Weird body facts

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fly larvae helps to heal wounds quickerlong
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.

• Weird body facts

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• ?

Sulci -fissures between convolutions of brain
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Organization of the nervous system
The Nervous System
Central Nervous System
Peripheral Nervous System
Brain
Spinal Cord
Somatic
Autonomic
Parasympathetic
Sensory
Motor
Sympathetic
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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

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Anatomy of a nerve cell
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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?vFZ3401XVYwwfeature
  related

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Three types of neurons

• Sensory (Afferent) Neurons
• INPUT from sensory organs to brain and spinal
  cord
• Sense and relay information from environment to
  CNS
• Located in clusters called ganglia
•  
• Interneurons
• 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

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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

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• 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

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Multiple sclerosis myelin sheath destruction
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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

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REFLEX ARC
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• http//www.youtube.com/watch?vY5nj3ZfeYDQ

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Homework

• Complete Move Fast! Poster lab write-up
• Read pg 354-360
• Qs 7, 9, 10

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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

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A sodium-potassium 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.
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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.

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• 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)
•  

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Action Potential
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• 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

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Saltatory Conduction
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All or none response

• A nerve or muscle fibre responds completely or
  not to a stimulus.
• Nerves have a threshold levelminimum level of a
  stimulus required to produce a response.

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Homework

• Watch Nerve Impulse Animation and make notes
• Synapses - Mouse Party Task Due Friday June 3rd
• Go tohttp//learn.genetics.utah.edu/content/addic
  tion/drugs/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

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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)

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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
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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
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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
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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
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Types of Neurotransmitters
Acetylcholine muscles, learning, memory
Serotonin (a derivative of tryptophan) sleep, relaxation, self esteem, too little depression, perception
Norepinephrine (aka noradrenaline) stress and fight/flight response, sympathetic NSBP heart rate
Dopamine prolactin (milk production), involved in pleasure, movement
Endorphins (-) pain, involved in pleasure
GABA (gamma aminobutyric acid) (-) anxiety, too little in parts of brain can lead to epilepsy
Glutamate Most common NT, memory, toxic
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FLIGHT OR FIGHT RESPONSE

• Sympathetic component prepares body for stress
  neurotransmitter usednorepinephrine
• Diverts blood from internal organs to skeletal
  muscles, heart brain
• Parasympathetic brings things back to normal
  neurotransmitter usedacetylcholine
• Work in conjunction/opposition to each other
• Ex. on / off switches

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You come across a bear on your walk to
schoolwhat happens?

• Sympathetic nervous system does what?
• Increases heart rate
• Increases breathing rate
• Dilates bronchioles
• Dilates pupils
• Inhibits digestion

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• Acetylcholine make post-synaptic membrane
  permeable to Na
• Cholinesterase (enzyme)breaks down
  Acetyltcholine...prevents constant depolarization

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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
• determines which chemicals will reach the brain
• cerebrospinal fluid surrounds brain and spinal
  cord
• acts as a shock absorber and a transportation
  medium of materials
• carries nutrients to brain cells
• relays wastes from cells to blood

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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

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The Brain

• comprised of three main regions
• forebrain
• midbrain
• Hindbrain

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Forebrain

• contains paired olfactory lobes
• receive info about smells
• thalamus (below the cerebrum)
• relay, consciousness, pain
• hypothalamus (below thalamus) (temperature,
  water, hunger, thirst, sex drive)
• 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

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The Brain
http//www.youtube.com/watch?vYpAe3mk1koQfeature
related
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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.

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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.

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• 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.

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Autonomic nervous system

• Sympathetic NS prepares body for stress
• Parasympathetic NS return body to normal
• Check out table

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Natural Painkillers

• Endorphins bond to sites on pain receptor ganglia
  (Substania GangliaSG).
• Opiates simulate natural endorphins (p. 437)
• Heroin, codeine, morphine etcmust continue to
  take in order to keep working (addiction!)

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HomeWork

• Case Study

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• Quick quiz
• Quizzes on a range of bio topics )
• Another good quiz
• A virtual body