The Nervous
System
Neurons
• A neuron consists of two major parts:
Cell Body
The central cell body contains the neuron's nucleus, associated cytoplasm, and
other organelles.
Nerve Processes
Nerve processes are "finger-like" projections from the cell body that are able to
conduct and transmit signals. There are two types:
Axons - typically carry signals away from the cell body. Axons are covered with a
lipid layer known as the myelin sheath , which insulates the axon.
Dendrites - typically carry signals toward the cell body.
Neurons usually have one axon (can be branched however). Axons usually
terminate at a synapse through which the signal is sent to the next cell, most
often through a dendrite.
Unlike axons, dendrites are usually more numerous, shorter and more branched.
Structure of the Nervous System
• The nervous system is divided into the peripheral nervous system
(PNS) and the central nervous system (CNS)
The PNS consists of
sensory neurons running from stimulus receptors that inform the CNS of
the stimuli
motor neurons running from the CNS to the muscles and glands - called
effectors - that take action.
The peripheral nervous system is subdivided into the sensory-somatic
nervous system (control movement of skeletal muscles) and the
autonomic nervous system (further divided into parasympathetic &
sympathetic system)
The CNS consists of
the spinal cord the brain
PERIPHERAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM
The Circulatory System
Transportation system by which
oxygen and nutrients reach the
body's cells, and waste materials
are carried away.
Parts of the Circulatory System
• Divided into three major parts:
– The Heart
– The Blood
– The Blood Vessels
The Blood Vessels
• The cardiovascular system has three types of
blood vessels:
• Arteries (and arterioles) – carry blood away
from the heart
• Capillaries – where nutrient and gas
exchange occur
• Veins (and venules) – carry blood toward the
heart.
Circulation
• Travels through pulmonary arteries to lungs
where it gets fresh oxygen and becomes bright
red
• Blood from lungs through pulmonary veins
back to the heart's left side pump
• Pumped out into the body
The Heart
•
•
•
•
•
Size of your fist
Thick muscular walls
Divided into two pumps
Each pump has two chambers
Upper chamber - atrium receives blood
coming in from the veins
• Lower chamber - ventricle squeezes blood out
into the arteries
The Immune System
• Lymphatic system
• Defence system
• Inside your body there is an
amazing protection
mechanism called the
immune system. It is
designed to defend you
against millions of bacteria,
microbes, viruses, toxins
and parasites (pathogens)
that would love to invade
your body
THE LYMPHATIC SYSTEM
• A network of vessels and nodes throughout
the body
• Lymph is a pale, yellow interstitial fluid
(similar to blood plasma)
LYMPH
• Lymph serves to maintain fluid balance in the
body
• Lymph nodes contain lymphocytes and
macrophages (phagocytic monocytes) which
serve to trap & destroy bacteria
LYMPH NODES