Chapter 16 - The Endocrine System

Question 1

Endocrine System

Answer 1

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

Question 2

Pituitary

Answer 2

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

Question 3

Pituitary - Growth Hormone (GH)

Answer 3

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

Question 4

Pituitary - Thyroid-Stimulating Hormone (TSH)

Answer 4

i. Target organ – thyroid gland

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

Question 5

Pituitary - Adrenocorticotropic Hormone (ACTH)

Answer 5

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

Question 6

Pituitary - Gona Dotropins

Answer 6

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

Question 7

Pituitary - Prolactin (PRL)

Answer 7

i. Target organs – breast secretory tissue

ii. Function – stimulate milk production

Question 8

Pituitary - Neurohypohysis

Answer 8

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

Question 9

Thyroid Gland

Answer 9

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

Question 10

Thyroid Gland - Follicle Cells

Answer 10

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

Question 11

Thyroid Gland - Para Follicular Cells

Answer 11

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

Question 12

Parathyroid Gland

Answer 12

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

Question 13

Adrenal Glands

Answer 13

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

Question 14

Adrenal Glands - Adrenal Cortex: Zona Glomerulosa

Answer 14

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

Question 15

Adrenal Glands - Adrenal Cortex: Zona Fasciculata

Answer 15

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

Question 16

Adrenal Glands - Adrenal Cortex: Zona Reticularis

Answer 16

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

Question 17

Adrenal Glands - Adrenal Medulla

Answer 17

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

Question 18

Pancreas

Answer 18

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

Question 19

Gonads: Ovaries

Answer 19

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)

Question 20

Gonads: Testes

Answer 20

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

Question 21

Pineal Gland

Answer 21

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

Question 22

Thymus

Answer 22

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