The Endocrine System

Endocrine System

• A set of glands that produce hormones-- chemical messengers that circulate in the blood

Hormone

• Chemical messengers produced by the endocrine glands and circulated in the blood • Similar to neurotransmitters in that they are also messengers • Slower communication system, but with longer lasting effects

Endocrine System

Hypothalamus

• Brain region that controls the pituitary gland • Controls homeostasis – the bodies ability to remain at a status quo level

Pituitary Gland

• The endocrine system’s gland that controls the other endocrine glands • Called the “master gland” • Located at the base of the brain and connects to the hypothalamus

Thyroid Gland

• Endocrine gland that helps regulate the energy level in the body • Located in the neck • Controls body temperature • Controls metabolism – our body’s ability to transform the food we eat into usable energy

Adrenal Gland

• Endocrine glands that help to arouse the body in times of stress • Located just above the kidneys • Release epinephrine (adrenaline) and norepinephrine (noradrenaline ) • Increase heart rate, blood pressure, and blood sugar

Pancreatic Gland

• Regulates the level of blood sugar in the blood by insulin • Insulin is needed in the body to break down sugars in the body

Sex Glands

• Ovaries (females) and testes (males) are the glands that influence emotion and physical development.

• Testosterone – primary male hormone • Estrogen – primary female hormone • Males and females have both estrogen and testosterone in their systems.

Gonads (sex organs)

• Testicles – release androgens (male hormones) • Ovaries – release estrogens (female hormones) • The presence of these chemicals influence male and female reproductive characteristics .

Maintaining Homeostasis

•

Homeostasis

is the maintenance of a stable internal state within an organism. • Organisms detect changes in their environment and respond to these changes in a variety of ways.

• A

feedback mechanism

occurs when the level of one substance influences the level of another substance or activity of another organ.

Feedback Mechanisms

•

Positive feedback

- designed to accelerate or enhance the output created by a stimulus that has already been activated.

• Designed to push levels out of normal ranges. • Example is the release of oxytocin to intensify the contractions that take place during childbirth. – The more oxytocin, the greater and more frequent the contractions, which in turn produces more oxytocin

Feedback Mechanisms

•

Negative feedback

– process in which a stimulus produces a response that opposes or shuts down the original stimulus.

Endocrine Disorders

blood sugar.

body. turn dehydrates them Diabetes • interruption of the feedback system that controls • Too little insulin = buildup of sugar in the blood • the kidneys use a lot more water to flush it out of the • extra water comes from surrounding cells, which in – leaves the cells vulnerable to infection and poisons.

• Type I – born with it – Controlled by insulin injections • Type II – acquired – Usually occurs in older people – May be controlled with diet

Endocrine Disorders

– Hyperactive thyroid- Behaviors may include excitability, insomnia, ADD, agitation, difficulty focusing – Hypoactive thyroid - Behaviors may include sleepiness, reduced muscle tone, overweight – Hypoglycemia - Too much insulin in the body devours all of the sugar in the blood. May appear sluggish and inattentive.