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Chapter 7
Anatomy and Physiology
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
Chapter 7 – The Endocrine Glands and Hormones
Overview
• 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.
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 surface
of 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 body
Almost 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
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.
Chapter 7 – The Endocrine Glands and Hormones
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.
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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 Hormones
Two 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 Glands
The endocrine system is composed of 10 glands.
1. Hypothalamus
2. Pituitary Gland
anterior and posterior
3. Pineal Gland
4. Adrenal Glands
cortex and medulla
5. Thyroid Gland
6. Parathyroid Glands
7. Pancreas
8. Thymus
9. Ovaries
10. Testes

http://health.howstuffworks.com/humanbody/systems/endocrine/adam-200091.htm
Endocrine Glands
Hypothalamus
Located above the pituitary gland
Controls the endocrine activity mainly the pituitary
Also controls appetite, body temperature, and sleep.
Pituitary
Anterior controlled by releasing hormones from hypothalamus
Posterior is under nerve cell control of the hypothalamus
Pineal
Produces the hormones
 melatonin-involved with regulating body rhythms
 serotonin-involved with appetite, emotions, moods and sleep.
Endocrine Glands
Adrenal Glands
Lie above each kidney
Two glands fused together
Adrenal cortex- the outer layer
Adrenal medulla- the inner layer
Adrenal Cortex
Produces Glucocorticosteroids
Regulate metabolism and inhibit ACTH
ACTH stimulates the secretion of cortisol
Cortisol helps metabolize lipids and proteins to
produce energy
Produces mineralocorticosteroids
Regulate the balance of electrolytes and water in the body
Aldosterone is the major mineralcorticosteroid
It regulates potassium and sodium in the body
Necessary for muscle and nerve function
Endocrine Glands
Adrenal Glands
Adrenal medulla
Produces Adrenaline (Epinephrine)
Produces Noradrenaline (Norepinephrine)
What causes the Adrenal glands to produce these hormones?
Heavy physical exertion
Stress
Low 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” response
Elevates the metabolic rate of muscle cells
Increases blood pressure and heart function
Noradrenaline affects nerve cell function related to the body’s
response to activity and stress.
Endocrine Glands
Thyroid 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 Glands
Pancreas
Large gland located under the stomach
Produces digestive enzymes for small intestines
Produces two hormones from endocrine cell clusters (islets)
Also produces hormones insulin and glucagon
Islets of Langerhans
Beta cells produce insulin
Alpha 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 Glands
Gonads:
Ovaries and Testes receive hormones from the pituitary gland.
FSH promotes the formation of eggs and sperms.
LH enables the maturation of eggs and sperm
LH 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 Males
Testosterone
produces male secondary sex characteristics
ensures sperm maturation
responsible for muscle development
Abuse of anabolic steroids by athletes
they are made up of chemicals resembling
testosterone.
High levels of testosterone
can induce brain tumors
cause cardiovascular problems
males may be affected by baldness
Pathology of the Endocrine System
Acromegaly
• 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 or
Excess of ACTH secretions.
Pathology of the Endocrine System
Diabetes Insipidus
Inadequate amount of ADH
Produces extreme water loss due to frequent urination.
Diabetes Mellitus
Caused 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 levels
Can lead to blindness, blood vessel destruction, kidney failure
Pathology of the Endocrine System
Hyperparathyroidism
Overproduction of parathyroid hormone
Caused by immune system disorders, kidney diseases,
parathyroid tumors, pregnancy
Produces elevated calcium levels, therefore calcium loss
from bones.
Results in kidney problems and weakening of bones
Hypothyroidism
Thyroid gland does not produce enough thyroxine
In children it results in mental retardation and short stature
In 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 thyroid
hormone. Caused by an autoimmune disease
Results in elevated metabolic rate and feelings of nervousness
or tension.