Endocrine System-Chapter 32

Hormone Changes- when a hormone binds to a target cell, four changes occur. These changes, which depend on the specific hormone and target cell, are:

1. Changes in plasma membrane permeability or electrical state 2. Synthesis of proteins or certain regulatory molecules in the cell 3. Activation or inactivation of enzymes 4. Stimulation of mitosis, a type of cell division

The stimuli that activate the endocrine organs are divided into three categories:

1. Hormonal control 2. Humoral control 3. Neural control

luteinizing hormone (LH)

LH is responsible for releasing both male and female sex hormones and influences the release of the ova in females. *gonadotropin hormone*

The thyroid gland secretes three important hormones

These hormones help the body maintain its calcium deposits and its metabolism. 1. Calcitonin-secreted when calcium levels become too hight 2. Thyroxine (T4): or tetraiodothyronine, is also known as T4-helps regulate energy production and influence metabolic rate 3. Triiodothyronine (T3): required to maintain a healthy metabolism

estrogen (estrone and estradiol)

are produced by the Graffian follicles in the ovaries. They stimulate the secondary sex characteristics in the female. Additionally, estrogen works with progesterone to prepare the uterus to receive a fertilized egg. This results in cyclic changes in the uterine lining (the menstrual cycle).

What does a hormone bind to?

binds to a receptor in the targeted tissue, which then causes that tissue to alter its behavior. This altered behavior can include the secretion of additional hormones that will affect still more endocrine glands or altering the rate at which an organ produces certain compounds.

Pituitary gland

called "master gland" because it regulates all of the other endocrine glands

relaxin hormone

causes the mother's pelvic ligaments and pubic symphysis to relax and become more flexible in preparation for childbirth.

hormone

chemicals secreted by tissues and glands of the endocrine system

thyroid-stimulating hormone (TSH)

controls another endocrine gland, the thyroid. TSH stimulates thyroid growth and the secretion of the two hormones: thyroxine (T4) and triiodothyronine (T3).

Hypothalmus

controls both pituitary lobes; controls a number of functions, including: sex drive hunger and thirst moods sleep cycles hormones released by various glands body temperature

exocrine glands

excrete secretions outside of the gland through a duct

ovaries

female gonads (ovaries) produce two groups of steroid hormones: estrogens and progesterone. The ovaries do not really begin to function until puberty.

When glucose levels fall, the pancreas secretes?

glucagon to encourage the liver to release glycogen so that sugar levels return to normal.

Insulin

helps move glucose from the blood to the cells in the body

human placental lactogen (hPL) hormone:

helps prepare the breasts for lactation.

hormonal control

hormone levels controlled by other hormones

neural control

hormone levels controlled by the nervous system

humoral control

hormone levels controlled through body fluid

enterogastrone

hormone that regulates gastric secretions

catecholamines

increase heart rate, blood pressure, and glucose levels. It also dilates the small passageways of the lungs, preparing the body to cope with short-term stresses

glucagon

increases level of glucose in the blood by stimulating the liver to release glycogen

Thymopoietin

influences the production of lymphocyte precursors and aids in their process of becoming T lymphocytes

target Organs

specific sites in the body which a hormone acts

growth hormone (GH)

stimulates bone, muscle, and tissue growth and the liver to manufacture an insulin-like growth factor to encourage bone growth. GH increases glucose levels and is released during exercise and sleep. *somatotrophic hormone*

gastrin

stimulates gastric acid secretion in the stomach, gallbladder, pancreas, and small intestine

adrenocorticotropic hormone (ACTH)

stimulates growth of the cortex, or outer layer, of the adrenal gland as well as its production of the steroidal hormones, particularly cortisol. *tropic hormone*

follicle-stimulating hormone (FSH)

stimulates ova maturation in the ovaries, hormone production, and ovulation. In males, FSH stimulates sperm production. Because it influences the gonads. *gonadotropin hormone*

melanocyte-stimulating hormone (MSH)

stimulates secretion of the skin's pigment, melanin, controlling skin pigmentation. The deposit of melanin in the skin helps to protect skin during exposure to sunlight.

Oxytocin (OT)

stimulates the female's uterine contractions during labor. OT is also secreted while a female nurses, encouraging milk production.

pancreozymin-cholecystokinin

stimulates the pancreas secreted by duodenal mucosa

Antidiuretic hormone (ADH): also called vasopressin

stimulates water reabsorption by the kidney tubules and increases blood pressure by causing the arterioles to constrict.

