The Systems of the Body
Neuron
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Cell body – source of life of the cell
Dendrites – branches on the cell bodies that
act as receivers of messages from adjacent
neurons.
Axon – projection through which messages
travel.
Synaptic knobs: Tips of branches at end of
axon. Sends messages to adjacent neurons.
Synapse: Fluid filled gap between neurons.
The Nervous System
Nervous
System
Central nervoussystem
Peripheral nervoussystem
(carriesvoluntarynerveimpulsesto
musclesandskin; carriesinvoluntary
impulsestomusclesandglands)
Brain
Spinal cord
Somaticnervoussystem
Autonomicnervoussystem
(controlsvoluntary
movement)
(controlsorgansthat
operateinvoluntarily)
Sympatheticnervoussystem Parasympatheticnervous
(mobilizesthebody
foraction)
system
(maintainsand
restoresequilibrium)
Three sections of the brain
Hindbrain
•Medulla
•Pons
•cerebellum
Midbrain
•Pathway connecting
hindbrain and
Forebrain.
Forebrain
•Diencephalon
•Telecephalon
Diencephalon
Telecephalon
•Thalamus
•Cerebrum
•Hypothalamus •Limbic system
Telencephalon

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Upper and largest portion of the brain
Involved in higher order intelligence,
memory, and personality
Composed of two hemispheres

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Left hemisphere – language processes, etc.
Right hemisphere – visual imagery,
emotions, etc.
Four lobes of the cerebral
cortex
Frontal
•Motor activity
•Higher level
intelligence
•Planning
•Problem solving
•Emotions
•Self-awareness
Parietal
•Bodily sensations,
e.g., pain, heat
•Body movement
Temporal
•Hearing
•Vision
•Smell
•Memory
Occipital
•Primary visual
area of the brain
Reticular Activating System
and Limbic System

Reticular activating system runs from
the medulla through the midbrain into
the hypothalamus.


Responsibility for activation of all areas of
the brain and if damaged – coma ensues
Limbic system controls emotion

It has three sub-circuits
Limbic System - emotions

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Amygdala and hippocampus – essential for
self-preservation, includes aggression.
Cingulate gyrus, the septum, and areas of the
hypothalamus – pleasure and sexual
excitement.
Areas of the thalamus and hypothalamus –
important to socially relevant behaviour
Diencephalon
Hypothalamus
Thalamus
•Command for the
•Chief relay centre for
control of autonomic
directing sensory messages functions such as heart
Helps regulate awareness
rate, blood pressure,
•Relays commands going
hunger, thirst.
to the skeletal muscles
•Role in emotions and
from the motor cortex.
motivation (e.g., thoughts
about fear get translated into
arousal through hypothalamus.)
Three sections of the brain
Hindbrain
•Medulla
•Pons
•cerebellum
Midbrain
•Pathway connecting
hindbrain and
Forebrain.
Forebrain
•Diencephalon
•Telecephalon
Diencephalon
Telecephalon
•Thalamus
•Cerebrum
•Hypothalamus •Limbic system
Cerebellum

Maintains body balance and
coordination of movement

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Damage to the cerebellum results motor
disorders such as ataxia.
Ataxia is a condition where our movements
become jerky and uncoordinated.
Hindbrain continued
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Consists of:
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Pons – involved in eye movement, facial
expressions and eye movement
Medulla – controls breathing, heart rate,
blood pressure
Midbrain
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Midbrain – top of brain stem, receives
visual and auditory information, also
important in muscle movement.
Reticular formation – controls states of
sleep, arousal, and attention.
Spinal cord

Transmits messages from the brain to the
other areas of the body.

Efferent – away from the brain out to the
body
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Produces muscle action
Afferent – from the periphery to the brain

Relays information from the sensory organs
Peripheral Nervous System

Autonomic nervous system

Somatic nervous system
Somatic nervous system
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Involved in both sensory and motor
functions, serving mainly the skin and
skeletal muscles.
Efferent impulses: carry messages
from the brain to the skeletal muscles
Afferent impulses: carry messages from
the sensory organs to the brain
Autonomic nervous system
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
Controls what is generally involuntary,
automatic activity
Consists of the sympathetic and
parasympathetic nervous systems.
Sympathetic nervous system

Fight of flight response


Sends out messages (neurotransmitters) to
the body preparing the body for fight or
flight.
Also prepares the body for strenuous
activity
Fight or Flight Response

