Download ppt


Weird body facts
fly larvae helps to heal wounds quicker
long ago, some doctors noticed soldiers that had maggots
on their wounds healed quicker than those without maggots.
maggots eat the dead skin cells and bacteria. maggot
therapy (also known as maggot debridement therapy (mdt),
larval therapy, larva therapy, or larvae therapy) is the
intentional introduction of live, disinfected maggots or fly
larvae into non-healing skin or soft tissue wounds of a human
or other animal. this practice was widely used before the
discovery of antibiotics, as it serves to clean the dead tissue
within a wound in order to promote healing.
?
Sulci -fissures between
convolutions of brain
ORGANIZATION OF THE NERVOUS SYSTEM
The Nervous System
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Somatic
Autonomic
Parasympathetic
Sensory
Motor
Sympathetic
VERTEBRATE NERVOUS SYSTEM
Two divisions:
 Central nervous system (CNS)- act as a
coordinating centre (brain & spinal cord)
 Peripheral nervous system (PNS)- effectors, carry
information to and from the CNS.


Further divided into
 Somatic
– control skeletal muscle, bones & skin
 Autonomic – control internal organs of body


Sympathetic
Parasympathetic
ANATOMY OF A NERVE CELL
ANATOMY OF NERVE CELLS

Two different types of cells
 Glial
(neurological cells; non-conducting, offer
structural support and metabolism of nerve cells)
 Neurons (functional units of nervous system)
 Three
groups
Sensory Neurons
 Interneurons
 Motor Neurons


http://www.youtube.com/watch?v=FZ3401XVYww&feature=related
THREE TYPES OF NEURONS

Sensory (Afferent) Neurons




Interneurons




INPUT – from sensory organs to brain and spinal cord
Sense and relay information from environment to CNS
Located in clusters called ganglia
PROCESSING
Link neurons within body
Integrate and interpret sensory information and connect neurons to
outgoing motor neurons
Motor (Efferent) Neurons


OUTPUT
Relay information to effectors, (muscles, organs, glands; effectors as
they produce responses) away from the CNS
RELAYING THE SIGNAL
Messages move from dendrite, through the
nerve cell body, to the axon
 Axons are covered with a myelin sheath
(insulation), made by Schwann cells which
prevent loss of charged ions from nerve cells
 Areas between sections of myelin are called
nodes of Ranvier; nerve impulses jump from
one node to another, speeding up messages






All nerve fibres found within peripheral nervous system
contain a thin membrane called neurilemma which
surrounds axon
Neurilemma promotes regeneration of damaged axons
Not all nerve cells contain neurilemma and a myelin
sheath
Nerves containing mylenated fibres and neurilemma
called white matter due to whitish appearance
Grey matter lack myelin sheath and neurilemma and do
not regenerate after injury
MULTIPLE SCLEROSIS – MYELIN SHEATH
DESTRUCTION
THE REFLEX ARC
The simplest neural circuit is the reflex arc.
Reflexes are involuntary. No brain coordination
is used. 5 essential components:
 Receptor
 Sensory neuron
 Interneuron (in spinal cord)
 Motor neuron
 Effector

REFLEX ARC

http://www.youtube.com/watch?v=Y5nj3ZfeYDQ
HOMEWORK
Complete Move Fast! Poster lab write-up
 Read pg 354-360

