Download Human Endocrine System

Human Endocrine System
Endocrine System

groups of endocrine glands that
produce hormones

hormones are chemical messengers
◦ substances that are made by one organ that
have an effect on another organ
.
When the body needs to bring about a longterm change, those messages are sent through
the endocrine system.
Types of Glands
Endocrine glands
- Ductless
 chemicals are hormones
 hormones travel through the blood
vessels until they reach the target
organ
Types of Glands
Exocrine glands (ducted)
 chemicals are transported by ducts (tubes)
directly into an area

◦ The chemicals are NOT hormones
Examples:
Sweat Gland, Tear Ducts, and Bile Duct,
Hormones work by binding to
specific chemical receptors on
target cells
Receptor: protein whose shape fits that of
a specific messenger molecule such as
a hormone
Target cells: cells that have receptors for
a particular hormone
Hormone Action
Chemical Classes of Hormones
Two major classes of hormones
Amino Acid Hormone – Water Soluble
Can not pass through cell membrane
Steroid hormones – Fat Soluble
Can pass through cell membrane
Endocrine Functions
Regulates metabolism
Maintains salt, water, and nutrient balance in the
blood
Controls the body’s response to stress
Regulates growth, development, and reproduction
HYPOTHALAMUS
Location:
Lower brain –links
nervous and
endocrine system.
 Function: controls
pituitary gland

The Hypothalamus

produces a set of chemicals called
releasing factors that stimulate the
pituitary to release Hormones
PITUITARY
Location: Base of
brain
 Function: “Master
gland”– releases
hormones that
control many other
glands.
(Tropic Hormones)
 Pea-sized

PITUITARY
PITUITARY
Hormones Secreted:

Thyroid Stimulating Hormone (TSH):
stimulates thyroid to produce thyroxine.

Growth Hormone (GH): Stimulates
the growth of bones
PITUITARY
Hormones Secreted:

Lutenizing Hormone (LH): Stimulates
development of ovaries and testes

Follicle Stimulating Hormone (FSH):
Stimulates gonads to produce sperm
and eggs
PITUITARY
Hormones Secreted:
Oxytocin: Stimulates Uterine contractions
during childbirth and milk production in
female breast after childbirth


Prolactin: Stimulates milk production
PITUITARY
Hormones Secreted:


ACTH (adrenocorticotropic hormone)
stimulates the adrenal gland to
make cortisol
ADH (antidiuretic hormone)
controls the blood fluid levels by
retaining water in the kidney nephron
How Do Hormones Know Which Part of Your Body to
Affect?
Hormones travel toward target cells –
designed to receive the chemical message
they carry.
 Target cells have specific receptors
molecules on them that lock into the
hormone like a lock-n-key.

Fig. 45-5-1
Fat-soluble
hormone
Watersoluble
hormone
Signal receptor
Transport
protein
TARGET
CELL
(a)
Signal
receptor
NUCLEUS
(b)
THYROID
Location: Front part of
neck
 “Bow-tie” or “Butterfly”
that hugs the trachea

Thyroid Gland


produces a hormone called
thyroxin
thyroxin is the only
molecule in our body that
utilizes iodine
Thyroxin

regulates the rate of metabolism by
stimulating cell respiration

is necessary for the normal physical and
emotional development
PARATHYROID
 Location:

4 tiny glands embedded in
thyroid gland
Hormone Produced:
Parathyroid Hormone (Parathormone, PTH):
regulates Calcium levels in blood.
Parathyroid Glands

PTH causes bone cells (osteocytes) to
take Ca2+ out of bone and put it into the
blood and increase kidney reaborption

calcium blood level INCREASE
◦ Ca2+ effects the release of neurotransmitters
by the terminal knobs of the neurons
Thyroid Revisited
second hormone secreted by the thyroid
gland is Calcitonin
 Calcitonin causes osteocytes to put
Ca2+ back into the bone
 calcium blood levels DECREASE

Homeostasis

CALCITONIN and
PARATHORMONE are
ANTAGONISTIC PAIRS
◦ They work against each other to control
blood calcium levels
PANCREAS
PANCREAS: “ISLETS OF LANGERHANS”
Location: glands found
within the pancreas
 Function: regulates blood
sugar levels

The Pancreas



pancreas is the ONLY
gland that is BOTH
exocrine and endocrine!
cell clusters called the
Islets of Langerhans
produce hormones
there are 2 cell types on
the pancreas
The Pancreas
 (alpha) cells make a hormone called
glucagon
 causes the liver to hydrolyze glycogen
into glucose
 blood glucose levels INCREASE

