内分泌系统 Endocrine System

External environment changes such as temperature, pressure, osmotic pressure. or contact with bacteria and toxins Internal environment Nervous system Endocrine System Emergency response reaction Interaction Interaction Homeostasis of the intemal environment Short-term effects ong-ter rmi effects Biological defense Endocrine Immune system Interact system

Endocrine System

Proferation of cells and their downgrowth into the subjace connective tssue exocrine endocrine Exocrine gland Cords of cells Folacular endocine getty ma gudoadddad Disappearance Endocrine organ Exocrine organ of duct colis No ducts ducts follicle, cord, net acin like arranged Glandular epi cells

exocrine endocrine Endocrine organ No ducts Exocrine organ ducts follicle, cord, net acini like arranged cells Glandular epi

Endocrine vs Neuronal secretion ● Extracellular siana YE Target sites on same cell AUTOCRINE SIGNALING Endocrine cell Adjacent target cell PARACRINE SIGNALING Blood vessel Hormone secretion into by endocrine glan Ways of Secretion Distant target cells OCRINE SIGNALING

Ways of Secretion

Glands can be one of three types Exocrine -release secretions that are carried within 0 a duct or tube -sweat glands, salivary glands, sebaceous glands Endocrine release secretions directly into the blood thyroid gland, adrenal gland, anterior pituitary gland Heterocrine contain both exocrine and endocrine brms components- pancreas, testis

Glands can be one of three types Exocrine – release secretions that are carried within a duct or tube – sweat glands, salivary glands, sebaceous glands Endocrine – release secretions directly into the blood – thyroid gland, adrenal gland, anterior pituitary gland Heterocrine – contain both exocrine and endocrine components – pancreas, testis

Steroid-secreting cells Nitrogen-secreting cel SER; lipid droplet; mitochrondria RER; Golgi complex secreting granules:

Steroid-secreting cells SER; lipid droplet; mitochrondria Nitrogen-secreting cell RER; Golgi complex; secreting granules;

Thyroid Gland Hack vicw Thyroid follicle Follicula Follicularcell follicles C: parafollicular cell

Thyroid Gland Follicular cell follicles C: parafollicular cell

Found at 2nd through 4th cartilages of the trachea v Small gland with four parathyroid glands attached to the posterior surface v Follicles are the structural unit of the gland v Follicle consists of a wall of simple cuboidal epithelium cells inclosing a space containing a jelly like substance called colloid if the colloid distends the follicles, the epithelial cells can become flattened almost like simple squamous. Colloid combines with iodine to form thyroid hormones -regulate body metabolism

✓Found at 2 nd through 4 th cartilages of the trachea ✓Small gland with four parathyroid glands attached to the posterior surface. ✓Follicles are the structural unit of the gland. ✓Follicle consists of a wall of simple cuboidal epithelium cells inclosing a space containing a jelly￾like substance called colloid. If the colloid distends the follicles, the epithelial cells can become flattened almost like simple squamous. Colloid combines with iodine to form thyroid hormones – regulate body metabolism

Follicles(simple cuboid /culumnar epi )+fenestrated capillary Follicular cell t basal lamina lodination of Follicular cell: t3, t4 Parafollicular cell calcitonin 0°g lodide oxidation T3, T4 Follicular cel T3,T4 Amino acids lodide Capillary lumen

Follicles(simple cuboid/culumnar epi.) + fenestrated capillary Follicular cell + basal lamina Follicular cell: T3, T4 Parafollicular cell: calcitonin Follicular cell

Colloid Between the follicles are located small groups of parafollicular cells which secrete hormone thyrocalcitonin or often called just calcitonin Calcitonin functions to reduce calcium levels in Follicular cells the blood by actively reducing breakdown of bone and inhibiting re absorption of calcium in Blood Blood digestive system capillary Parafollicular

Between the follicles are located small groups of parafollicular cells which secrete hormone thyrocalcitonin or often called just calcitonin. Calcitonin functions to reduce calcium levels in the blood by actively reducing breakdown of bone and inhibiting re￾absorption of calcium in digestive system

arafollicular cell B

parafollicular cell