Endocrine system

Endocrine system composed of

Ductless endocrine glands/ cells that synthesize and secrete hormones into the blood stream

Ligrans role in endocrine

Chemical messengers that binds to receptor and signal for respond

Functions of Endocrine Sytem

Regulating development, growth and metabolism

Maintaining blood composition and volume

Controlling digestive processes

Controlling reproductive activities

Endocrine glands

Pituitary glands

Pineal Glands

Thyroid glands

Parathyroid glands

Adrenal glands

Types of stimulation of endocrine glands

Hormonal stimulation

Humoral Stimulation

Nervous System stimulation

Hormonal stimulation definition

Gland cell releases its hormone when some other hormone binds to it

Humoral stimulation

Gland cell releases its hormone when there is a certain change in levels of nutrient or ion in the blood

Nervous System stimulation

Gland cell releases its hormone when neuron stimulates it

Circulating hormone

Transported throughout the blood stream

Local Hormone

Signaling hormones that do not circulate in the blood

Paracrine

Bind to neighboring cells

Autocrine

Bind to themselves

What is steroid hormone

Lipid-soluble molecules synthesized from cholesterol

Type of steroid hormones

Gonadal steroid hormones: Estrogen and Testosterone

Adrenal Cortical hormones: Aldosterone, Cortisol, Androgens

Calcitriol- active form of vitamin D

What is biogenic amines (Monoamines)

Modified amino acids

Water soluble ex) thyroid hormone (non-polar)

Types of monoamines

C atecholamines :Epinephrine, Norepinephrine, dopamine

Pineal Gland: Melatonin

Thyroid Hormones: T3 (active), T4 (inactive)

Types of proteins hormone

Antidiuretic hormone

Insulin

Glucagon

Growth hormone

Erythropoietin

What is Eicosanoids

Local hormones formed from fatty acids (within phospholipid bilayer)

Types of Eicosanoids

Prostaglandins

Thromboxanes

Leukotrienes

Prostaglandins

Stimulate fever, induce stomach acid secretion, trigger inflammatory cascade, stimulating pain pathways.

Thromboxanes

Hemostasis (blood clotting, vascocontriction, inflammation

Leukotrienes

Inflammation and allergic reactions

How to create Eicosanoids

Phospholipase A2 —> removes arachidonic acids from plasma membrane —> other enzymes conver arachidonic acid into the Eicosanoids

What is arachidonic acid

20-carbon fatty acid

Mechanism of transport hydrophilic

Homrones freely travel though blood stream, doesn’t require carried.

Mechanism of transport hydrophobic

Hormones required carried protein to travel the blood stream. Via Albumin

Controling hormones by

Release: Blood and hormones concentration increases

Elimination: Blood and hormones concentration decreases

• Enzymatic degradation in liver cells

• Removal from blood via kideny excretion

• Uptake by target cell

Hydrophoic hormones mechanism of action

Lipid-soluble hormones diffuse through cell membrane, then bind to receptor (cytosolic, nuclear).

Hormone + receptor = hormone receptor complex

Hormone receptor complex bind to hormone response element (HRE)

Will influence gene expression

Hydrophilic hormones mechanism of action

Water-soluble hormones binds to plama membrane receptor, start signal and amplified 2nd messenger cascade

GTP replaces GDP, activating intracellular G-Protein

G-Protein activation causes activation of membrane enzyme such as adenylate cyclase or phospholipase C

Activated enzymes catalyzes formation of 2nd messengar - carry out function of hormone

Modify cellular activity

Adenylate Cyclase

Come from activatied G-Protein

Function as increases formation of 2nd messenger “cAMP”

cAMP activated protein kinase A for phosphorylation of intracellular molecules

Phosphorylation come from activation or inhibition of molecules

Phospholipase C

From activated G-Protein

Function as split PIP₂ into Diacylglycerol (DAG) and inositol triphosphate (IP₃)

• DAG- remain in plasma membrane and activated protein kinase C for 2nd messenger cascade

• IP3- Diffuses into cytosol, increase concentration of Ca²⁺ “Ca+ is 3rd messenger that affect plasma membrane permeability and activates protein kinase”

Types of receptor on target cell

Up-regulation: increases receptor when blood and hormone concentration is low

Down-regulation: decreases receptor when blood and hormone concentration is high

Synergistic response

1 hormones reinforces activity of another hormone

ex) estrogen + progesterone

Permissive response

1 hormone requires for activity of another hormone

ex ) oxytocin “milk sender” require prolactin “milk maker”

Antagonistic response

1 hormone opposes activity of another hormone

ex) glucagon increases blood sugar while insulin lower