The Pancreas
 (beta) cells make a hormone called
insulin
 stimulates the cells to absorb glucose by
making the plasma membranes more
permeable
 blood glucose levels DECREASE

Target Tissues for Insulin and Glucagon

Insulin reduces blood glucose levels by
◦ Promoting the cellular uptake of glucose
◦ Slowing glycogen breakdown in the liver
◦ Promoting fat storage
Target Tissues for Insulin and Glucagon

Glucagon increases blood glucose levels by
◦ Stimulating conversion of glycogen to glucose
in the liver
◦ Stimulating breakdown of fat and protein into
glucose
Homeostasis
Insulin and glucagon are
ANTAGONISTIC PAIRS
 They work against each other to control
glucose levels in the blood

Adrenal Glands

Location: Triangular glands
that sit on top of kidneys

Hormones Produced:
◦ Cortisol: Stimulates conversion
of fat and protein into glucose.
◦ Adrenaline/Epinephrine:
In times of stress it increases
blood sugar, heart, & breathing
rates
ADRENAL

Other Hormones Produced:
Aldosterone – stimulates the
reabsorption of Na+ in the
nephron tubule
 Cortisone – reduces swelling in
tissues
 Androgen – steroids similar to
the male sex hormone

GONADS: OVARIES & TESTES
GONADS: OVARIES & TESTES
OVARIES
 Location: in the pelvis of female

Hormones Produced:
◦ Estrogen- development of female secondary
sex characteristics
◦ breast development
◦ changes in fat distribution which bring about
changes in body shape
◦ menstrual cycle
GONADS: OVARIES & TESTES
OVARIES

Hormones Produced:
◦ Progesterone- increase uterine lining for fetus
development during pregnancy.
GONADS: OVARIES & TESTES
TESTES
 Location: in the scrotum of male
 Hormones Produced:
◦ Testosterone- development of male secondary sex
characteristics
◦ thicker, darker body hair
◦ increased muscle development
◦ thickening of vocal chords
Feedback Mechanisms

Self-regulated way to maintain proper levels of
hormones in body.

Two Types:
◦ Negative feedback:A change in the opposite direction
from the current condition to bring your body back to
homeostasis
Positive feedback: An increase in an already existing
condition that moves your body further away from
homeostasis.
Examples of Positive Feedback
Blood Clotting - increase enzymes released by platelets
causes an increase fibrin production which aids in
clotting of damaged area
Childbirth- contractions cause babies head to press on
cervix, which causes release of Oxytocin causing more
contractions until baby is delivered…
Examples of Negative Feedback
Maintaining thyroid hormone levels in your body
Recognizing when levels are high or low and making
appropriate adjustments)
Maintaining Thyroid Hormone Levels in Your Body
Hypothalamus detects level of
thyroxine in blood…
If LOW – tells pituitary
to secrete TSH, which tells
thyroid to secrete thyroxine.
If HIGH – tells pituitary
to stop secreting TSH, so that
thyroid will STOP secreting
thyroxine.
HOMEOSTASIS is restored!!
Examples of Negative Feedback
Maintaining proper sugar levels in your body
by releasing insulin and glucagon when necessary)
Examples of Negative Feedback
Maintaining proper body temperature at 98.6 F
By your body by shivering and sweating)
Fig. 45-11
Pathway
–
Stimulus
Endocrine
cell
Blood
vessel
Target
cells
Response
Maintaining Proper Sugar Levels in Your Body
What is happening here?
Graph of secretion of hormones
Malfunctions of the
Human Endocrine
System
Too MUCH or too little of any hormone
disrupts homeostasis in your body.
The levels need to be just right!
Diabetes Mellitus
Diabetes mellitus is perhaps the best-known
endocrine disorder
 It is caused by a deficiency of insulin or a decreased
response to insulin in target tissues
 It is marked by elevated blood glucose levels

Diabetes
Must take insulin injections or Diet Control
Causes many problems including Vascular disease and
Blindness
Very taxing on kidney, could lead to kidney failure
Mechanism of Diabetes

Type I diabetes mellitus is an autoimmune disorder
in which the immune system destroys pancreatic
beta cells

Type II diabetes mellitus involves insulin deficiency
or reduced response of target cells due to change
in insulin receptors
Growth Hormone Malfunction


Too MUCH human
Growth Hormone
(hGH)
Results in Giantism or
Acromegaly
Too LITTLE
Growth Hormone
(hGH)
 Results in Dwarfism

Growth Hormone Malfunction
The world's
tallest man, Sultan Kosen
Measured at 8 feet 1 in. was
in NYC last year as part of his
Guinness Book of World
Records’ Tour
Thyroid Malfuctions

