Chapter 7

Anatomy and Physiology

Chapter 7

The Endocrine Glands and Hormones

Chapter 7 – The Endocrine Glands and Hormones

Applied Learning Outcomes

Use the terminology associated with the endocrine system

Learn about hormones, glands, and their functions

Understand the aging and pathology of the endocrine system

• The endocrine system is a complex collection of hormones that coordinate many of the body’s functions.

• It is composed of glands that produce endocrine secretions.

• Endocrine secretions are cellular signals that go directly into the blood.

Overview

Chapter 7 – The Endocrine Glands and Hormones

Jobs of the Endocrine System

• Controls blood sugar• Maintains salt and water balance• Controls development and growth• Controls blood pressure and heart rate• Nervous system works with the endocrine system in

response to danger and stress• Regulates metabolism• Determines gender and fertility• Controls human reproduction

Glands• A group of cells that manufacture secretions.• Two types of glandular secretions

• Exocrine- deposited into the body cavity or surfaceof skin through a tunnel of cells or ducts

• Endocrine secretions typically sent into blood• Receive signals from environment (such as atmospheric

gases, gravity, nutrients, sunlight, temperature)• Receives cellular signals or hormones that originate

inside the bodyAlmost any organ in the body can produce endocrine

secretions.

Endocrine System• Composed of 10 endocrine glands.• Called ductless glands • They do not travel through tubes. Enter blood

stream.• Cells with certain receptors respond to

endocrine secretions.• Target cells are cells that have these

receptors.

The Endocrine Glands – Pituitary and Pineal

Chapter 7 – The Endocrine Glands and Hormones

The pituitary gland is known as the master endocrine gland because its numerous hormones control most of the other endocrine glands and is intimately linked to the overall coordination of the body’s organ systems.

The pineal gland is responsible for producing melatonin and serotonin.

The Pituitary Gland and its Secretions

Pituitary gland (Anterior)• Growth Hormone (GH) Affects Bone• Adrenocorticotropic hormone (ACTH) Affects Adrenal cortex• Thyroid stimulating hormone (TSH) Affects Thyroid gland• Follicle Stimulating Hormone (FSH) affects ovaries and testes• Lutenizing hormone (LH) affects ovaries and testes• Melanocyte stimulating hormone (MSH) affects Skin• Prolactin affects Mammary glands(PRL)Pituitary gland (Posterior)• Oxytocin affects Mammary glands(OT)• Oxytocin affects Uterus • Antidiuretic hormone (ADH) affects Kidney tubules

Hormone Function• A ligand is a chemical that attaches to a receptor• Hormones are a category of ligands.• Hormones can attach to receptors on target cells internally or

externally.• Surface receptors are located on the surface of the cell. • Internal receptors are located within a cell.• Surface receptors rely on blood’s watery fluid to carry the

hormone to the cel membrane. • If hormone is the correct shape it will attach to the receptor on the

cell membrane.• Causes changes within the target cell (effector)

Internal receptors and how they work

• Carrier proteins bring hormones to target cells (effectors) that use internal receptors.

• One group of carrier proteins is created by the liver• They help to transport these hormones in the blood to the cell• Another group of carrier proteins produced in the cell attach the

hormone to internal receptors on genetic material.• Transported hormones bind to a special receptor that interacts

with the DNA• This interaction either switches on or switches off a distinct trait.

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Endocrine Secretions• Autocrine secretions are self governing and usually

do not travel in the blood. They interact with the cell that produced them.

• Paracrine secretions also travel a short distance via the blood or body fluid. They signal and target cells that are close by.

• Endocrine secretions travel long distance via blood. They signal and target cells that are far away.

• Pheromones are secretions that leave the body and signals the cells of other organisms.

Cell Signaling

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Cell Signaling

Negative feedback System•Most hormones work on a negative feedback system•Example is the hormone Thyroxine •Causes increase in metabolic rate. This causes body to produce heat. •Thyroxine produced as long as body temperature is low.•Thyroxine shuts its own production off as body temperature reaches a normal level.Thyroxine is not produced unless body temperature drops.