 Q’s
#7, 9, & 10
ELECTROCHEMICAL IMPULSE





The Electrocardiogram (ECG) is used to diagnose heart
problems.
The Electroencephalograph (EEG) is used to measure
brain-wave activity
Action Potential – the voltage difference across a nerve
cell membrane when the nerve is excited
Resting Potential – voltage difference across a nerve
cell membrane during the resting stage (usually
negative)
Unlike most cells, neurons have a rich supply of positive
and negative ions inside and outside the cell
A sodiumpotassium pump
maintains resting
membrane
potential after
ions “leak” down
their
concentration
gradient
- 3 Na+ ions are
actively pumped
out while 2 K+
ions are pumped
in.
ACTION POTENTIAL
• action potentials – the movement of an electrical
impulse along the plasma membrane of an axon.
•
• that are abrupt, pulse-like changes in the membrane
potential that last a few ten thousandths of a second.
• Action potentials can be divided into three phases:
the resting or polarized state, depolarization, and
repolarization
• The amplitude of an action potential is nearly
constant and is not related to the size of the stimulus,
so action potentials are all-or-nothing events.
Depolarization must be completed and the
nerve repolarized before the next action
potential can be conducted as nerves
conducting an impulse cannot be activated
until the condition of the resting membrane is
restored
 This time is called the refractory period (usually
1-10 ms)


Action Potential



ION GATES CONTROL THE MOVEMENT OF IONS ACROSS
THE CELL MEMBRANE.
The separation of electrical charges by the “polarized
membrane” has the ability to do work, expressed in
millivolts (mV).
Upon excitation, nerve cell membrane becomes more
permeable to Na than K




Na ions rush into cell causing depolarization
Once voltage inside cell is +ve, then Na gates close
The sodium-potassium pump located in cell membrane
restores condition of resting membrane by transporting
Na+ ions out of the neuron while moving potassium ions
inside the neuron in a ration of 3 Na+: 2K+ ions
ATP fuels the pump
Saltatory Conduction
ALL OR NONE RESPONSE


A nerve or muscle fibre
responds completely or
not to a stimulus.
Nerves have a threshold
level…minimum level of
a stimulus required to
produce a response.
HOMEWORK
•
Watch Nerve Impulse Animation and make
notes
•
Synapses - Mouse Party Task: Due Friday June 3rd
Go
to:http://learn.genetics.utah.edu/content/addiction/dr
ugs/mouse.html
– Explore the effects of any three of the following
drugs on brain function in mice:
•
•
–
Heroine, ecstasy, marijuana, methamphetamine, alcohol,
cocaine, LSD
In your own words, explain how the drug affects
brain function and draw a labeled diagram of the
synapse depicting the effects for each drug
Terminology
• Synapse
– Region at which neurons come nearly together to communicate.
(neuron or effector organ)
• Synaptic Cleft
– Gap between neurons (at a synapse)
– Impulses can not propagate across a cleft
• Synaptic Vesicle
– Packets of neurotransmitter in presynaptic neuron
• Presynaptic Neuron
– Neuron sending a signal (before the synapse)
• Postsynaptic Neuron
– Neuron receiving a signal (after the synapse)
Neurotransmitters
5 general criteria:
1) synthesized and released by neurons
2) released at the nerve terminal in a 'chemically identifiable' form
3) the chemical should reproduce the activity of the presynaptic neuron
4) can be blocked by competitive antagonist based on concentration
5) active mechanisms to stop the function of the neurotransmitter
Classical transmitters are small molecules (often amino acid based)
Non-classical transmitters can be peptides or even gasses
5 Steps of Neurotransmission
1) synthesis of the neurotransmitter
precursors and enzymes should be in
the correct place
2) storage of neurotransmitter OR
precursor
often stored in presynaptic vesicles
5 Steps of Neurotransmission
3) release of the neurotransmitter
generally by vesicle fusion
4) binding to target receptor
ionotropic receptors open ion
channels
metabotropic receptors modulate
other signals
5 Steps of Neurotransmission
5) termination of the signal
active termination caused by
reuptake or chemical breakdown
*For e.g. acetylcholine is broken
down by . . .
passive termination uses diffusion
Types of Neurotransmitters
Acetylcholine
+ muscles, learning, memory
Serotonin (a derivative
of tryptophan)
Norepinephrine (aka
noradrenaline)
Dopamine
Endorphins
+ sleep, relaxation, self esteem,
too little = depression, perception
+ stress and fight/flight response,
sympathetic NS:+BP & heart rate
+ prolactin (milk production),
involved in pleasure, movement
(-) pain, involved in pleasure
GABA (gamma
aminobutyric acid)
Glutamate
(-) anxiety, too little in parts of
brain can lead to epilepsy
Most common NT, memory, toxic
“FLIGHT OR FIGHT RESPONSE”
Sympathetic component prepares body for
stress [neurotransmitter used=norepinephrine]
•Diverts blood from internal organs to skeletal
muscles, heart & brain
Parasympathetic brings things back to normal
[neurotransmitter used=acetylcholine]
•Work in conjunction/opposition to each other
–Ex. “on” / “off” switches
You come across a bear on your walk to
school…what happens?
•
•
•
•
•
•
Sympathetic nervous system does what?
Increases heart rate
Increases breathing rate
Dilates bronchioles
Dilates pupils
Inhibits digestion
Acetylcholine – make post-synaptic membrane
permeable to Na+
 Cholinesterase (enzyme)…breaks down
Acetyltcholine...prevents constant depolarization

