Lab unit 1- Endocrine system

Endocrine system

Glands that secrete hormones into the bloodstream, transported through body in blood and bind to target cells. Cause changes in activity to keep body in homeostasis

Hypothalamus

Hormones produced by hypothalamus regulate pituitary gland → they're called tropic hormones because they target another endocrine gland

Pituitary gland (hypophysis)

Composed of anterior and posterior pituitary

Intermediate lobe

Present in the fetus but ↓ during fetal development

Infundibulum

Stalk that connects hypothalamus to the pituitary gland and contains a direct blood supply to the pituitary

Anterior pituitary

Composed of glandular epithelial tissue that makes and secretes 7 hormones

GH (one of 7 hormones)

Growth hormone

TSH(one of 7 hormones)

Thyroid stimulating hormone

FSH(one of 7 hormones)

Follicle stimulating hormone

LH(one of 7 hormones)

luteinizing hormone

PRL(one of 7 hormones)

Prolactin

ACTH(one of 7 hormones)

Adenocorticotropic hormone

MSH(one of 7 hormones)

Melanocyte stimulating hormone

Hormones secreted by hypothalamus

Stimulate or inhibit secretion of anterior pituitary hormones

Posterior pituitary

Composed of nervous tissue that stores and releases antidiuretic hormone (ADH)and oxytocin (OT) into the blood

Thyroid gland

2 lobes with connecting isthmus and lies on both sides of the trachea near the Adam's apple

Inside the thyroid:

Made of tiny sacs called follicles that are lined with follicular cells (thyrocytes)

Follicular cells

Make thyroid hormones ( T4 - thyroxine and T3 - triiodothyronine ) T3 and T4 are made from thyroglobulin. Follicular cells first make thyroglobulin the it's stored as colloid

C cells (parafollicular cells)

Sit between follicles - release calcitonin

2 types of cells found in the parathyroid glands

The chief cells /principal cells and oxyphil cells

Chief cells

Produce parathyroid hormone - more numerous and smaller

Oxyphil cells

Function unknown

Adrenal glands

Each gland has a capsule with cortex (outer) and medulla (inner)

Zone glomerolosa

Outer layer, small cell columns, secretes mineral corticoids (aldosterone)

Zone fasciculata

Middle/largest layer , long cords, secretes glucocorticoids (cortisol)

Zone reticularis

Inner layer, branching cords, secretes androgens ( DHEA → testosterone or estrogen - only estrogen source in postmenopausal women)

Adrenal medulla

Acts like sympathetic mucous system ganglia , made of chromaffin cellsreleases epinephrine and norepinephrine

Pancreas

Head, body, tail

Exocrine

Digestive enzymes → duodenum via pancreatic duct

Endocrine

Islets of langerhans

Alpha cells

Glucagon

Beta cells

Insulin

Ovaries

Female gonads → produce ova, estrogen and progesterone

Testes

Male gonads → produce sperm and testosterone

Pineal gland

Near thalamus → secretes melatonin → controls biological clock

Thymus

Above heart → immune function → secretes thymosin (larger in children)

Human growth hormone ( HGH )

Cartilage, bone → stimulate body growth and metabolism