Chapter 11: The Endocrine System

Pituitary anterior lobe

Adrenocorticotropic hormone (ACTH) regulates function of adrenal cortex Gonadotropins Follicle-stimulating hormone (FSH)- stimulates growth of eggs in female and sperm in males Luteinizing hormone (LH)- regulates function of male and female gonads and plays a role in releasing ova in females Growth hormone (GH)- stimulates growth of the body Melanocyte-stimulating hormone- stimulates pigment in skin Prolactin- stimulates milk production Thyroid-stimulating hormone (TSH)- regulates function of thyroid gland

Pituitary posterior lobe

Antidiuretic hormone (ADH)- stimulates reabsorption of water by the kidneys Oxytocin- stimulates uterine contractions and releases milk into ducts

Thyroid gland

Calcitonin (CT)- stimulates deposition of calcium into bone Thyroxine (T4)- stimulates metabolism in cells Triiodothyronine (T3)- Stimulates metabolism in cells

Adrenal medulla

Epinephrine (adrenaline)- intensifies response during stress; "fight or flight' response Norepinephrine- chiefly a vasoconstrictor

Ovaries

Estrogen- stimulates development of secondary sex characteristics in females; regulates menstrual cycle Progesterone- prepares for conditions of pregnancy

Pancreas

Glucagon- stimulates liver to release glucose into the blood Insulin- regulates and promotes entry of glucose into cells

Adrenal cortex

Glucocorticoids (cortisol)- regulated carbohydrate levels in the body Mineralocorticoids (aldosterone)- regulates electrolytes and their fluid volume in body Steroid sex hormones (androgen)- male sex hormones from adrenal cortex may converted to estrogens in the bloodstream. Responsible for reproduction and secondary sexual characteristics.

Thymus Gland

In addition to its role as part of the immune system, the thymus is also one of the endocrine glands because it secretes the hormone thymosin. Thymosin is important for proper development of the immune system. The thymus gland is located in the mediastinal cavity anterior and superior to the heart. The thymus is present at birth and grows to its larger size during puberty. At puberty it begins to shrink and eventually is replaced with connective and adipose tissue. The most important function of the thymus is the development of the immune system in the newborn. It is essential to the grown and development of the thymic lymphocytes or T cells.

Parathyroid glands

Parathyroid hormone (PTH)- stimulates bone breakdown; regulates calcium level in the blood

Pineal gland

Pineal means shaped like a pine cone. The pineal gland is part of the thalamus region of the brain and secretes melatonin, a hormone not well understood, but that plays a role in regulating the body's circadian rhythm.

Testes

Testosterone- promotes sperm production and development of secondary sex characteristics in males

Pancreas

The Pancreas is located along the lower curvature of the stomach. It is the only organ in the body that has both endocrine and exocrine functions. The exocrine portion of the pancreas releases digestive enzymes through a duct into the duodenum of the small intestine. The endocrine sections of the pancreas, islets of Langerhans, are named after Dr. Paul Langerhans, a German anatomist. The islets cells produce two different hormones; insulin and glucagon. Insulin, produced by beta islet cells stimulates the cells of the body to take in glucose from the bloodstream, lowering the body's blood sugar level. This occurs after a meal has been eaten and the carbohydrates are absorbed into the bloodstream. In this way the cells obtain the glucose they need for cellular respiration. Another set of islet cells, the alpha cells, secrete a different hormone, glucagon, which stimulates the liver to release glucose, thereby raising the blood glucose level. Glucagon is released when the body needs more sugar, such as at the beginning of strenuous activity or several hours after the last meal has been suggested.

Intro

The endocrine system is a collection of glands that secrete hormones directly into the bloodstream. Hormones are chemicals that act on their target organs to either decrease or increase the target's activity level. IN this way the endocrine system is instrumental in maintaining homeostasis (adjusting the activity level of most of the tissues and organs of the body to maintain a stable internal environment) The body actually has two distinct typed of glands, exocrine and endocrine. Exocrine glands release their secretions into a duct that carries them to the outside of the body or to a passageway connected to the outside of the body (ex. sweat glands) Endocrine glands release hormones directly into the bloodstream, also referred to as ductless glands. The endocrine system consists of the following glands; 2 adrenal glands, 2 ovaries, 4 parathyroid glands, the pancreas, the pineal gland, the pituitary gland, 2 testes in the male, the thymus gland, and the thyroid gland. The endocrine glands as a whole affect the functions of the entire body

Parathyroid glands II

The four tiny parathyroid glands are located on the dorsal surface of the thyroid gland. The parathyroid hormone secreted by these glands regulates the amount of calcium in the blood. If blood calcium levels fall too low, parathyroid hormone levels in the blood are increased and will stimulate bone breakdown to release more calcium into the blood. A calcium deficiency in the system can result in tetany, or muscle excitability and tremors. If the parathyroid glands are removed during thyroid surgery, calcium replacement in the body is often necessary.

Pituitary gland (master gland)

The pituitary gland is located underneath the brain. The small marble-shaped gland is divided into an anterior lobe and a posterior lobe, both are controlled by the hypothalamus, a region of the brain the regulated automatic body responses. The anterior pituitary secretes several different hormones. Growth hormone (somatropin), promotes growth of the body by stimulating cells to rapidly increase in size and divide. Thyroid-stimulating hormone regulates the function of the thyroid gland. Adrenocorticotropic hormone regulates the function of the adrenal cortex. Prolactin stimulates milk production in the breast following pregnancy and birth. Follicle-stimulating hormone and luteinizing hormone both exert their influence on the male and female gonads. Therefore these two hormones together are referred to as the gonadotropins. Follicle-stimulating hormone is responsible for the development of ova in ovaries and sperm in testes. It also stimulates the ovary to secrete estrogen. Luteinizing hormone stimulates secretion of sex hormones in both males and females and plays a role in releasing ova in females. Melanocyte-stimulating hormones stimulates melanocytes to produce more melanin, thereby darkening the skin. The posterior pituitary secretes two hormones, antidiuretic hormone and oxytocin. Antidiuretic hormone promotes water reabsorption by the kidney tubules. Oxytocin stimulates uterine contractions during labor and delivery, and after birth the release of milk from the mammary glands. There is another type of diabetes called diabetes insipidus (DI) that is a result of the inadequate secretion of the antidiuretic hormone from the pituitary gland.