CENTRAL NERVOUS SYSTEM


concentrated in the anterior portion of most animals
brain is covered by meninges

three-layer protective membrane forms the blood/brain
barrier


cerebrospinal fluid surrounds brain and spinal cord

acts as a shock absorber and a transportation medium of
materials


determines which chemicals will reach the brain
carries nutrients to brain cells
relays wastes from cells to blood
THE SPINAL CORD

carries sensory nerve messages from receptors of
brain and relays motor nerve messages to
muscles
 organs
 glands

interneurons are organized into nerve tracts which
connect the spinal cord with the brain
 dorsal nerve tract brings sensory info into spinal
cord
 ventral nerve tract carries motor info from spinal
cord to peripheral muscles, organs, and glands

THE BRAIN

comprised of three main regions
 forebrain
 midbrain
 Hindbrain
FOREBRAIN

contains paired olfactory lobes


thalamus (below the cerebrum)






relay, consciousness, pain
hypothalamus (below thalamus) (temperature, water,
hunger, thirst, sex drive);


receive info about smells
direct connection between hypothalamus and pituitary connects
nervous system with endocrine system
cerebrum (2 hemispheres connected by the corpus callosum,
surrounded by cerebral cortex and divided into 4 lobes:
frontal- voluntary muscles, walking, speech, personality, intellect
parietal- touch, temperature awareness, emotion, interpreting speech
occipital- vision and interpreting visual information
temporal – vision, hearing, memory, interpretation of sensory
information
THE BRAIN
http://www.youtube.com/watch?v=YpAe3mk
1koQ&feature=related
MIDBRAIN
relays information to sensory areas
(connective)
 temporal- vision and hearing, linked to memory
 Associative cortex: conceptualization, planning,
contemplation, memory.
 Motor cortex: voluntary movement of skeletal
muscles.
 Sensory cortex: vision, hearing, smell.

HINDBRAIN
Primitive, controls breathing, heart rate, blood
pressure.
 Main regions of hindbrain



cerebellum, pons, and medulla oblongata
Cerebellum
located immediately beneath two cerebral hemispheres
 largest section of hindbrain
 deals with coordination and muscle control.


Pons acts as a bridge.

Passes information between two regions of cerebellum
and between cerebellum and medulla


Medulla oblongata
Acts as connection between peripheral and central
nervous system
 controls involuntary muscle action

 diaphragm,

heart rate, blood vessel dilation etc.
also acts as coordinating centre for autonomic nervous
system.
AUTONOMIC NERVOUS SYSTEM
Sympathetic NS – prepares body for stress
 Parasympathetic NS – return body to normal
 Check out table

NATURAL PAINKILLERS
Endorphins bond to sites on pain receptor
ganglia (Substania Ganglia…SG).
 Opiates simulate natural endorphins (p. 437)
 Heroin, codeine, morphine etc…must continue
to take in order to keep working (addiction!)

HOMEWORK

Case Study
Quick quiz
 Quizzes on a range of bio topics :)
 Another good quiz
 A virtual body
