U7 - Endocrine Glands & Hormones

endocrine system

1. made of glands that produce and secrete hormones (chemical messengers)

2. responsible for regulation of growth, metabolism, and sexual development

3. produces responses to stress and injury

4. provides homeostasis

paracrine

referring to local chemical messaging (prostaglandins)

endocrine

referring to internal, long-term secretions/messaging

exocrine

referring to external secretions (sweat)

tropic hormones

hormones that stimulate other glands to release their hormones

hypothalamus

- controls the actions of the pituitary gland

- releases many tropic hormones, such as GnRH

gonadotropin-releasing hormone (GnRH)

Secreted By: Hypothalamus

Target: Anterior Pituitary Gland

Function: controls reproduction hormone and gamete production (LH/FSH), controls release of gonadotropins by anterior pituitary gland

pituitary gland

- considered the master gland of the endocrine system

- actions are controlled by the hypothalamus, to which it is attached

- releases tropic hormones

Two Regions to Know: anterior (GH, TSH, PRL, ACTH, LH, FSH) and posterior (ADH, OT)

growth hormone (GH)

Secreted By: Anterior Pituitary Gland Lobe

Targets: most if not all tissues and cells

Functoin: stimulates childhood growth; for adults-maintains muscle and bone mass and fat distribution in body

thyroid-stimulating hormone (TSH)

Secreted By: Anterior Pituitary Gland Lobe

Targets: thyroid gland

Function: stimulates the thyroid gland to make thyroid hormones (T3/T4), which then regulates the body's metabolism and nervous system development

prolactin (PRL)

Secreted By: Anterior Pituitary Gland Lobe

Targets: mammary gland

Functions: stimulates milk production from a woman's breasts after child birth; can affect sex hormone levels in women's ovaries or men's testes

adrenocorticotropic hormone (ACTH)

Secreted By: Anterior Pituitary Gland Lobe

Targets: adrenal cortex

Functions: stimulates cortisol production by adrenal glands

luteinizing hormone (LH)

Secreted By: Anterior Pituitary Gland Lobe

Targets: ovaries or testes (Leydig cells)

Functions: regulates testosterone in men and estrogen in women; gonadotropin

follicle-stimulating hormone (FSH)

Secreted By: Anterior Pituitary Gland Lobe

Targets: ovaries or testes (tubules)

Functions: promotes sperm production in men and ovulation of ovaries in women; gonadotropin

antidiuretic hormone (ADH)

Secreted By: Posterior Pituitary Gland Lobe

Targets: kidney ducts, blood vessels of smooth muscle

Functions: regulates water balance and blood pressure

aka vapopressin

oxytocin (OT)

Secreted By: Posterior Pituitary Gland Lobe

Targets: mammary glands, uterine smooth muscle

Functions: causes milk letdown in breasts, causes uterine contractions during childbirth

thyroid gland

hormones secreted by this gland control your body's metabolism--the ability to break down food and store and release its energy

T3/T4, calcitonin

thyroxin/tri-iodothyronine (T4/T3)

Secreted By: Thyroid Gland

Targets: most tissues and cells

Functions: increase the rate at which cells release energy from carbohydrates, regulate metabolism

goiter

enlargement of the thyroid gland caused by an iodine deficiency

calcitonin

Secreted By: Thyroid Gland

Targets: osteoblasts in bone

Functions: lowers the calcium concentration in the blood by stimulating osteoblasts to pull it out

parathyroid glands

located behind the thyroid; four tiny glands

parathyroid hormone (PTH)

Secreted By: Parathyroid Gland

Targets: osteoclasts in bone

Functions: raises calcium concentration in blood; increases resorption; takes calcium from bones to make it available in blood; opposes calcitonin

adrenal glands

located at the top of the kidneys

Adrenal Glands = Adrenaline

Two Regions to Know:

- adrenal cortex: outer area

- adrenal medulla: inner area

aldosterone

Secreted By: Adrenal Cortex

Targets: kidneys

Functions: steroid that helps kidneys regulate Na+ and K+ salt levels; maintain blood pressure

cortisol

Secreted By: Adrenal Cortex

Targets: most tissues and cells

Functions: "stress hormone," rest & digest, increases glucose metabolism, controls blood pressure, reduces inflammation

epinephrine/norephinephrine

Secreted By: Adrenal Medulla

Targets: most tissues and cells (respiratory system)

Functions: fight or flight hormone released in response to stress, increase heart/breathing rate, elevate blood pressure, constrict peripheral blood vessels, complement sympathetic nervous system function

pancreas

organ that has both endocrine and digestive functions

-> helps body maintain healthy blood sugar levels

Islets of Langerhans: pancreatic cells that secrete glucagon and insulin

glucagon

Secreted By: Pancreas; alpha cells

Targets: primarily liver

Functions: raises blood sugar concentration by stimulating the liver to break down glycogen

insulin

Secreted By: Pancreas; beta cells

Targets: most tissues and cells

Functions: lowers blood sugar concentration by simulating cells to increase their uptake

diabetes mellitus

a group of diseases relating to insulin; end result is high blood sugar (hyperglycemia); excess excreted in urine

caused by:

- an insulin deficiency (Type I)

- failure to respond to insulin at the cellular level (Type II)

consequences:

1. blood vessels in epithelial cells are damaged

2. neuropathy = destroyed nerve fibers

3. most seen in organs with large networks of small blood vessels (eye, kidneys), distal body regions with less blood flow

Type I Diabetes

aka insulin-dependent diabetes mellitus or juvenile-onset diabetes

- caused by an autoimmune disorder that destroys pancreatic beta cells, leading to an insulin deficiency

Type II Diabetes

aka adult-onset diabetes

- cells stop responding to responding to insulin

- 90% of all diabetes mellitus

- related to genetic, diet, and lifestyle factors

- controlled with diet and exercise

Gestational Diabetes

pregnancy hormones block insulin, which leads to elevated blood glucose levels and complications for the mom and baby

hypoglycemia

more immediate problem of low blood glucose levels; can be temporarily reversed with a direct injection of glucose (glucagon) or consumption of a high sugar product

Diabetes Insipidus

uncommon condition that occurs when kidneys are unable to conserve water as they filter blood

Causes:

1. not enough ADH produced and released

2. kidneys don't respond to ADH

Symptoms:

1. excessive thirst

2. excessive urine volume

pineal gland

located between cerebral hemispheres, secretes melatonin

melatonin

Secreted By: Pineal Gland

Targets: most tissues and cells

Functions: maintains Circadian rhythms (light/dark activity)

thymus gland

larger in younger children but gradually shrinks with age, secretes thymosins

thymosin

Secreted By: Thymus Gland

Targets: T-lymphocyte cells in blood

Functions: immune function

reproductive glands

Glands, such as the ovaries (women) or testes (men), that serve sex-specific functions

estrogen

Secreted By: Ovaries

Targets: female reproductive organs

Functions: regulates female reproductive system; promotes secondary female sex traits: breasts, hair, hips

progesterone

Secreted By: Ovaries

Targets: uterus

Functions: uterine condition/shape, menustrual cycle, pregnancy

testosterone

Secreted By: testes

Targets: male reproductive organs

Functions: male reproductive organ development; promotes secondary male sex traits: increased muscle/bone mass, body hair growth