Chapter 16 - The Endocrine System Flashcards Preview

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Flashcards in Chapter 16 - The Endocrine System Deck (22):

Endocrine System

A. Functions – influence metabolic activity by means of hormones (chemical substances which are secreted by cells into the extracellular fluids
B. Method of control
1. Endocrine glands
a. Exocrine – none hormonal substances; sweat, saliva and they have ducts that’s secreted and makes its way to a membrane surface
b. Endocrine – ductless glands that produce hormones and release it into the surrounding tissue fluid (blood or interstitial fluid)
2. Hormones – regulate the metabolic function of other cells in the body
a. Means of travel – through blood stream or though bodily fluids; either water soluble or lipid soluble
b. Target cells – cells where hormones elicit their effect, capable of responding to hormones because they bear receptors to which the hormone can bind
c. Speed of control – some hormones elicit target organ responses immediately; some (steroids) take days to weeks



AKA hypothesis; it’s tiny and secretes 8-9 hormones, it’s found to be bilobed
1. Location – seated in the sella tursca of the sphenoid bone
2. Adenohypophysis – anterior pituitary; composed of glandular tissue, it manufactures and releases about 6 hormones


Pituitary - Growth Hormone (GH)

Produced by cells that are called somatotrophs of the anterior lobe
i. Target organs – bones and skeletal muscle
ii. Function – stimulates the body’s cells to increase cell divide; mostly growth promoting


Pituitary - Thyroid-Stimulating Hormone (TSH)

i. Target organ – thyroid gland
ii. Function – stimulates the normal development and secretory activity of the thyroid gland


Pituitary - Adrenocorticotropic Hormone (ACTH)

i. Target organs – stimulated adrenal glads
ii. Function – stimulates the adrenals to release cortical steroid hormones (gluecocordisol – cortisol; mineral corticol – aldosterone)


Pituitary - Gona Dotropins

i. Follicle-stimulating hormone (FSH)
A. Target organs – ovaries and testies
B. Function – stimulate gamete production (sperm and egg)
ii. Luteinizing hormone (LH)
A. Target organs – testies and ovaries
B. Functions – males – stimulates the interstitial cells in the testies to produce testosterone; females – triggers ovulation and helps ovarian follicle to mature


Pituitary - Prolactin (PRL)

i. Target organs – breast secretory tissue
ii. Function – stimulate milk production


Pituitary - Neurohypohysis

a. Oxytocin
i. Target organs – uterus and breasts
ii. Functions – stimulate contractions in the uterus also to allow milk ejection from the breasts
b. Antidiuretic hormone (ADH)
i. Target organs – kidneys
ii. Function – prevent wide swings in water balance and help the body avoid dehydration and water loss


Thyroid Gland

Butterfly shape and has 2 lateral lobes that are connected by a median tissue mass (isthmus)
1. Location – anterior neck on the trachea just inferior to the larynx


Thyroid Gland - Follicle Cells

Cuboidal or squamous cells
a. Thyroid hormone (TH) – thyroxine (T4) and triiodo thyronine (T3) – made in the follicle by thyro gobulin and iodine
i. Target organs – effects almost every cell in the body
ii. Functions – increases basal metabolic rate, body heat production, maintain blood pressure, regulates tissue growth, regulates tissue development, involved in skeletal and nervous development and maturation, and important for reproductive capabilities


Thyroid Gland - Para Follicular Cells

AKA C cells of the thyroid gland
a. Calcitonin – polypeptide hormone
i. Target organs – skeleton (bone sparing effect)
ii. Function – lower blood calcium levels antagonizing the effect of parathyroid hormone


Parathyroid Gland

Tiny yellow brown glands and their usually 4 but varies
1. Location – posterior aspect on the thyroid gland
2. Chief cells – numerous small cells
a. Parathyroid hormone (PTH) – parathormone
i. Target organs – skeleton, kidneys and GI (intestine)
ii. Function – stimulates the ostoclayst, enhance the reabsorbing of calcium, and increase absorption of calcium. Increase calcium levels in blood


Adrenal Glands

Paired pyramid shaped enclosed in a fibrous capsule and cushioned in fat
1. Location – on top of each kidney


Adrenal Glands - Adrenal Cortex: Zona Glomerulosa

Zona glomerulosa – most superficial layer
i. Mineralocorticoids (aldosterone) – regulated the electrolyte concentration
A. Target organs – distal tubal of the kidneys
B. Functions – increase blood levels of sodium


Adrenal Glands - Adrenal Cortex: Zona Fasciculata

Zona fasciculata – middle layer of the cortex
i. Glucocorticoids (cortisol)
A. Target organs – most of the body’s cells
B. Functions – influences energy metabolism and helps resist stressors


Adrenal Glands - Adrenal Cortex: Zona Reticularis

Inner most layer and it produces small amounts of sex hormones in the adrenal cortex


Adrenal Glands - Adrenal Medulla

Most inner part of adrenal gland; more like a knot of the nervous system than a gland, it’s part of the sympatric system
a. Catecholamines (epinephrine and norepinephrine) (adrenalin or none adrenalin)
i. Target organs – sympathetic nervous system target organs
ii. Functions – mimic sympatric activation, increase heart rate, metabolic rate and blood pressure



1. Location – partially behind the stomach in the abdomen
2. Pancreatic islets – tiny cell clusters that produce pancreatic hormones
a. Alpha (α) cells
i. Glucagon
A. Target organ – liver, muscle and fat
B. Function – release glucose into the blood
b. Beta (β) cells
i. Insulin
A. Target organs – most body organs
B. Function – lower blood glucose levels


Gonads: Ovaries

Ovaries – paired small oval organs
a. Location – female abdominal pelvic cavity
b. Estrogens
i. Target organs – female reproductive organs
ii. Functions – responsible for maturation of the reproductive organs and the appearance of secondary sex characteristics
c. Progesterone
i. Target organs – female reproductive organs
ii. Functions – promote breast development and cause cycle changes in menstrual cycle; also involved in pregnancy gestation (carrying the baby)


Gonads: Testes

a. Location – anterior side in and extra abdominal skin pouch called the scrotum
b. Testosterone
i. Target organs – male reproductive organs
ii. Functions – during puberty, initiates the maturation of male reproductive organs and help in appearance in the secondary sex characteristics, involved in males sex drive and normal sperm production


Pineal Gland

Tiny pine cone shaped gland
1. Location – hanging from the roof of the 3rd ventricle in the diencephalon
2. Melatonin – sleep wake cycle because it receives signals from the visual pathways (light and dark)
a. Target organs
b. Functions – not clear; behaves as a powerful antioxidant and its involved in sleep



Large in childhood; it diminishes in adulthood; fat and fibrous tissue by old age
1. Location – deep to the sternum in the thorax in between the lungs
2. Thymosins
a. Target organs – various areas in the body
b. Function – involved in normal development of T lymocytes and the immune system