Posterior lobe or neurohypophysis of the pituitary gland

stores and releases the hormones oxytocin and vasopressin.

adrenal medulla

synthesizes, secrets, and stores catecholamines (dopamine, epinephrine, and norepinephrine).

thymus gland

this gland is primarily a lymph organ that produces T-cell lymphocytes, which are needed for the immune system. Also functions as an endocrine gland by releasing thymosin and thymopoietin.

adrenal glands

two bean-shaped glands that sit on top of each kidney. There are two parts to the adrenal gland: 1) the adrenal cortex and 2) the adrenal medulla.

prolactin (PRL)

(PRL) is also know as lactogenic hormone. Stimulates breast development. In the female after the birth of a child (post-partum), prolactin stimulates milk production in the mammary glands. *gonadotropin hormone*

Hormones secreted by the anterior lobe or adenohypophysis of the pituitary gland.

Adrenocorticotropic Hormone (ACTH) Follicle-Stimulating Hormone (FSH) Growth Hormone (GH) Luteinizing Hormone (LH) Melanocyte-Stimulating Hormone (MSH) Prolactin (PRL) Thyroid-Stimulating Hormone (TSH)

Negative feedback mechanisms are the chief means of regulating blood levels of nearly all hormones

Negative feedback mechanisms ensure homeostasis; when the level of hormone is too high, negative feedback works to decrease it; when the level of hormone is too low, negative feedback works to increase it.

pancreas

The pancreas is the only organ to hold both endocrine and exocrine functions.

progesterone

is produced by the corpus luteum of the ovaries. Progesterone works with estrogen to bring about the menstrual cycle. It also prevents uterine contractions once an embryo has been implanted in the uterus.

human chorionic gonadotropin (hCG) hormone:

is produced in early pregnancy. It stimulates the ovaries to continue to produce estrogen and progesterone so that the lining of the uterus is not sloughed off. Home pregnancy tests test for hCG.

What is the exocrine role of the pancreas?

is related to digestion, releasing enzymes to help the body break down food for absorption.

What is the endocrine role of the pancreas?

is to release insulin and glucagon.

parathyroid hormone (PTH)

it moves the body's calcium from the bones into the bloodstream, where it is required for proper muscle function. Calcium comes into the body by way of your food and drink and is absorbed in the small intestine. After absorption, it is stored in the bones until needed. If blood calcium decreases, PTH is secreted to restore the body to homeostasis.

adrogens

male sex hormones

parathyroid glands

parathyroid hormone (PTH) is secreted here

placenta

plays a role in respiration, excretion, and nutrition-delivery for the growing baby. In addition, it produces several protein and steroid hormones to help maintain the pregnancy.

testes

produce the male sex hormone testosterone, which is responsible for the male's secondary sex characteristics and also regulates sperm production.

thymus

produces the hormone thymosin, which is vital in the maturation of T-cell lymphocytes and also in the development of a newborn's immune system. To that effect, the thymus is present at birth, grows until puberty, and shrinks in adulthood.

Endocrine System-vital function

production and regulation of hormones

glucocorticoids

promote normal cellular metabolism, and help the body resist long-term stressors, primarily by increasing glucose levels. Glucocorticoids help to control the unpleasant effects of inflammation, and inhibiting prostaglandins, which produce pain.

mineralocorticoids

regulate mineral content of the blood, particularly the concentrations of sodium and potassium.

thymosin

required for the maturation of T-cell lymphocytes important in the development of a newborn;s immune system

thyroid gland

responsible for metabolism

gastrointestinal mucosa

scretes the hormone gastrin

secretin

secreted by the mucosa of the duodenum and jejunum; stimulates pancreatic juice, bile, and intestinal secretions.

adrenal cortex

secretes groups of steroid hormones called corticosteroids. These are classified as mineralocorticoids (aldosterone), glucocorticoids (cortisol and corticosterone), and sex hormones (androgens and estrogens).

endocrine glands

send messages throughout the body through the bloodstream via hormones

The islets of Langerhans

small clusters of cells within the pancreas. Alpha, beta, delta cells. 1. Alpha cells secrete glucagon; causes increase in blood sugar. 2. Beta cells secrete insulin; lowers blood sugar 3. Delta cells secrete somatostatin; suppresses release of glucagon and insulin