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Increase in
Epinephrine &
norepinephrine
Cortisol
Heart rate & blood
pressure
Levels & mobilization of
free fatty acids,
cholesterol &
triglycerides
Platelet adhesiveness &
aggregation

Decrease in
Blood flow to the
kidneys, skin and gut
Parasympathetic nervous
system
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Restores equilibrium in the body
Decreases arousal, slows breathing and
heart rate, lowers heart rate and blood
pressure, etc.
Neurotransmitters

Electrochemical messengers:


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Catecholamines, consisting of epinephrine
and norepinephrine
Dopamine
Acetycholine
Serotonin
The Endocrine System

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Set of glands
Works in close association with the
autonomic nervous system
Communicates via chemical substances
like hormones
Examples are adrenaline, cortisol,
somatotropic hormone, gonadotropic
hormone, etc.
Endocrine and autonomic
systems work together

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Connection between the hypothalamus
in the brain and the pituitary gland
(“master gland”)
The pituitary gland sends out hormones
that communicates with other glands to
send out hormones
Adrenal gland

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Located on top of each kidney
Comprised of the adrenal medulla and
the adrenal cortex.
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Adrenal medulla secretes adrenaline
(epinephrine) and noradrenaline
(norepinephrine)
Adrenal cortex secretes steroids (including
mineralocorticoids and glucocorticoids,
androgens, and estrogens)
Thyroid gland

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Located in the neck
Produces hormone (thyroxin) that regulates
activity level and growth.
Hypothyroidism: Insufficient thyroid
hormones (leads to low activity levels and
weight gain)
Hyperthyroidism: Over-secretion of thyroid
hormones (leads to hyperactivity and weight
loss, insomnia, tremors, etc.)
Pancreas



Located below the stomach
Regulates level of blood sugar by
producing insulin which absorbs blood
sugar.
Important gland in diabetes mellitus
Digestive system



Enzymes: break-downs food substances
Commands from the brain stem
activates the production of saliva.
Saliva contains enzymes that
breakdown starches.
Esophagus pushes food to the stomach
using peristalsis.
Digestive system - continued
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Stomach uses gastric juices and churning to
further breakdown food.
Peristalsis moves food from the stomach to
the duodenum (small intestine)
Acid food mixture becomes chemically
alkaline from secretions of the pancreas,
gallbladder, and small intestine wall.
Digestive system - continued
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Additional enzymes and bile continue
the food breakdown.
Absorption occurs.
Large intestine (mainly colon) continues
absorption of water and passes the
remaining waste to the rectum for
excretion.
Disorders of the Digestive
System
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Peptic ulcers – open sores in the stomach or
duodenum. Causes by excessive gastric juices
and bacterial infection.
Hepatitis – liver becomes inflamed.
Cirrhosis – liver cells die and are replaced by
scar tissue. Caused by hepatitis and heavy
alcohol consumption.
Disorders of these Systems
Diabetes

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
Type I – insulin-dependent diabetes where
person has to take exogenous insulin to make
up for the lack of insulin produced by the
pancreas.
Type II – non-insulin dependent diabetes
where body is not sufficiently responsive to
insulin
Leading cause of blindness in adults and 50%
of dialysis patients (kidney failure) have
diabetes.
Respiratory System
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Air enters the body through the nose
and mouth.
It travels past the larynx and down the
trachea and bronchial tubes into the
lung.
Bronchial tubes divide into small
branches called bronchioles, and then
tiny sacs call alveoli.
Disorders of the Respiratory
System
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Asphyxia – too little oxygen and too much
carbon dioxide (can occur in small breathing
space).
Anoxia – shortage of oxygen (occurs at very
high altitudes). Person looses judgment,
pass into comma.
Hyperventilation – deep rapid breaths that
reduce the amount of carbon dioxide.
Disorders of the Respiratory
System - continued
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Hay fever – seasonal allergic reactions.
Body produces histamines in response
to the irritants entering the lungs.
Asthma – more severe allergic reaction.
Muscles surrounding the air tubes
constrict.
Viral infections (e.g., flu)
Bacterial infections (e.g., strep throat)
Cardiovascular System
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Transport system of the body.
Consists of the heart, blood, and blood
vessels
Blood vessels consist of:


Arteries that carry oxygenated (red) blood
from the heart to the periphery and brain.
Veins carries de-oxygenated (blue) blood
back to the heart and lung
Heart




Fist-sized muscle that circulates blood
to and from the lungs to the body.
Four chambers – atrium (right & left)
and ventricles (right & left)
Left side pumps oxygenated blood from
lungs out to periphery and brain.
Right side takes deoxygenated blood in
to the lungs.
Blood pressure (BP)



Pressure of blood in the arteries.
As the heart contracts and pushed
blood into the arteries (systolic cardiac
cycle) the BP rises.
As the heart rests between beats and
no blood is pumped (diastolic cardiac
cycle) BP is at its lowest.
Dynamics of Blood Pressure (BP)
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Cardiac output – force of contraction of
the heart muscle
Heart rate – speed of contraction
Blood volume – amount of blood in the
system
Peripheral resistance – ease with which
blood can pass through the arteries (as
resistance increases, BP increases)
Dynamics of Blood Pressure (BP)


Elasticity – is the give and take in the
arterial walls. As elasticity decreases BP
increases.
Viscosity – thickness of the blood. BP
increases when the thickness of the
blood increases.
Blood pressure (BP) is Dynamic



When arteries dilate (e.g., in heat)
diastolic BP decreases.
BP increases when heart rate or cardiac
output increases in response to activity,
change in posture, while talking, when
under stress, temperature, etc.
BP follows a circadian (daily) rhythm such
that it is lowest when in deep sleep.
Hypertension

Permanently high blood pressure


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Systolic blood pressure >= 140 mmHg
Diastolic blood pressure >= 90 mmHg
Essential (primary) – no known physical
cause (90-95% of cases are of this
type)
Secondary hypertension – due to
specific cause, e.g., adrenal tumor.
Risk Factors for Essential
Hypertension
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Lack of exercise
Body weight
Salt consumption
Stress
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Age
Gender
Ethnicity (blacks at
higher risk)
Genetics
Blood

Two components
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Formed elements
Plasma
Formed elements consist of three
elements:
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
Red blood cells
Leukocytes (white blood cells)
Platelets
Formed Blood –
Red Blood Cells
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Most abundant cells
Formed in bone marrow
Contains hemoglobin – a protein that
attaches to oxygen and transports it to
the cells and tissue
Anemia is when level of red blood cells
are below normal
Leukocytes (white blood cells)
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Serve a protective function (e.g.,
destroys bacteria).
Produced in bone marrow and various
organs of the body.
Leukemia is when there is an excessive
production of white blood cells that
crowd out plasma and red blood cells.
Platelets
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Granular fragments that can clump
together to prevent blood loss at site of
cuts.
Produced by bone marrow
Hemophilia is when platelets don’t
function properly to produce clotting
and so if the person receives a cut
could bleed excessively.
Plasma
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55% of the blood is plasma
Composed of 90% water and 10%
plasma protein and other organic and
inorganic substances.
Other substances include hormones,
enzymes, waste products, vitamins,
sugars, fatty material etc.
Plasma - continued
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An important fatty substance is lipids.
Consist of:
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Cholesterol
Low and high-density lipoprotein
Triglycerides
High lipid content in the plasma can lead to
plaque build-up on arteries and lipid deposits
in arterial wall, causing hardening of the
arteries.
Disorders of the Cardiovascular
System – Hardening of Arteries
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
Atherosclerosis – deposits of cholesterol
and other substances on the arterial
wall, forming plaques that can block the
artery.
Ateriosclerosis – calcium and other
substances get deposited on the arterial
wall leading to hardening of the
plaques.
Risk Factors for Atherosclerosis
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Hypertension
High fat intake leading to hyperlipidemia
Smoking
Stress
Diabetes,
Lack of exercise
Genetics
Gender
Stress and Atherosclerosis
Coronary Artery Plaque in
Monkeys
0 .8
0 .7
Plaque
Area
(mm2)
0 .6
0 .5
0 .4
D o m in a n t
0 .3
S u b o rd in a te
0 .2
0 .1
0
S ta b le
U n sta b le
Stress and Atherosclerosis
Coronary Artery Plaque in
Monkeys
0 .8
0 .7
Plaque
Area
(mm2)
0 .6
0 .5
0 .4
D o m in a n t
0 .3
S u b o rd in a te
0 .2
0 .1
0
T re a te d
U n tre a te d
Consequences of Atherosclerosis


