AMA 176 - Anatomy & AMA 176 - Anatomy & Physiology/Medical Physiology/Medical

Terminology/Pathology 7 Terminology/Pathology 7 Endocrine SystemEndocrine System

Endocrine SystemEndocrine System Function:Function: an information signaling system (like an information signaling system (like

nervous system) that uses blood vessels as information nervous system) that uses blood vessels as information channels (rather than nerves). Glands located all over channels (rather than nerves). Glands located all over the body release chemical messengers called hormones the body release chemical messengers called hormones which regulate specific bodily functions; e.g. growth, which regulate specific bodily functions; e.g. growth, puberty, metabolism, reproduction, etc. Help to puberty, metabolism, reproduction, etc. Help to maintain homeostasis or balance in the body. maintain homeostasis or balance in the body.

Hormones:Hormones: work by binding to sites on various tissues work by binding to sites on various tissues that recognize them causing the intended biological that recognize them causing the intended biological effect, somewhat like a lock and key. Each receptor is effect, somewhat like a lock and key. Each receptor is the lock and the specific hormone that is attracted to the lock and the specific hormone that is attracted to that receptor is the key that opens that lock and causes that receptor is the key that opens that lock and causes the intended biological effect. (e.g. the pituitary gland the intended biological effect. (e.g. the pituitary gland secretes growth hormone that opens the “lock” in bones secretes growth hormone that opens the “lock” in bones and tissues and causes growth). and tissues and causes growth).

Structure of the Endocrine Structure of the Endocrine SystemSystem

Two types of glands:Two types of glands: Endocrine:Endocrine: secrete hormones into the secrete hormones into the

bloodstream. (examples: pineal, thymus, bloodstream. (examples: pineal, thymus, thyroid, parathyroid, adrenal, pancreas, thyroid, parathyroid, adrenal, pancreas, pituitary, ovaries, testes)pituitary, ovaries, testes)

Exocrine:Exocrine: send chemical substances send chemical substances (tears, sweat, saliva) via ducts to the (tears, sweat, saliva) via ducts to the outside of the body. (examples: sweat, outside of the body. (examples: sweat, mammary, mucous, salivary, lacrimal mammary, mucous, salivary, lacrimal (tear) glands)(tear) glands)

Pineal & Thymus:Pineal & Thymus:

Pineal:Pineal: located in the brain. located in the brain. Secretes melatonin to regulate the Secretes melatonin to regulate the body’s “biological clock”. body’s “biological clock”.

Thymus:Thymus: located behind the located behind the sternum. Produces thymosin and T-sternum. Produces thymosin and T-cells and is responsible for immune cells and is responsible for immune responses (more so in childhood, responses (more so in childhood, shrinks as we age).shrinks as we age).

Thyroid:Thyroid: Located in the neck.Located in the neck.

Secretes thyroxine (tetraiodothyronine) Secretes thyroxine (tetraiodothyronine) (T4) and triiodothyronine (T3). (T4) and triiodothyronine (T3).

These are hormones synthesized from These are hormones synthesized from iodine from the bloodstream; necessary iodine from the bloodstream; necessary to maintain metabolism by helping cells to maintain metabolism by helping cells take in oxygen.take in oxygen.

Parathyroid:Parathyroid:

Located on either side of the thyroid Located on either side of the thyroid in the neck (four small oval bodies). in the neck (four small oval bodies).

Parathyroid hormone (PTH) takes Parathyroid hormone (PTH) takes calcium from bones and puts it into calcium from bones and puts it into the bloodstream to help with proper the bloodstream to help with proper functioning of body tissues, functioning of body tissues, especially the muscles.especially the muscles.

Adrenal:Adrenal: Two small glands on top of each kidney. Composed of Two small glands on top of each kidney. Composed of

two parts; an inner (medulla) and outer (cortex) portion. two parts; an inner (medulla) and outer (cortex) portion.

Cortex:Cortex: secretes corticosteroids (complex chemicals secretes corticosteroids (complex chemicals made from cholesterol) made from cholesterol)

CortisolCortisol to regulate glucose, fat and protein to regulate glucose, fat and protein metabolismmetabolism

AldosteroneAldosterone to regulate electrolytes or salts to regulate electrolytes or salts AndrogensAndrogens and and EstrogensEstrogens to regulate male and to regulate male and

female sex characteristicsfemale sex characteristics

Medulla:Medulla: secretes catecholamines (chemicals made secretes catecholamines (chemicals made from amino acids). from amino acids).

EpinephrineEpinephrine to increase heart rate and BP, dilate to increase heart rate and BP, dilate bronchial tubes, release glucose and glycogen for more bronchial tubes, release glucose and glycogen for more energy – “flight or fight”energy – “flight or fight”

NorepinephrineNorepinephrine constricts blood vessels to raise BP) constricts blood vessels to raise BP)

Pancreas:Pancreas:

Located near stomachLocated near stomach

Made of specialized hormone Made of specialized hormone producing cells called the islets of producing cells called the islets of Langerhans that produce insulin and Langerhans that produce insulin and glucagon which regulate blood sugar glucagon which regulate blood sugar levels. levels.

Also secretes digestive enzymes into Also secretes digestive enzymes into the digestive tract.the digestive tract.

Pituitary:Pituitary:

Also called hypophysis; small pea-sized Also called hypophysis; small pea-sized gland located in brain. gland located in brain.

The hypothalamus in the brain sends The hypothalamus in the brain sends signals to cause the pituitary to release or signals to cause the pituitary to release or inhibit many hormones such as growth, inhibit many hormones such as growth, thyroid stimulation, pregnancy, etc.thyroid stimulation, pregnancy, etc.

Basically the pituitary hormones tell other Basically the pituitary hormones tell other glands what to do. glands what to do.

Ovaries & Testes:Ovaries & Testes: Ovaries:Ovaries: located in the lower abdomen located in the lower abdomen

in females. Produce eggs (gamete or in females. Produce eggs (gamete or ovum) as well as hormones responsible ovum) as well as hormones responsible for female sex characteristics and for female sex characteristics and regulation of the menstrual cycle. regulation of the menstrual cycle.

Testes:Testes: located in the inguinal region of located in the inguinal region of the male, suspended in the scrotum. the male, suspended in the scrotum. Produce sperm and testosterone Produce sperm and testosterone responsible for male sex characteristics. responsible for male sex characteristics.