amine hormones?

All derived from Tryptophan or Tyrosine

What are steroid hormones?

All derived from cholesterol

What is the pathway of peptide hormone production?

Synthesised as preprohormone Cleaved into prohormone Stored in vesicles Cleaved into active hormone and peptide fragments and all secreted

What are preprohormones?

Inactive prohormones in a chain of 1 or more copy

Where are preprohormones made?

Ribosomes

How are prohormones formed?

Preprohormones cleaved into smaller units in the endoplasmic reticulum

Where are prohormones packaged into vesicles?

Golgi apparatus

Prohormones are stored with what in vesicles?

Proteolytic enzymes

Proteolytic enzymes break prohormones into what?

Hormone and fragments

What is co-secretion?

Hormones and fragments released into plasma together

What is C-peptide?

Inactive fragments cleaved from insulin prohormone

Why is C-peptide measured instead of blood insulin?

Because diabetic patients will have injected insulin recently

What are typical C-peptide levels relative to insulin?

5x ENDOGENOUS insulin

Peptide hormones typically work via what cell surface receptors?

Modulation of GPCR or Tyrosine Kinase Linked signalling pathways

GPCR and Tyrosine Kinase Linked signalling pathways work how?

Phosphorylation of existing proteins to modify their function

How does a g-protein coupled receptor system work?

Activated 2nd messenger system and/or ion channels with rapid response

How does a tyrosine kinase linked receptor pathway work?

Alters gene expression | Slower, longer lasting activity

Amine hormones are mostly derived from what?

Tyrosine (amino acid)

Which hormones are hydrophilic?

Peptide hormones | Catecholamines

Which hormones are lipophilic?

Steroid hormones | Thyroid hormones

Which amine hormone is not derived from tyrosine? What is it derived from?

Melatonin - derived from tryptophan

What are the two different groups of tyrosine derived hormones?

Catecholamines - hydrophilic | Thyroid hormones - lipophilic

When are steroid hormones synthesised? Why?

Directly as needed | They can't be stored by lipid membranes

How are steroid hormones carried?

Bound to albumin

Why are steroids bound to albumin?

Protects them from enzymes | Stabilises them, increasing their half life (60-90m)

Where are steroid hormones produced?

Gonads - Sex steroids Placenta - hCG, Sex steroids Kidney - Vitamin D3 Adrenal CORTex - CORTicosteroids

Cholesterol becomes what in the adrenal cortex?

Aldosterone | Cortisol

Cholesterol becomes what in the ovary?

Estradiol

Receptors for steroid hormones are located where?

``` Inside cells (cytoplasm & nucleus) Outside cells - rapid response ```

What is the effect of steroid hormones?

Genomic effect | Activate or inhibit gene function

The degree of effect of a hormones actions is dependent on what?

The extent of protein binding | The extent of receptors

Why are steroid/thyroid hormones bound to carrier proteins?

Steroid/thyroid hormones have poor solubility in plasma | Protection from degradation

Albumin is a type of what?

Non-specific carrier protein

Give an example of specific carrier protein?

Corticosteroid-binding globulin

What increases as a steroid is taken up?

More is released from the carrier allowing for a reservoir of action

Peptide and catecholamine hormones are soluble in what?

Water/plasma

Why do Peptide and catecholamine hormones have a short half life? How long is it?

Unbound so vulnerable to degradation | 2-4minutes

How do steroid/thyroid hormones alter protein synthesis?

Modify gene expression

A [Hormone]plasma is determined by what?

Secretion:degradation/excretion | Negative feedback

Parathyroid hormone is stimulated by what?

Low [Ca2+]

Parathyroid hormone effects what organs?

Bone and Kidneys

Parathyroid hormone has what effect?

Increased bone resorption Increased kidney Ca2+ reabsorption Increased Calcitrol (Increased [Ca2+]plasma)

(Increased [Ca2+]plasma) causes what?

Negative feedback: | Inhibition of the parathyroid cell

Prolonged exposure to low [hormone]plasma often leads to what?

Up-regulation of receptor number | increased tissue sensitivity to hormone

Prolonged exposure to high [hormone]plasma typically leads to what?

Down-regulation of receptor number | decreases tissue sensitivity to hormone

What are permissive effects?

Presence of one hormone enhances the effect of another

What are antagonistic effects?

Presence of one hormone reduces the effect of another

Thyroid hormone has what permissive effect?

TH increases the synthesis of receptors for epinephrine on adipocytes - increasing lipolysis