Gut Liver Kidneys Skin Vascular Endothelium Adipose tissue

Introduction 01 Flashcards by Ibby Khan

What is a hormone?

Secreted products – act
DISTANTLY (enter circulation) via specific receptors

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4 Types of Hormone Action

haemocrine
paracrine
solinocrine
autocrine

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Define Haemocrine

secreted into circulation (blood stream)

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Define Paracrine

Acts on nearby cell

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Define Solinocrine

Secreted into gut

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Define Autocrine

Acts on the SAME cell

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Name the classical Endocrine Glands (8)

Pituitary (brain)
Pineal Gland (brain)
Thyroid (neck)
Parathyroid (x4 neck)
Adrenal (x2 kidneys)
Pancreas
Ovaries
Testes

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6 Endocrine Organs

Gut
Liver
Kidneys
Skin
Vascular Endothelium
Adipose tissue

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Different molecules as hormones (6)

Catecholamines & other small molecules
(eg adrenaline, nor-adrenaline, melatonin)
Peptide hormones (eg insulin, parathyroid
hormone)
Eicosanoids (derived from fatty acids eg
prostaglandins)
Steroid hormones (cortisol, sex steroids,
vitamin D)
Thyroid hormone
Gases (eg nitric oxide in blood vessels)

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4 Different
receptor types

EXTRACELLULAR - G-PROTEIN COUPLED
* Catecholamines, peptide hormones
* Nitric oxide
EXTRACELLULAR - PHOSPHORYLATION OF INTRACELLULAR
proteins
* Insulin
* Cytokines
EXTRACELLULAR - ION LINKED
* Some neurotransmitters
INTRACELLULAR - NUCLEAR RECEPTORS
* Steroid hormones
* Thyroid hormone
* Vitamin D

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Each hormone has its own…

SPECIFIC receptor

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5 Actions of Insulin:

(lowers blood glucose conc)
* Increases GLUCOSE UPTAKE into fat and muscle
* Stimulates GLYCOGEN SYNTHESIS in liver and muscle
* Stimulates STORAGE OF TRIGLYCERIDE (fat) in adipose tissue
* Increases PROTEIN SYNTHESIS
* DECREASES hepatic glucose synthesis
(‘GLUCONEOGENESIS’)

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What is Type 1 Diabetes

absolute insulin
deficiency

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What is Type 2 Diabetes

insulin resistance and
insulin deficiency

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What happens in type 1 diabetes

Uncontrolled gluconeogenesis
Failure of glucose uptake into
muscle and fat
Use of alternative fuels (fatty acids)
Development of HYPERGLYCAEMIA,
KETOACIDOSIS
( eventual coma and
death if untreated)

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What do we get from Insulin excess

hypoglycaemia

Sympathetic response (sweating,
tachycardia, hunger)
Confusion and coma as brain starved of glucose

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How can we get Insulin Excess

– usually in treatment of
diabetes

Can also occur with rare insulin secreting pancreatic tumour (insulinoma)

Thyroid hormone uses co-factor…

RA
Retinoic Acid

Result of thyroid hormone

Increased metabolic rate

Enhanced response to catecholamines etc.

hypothyroidism
how are T4,T3 and TSH levels

LOW T3 & T4
HIGH TSH

hyperthyroidism
how are T4,T3 and TSH levels

HIGH T3 & T4
LOW TSH

Excess production of thyroxine results in…

Thyrotoxicosis

Symptoms and signs
* Tachycardia, palpitations
* Weight loss
* Heat intolerance
* Tremor

How do we get excess production of thyroxine (Thyrotoxicosis)

Often due to autoimmune
activation of thyroid

hypothyroidism

(underactive thyroid)
when thyroid gland does not produce enough hormones

Coarse Features
Dry Skin
Cold
Slow reflexes
Slow pulse
Thyroid hormones (T4 and T3)
low
Thyroid stimulating hormone
(TSH) high

Steroid hormones are synthesised from...

Cholesterol -Tissue specific enzymes determine final product

Example of a steroid hormone

Cortisol

Steroid Hormones can affect

Skin Bone Teeth Cardiovascular Metabolic Immune system (anti-inflammatory effects)

Feedback regulation of adrenal function

hypothalamus releases CRH (corticotrophin releasing hormone) pituitary releases ACTH (adrenocorticotrophic hormone) adrenal releases Cortisol (CYCLE)

Cushing’s Syndrome causes

- overproduction of ACTH from pituitary (Cushing’s Disease) or CORTISOL from adrenal (RARE) - use of steroids to treat disease (COMMON) * Typically causes central obesity * Associated with diabetes and hypertension * Suspect if proximal muscle weakness, thin skin, striae, fractures, typical appearance

What is Addison’s disease

Adrenal Insufficiency *Prevalence: 1:100 000; presents at any age *Presents with weight loss, dizzy spells/ collapse, hyperpigmentation

Cause of Addison’s disease

autoimmune destruction of adrenal gland (most commonly)

Pineal gland (centre of brain) produces..

Melatonin (at night)

4 Hormones in Menstrual Cycle

FSH OESTROGEN LH PROGESTERONE

Excess Growth Hormone results in...

Gigantism Acromegaly

3 unexpected Endocrine Tissues

Stomach GI Tract Adipose Tissue

Stomach hormone that increases food intake:

Ghrelin

What is GLP-1 (Glucagon-like peptide-1)

a gut peptide for treatment of diabetes and obesity

GLP-1 is secreted by..

L-cells in duodenum and ileum - released into the circulation after eating also produced in the brain (nucleus tractus solitarus)

Principle effects of GLP-1 include:

- stimulation of post-prandial (after meal) INSULIN SECRETION ('incretin effect') in a glucose-dependent manner - part of the normal satiety signalling cascade Appetite regulation: - decreased appetite -decreased energy intake Glucose Regulation: - increase Insulin - decrease Glucagon - decrease Glucose

What is Leptin

a hormone from fat that controls food intake

Congenital leptin deficiency causes

severe obesity