Endocrine System

Endocrine vs Exocrine

Endocrine- into blood, ductless

Exocrine- secrete onto skin or hollow tubes inside the body, ducts,

Pancreas

Too much blood sugar—> released insulin, causing liver cells to intake glucose and turn it into glycogen

Too little blood sugar —> released glucagon which causes liver cells to release glucose from glycogen stores

What is a normal blood glucose level?

70-110 mg/dL

Type 1 diabetes

autoimmune disorder, body destroys beta cells which create insulin, treated through insulin shots

Type 2 diabetes

cells are resistant to insulin messages, treated with metformin

Gestational

high blood glucose during pregnancy

Diabetes insipidus

lack of ADH, antidiuretic hormone

What hormones create new hormones?

TRH-TSH

What hormone turns enzymes on or off?

Thyroid hormone

What hormone changes the rate of mitosis or cell growth?

GH

What hormone makes cells more permeable to external substances?

Insulin

What hormone impacts protein synthesis and gene expression?

steroid hormones

What are the basic characteristics of the endocrine system?

Individual ductless glands that pour into the bloodstream

Rich in capillaries

Form and secrete hormones for specific target organs/cells

List the strictly endocrine glands

Pituitary, thyroid, parathyroid, adrenal and pineal glands

List the endocrine glands that can also be exocrine

The pancreas and gonads

What are hormones?

A molecule released by a cells of gland in one part of the body that sends out signals to other parts of the body through lymph or blood. (long distance)

What are the two major classes of hormones?

Peptide hormones (amino acid chains) (largest group)

Steroid- made of cholesterol

Two ways hormones impact their target cells

Direct actions (lipid soluble)

Through Second messengers (water soluble)

Describe Water-soluble, peptide hormones

Short lived (1-2 min)

Need to bind to specific plasma receptors

Trigger transcription and translation

Fast response time

Describe steroid hormones

Made of lipids or cholesterol (testosterone, cortisol, ETC.)

Long lived (16-20 min)

Diffuse through the cell’s membrane

Regulate gene activity

Long activation time

Hypothalamus

Connects the endocrine system to nervous system

Makes regulatory hormones

• GHRH- Growth Hormone Releasing Hormone

• TRH- Thyrotropin releasing hormone

• GnRH- gonadotropin releasing hormone

Makes hormones to be stored in the posterior pituitary gland

• ADH

• Oxytocin

Controls the Adrenal Medulla with hormones

Pituitary Gland

Conductor of the endocrine system

Located in the sphenoid bone

Produces 6 major hormones

Separated into anterior and posterior lobes

What hormones does the Anterior Pituitary gland make?

Tropic hormones that have other endocrine glands as their targets

• GH- growth hormone, stimulate growth and development

• ACTH- Adrenocorticotropic hormone- stimulates production of cortisol

• FSH- follicle stimulating hormone, stimulates estrogen production and gamete production

• LH- luteinizing hormone- Triggers ovulation and stimulate testosterone and progesterone production

• Prolactin- development of mammary glands and milk production

  • Melanocyte Stimulating Hormone- MSH- in intermediate zone of pituitary, stimulates melanocyte production

Posterior Pituitary hormones

Oxytocin- stimulates contractions and milk ejection (positive feedback loops)

ADH- helps reabsorb water (low levels causes diabetes insipidus)

Pineal Gland

located in the epithalamus, controls the circadian rhythm, produces melatonin (pinealocytes detect light levels)T

Thyroid Gland

Largest endocrine gland

Located in front of the trachea

Composed of thyroid follicles, made of a cuboidal, gelatinous substance

TSH from the pituitary triggers thyroid to make T3 cells (iodine is required to work)

Develops C cells which produce calcitonin (lowers blood calcium levels)

Stimulates digestion, heartrate, warms the body

Parathyroid glands-

2 pairs embedded on the back of the thyroid

Produce parathyroid hormone (PTH)

Made of chief cells and oxyphil cells

Chief cells create PTH (needed to control muscle spasms)

PTH also regulated vitamin D levels in Kidney and calcium levels

Adrenal Glands

Found above the kidneys

Composed of

Adrenal Medulla- neuroendocrine part (inner)

Adrenal cortex- tissue that encapsulates the Medulla (outer)

Regulated by Hypothalamus - CRH Corticotropin releasing hormone - acts on Pituitary Gland to make ACTH - adrenocorticotropin, which acts on adrenal cortex to make cortisol:

Adrenal Medulla

Produces Epinephrine and Norepinephrine

• Epinephrine- more powerful, speeds up heart

• Norepinephrine- focus and blood vessel constriction

  • Low levels can cause ADHD and depression

Adrenal Cortex-

Glucocorticoids - cortisol - stress hormone, inhibit growth, rises glucose level in blood, brakes tissues down to release energy

2. Mineralocorticoids - regulate mineral balance increases sodium reabsorption by kidneys, also increase Blood Pressure

3. Androgens - muscle building, sex characteristics

Addison’s Disease vs Cushing’s syndrome

Addison’s- hypofunctional adrenal gland, small, weak, and tanned

Cushings- hyper functional adrenal gland, lots of steroids, big, round, hairy

Other Hormone producing structures

Heart, GI tract, kidneys, skin, bones, fat

Thymus

Located deep to the sternum

Triggers the development of T cells from premature to mature

Hormones: Thymopoietin and thymosin

Shrinks rapidly with age

Free vs bound hormones

Free- not attached to cells, short lived

Bound- steroids and thyroid hormone, attached to cells, long lasting

How are hormones removed from the blood?

Degrading enzymes

Kidneys/liver

What do the numbers in T3 and T4 represent?

Iodine atoms

What are the two basic thyroid problems?

Hypothyroidism- not enough hormones produced, low metabolic rate, causes respiratory and cardiac fatigue (Hashimoto

s)

Hyperthyroidism - too many hormones produced, heightened cardiac rates, weight loss, and heat intolerance (Grave’s Disease)

Make sure to watch the videos she posted in GC. Also play the kahoot