Testes

The testes are two oval glands located in the scrotal sac of the male. They are the male gonads which produce the male gametes, sperm, and the male sex hormone testosterone. Testosterone produces the male secondary sexual characteristics and regulates sperm production.

Thyroid gland

The thyroid gland, which resembles a butterfly in shape, has right and left lobes. It is located on either side of the trachea and larynx. The thyroid cartilage, or Adam's apple, is located just above the thyroid gland. This gland produces the hormones thyroxine and triiodothyronine. These hormones are produced in the thyroid gland from the mineral iodine. Thyroxine and triiodothyronine help to regulate the production of energy and heat in the body to adjust the body's metabolic rate. The thyroid gland also secretes calcitonin in response to hypercalcemia. Its action is the opposite of parathyroid hormone and stimulates the increased deposition of calcium into bone, thereby lowering blood levels of calcium. Iodized salt is one of the best sources of iodine for people living in the Goiter Belt, composed of states located away from saltwater. A lack of iodine in the diet can lead to thyroid disorders, including goiter.

Adrenal Glands

The two adrenal glands are located above each of the kidneys. Each gland is composed of the adrenal cortex and adrenal medulla. The outer adrenal cortex manufactures several different families of hormones; mineralocorticoids, glucocorticoids, and steroid sex hormones. However because they are all produced by the cortex, they are collectively referred to as corticosteroids. The mineralocorticoid hormone aldosterone regulates sodium and potassium levels in the body. The glucocorticoid hormone cortisol regulates carbohydrates in the body. The adrenal cortex of both men and woman secrets steroid sex hormones, androgens (which may be converted to estrogen once released into the bloodstream). These hormones regulate secondary sexua; characteristics. All hormones secreted by the adrenal cortex are steroid hormones. The inner adrenal medulla is responsible for secreting the hormones epinephrine (adrenaline), and norepinephrine. These hormones are critical during emergency situations because they increase blood pressure, heart rate, and respiration levels. This helps the body perform better during emergencies.

Thymus

Thymosin- promotes development of cells in immune system

lapar/o

abdomen

-osis

abnormal condition

adren/o

adrenal gland

post-

after

anti-

against

pan-

all

-emia

blood condition

endocrinology

branch of medicine involving diagnosis and treatment of conditions and diseases of endocrine glands. Physician is an endocrinologist.

mast/o

breast

calc/o

calcium

carcin/o

cancer

cyt/o

cell

-ia

condition

edema

condition in which the body tissues contain excessive amounts of fluid

exophthalmos

condition in which the eyeballs protrude, such as in Graves' disease. This is generally caused by an overproduction of thyroid hormone

gynecomastia

development of breast tissue in males. may be a symptom of adrenal feminization

-pathy

disease

chem/o

drug

-megaly

enlarged

hyper-

excessive

acr/o

extremities

ophthalm/o

eye

gynec/o

female

adrenopathy

general term for adrenal gland disease

endocrinopathy

general term for diseases of the endocrine system

aden/o

gland

glycosuria

having a high level of sugar excreted in the urine

adrenomegaly

having one or both adrenal glands enlarged

-itis

inflammation

-meter

instrument to measure

hypo-

insufficient

lob/o

lobe

poly-

many

or/o

mouth

neur/o

nerve

cortic/o

outer portion

ex-

outward

ovari/o

ovary

pancreat/o

pancreas

parathyroid/o

parathyroid gland

-al

pertaining to

-ary

pertaining to

-ic

pertaining to

-tic

pertaining to

adrenal

pertaining to the adrenal glands

ovarian

pertaining to the ovary

pancreatic

pertaining to the pancreas

parathyroidal

pertaining to the parathyroid gland

pituitary

pertaining to the pituitary gland

testicular

pertaining to the testes

thymic

pertaining to the thymus gland

thyroidal

pertaining to the thyroid gland

pineal/o

pineal gland

pituitar/o

pituitary gland

toxic/o

poision

kal/i

potassium

-scopy

procedure to visually examine

-graphy

process of recording

immun/o

protection

radi/o

ray

-emic

relating to a blood condition

-prandial

relating to a meal

retin/o

retina

natr/o

sodium

-ism

state of

-logy

study of

glyc/o

sugar

glycos/o

sugar

-ectomy

surgical removal

testicul/o

testes

Ovaries

the two ovaries are located in the lower abdominopelvic cavity of the female. They are the female gonads. Gonads are organs that produce gametes or the reproductive sex cells. In the case of females, the gametes are the ova. Of importance to the endocrine system, the ovaries produce the female hormones estrogen and progesterone. Estrogen is responsible for the appearance of the female sexual characteristics and regulation of the menstrual cycle. Progesterone helps to maintain a suitable uterine environment for pregnancy.

-dipsia

thirst

thym/o

thymus gland

thyr/o

thyroid gland

thyroid/o

thyroid gland

-pressin

to press down

crin/o

to secrete

-oma

tumor

-uria

urine condition

vas/o

vessel

endo-

within