Interaction in living things: the nervous system

Unit 08 Interaction in living things

7
Unit 08
Interaction in
living things
2° PAI
Macarena Arechavaleta JaniniUnit 8 Interaction in living things

1. Interacting with the Environment Living and non- Living things
2. Stimuli
   a) Physical stimuli
   b) Quemical stimuli
3. Receptors
4. Coordination in animals
5. The Nervous System
6. Nerve Cells: neurons and neuroglia
7. Nerve impulses and synapses
8. Central nervous system: Brain and spinal Cord
9. PNS: The autonomic nervous system: parasympathetic and sympathetic
10. PNS: Somatic Nervous System: reflexes and instincs
11. Plant responses: tropisms and nastic movements
12. Responses in unicelular organisms
13. Endocrine system

· All living things interact with their environment. This includes both the
surroundings and the organisms that live in it.
The environment is always changing. To be able to survive and reproduce, living
organisms must detect these changes and respond to them accordingly.

1. Interacting with the Environment

· Through interaction with the environment, living organisms detect changes
around and inside them and respond appropriately. The response of an organism
to stimuli occurs in three different stages:
A stimulus is detected by structures or organs called receptors.
v The stimulus is relayed to coordination systems. These systems interpret the
signal and produce a response.
v The organism responds by means of organs or structures called effectors.· Physical stimuli:

2. Stimuli

changes that occur in an
organism's external and
internal environment, which
the organism can detect.
v Light.
O
v Electrical.
v Gravitational.
C
v Mechanical.
v Thermal.
v Magnetic.
· Chemical stimuliLight. Stimuli caused by light
radiation. Visible light is the light
radiation that humans perceive
through their eyes.
Physical stimuli
Electrical. Stimuli caused by
electrical phenomena. The elec-
tricity generated by animal muscles
and nerves is a stimulus that can be
detected by some predators.
Gravitational. Gravity is a
stimulus for many living organ-
isms. The Earth's gravitational field
directs plant growth.
Mechanical. Changes in pres-
sure, contact forces, and vibra-
tions in a medium. Sound is a
vibration that propagates through
a medium and is therefore consid-
ered a mechanical stimulus.
Thermal. Stimuli related to
changes in temperature. Living
organisms and objects give off
more or less heat, depending on
the temperature they are at.
Magnetic. Stimuli caused by
magnetic phenomena. The Earth's
magnetic field points in certain direc-
tions, and some living organisms use
it to orient themselves.
··· Chemical stimuli ....
Chemical. Stimuli caused by
the presence of certain sub-
stances, either dissolved in air or
water or a part of solids. The pres-
ence of certain substances in the air
can be detected by the smell.

3. Receptors

Receptors may also have different degrees of complexity in
living organisms:
· The receptors in unicellular organisms are molecules or cell
organelles.
· The receptors in plants are cells that do not form specialized
organs.
· The receptors in animals are complex structures known as
sensory organsReceptors in animals
Interoceptors
Interoceptors-or internal receptors-
collect information about the human provide information from the body's outside
body's internal conditions. These receptors,
environment and are therefore located on
the surface of the body. Sense organs are
exteroceptors.
located in the internal environment, mostly
respond to chemical stimuli.
Oxygen levels in the blood is detected
by interoceptors.
Exteroceptors
Exteroceptors-or external receptors-
The eyes contain receptors that detect
light stimuli from the external envi-
ronment.
Propioceptors
Proprioceptors provide information concern-
ing body position and body motion, as well
as on the relative position of body parts. These
receptors are located in the inner ear's ves-
tibule and the locomotive system (muscles,
tendons, and articulations), respectively.
Propioceptors inform about the relative
position and condition of each of the body's
muscles.Receptors
Stimuli
Sense organs
Sense(s)
sound
ears
hearing
and
balance
mechanoreceptors
pressure
contact
skin
touch

3. Receptors Classification

Can be classified based
on the stimulus they
detect
photoreceptors
light
eyes
sight
thermoreceptors
changes in
temperature
skin
-
touch
nose
chemoreceptors
chemical
substances
tongue
U
smell
taste

4. Coordination in animals

Multicellular organisms, especially animals, need all their cells, tissues, and organs to
be properly organized and coordinated. Only this way can they respond to changes in
their environment and inside them.
The role of coordinating systems is to:
v Receive the information collected by the receptors
(cells and organs).
v Interpret the information received and produce an
appropriate response.
v Activate the organs required to perform this responseCoordination
spinal cord
brain
nerves
The nervous system is a network of specialized
cells, neurons, that manage information by
means of electric impulses.
pineal gland
hypothalamus
adrenal glands
pituitary gland
parathyroid gland
thyroid gland
testes
(male)
pancreas
The endocrine system is performed by
hormones, produced by cells or specialized
organs-they act as chemical signals and trigger
slow responses in other cells, tissues, and organs,
but they have a longer lasting effect.

