CH. 13 Endocrine System

What is the General Characteristics of the Endocrine System?

Regulates homeostasis, growth, metabolism, reproduction, stress

Uses hormones as chemical messengers, which are then released into the bloodstream

What is an endocrine glands?

cells, tissues, and organs that make up the endocrine system

They are ductless & secrete hormones into the bloodstream

What is an exocrine glands?

Glands that secrete into ducts or tubes that lead to a body surface or cavity

What are paracrine secretions?

They are secretions that act on nearby cells

What are autocrine secretions?

Secretions that act on the same cells that secrete the substance

List the endocrine glands

Hypothalamus

Pituitary gland

Thyroid gland

Parathyroid glands

Adrenal glands

Pancreas

Pineal gland

Thymus

Reproductive glands

Where is the Hypothalamus, Pineal, & pituitary gland located?

brain

What controls the pituitary gland?

Hypothalamus

What controls the anterior pituitary gland?

Hormonal control under the hypothalamus

What controls the posterior pituitary gland?

Neuronal control under the hypothalamus

Where is the thyroid gland located?

In the neck below the larynx

Where is the parathyroid gland located?

Posterior (rear) part of thyroid

Where are the adrenal glands located?

Kidneys

Where is the pancreas?

Abdomen

Where is the thymus gland located?

In the chest above the heart

Where are the reproductive glands located?

Ovaries

Testes

What are the characteristics of a hormone?

Chemical messengers that travel in blood by binding to their receptors on/in target cells

Number of receptors determines strength of response

Most formal secretion is under a negative feedback control

What is a target cell?

A cell that has specific receptors for a hormone to carry out functions

No receptor = No response

What does a hormone do?

Regulates body process and maintains homeostasis

Controls growth, metabolism, reproduction, stress

What are two types of hormones?

Steroid

Non-steroid

What is a steroid hormone?

Derived from cholesterol, lipid-soluble (hydrophobic); need to be bound to a water-soluble protein so they can be transported through the blood.

How do steroid hormones enter the cell?

by diffusing through cell membrane

Once in the cell What does a steroid hormone do?

they bind intracellular receptor, alter gene transcription, and make new proteins

What is a non-steroid hormone?

Derived from amino acids, water soluble, can’t cross cell membrane

What is the action after a non-steroid hormone reaches its target cell?

they are unable to pass through the cell membrane and have to bind with receptors on the surface of the cell membrane.

What happens once a non-steroid hormone binds to its receptors?

the second Messenger system is activated (cAMP)

What is cAMP?

The second messenger inside cells that helps transmit signals from hormones to trigger a cellular response

What is up regulation?

Increase in number of receptors on target cell, in response to a decrease in hormone level

What is down regulation?

Decrease in number of receptors on target cell, due to an increase in hormone level

Most hormone secretion is under….

Negative feedback control

What hormones are released by the hypothalamus?

CRH, TRH, SS, PIH, GnRH, GHRH, PFR

What is the action of the hormones in the hypothalamus gland?

CRH > release ACTH

TRH > stimulates TSH

SS > stops GH & TSH

PIH > stops prolactin

GnRH > release LH & FSH

GHRH > release GH

PFR > release prolactin

What hormones are released by the anterior pituitary gland?

FSH, LH, ACTH, TSH, GH, prolactin

What is the action of the hormones in the anterior pituitary gland?

FSH: stimulates ovaries/testes; gamete production

LH: triggers ovulation and testosterone production

ACTH: stimulates adrenal cortex

TSH: stimulates thyroid

GH: growth, protein synthesis, fat breakdown

prolactin: milk production

What hormones are released by the posterior pituitary gland?

ADH, oxytocin

What is the action of the hormones in the posterior pituitary gland?

ADH: water retention by kidneys

Oxytocin: uterine contractions, and milk ejection

What hormones are released by the thyroid gland?

T3/T4 & calcitonin

What is the action of the hormones in the thyroid gland?

T3/T4: increases metabolism, growth, development

Calcitonin: lowers blood calcium

What hormones are released by the parathyroid gland?

PTH

What is the action of the hormones in the parathyroid gland?

PTH: raises blood calcium

What hormones are released by the adrenal cortex?

Cortisol, aldosterone, androgens

What is the action of the hormones in the adrenal cortex?

Cortisol: stress hormone

Aldosterone: retains Na+

Androgens: sex hormones

What hormones are released by the adrenal medulla?

Epinephrine and norepinephrine

What is the action of the hormones in the adrenal medulla?

Epinephrine & norepinephrine: fight or flight response

What hormones are released by the pancreas?

Insulin, glucagon, somatostatin

(both endocrine and exocrine)

What is the action of the hormones in the pancreas?

Insulin: lowers blood sugar

Glucagon: raises blood sugar

Somatostatin: stops insulin and glucagon release

What hormones are released by the pineal gland?

Melatonin

What is the action of the hormones in the pineal gland?

Melatonin: regulate sleep/wake cycle

What hormones are released by the reproductive gland?

Ovaries and testes

What is the action of the hormones in the reproductive gland?

Ovaries: estrogen and progesterone (pregnancy)

Testes: testosterone (sperm)

What hormones are released by the thymus gland?

Thymosin

What is the action of the hormones in the thymus gland?

Thymosin: stimulates T cell development (immune system)

What are the disorders caused by GH?

1. Hypopituitary dwarfism: low GH in childhood

2. Gigantism: high GH before epiphyseal closure

3. Acromegaly: high GH after epiphyseal closure

What are the disorders of the thyroid gland?

1. Hyperthyroidism

2. Graves’ disease

3. Hashimoto disease

4. Infantile hypothyroidism

5. Adult hypothyroidism

6. Simple goiter

Hyperthyroidism

excess thyroid hormone

Graves’ disease

autoimmune hyperthyroidism

Hashimoto disease

autoimmune hyperthyroidism

Infantile hypothyroidism

poor growth, mental retardation

Adult hypothyroidism

weight gain, cold intolerance

Simple goiter

iodine deficiency

What is aldosterone?

A hormone that increases sodium and water reabsorption in the kidneys, raising blood pressure

What is renin-angiotensin?

Raises BP when it’s low

What are the type of cells of the pancreas?

Alpha, beta, delta

What hormone does alpha cells secrete?

Glucagon

What hormone does beta cells secrete?

Insulin

What hormone do delta cells secrete?

Somatostatin

What are the two types of diabetes?

Type 1: insulin production

Type 2: insulin resistance

What are the two types of stress?

Acute stress: short term, fight/flight

Chronic stress: long term; damaging