Too MUCH Thyroxine

Hyperthyroidism: includes weight loss,
increased heart rate and blood
pressure
◦ thin body
◦ nervousness
◦ Excitability
Thyroid Malfuctions

Too LITTLE Thyroxine

Hypothyroidism: Slows body
processes, fatigue, slow heart rate,
weight gain
Thyroid Malfunctions
Goiter:
Thyroid gland becomes severely enlarged

Thyroid Malfunctions
Goiter:
Caused By:
 Low level of Thyroxin in the body

Thyroid enlarges to compensate for low level

A diet deficient in Iodine
◦ Not common in America because we have
Iodized Salt
Goiter
Goiters
Thyroid Malfunctions
Graves’ disease is a form of hyperthyroidism
in humans
It is an autoimmune disease that
affects the thyroid. It can also affect
the eyes causing them to bulge
Review Questions…
Review Questions…
How do hormones know which cells in the
body to affect?
 What is the difference between positive and
negative feedback?
 Provide an example of negative feedback.
 Provide an example of positive feedback.
 What symptoms would a person with a
hyper secretion of growth hormone
exhibit?

Review Questions…
What symptoms would a person with a hypo
secretion of thyroxin exhibit?
 What is the one gland in the body that is both
an endocrine and an exocrine gland?
 How do glucagon and insulin regulate the
blood sugar level of a person?
 What might be lacking in the diet of a person
who develops goiter?

Question #1

The two systems that work together to
maintain homeostasis in most animals are
the
◦
◦
◦
◦
Nervous and endocrine
Nervous and locomotive
Endocrine and excretory
Excretory and locomotive
Question #2

Structures that are adapted to convert a
stimulus into a nerve impulse in the body
is known as
◦
◦
◦
◦
Receptors
Effectors
Muscles
Glands
Question # 3

In a reflex arc, the pathway for an
imupulse is along a sensory neuron
directly to a motor neuron through
◦
◦
◦
◦
A receptor
The brain
An effector
An interneuron
Question # 4

Which two terms are most closely
associated with the endocrine system?
◦
◦
◦
◦
Digestive glands and enzymes
Neurons and neurotransmitters
Receptors and effectors
Ductless glands and hormones
Question # 5

Many animals have complex reproductive
cycles and growth patterns that are
regulated by chemical secretions known
as
◦
◦
◦
◦
Hormones
Intercellular fluids
Antibodies
Neurotransmitters
Homeostasis
A state of balance
in the body
Homeostasis
A condition in which the internal
environment of the body remains
relatively constant despite changes in
the internal and external environment.
Feedback Mechanisms

Maintain or restore homeostasis
Negative
Feedback Loops
Consist of Three
Parts:
1. Receptor
monitors conditions and detects changes
2. Control center
determines next action and sends a
message
3. Effector
receives directions from the control center;
produces a response that restores the
homeostasis
Temperature Regulation in Homes
thermostat detects
house getting cooler
furnace turns
off
furnace turns
on to release
heat
thermostat detects
room temperature
has increased
Regulation of Body Temperature through Negative Feedback
Hyperthermia
Heat receptors
in the skin
Hypothalamus
Sensors
Control Center
Stress
Negative feedback:
hypothalamus
stops sending
message
Perspiration
evaporates cooling
the skin; increased
blood flow
releases heat
Increased
activity of
sweat glands
Increased blood
flow to the skin
Effectors
Effect
Regulation of Body Temperature through Negative Feedback
Hypothermia
receptors in the
skin
Stress
Control Center
Sensors
Negative feedback:
hypothalamus
stops sending
message
Shivering
generates heat;
decreased blood
flow retains body
heat
Effect
Hypothalamus
Muscles
contractions
(shivering)
Decreased blood
flow to the skin
Effectors
Regulation of Blood Sugar through Negative
Feedback
Hyperglycemia
Stress
Pancreas-beta cells
Sensor and Control center
Negative
Feedback:
Insulin release
inhibited
Blood glucose
is reduced
Liver and Muscle cells
take up glucose from
the blood
Effectors
Insulin is released
into blood
Regulation of Thyroxin through Negative Feedback
Low conc. of
thyroxin in blood
Pituitary gland
Sensor and Control center
Stress
Negative
Feedback: TSH
secretion
inhibited
Thyroxin
levels in the
blood increase
Thyroid gland
secretes thyroxin
Effectors
Thyroid
stimulating
hormone (TSH)
released
Guard Cells in Leaf
Guard Cells in Leaf
plant detects
water shortage
water levels return
change
to normal;
stomata
guard cells change
shape to open stomata
transpiration
is reduced
guard cells
shape to close