Endocrine system -BIOL1209

Gland

Cells or organ that produce secretions for use in
the body

Exocrine gland (Ducted gland)

secretes substances through ducts

Endocrine gland (Ductless Gland)

ductless glands that secrete hormones into
interstitial fluid then blood and lymph to target cells in the body

Glandular tissue

Tissue that solely responsible for secretion in Gland

Product of Exocrine glands

Very diverse such as saliva, milk, sweat, etc

Product of Endocrine glands

Hormone

Purpose of hormone secretion

• Stimulate part of the body

• Growth

• Reproduction

• Inhibitory action

Functions of Hormone

• Stimulate secretion of exocrine and endocrine glands

• Affect growth, development and personality

• Regulate metabolism of cells

• Regulate contraction of muscle tissue

• Control reproduction processes

Purpose of Hormone Regulation

prevent abnormal hormone levels and
a potential disease state, hormone levels
must be tightly controlled

Maintainance of Hormone Regulation

Feedback loops govern the initiation and
maintenance of most hormone secretion
in response to various stimuli

Humoral stimulus

Occur when a hormone is released in response to a change in the blood or other body fluids

Hormonal stimulus

Occur when a secretion of a hormone is cause by another hormone

Neural stimulus

Occur when secretion of hormone is cause by stimulus from a neuron

Hormones

• Chemical messengers that regulate activities of various body organs

• Released in one part part of the body to help regates metabolic activities of cells in another part of the body

2 types of Hormones

• Amino acid based

• Lipids based

pathways of Hormone Action

The message a hormone sends is
received by a hormone receptor, a protein located
within the cell membrane.

Contrast between Hormones and Nervous system

• Both regulate and coordinate activities of other systems

• Nervous system is fast, direct from one point to another with short-term effect

• Endocrine system is slower but longer effect with one point reaching multiple place at the same time

The bridge between endocrine and nervous systems

Hypothalamus

Hypothalamus

• Produces releasing hormones that
  stimulate the secretion of separate
  hormones from the anterior pituitary

• Also produces inhibiting hormones

• Produces oxytocin and ADH that is
  transported via neurons to be stored
  and released in the posterior pituitary

Tropin or Tropic Hormone

Hormone that stimulates endocrine gland to release other hormone

Trophin or Trophic Hormone

Hormone that stimulates growth and maintainence of the target tissue

ADH (vasopessin) (Posterior Pituitary)

Increase water reabsortion in the kidney

ACTH

stimulates adrenal cortex to produce glucocorticoids

TSH

Stimulated thyroid gland to release thyroxin

FSH

• Stimulates growth and hormone activity of ovarian follicles

• Stimulates testes growth and sperm formation

LH

• Causes development of corpus luteum

• Stimulates secretion of testosterone

GH

• Promotes growth in all body tissues

Prolactin

• Stimulates mammary glands to produce milk after birth

Oxytocin (Posterior Pituitary)

• causes contraction of uterus to
  expel fetus

• causes ejection of milk from
  mammary glands

Thyroxin

• Increases metabolic rate

• Increases breakdown of fats and
  carbohydrates

• Increases protein synthesis

• Maintains body temperature

• Stimulates growth of the nervous
  and skeletal systems

Anterior Pituitary Hormones

• F(SH) = Follicle-Stimulating Hormone

• L(H) = Luteinizing Hormone

• A(CTH) = Adrenocorticotropic Hormone

• T(SH) = Thyroid Stimulating Hormone

• P(rolactin) = stimulates milk in female mammary glands

• i(gnore)

• G(H) = Growth Hormone

Thyroid gland is controlled by ?

• Hypothalamic TRH

• TSH from anterior pituitary

Calcitonin is controlled by ?

• Negative feedback of calcium levels in
  the blood

Calcitonin function

• Lower blood calcium and phosphate through inhibiting osteoclast activity and stimulte the uptake of calcium and phosphate into bone matrix

Parathryoid hormone

• Secreted by parathyroid gland

• Increase calcium level in blood

How does parathyroid Hormone increase calcium level in blood?

• Calcium and phosphate release from bone

• Increased calcium re-absorption in kidney

• Increased calcium absorption from intestinal
  mucosa