general intro. of hormones

Define hormones

chemical signaling molecules secreted by specific cells that regulate biological processes in the body.

7 Characteristics of hormones

• are synthesized by specific tissues called glands

• are secreted directly to blood (without ducts)

• are transported to work in distant sites

• have systemic action

• are present at very low levels in blood

• act via specific receptors in target tissues/cells

• have different special mechanisms of actions

What are the 2 different classification of hormones?

Mechanism

Chemical nature

What are the 4 mechanism classification of hormones, describe each

Autocrine- cytokines are in an example where the hormone is secreted and affected by the same cell

Paracrine- Estrogen and testosterone are examples where a hormones is secreted from one cell and act on another

Endocrine- growth hormone is an example of a cell that secretes a hormone thought eh bloospd annf acts on antother cell

Neurocrine- Norepinephrine is an example of a neurotransmitter that secreted a hormone via blood into affect another cell

What are the 4 chemical classification of hormones, describe them

Protein hormone- less than 20 aa. Insulin, igf-1, growth hormone

Peptide hormone- more than 20aa. Somatostatin, TRH, GnRH Amino Acid D erived Hormones

Tyrosine derivatives/(Amine Hormones)- Modified amino acids. Thyroxin (T4), Catecholamines, Dopamine

Steroid Hormones derivatives- Cholesterol Metabolites. Estrogen, Testosterone, Glucocorticoids

what it’s the mechanism of hormone action

Al l types of hormones bind receptors on or in cells to initiate various responses Is intracelluar.

______ expression of receptors allows for _______effects of hormones

Selective, targeted

Se lective expression of receptors allows for targeted effects of hormones- why is that?

Th is ensures hormones act only on the cells they should

define hormone cascades

• Hormones regulate each other through multiple

po sitive and negative feedback loops

Advantages of hormone cascades?

1. Very sensitive control of biological functions

2. One hormone can have many effects

3. Amplification

4. Redundancy

5. Negative feedback

How is the cascade initiated?

Though brain stimulation usually though the senses. These signals transmitted to part of the brain called the hypothalamus that initiates Individual cascades.

Describe the hypothalamus role in the regulation of hormone secretion

The hypothalamus is the main neurohormonal control center It forwards these signals to an organ called the pituitary gland that in turn releases hormones that affect multiple organ systems.

hypothalamic-pituitary axis (HPA)

Interaction of pituitary gland and hypothalamus

What are the 2 parts of the pituitary gland and how does it affect home secretion

– Anterior Pituitary:Secretion of hormones from this component is controlled by Hypothalamus “Releasing” or “Release Inhibiting” Hormones (RH, IH)

– Posterior Pituitary:Secretion of hormones from this component is controlled by Neuronal signal stimuli

Where do hormones go after release from the pituitary gland?

They reach peripheral tissues where they may induce the secretion of additional hormones, some of these inhibit the secretion of hormones from the hypothalamus and pituitary