•http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter20/animation__positive_and_negative_feedback__quiz_1_.html

Types of Hormones•Hormone- any chemical that signals a cell to alter its metabolism.•Agonists- are chemicals that act like hormones.

•Example- foods that contain phytoestrogens act like estrogen in the body.

•Antagonists- are chemicals that block the action of hormones.•Many chemical pollutants can interfere with hormonal communication because they mimic hormones.

Types of HormonesTwo categories of hormones:

•Peptide hormones•Composed of Amino acids•DNA contains program to build them•Usually responsible for rapid changes in the body•Most are involved in short term or immediate changes needed to regulate metabolism.•Some have permanent effects on body-ex. GH

Types of hormones•Lipid hormones

•Made from existing lipids in the body or taken in through diet.•Fewer types than peptide hormones•Valuable role in fluid regulation and sexual reproduction•Two types- hormone-like lipids and steroids.•Don’t travel as easily through the blood•A carrier molecule secreted into the blood moves them through the body•Readily crosses the plasma (cell) membrane.•Many lipid hormones have long term effects on body because they directly control DNA.

The Endocrine GlandsThe endocrine system is composed of 10 glands.

1. Hypothalamus2. Pituitary Gland

anterior and posterior3. Pineal Gland4. Adrenal Glands

cortex and medulla5. Thyroid Gland6. Parathyroid Glands7. Pancreas8. Thymus9. Ovaries10. Testes http://health.howstuffworks.com/human-bod

y/systems/endocrine/adam-200091.htm

Endocrine Glands

HypothalamusLocated above the pituitary glandControls the endocrine activity mainly the pituitaryAlso controls appetite, body temperature, and sleep.

PituitaryAnterior controlled by releasing hormones from hypothalamusPosterior is under nerve cell control of the hypothalamus

PinealProduces the hormones melatonin-involved with regulating body rhythms serotonin-involved with appetite, emotions, moods and sleep.

Endocrine GlandsAdrenal Glands

Lie above each kidneyTwo glands fused together

Adrenal cortex- the outer layerAdrenal medulla- the inner layer

Adrenal CortexProduces Glucocorticosteroids

Regulate metabolism and inhibit ACTHACTH stimulates the secretion of cortisol

Cortisol helps metabolize lipids and proteins to produce energy

Produces mineralocorticosteroidsRegulate the balance of electrolytes and water in the body

Aldosterone is the major mineralcorticosteroidIt regulates potassium and sodium in the bodyNecessary for muscle and nerve function

Endocrine GlandsAdrenal Glands

Adrenal medullaProduces Adrenaline (Epinephrine)Produces Noradrenaline (Norepinephrine)

What causes the Adrenal glands to produce these hormones?Heavy physical exertionStressLow blood sugar

What effects do these hormones have on the body?•Increase the discharge of glucose and fats into the blood•(immediate energy needed to fuel metabolism•Adrenaline diverts blood away from many of the body organs and to muscles.“fight or flight” responseElevates the metabolic rate of muscle cellsIncreases blood pressure and heart functionNoradrenaline affects nerve cell function related to the body’s response to activity and stress.

Endocrine GlandsThyroid and Parathyroid glands work together

•Described as paired endocrine glands•Located just below and in front of the voice box in the middle of the neck

Thyroid Gland•Under control of TSH•Low body temp and stress prompt release of TSH•Causes thyroid to release thyroxine•Thyroxine increases cellular metabolism

Too much Thyroxine:•Causes accelerated heart rate, fatigue, hair loss, light or absent menstrual periods, muscle weakness, trembling hands, and weight loss

Too little Thyroxine:•Causes cold intolerance, constipation, fatigue, irritability, memory loss, muscle cramps, and weight gain.

