BIOLOGY AND GEOLOGY 3º DE E.S.O.
Chapter 4: THE INTERACTION
1. The interaction function
The interaction function
are perceived thanks to the
which send
The receptors Stimuli
Messages to
The nervous system
Stimulus: any change that results in a change in the organism.
The interaction function
The nervous system
it produces
Responses
transmitted by
Nerve impulses
That are sent to
Effectors (muscles)
Response: any action resulting from a stimulus.
contraction of muscle cells
UNIT
4
The interaction functionit produces Responses transmitted by Hormones through Chemical reactions
that are sent to
Effectors (glands)
Response: any action resulting from a stimulus.
contraction of muscle cells secretion by a gland
6. NERVOUS COORDINATION
This communication
system controls and
coordinates functions
throughout the body and
6.1 NEURONS AND NERVOUS
IMPULSE
A
nerve
is an organ
containing a lot of
nerve cells called
neurons.
Neurons carry
electrical messages
called
impulses
throughout the
6.1 NEURONS AND NERVOUS
IMPULSE
Each neuron
Each neuron
consists of:
consists of:
The cell body.
The cell body.
Dendrites.
Dendrites.
The axon.
Cell body consists of nucleus
Cell body consists of nucleus
Dendrites consist of nerve fibers that carry impulses toward
Dendrites consist of nerve fibers that carry impulses toward
the cell body
the cell body
Axon is a single nerve fiber that carries impulses away
Axon is a single nerve fiber that carries impulses away
from the cell body
from the cell body
Myelin covers the axon (fat covering) that insulates
Myelin covers the axon (fat covering) that insulates
and maintains the axon
and maintains the axon
Nodes of Ranvier are areas where no myelin is present
Nodes of Ranvier are areas where no myelin is present
Because neurons
never touch,
chemical signals
called
neurotransmitters
must travel
through the
space called
synapse between
two neurons.
The axon of one neuron lies next
The axon of one neuron lies next
to the dendrites of another
to the dendrites of another
neuron
neuron
The spaces between them are
The spaces between them are
called synapses
called synapses
Impulses coming from one axon
Impulses coming from one axon
“jump” the synapse to get to the
“jump” the synapse to get to the
dendrite of another neuron which
dendrite of another neuron which
carry it in the right direction
carry it in the right direction
Special chemicals,
Special chemicals,
neurotransmitters, found at the
neurotransmitters, found at the
end of each neuron allow
end of each neuron allow
impulses to pass from one
impulses to pass from one
neuron to another so impulses
neuron to another so impulses
can follow many different routes
can follow many different routes
6.2 THE NERVOUS SYSTEM
This communication
system controls and
coordinates functions
throughout the body and
6.2 THE NERVOUS SYSTEM
There are two main parts:
Central nervous system (CNS): consists of
Brain
Spinal cord
Peripheral nervous system (PNS): consists of
Nerves
•
The CNS is the control center of
the body:
•
Receives information
•
Processes and coordinates
information
•
Elaborates responses
6.3 THE CENTRAL NERVOUS SYSTEM
brain
Spinal Cord
Cerebellum
Cerebrum
Brain stem: Medulla Oblongata
Cerebrum
Voluntary or conscious activities
of the body (learning, thinking)
Cerebellum
Coordinates and balances the
actions of the muscles and helps
us keep our balnce.
Brain stem:
Medulla
Oblongata
Controls involuntary actions like
blood pressure, heart rate,
breathing, and swallowing
Spinal Cord
between the brain and the rest of
The main communications link
the body. Control reflexes
Spinal Cord
• Links communication
between the brain and the rest of the body
• 31 pairs of spinal nerves branch out from the spinal cord connecting brain to body
• Reflexes = quick, automatic responses to stimuli are
processed directly in the spinal cord
Spinal Cord
Receptors in the skin send information to the spinal cord through the spinal nerves. The
nerve fibers enter the spinal cord through the sensory root. Some
fibers make synapses with other neurons and continue up to the brain. After that the response travels through the
motor root to muscles to control movement.
6.4 Peripheral Nervous
System
• Consists of nerves and associated
cells that are not part of the brain or spinal cord
• Receives information from the
environment and relays commands from the CNS to organs and glands
• Divided into two parts:
• Sensory division: transmits impulses from sense organs to the CNS
• Motor division: transmits impulses from the CNS to the muscles or glands
PNS animation (Pain receptor) :
http://pennhealth.com/encyclopedia/e m_DisplayAnimation.aspx?
Somatic System
•
Part of motor division that
Autonomic System
• Part of the motor division that regulates activities that are
automatic or involuntary (heart beat and smooth muscle in digestive
system and blood vessels)
• Two parts that have opposite effects on the organs they control:
• Sympathetic (“gas pedal”)
Concept Map
which consists of is divided into
that make up
which is divided into
Reflexes (reflex action) = quick,
automatic responses to stimuli are processed directly in the spinal cord
6.5.1 Reflex action
6.5.1 Reflex arc
•
The pathway that an
impulse travels:
• 1. from the sensory receptor
• 2. up the sensory neuron
• 3. over the synapse
• 4. to the spinal cord (interneuron)
• 5. over another synapse
• 6. back down the motor neuron
8.1 The endocrine system
• Main Function:
It releases hormones into the blood to
signal other cells to behave in certain
ways. It is a slow form of communication.
Endocrine glands
Release hormones into the bloodstream.
Hormones are chemicals released in one part of the body that travel through the bloodstream and
affect the activities of cells in other parts of the body.
Consists of:
8.1 The endocrine system
8.1 The endocrine system
The hypothalamus is
located in the
brain
and controls the
release of hormones
from the
pituitary
gland. It is an
important link
between the
endocrine and
nervous systems
.
http://www.youtube.com/watch?v=nNLsXKkLSTs
•
Functions
:
-The adrenal glands
release Adrenaline in
the body that helps
prepare for and deal
with stress.
-Also regulates kidney
function.
• Function: The Insulin
and Glycogen in the Pancreas help to keep the level of glucose in the blood stable.
• Disorders: When the
Pancreas fails to
produce or properly use Insulin, it can cause a condition known as Diabetes Mellitus.