Diabetes and Endocrine Introduction Flashcards
What are paracrine chemicals?
Act local to the site of synthesis and do not travel?
What are autocrine chemicals?
Act in/on the same cell that synthesises it?
What are exocrine chemicals?
Released from exocrine glands via ducts to the external environment including the GI tract
What is the effect of an exocrine chemical on a cell without the respective receptor?
No response
What is a neurotransmitter?
Chemical released by a neurone which acts locally within the synaptic cleft
What is the neuroendocrine system?
Nerves releasing hormones into the blood to the target cells
How is the adrenal medulla activated?
Sympathetic NS
What are the target tissues of insulin?
Skeletal/adipose tissue
Liver
What is the response of skeletal muscle/adipose tissue to insulin?
Increased glucose uptake
What is the response of the liver to insulin?
Increased Glycogenesis
Decreased gluconeogenesis
The pineal gland produces what hormones?
Melatonin
The hypothalamus produces what hormones?
Trophic hormones
The posterior pituitary produces what hormones?
Oxytocin
Vasopressin (ADH)
The anterior pituitary produces what hormones?
Prolactin HGH ACTH TSH Follicle stimulating hormone Luteinizing hormone
The thyroid gland produces what hormones?
Trilodothyronine and thyroxine
Calcitonin
The parathyroid gland produces what hormones?
Parathyroid hormone
The thymus gland produces what hormones?
Thymosin
Thymopoeitin
The heart produces what hormone?
Atrial natriuretic peptide
The liver produces what hormone?
Angiotensinogen
Insulin-like growth factors
The adrenal cortex produces what?
Aldosterone
Cortisol
Androgens
The adrenal medulla produces what hormones?
Epinephrine
Norepinephrine
The pancreas produces what hormones?
Insulin
Glucagon
Somatostatin
Pancreatic polypeptide
The kidney produces what hormone?
Erythropoeitin
Vitamin D3
The testes produce what hormone?
Androgens
Inhibin
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
