Endocrine System- Unit 1

Bio 1203

Gland? Secretion?

• organ that produces a secretion

• secretion: enzymes/hormones (produced by specialized cells within gland)

• secreted onto body surface (skin) / into body tissue (blood)

Internal Environment

extracellular component (in body, outside of cells)

Function of Hormones

• stimulate exocrine glands to secrete

• stimulate other endocrine glands

• affect growth/development/personality

• regulate body chem/metabolism

• regulate muscle contraction/nervous stimulation

• control reproductive processes

Exocrine Glands

• ducts (short/branched) carry secretions to another part of body

• discharged onto surface of epithelium/body cavity

• products: enzymes, ions

• ex. sweat glands

Endocrine Glands

• ductless

• secretion discharged into IF & enters bloodstream

• secrets hormones

• products distributed by blood/lymph, bind to receptors on target cells

• ex. pituitary gland/thyroid

Amino Acid Hormones

membrane receptors

alters cell activity through intracellular signalling

Amine: single AA, ex. norepinephrine

Peptide/Protein: multiple AA linked, forming AA chain

• peptide: shorter chains, ex. ADH

• protein: longer chains, ex. GH

Lipid Hormones

• steroids

• longer half life than AA hormones

• travels to target cell bound to transport protein

• intracellular receptors

• protein production

Releasing v. Inhibiting Hormones (Hypothalamus)

R: Stimulates anterior pituitary to release corresponding hormones

I: Inhibits hormone production from anterior pituitary

• controls prolactin/GH

Hormone Receptor

• receive/process msg sent by hormone

• protein found inside cell/within cell membrane

Endocrine v. Nervous System

• directed by hypothalamus

Endocrine: slower acting, long lasting, releases hormones

NS: fast acting, releases neurotransmitters

Anterior v. Posterior Pituitary

A: glandular tissue, produces hormones

P: neural tissue (extension of hypothalamus), only releases (ADH, Oxytocin)

Hypothalamus

• targets pituitary gland

• regulates blood pressure, body temp, glucose level

Pituitary Gland

• directs other parts of body

• anterior vs. posterior areas

Hypothalamus & Anterior Pituitary

1. Hypothalamus secretes R/I hormones into primary capillary plexus

2. Hormones travel through portal veins to anterior pituitary, stimulate/inhibit release

3. Pituitary secretes hormones into secondary capillary plexus, empties into general circulation

What is the main role of the adrenal gland?

responding to stress

stress: stimulus that disrupts homeostasis

• phys (external: heat internal: emotion)

• physiological

General Adaptive Syndrome: Alarm Phase

• “fight/flight response”

• response to short term stressor

• release of epinephrine/norepinephrine

• prepares body for stress (ex. increase heart rate, dilate airways)

• body quickly returns to norm after stressor

General Adaptive Syndrome: Resistance Phase

• attempt to adapt to stressor

• cortisol secreted by adrenal cortex

• blood glucose/pressure & gluconeogenesis increase (more energy)

General Adaptive Syndrome: Exhaustion Phase

• stressor continues longer term

• resistance fails, body resources depleted

• damages organ systems

Prostaglandins

• produced by cells from lipids in their plasma membrane (not glands)

• have effects on tissue where they’re produced

• type depends on cell producing them

Pancreas- Exocrine Function

secrets digestive enzymes

Pancreas- Endocrine Function

• Clusters of cells (Pancreatic Islets) secrete hormones (ex. insulin/glucagon)

• 2 types: Alpha cells (produce: glucagon), Beta cells (produce: insulin)

• more beta

3 Zones of the Adrenal Cortex

1. Mineralocorticoids (Aldosterone)

2. Glucocorticoids (Cortisol)

3. Cortical sex hormones (Testosterone/Estrogen)