4. Animal interaction and coordination

Interaction is the response with effector organs to stimuli
Stimuli
Sensory
receptors
Changes in
environment
that affect the
body
Found in sense
organs, receive
stimuli
Nervous
system
Information
processor.
Receives
information,
initiates and
coordinates
response
Effector organs
Endocrine
system
(secretory
responses) /
musculoskeletal
system (motor
responses)

5. The Nervous System

· Receives and processes the information collected by receptors,
and which coordinates the action of the organs that need to
produce a quick response.
Made up of nerve cells: These cells are organized into tissues
and specialized organs.
· Allows animals to respond rapidly-a characteristic lacked by all
other multicellular organisms, such as plants, fungi, and algaeThe nervous system in animals
Cerebrum
Brain
Cerebellum
Central nervous
system
Spinal cord
Brain stem
Nervous
system
Sympathetic
Autonomic
nervous system
Parasympathetic
Peripheral
nervous system
Sensory nerves
Somatic nervous
system
Motor nerves

6. Nerve cells

· Nervous tissue is made up of two types of cells: Neurons and neuroglia
· Neurons
· Highly specialised cells.
· Star-shaped cells unable to divide.
· Initiate and transmit nerve impulses.
· Made up of
· Soma (1)
· Dendrites (2)
· Axon (3)
Soma
Dendrites
-2
1
3
AxonNeurons
· The soma or body of a neuron contains the nucleus.
· The axon is the longest extension of the cell body. It is the only extension
that carries outgoing impulses-that is, impulses traveling to other neurons
or effectors.
· Dendrites are short protrusions that generally transmit incoming nerve
impulses-that is, signals that reach the neuron from other neurons.
-
Soma
Axon
Dendrite

6. Neuroglia Nerve cells

Astrocytes
. Neuroglia: Located between neurons, they support, nourish and protect
them.
1
· Astrocytes (1), nurture neurons, remove neurotransmitters
· Oligodendrocytes (2), wrap around several axons, form an
insulating layer called the myelin sheath.
· Schwann cells (3), wrap around a part of one axon, form an
insulating layer called the myelin sheath.
2
O
Schwann cells
O
Oligodendrocytes
3Nerve cells
under the
electronic
microscope

7. Nerve impulses and synapses

· Synapses are structures that connect the axon of a neuron with another
neuron or effector.
· The nerve impulse at the axon ending causes the release of
neurotransmitters, substances that relay impulses between neighboring
cells
VESICLES
AXON
DENDRITE
NEUROTRANSMITTERS
RECEPTORS
SYNAPSEFirst neuron
Direction of
nerve impulse

7. Nerve impulses and synapses

Nerve impulse
generated in the
second neuron
Second neuron
Synaptic vesicle
with
neurotransmitters
0
0
Receptors
Neurotransmitters

8. Central nervous system (CNS)

Brain is protected by the skull
and it has the meninges for
further protection
skull
skin
arachnoid
mater
brain
dura mater
spinal
cord
pia mater
spinal column
skull
Cerebrum
Main function: receive and process information relayed by the
receptors and produce the appropriate responses.
Cerebellum
Brain Stem

8.1. Brain

Cerebrum
Cerebellum
Brainstem

8.2. The spinal cord

· Connected to brain stem.
· Extends down the back of the body, protected by
spinal column formed by vertebrae.
· Two functions
· Conduit function: takes information from
sense organs to brain and response from brain
to effector organs (muscles).
· Reflex function: initiates involuntary motor
responses.
Spinal nerve

9. PNS: The autonomic nervous system

Subdivided into
Sympathetic nervous system
Prepares body for emergency, react to stress, fear, etc ... , increases
energy expenditure.
Dilates pupils, increases heartbeat, inhibits activity of digestive
system.
Parasympathetic nervous system
Associated with situations of rest and calm, decreases energy
expenditure.
Activates digestive system, slows heartbeat.The autonomic nervous system
constrict pupils
dilate pupils
stimulate
saliva
inhibit
saliva
PARASYMPATHETIC
slow
heartbeat
increase
heartbeat
NERVOUS SYSTEM
constrict
airways
relax
airways
stimulate stomach
activity
inhibit stomach
activity
inhibitrelease
of glucose
stimulate release of
glucose
contract
bladder
relax
bladder
SYMPATHETIC
NERVOUS SYSTEM

10. PNS: Somatic Nervous System

· This part is formed of:
· Sensory nerves: connect the sense organs to the nerve centres.
· Motor nerves: connect the nerve centres to the skeletal muscles.
Reflexes are automatic, involun-
tary, and instantaneous responses
coordinated by the nervous system.
They do not travel to the brain to be
processed.
Pain receptors on the skin detect
a stimulus and send an electrical
signal up the sensory nerves and to
the spinal cord.
" It controls
Instincts are complex responses
that require a long lasting action
on the part of the animal, who acts
driven by a need caused by certain
stimuli.
Newly-hatched sea turtles in-
stinctively drag themselves to-
wards the sea.