Endocrine Glands

Thyroid Gland•Calcitonin produced by thyroid gland•Works with parathyroid glands to adjust calcium level in blood and bones•Calcitonin lowers blood calcium•Encourages retention of calcium in bone

Parathyroid Gland•PTH increases the calcium level in the blood by removing it from bone tissue •Stimulates vitamin D production which helps with calcium absorption.•Encourages kidneys to retain calcium and helps digestive system to absorb calcium

Endocrine GlandsPancreasLarge gland located under the stomachProduces digestive enzymes for small intestinesProduces two hormones from endocrine cell clusters (islets)Also produces hormones insulin and glucagonIslets of Langerhans

Beta cells produce insulinAlpha cells produce glucagon

Insulin is made:•In response to high glucose levels•Insulin stimulates the insulin receptors•This causes the cells to take in the glucose•Insulin secretion speeds up the conversion of glucose into glycogen•Insulin also causes the body to store unused glucose as fat cells.•Improper insulin function can result in high blood glucose levels and cause blood vessel decay, dehydration, and kidney damage.

Endocrine Glands

Pancreas:Glucagon

•Has the opposite role of insulin•Produced when we have low blood sugar (hypoglycemia)•Encourages the metabolism of fats and proteins for energy•As a way of preserving existing glucose until blood sugar levels return to normal.

Endocrine GlandsGonads:Ovaries and Testes receive hormones from the pituitary gland.FSH promotes the formation of eggs and sperms.LH enables the maturation of eggs and spermLH help males produce testosterone and females produce estrogen and progesterone.Testes produce testosterone.Ovaries produce estrogen and progesterone.

Sex hormones in Females

Estrogen give females secondary sex characteristics and also essential for bone maintenance.Adrenal glands of females are able to convert steroids into male hormones----androgens. It works with estrogen to promote muscle tone and also cause sex drive in females.Progesterone-works with estrogen to produce the menstrual cycle and induce changes during pregnancy.

Sex Hormones in MalesTestosterone

produces male secondary sex characteristicsensures sperm maturationresponsible for muscle development

Abuse of anabolic steroids by athletesthey are made up of chemicals resembling testosterone.

High levels of testosteronecan induce brain tumorscause cardiovascular problemsmales may be affected by baldness

Pathology of the Endocrine SystemAcromegaly

• due to increase in GH in adulthood• Results in enlargement of skull, hands, feet, tongue• Abraham Lincoln may have had this.

Addison’s Disease•decrease in adrenal cortex hormones•due to malfunction of adrenal glands or pituitary gland•Results in darkening of the skin due to excess melanin production, dehydration, low blood pressure, low blood

sugar, and sodium loss. Cushing’s syndrome

•Due to overproduction of adrenal cortex hormone

due to malfunction or tumor of adrenal glands orExcess of ACTH secretions.

Pathology of the Endocrine SystemDiabetes Insipidus

Inadequate amount of ADHProduces extreme water loss due to frequent urination.

Diabetes MellitusCaused by decreased insulin production (Type I)or Body’s inability to detect insulin signals (Type II)Results in high blood sugar and a variety of disorders due to

abnormal glucose levelsCan lead to blindness, blood vessel destruction, kidney failure

Pathology of the Endocrine SystemHyperparathyroidism

Overproduction of parathyroid hormoneCaused by immune system disorders, kidney diseases, parathyroid tumors, pregnancyProduces elevated calcium levels, therefore calcium loss from bones.

Results in kidney problems and weakening of bones

HypothyroidismThyroid gland does not produce enough thyroxineIn children it results in mental retardation and short statureIn adults it causes lethargy, weight gain, dry hair and skin,and sensitivity to cold.

Pathology of the Endocrine System

Graves’ Disease (hyperthyroidism)caused by inflammation of thyroid gland due to elevated thyroidhormone. Caused by an autoimmune diseaseResults in elevated metabolic rate and feelings of nervousnessor tension.