Angina pectoris – insufficient oxygen supply
to the heart for its need and removal of waste
products resulting in chest pain.
Myocardial infarction (heart attack) – when
there is a blockage of blood supply to an area
of the heart cutting off oxygen supply to the
tissue in the area and resulting in tissue
death
Immune System
The Immune System

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
Antigens are any substance (e.g., bacterial,
viral, fungi) that can trigger an immune
response.
Bacterial – microorganisms in the
environment. Grow rapidly and compete with
our cells for nutrients.
Fungi – organisms like mould and yeast.
Also, absorbs nutrients.
Viruses – proteins and nucleic acid. They
take over the cell and generate their own
genetic instructions.
Immune System


Immune system recognizes itself and
foreign material
Transplant success can by increased by:


Using close genetic tissue match.
Using medications that inhibit the immune
system’s attack on the foreign material.
Immune System


Allergies are immune response to
(normally) harmless substances.
Allergins are substances that trigger an
allergic response (e.g., pollen, cat
dander)
Organs of the Immune System

Lymphatic and lymphoid organs


Deploys lymphocytes
Lymphocytes


White blood cell that provides main
defense against foreign material
Produced by bone marrow
Organs of the Immune System

Lymphocytes


Form of white blood cells that provide main
defense against foreign matter
Lymphocytes originate from bone
marrow
Organs of the Immune System

Lymph Nodes




Bean-shaped spongy tissue
Largest are in the neck, arm-pit, abdomen, and
groan
Filters to capture antigens (foreign material) and
has compartments for lymphocytes.
Lymph vessels

Connects to lymph nodes and carries fluid called
lymph into the blood stream
Organs of the Immune System

Spleen




Upper left side of the abdomen
Filters antigens that the lymph vessels put
into the bloodstream
Home base for white blood cells
Removes worn out red blood cells
Soldiers of the Immune
System

Phagocytes


Two types:



Engulf and ingest antigens
Macrophages – attach to tissue and stay
there
Monocytes – circulate in the blood
Nonspecific immune processes
Specific Immune Processes



Cell-mediated immunity
Killer t-cells (CD8) – destroy foreign
tissue, cancerous cells, cells invaded by
antigens
Memory t-cells – remember previous
antigen in order to defend against
subsequent invasions.
Specific Immune Processes



Delayed hypersensitivity t-cells – involved in
delayed immune reactions. Produce
lymphokines that stimulate other t-cells to
grow, reproduce and attack.
Helper t-cells (CD4 cells) – get information of
invasions and report to spleen and lymph
nodes to stimulate lymphocytes for attack.
Suppressor t-cells – slow down or stop
immune processes.
Immune System


Antibodies – proteins produced in the
body in response to antigens. They
combine chemically with antigens to
overcome their toxic effects.
B lymphocytes – secrete antibodies
that protect body against bacterial
infection and viral infections.
Immune Response
Foreign
material
Cough
Sneeze
Phagocytes
engulf it
Interlukin-1
Th
cells
Gammainterferon
B cells
Killer
Tc cells
Why Can’t We Fight Cancer


Some cancer cells release substances
that suppress the immune response.
Some antigens may be difficult for the
immune system to recognize.
Less Than Optimal Defenses


Immune function changes during the lifespan,
increasing in childhood and decreasing in old
age.
Unhealthy lifestyles impair immune
functioning




Insufficient vitamin A or E decrease production of
lymphocytes and antibodies
Vitamin C in important in effectiveness of
phagocytes
High fat and cholesterol intake impair immune
functioning
Poor sleep impairs immune functioning
Diseases of the Immune
System

Autoimmunity Disorders





Immune response attacks its own tissue
Arthritis
Rheumatic fever
Multiple sclerosis
AIDS
Stress and the Immune
System




Stress appears to suppress the immune
response.
Killer T-cells are lower during periods of high
stress.
Adrenaline and cortisol that are released
during stress appear to increase suppressor
T-cells, decrease helper T-cells, and decrease
functioning of phagocytes and lymphocytes.
Chemicals released by our nerves suppress
immune functioning in nearby cells.
Please answer anonymously
these questions



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What is the main thing you learned from this
lecture?
What is the main question you have that wasn’t
answered?
The things the instructor did best …OR the best
things about the lecture that were?
The things the instructor did worst …OR the
worst things about the lecture that were?