What are endocrine glands?
Ductless glands that secrete into the blood then the blood delivers the hormone to all the body parts
What are hormones?
- Chemical secreted in small quantities by endocrine cells
- Alter the physiological active of target cells
What are target cells/organs?
Where hormone produces its effect
Endocrine action
Hormones travel in the blood for long distance signals
Autocrine action
Hormone affects the same cells that secrete it
Paracrine action
Hormone affects neighboring cells
ex: somatostatin in pancreas
Differences between endocrine, exocrine and mixed glands
- Endocrine: ductless (ex: thyroid)
- Exocrine: have ducts (ex: salivary gland)
- mixed glands: both endo and exo parts (ex:pancreas)
Nervous system
NS:
- Neurotransmitters
- muscles and glands
- quick but effect for short time
Endocrine system
- Hormones
- control almost all
- slow but effect for long time
Chemical nature of hormones
- Water-soluble
- Lipid-soluble
- Eicosanoids
Water-soluble hormones
Amino acid based hormones
- simple amines: modified amino acids
- peptide hormones: short chain 3-49 amino acids
- protein hormones: long chain >50 amino acids
Simple amines
- epinephrine and norepinephrine
- serotonin
- melatonin
Peptide hormones
- ADH
- oxytocin
Protein hormones
- Insulin
- hGH
Lipid-soluble
- Steroid hormones: derived from cholesterol (ex: sex hormones: testis & ovaries)
- thyroid hormones: T3 &T4
- nitric oxide gas (NO)
Eicosanoids
- local hormones - autocrine and paracrine
- lipids
- derived from 20 carbon fatty acids (Arachidonic acid)
Prostaglandins (PGs)
a group of lipids with hormone-like actions that your body makes at sites of tissue damage or infection
- clotting
- pain
- inflammation
Leukotrienes (LTs)
- chemicals your body releases
- mediate allergy and inflammation
Hormone-Target cell specificity
A hormone produces its effects only on specific cells/organs
Why does a hormone act on a specific target?
Because the target cells has a specific receptor that it will bind to
Down regulation
too much hormone -> # of receptor goes down
Up regulation
too little hormone-> # of receptors goes up
Direct Gene Activation
- For steroid hormones + thyroxine
- hormone enters the cell
- hormones bind to receptors in nucleus or cytoplasm
- activate specific part of DNA
Second-Messenger system
- for most hormones
- hormones does not enter cell; second messenger is formed
- receptors on plasma membrane
- activates enzymes in cytoplasm
2 types of Diabetes Mellitus
Type I — insulin dependent DM (IDDM)
Type II — non insulin dependent DM (NIDDM)
Type I
- appear before 15
- beta cells produces insulin are destroyed by autoimmune
Type II
- occurs after 40
- 90% of all DM are type II & obese
- familial and hereditary disposition
3 cardinal signs of DM
- Polyuria (too much urine)
- polydipsia (excessive thirst)
- Polyphagia (eat too much)
DM consequences
- blindless
- cataract
- kidney failure
- strokes
- heart attack
Why is hypothalamus considered a neuronendocrine organ?
it releases neural hormones inside the brain
Hypophyseal portal system
A system of blood vessels that carries the blood with releasing hormones and from hypothalamus directly instead of taking it to the general blood stream
Leptin
- Made by fat and regulates fat stored in the body
- inhibits sensation of hunger
- increase energy expenditure
Ghrelin
Hunger hormone
stomach empty -> ghrelin secreted
regulates the distribution and rate of use of energy