Introduction 01 Flashcards
What is a hormone?
Secreted products – act
DISTANTLY (enter circulation) via specific receptors
4 Types of Hormone Action
haemocrine
paracrine
solinocrine
autocrine
Define Haemocrine
secreted into circulation (blood stream)
Define Paracrine
Acts on nearby cell
Define Solinocrine
Secreted into gut
Define Autocrine
Acts on the SAME cell
Name the classical Endocrine Glands (8)
Pituitary (brain)
Pineal Gland (brain)
Thyroid (neck)
Parathyroid (x4 neck)
Adrenal (x2 kidneys)
Pancreas
Ovaries
Testes
6 Endocrine Organs
- Gut
- Liver
- Kidneys
- Skin
- Vascular Endothelium
- Adipose tissue
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)
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
Each hormone has its own…
SPECIFIC receptor
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’)
What is Type 1 Diabetes
absolute insulin
deficiency
What is Type 2 Diabetes
insulin resistance and
insulin deficiency
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)
What do we get from Insulin excess
hypoglycaemia
- Sympathetic response (sweating,
tachycardia, hunger) - Confusion and coma as brain starved of glucose
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
