The Endocrine System

How our hormone

s function

The Endocrine

SystemClip

What is the Endocrine System?

Series of cells, tissues, and organs that secrete hormones into body fluids (blood).

Hormone= a chemical secreted by endocrine glands which has a specific effect on another cell or organ.

Where are the major endocrine glands located?

• Added info

– Gland= organ that is made up of epithelial tissue

– Secrete hormones.

What do hormones control?

• Reproduction• Growth and development• Maintain homeostasis• Regulation of metabolism• Increasing bodies defenses• Gets “stuff” through cell

membranes.

How do hormones work?

Hormones are produced by specialized cells in glands.

Glands secrete hormones into extra-cellular fluids

Blood transfers hormones to target sites

Hormones cause changes in target cells

What organic compounds are hormones made of?

Amino acid-based hormones

Steroids – made from cholesterol; sex hormones, and adrenal cortex

Prostaglandins – local hormones made from lipids

What are the two types of hormones? Fig 9.1

• Steroid Hormones

– Soluble in fat. Penetrate cell membrane.

– Reach nucleus

• Nonsteroid Hormones

– Not soluble in fat. Bind to cell membrane.

– Cascade of chemical reactions. Adrenalin The non Steroid

Hormone

Steroid Hormone

How are Hormone Secretions Controlled?

Negative Feedback System

Gland A secretes causing Gland B to secrete. Gland B’s secretions inhibit A. Like a thermostat.

Nerve Control

Controlled by the brain. Complicated.

There are Positive feedback systems- but they are limited.

Neg.Sys.

What can go wrong if there is a loss of hormonal control?

• Dwarfism (Hypopitutiary dwarfism)– GH= Growth hormone– When inadequate amounts are secreted.– Short, underdeveloped, lack full adult

sexual features.– Treatment: Hormone therapy if diagnosed early

DwarfismMovies

Gigantism can also be an issue.

• Too much growth hormone.

• 8ft +

• Usually caused by a tumor that has developed in the pituitary gland causing too much GH to be secreted.

• Life expectancy is not full due

to strain on the heart.

The Pituitary Gland

Location: Between the eyes and ears.

Hangs by the hypothalamus stalk.

Has two functional lobes

Anterior pituitary – glandular tissue

Posterior pituitary – nervous tissue

6 Hormones of the Anterior Pituitary

Gland Growth Hormone (GH)- Stimulates Mitosis

Prolactin- Milk Production After Birth of Baby

Thyroid Stimulating Hormone (TSH)- Plays role in MetabolismAdrenocorticotropic hormone (ACTH) And

Luteinizing hormone (LH)- Releases egg from follicle & regulates testosterone

Follicle Stimulating Hormone (FSH)- Stimulates follicles to develop in the ovaries & sperm to develop in the testes.

PituitaryAnd

Hormones

The 2 Hormones of the Posterior Pituitary

Oxytocin- Contracts uterus during labor & stimulates milk ejection.

Antidiuretic hormone (ADH)- Inhibits urine production, can increase blood pressure through vasoconstriction/water retention.

Thyroid Gland

Butterfly shape at the base of the throat

Produces two hormones

Thyroid hormones (T4 & T3) regulate the metabolism of carbs, lipids, & proteins.

Calcitonin decrease Ca+ in the blood (more for your bones).

Thyroid GlandRotation

What can go wrong with the Thyroid?

A goiter.

A lack of Iodine in the diet (3rd world countries) or too much TSH (Thyroid Stimulating hormone)

Thyroid GlandTumor

Parathyroid Glands

On each of the 4 corners of the thyroid.

Stimulate osteoclasts to remove calcium from bone

Stimulate the kidneys and intestine to absorb more calciumRaise calcium levels in the blood

Parathyroid GlandRotation

Adrenal Glands Two glands

Cortex – outer glandular region

Medulla – inner neural tissue region

Sit on top of the kidneys

Hormones of the Adrenal Cortex

Glucocorticoids (including cortisone and cortisol)

Increases the use of fat, proteins (A.A) and sugar when body needs energy

Mineralocorticoids (aldosterone)Regulate electrolyte balance

Target organ is the kidney

Hormones of the Adrenal Cortex

Sex hormones

Produced in the inner layer of the adrenal cortex

Androgens (male) and some estrogen (female)

Hormones of the Adrenal Medulla

Produces two similar hormones that prepare the body to deal with short-term stress

Epinephrine

Norepinephrine

Pancreatic Islets The islets of the pancreas produce hormones

Insulin – allows glucose to cross plasma membranes into cells from beta cells

Glucagon – allows glucose to enter the blood from alpha cells

These hormones are antagonists that maintain blood sugar homeostasis.

The pancreas,Insulin, Glucose,

& Diabetes

Pineal Gland

Found on the third ventricle of the brain

Secretes melatonin

Helps establish the body’s wake and sleep cycles

Thymus

Located posterior to sternum

Largest in infants and children

Produces thymosin

Matures some types of white blood cells

Important in developing the immune system

Hormones of the Ovaries

EstrogensStimulates the development of secondary female characteristics

Matures female reproductive organs

Also produced by the placenta.

Helps prepare the uterus to receive a fertilized egg

Helps maintain pregnancy

Prepares the breasts to produce milk

Estrogen, continued

Progesterone

Produced by the corpus luteum

Acts with estrogen to bring about the menstrual cycle

Helps in the implantation of an embryo in the uterus

Hormones of the Testes

Interstitial cells of testes are hormone-producing

Produce several androgens Testosterone is the most important of them.

Testosterone

Responsible for adult male secondary sex characteristics

Promotes growth and maturation of male reproductive system

Required for sperm cell production

Other Hormone Producing Tissues and Organs

Parts of the small intestine

Parts of the stomach

Kidneys

Heart

Many other areas have scattered endocrine cells

Placenta

Development Aspects ofthe Endocrine System

Menopause

Growth hormone production declines with age

Many endocrine glands decrease output with age