Endocrine SystemChapter 10

Regulating Body FunctionWorking closely with

your nervous system is the endocrine system, a chemical communication system that regulate many body functions.

Exocrine vs EndocrineExocrine Glands Endocrinesecrete their products

into ducts that empty onto a surface or into a cavity.

Ex: Sweat glands and salivary glands

Ductless glands. They secrete

chemicals (hormones) into intracellular spaces.

NOT

Regulating Body FunctionA gland is a group of cells, or an organ, that

secretes a chemical substance. The endocrine glands secrete chemicals

called hormones directly into the bloodstream.

The blood carries the hormones directly to the tissue they are targeted to affect.

Some hormones are produced continuously, while others are produced only at certain times.

Regulation of Hormone SecretionNegative Feedback Positive FeedbackHomeostatic control

mechanism that reverses what is happening in the body

More common than positive feedback. Ex: Insulin, Body

Temperature, Blood Pressure

Amplifies changes rather than reverses them. Ex: Labor – amplified

contractions.

Mechanisms of Hormone ActionNonsteroid Hormones

Steroid HormonesSecond messenger

mechanism: nonsteroid hormones serve as 1st messenger between gland and cells; Another molecule will then act as a 2nd messenger providing communication within the target cell

Lipid-solubleCan pass through cell

membrane of target cellBind with receptors on

the nucleus and act on DNA

Meet the GlandsEndocrine System

PituitaryThe pituitary gland at the base of the brain

is a gland that signals other endocrine glands to produce hormones when needed.

It is also known as the “Master Gland” and is located at the base of the brain.

It secretes several hormones. These regulate the thyroid gland, adrenal

glands, and kidneys- plus your growth and development. It produces growth hormones.

PituitaryAnterior PosteriorTSH

Thyroid stimulating

ACTH Adrenocorticotropic

FSH Follicle-stimulating

LH luteinizing

GH growth

Prolactin

ADHAnti-duretic

Oxytocin

HypothalamusThe

hypothalamus is a vital neuroendocrine and autonomic control center beneath the thalamus.

Secretes:Releasing

hormones Anterior pituitary

Inhibiting hormones Posterior pituitary

ParathyroidThe parathyroid

glands direct the distribution of certain minerals in your body.

Increase Ca+ in blood

SecretesParathyroid

hormone or PTH

PancreasThe pancreas is part of two body systems-

the digestive system and the endocrine system.

It is located behind the stomach and supplies the small intestine with digestive juice.

It produces insulin and contains small clusters of cells called the islets of Langerhans, which control blood sugar levels.

It produces insulin.

Pancreas

ThymusThe thymus gland

is located in the mediastinum.

It is a vital part of the body’s immune system.

Produces thymosin

Pineal GlandThe pineal gland is located in the third

ventricle of the brain.It produces melantonin.

ThyroidThe thyroid gland

is located where the larynx and trachea meet.

It regulates the chemical reactions of nutrients in the cells.

It produces thyroxine.

AdrenalThe adrenal glands are located on your

kidneys. They secrete hormones that help the body

maintain its levels of sodium and water, aid the digestive process, and control your body’s response to emergencies.

It produces adrenaline.

Adrenal

The Body’s Response to StressWhen your brain

recognizes a stressful situation, your adrenal glands responds by releasing the hormone adrenaline. This hormone prepares your body to respond to stress.

ReproductiveDuring adolescence, the endocrine system

plays an important role in growth and development.

OvariesThe ovaries are the

female reproductive glands.

They control the development of secondary sex characteristics during adolescence.

It produces estrogen.

PlacentaThe placenta anchors the developing fetus to

the uterus and provides a “bridge” for the the exchange of nutrients and waste products between the mother and the developing baby.

TestesThe testes are the

male reproductive glands.

They control the development of secondary sex characteristics during adolescence.

It produces testosterone.

Problems or AbnormalitiesEndocrine System

Secretions of HormonesHyposecretion HypersecretionProduction of too little

hormone by a diseased gland

Production of too much hormone by a diseased gland

DiabetesDiabetes mellitus is a disease that may be

caused by inadequate insulin production by the pancreas.

Symptoms include: lack of energy weight loss extreme thirst frequent urination

THYROIDHYPOTHRYOIDISM HYPERTHYROIDISMUnderactive thyroid

gland can cause a dull facial expression, hoarse voice, facial puffiness, coarse, dry skin and hair, and weight gain.

Goiter- caused by low dietary iodine intake

Cretinsim- when hyposecretion occurs in infants/toddlers

Overactive thyroid gland produces symptoms that may include protrusion of eyeballs, warm, moist skin, trembling hands, nervousness, increased sweating, disturbed sleep, and weight loss.

Growth Hormonehyposecretion hypersecretionDwarfisim Gigantism

Acromegaly results when GH is secreted too much after adolescents.

ParathyroidParathyroid hormone (PTH) and vitamin D

help manage calcium balance in the bodyCalcium is important to many body functions,

including:Bone formationHormone releaseMuscle contractionNerve and brain function

Parathyroid and Nerve Cells

Parathyroidhypersecretion hyposecretionResults in

hypercalcemiaCauses several

abdominal, muscle, kidney and psychological symptoms

Results in hypocalcemia

Symptoms include:Petechiae (red spots on

skin)Strong muscle

contractions of the hand (cramping)

Life threateningECG changes