Transcript Human Body Systems - Whitehall District Schools

Human Body Systems
The Nervous
System
Overview of organization
Cells
Tissues
Organs
Organ Systems
• Tissues are groups of similar cells that perform
a particular function
• Muscle, Epithelial, Nervous, and Connective
tissues
• The human body is composed of 11 organ
systems.
Homeostasis
• The body’s ability to physiologically maintain a
stable, internal condition within narrow limits
Neurons
• The basic structural unit
of the nervous system
that transmits impulses
throughout your body
• 3 Types:
– Sensory
– Motor
– Interneuron
Nerve Impulses
• Electrical impulse due to a chemical change along
the membrane of a neuron
• Resting Potential: electrical potential of the
neural membrane (70mV), created by Na/K
pump, creates charge difference
• Threshold: Minimum level of stimulus to activate
a neuron, a neuron is an all or nothing response
• The Moving Impulse: a domino effect, selfpropagating
Synapse
• Is defined as a gap that separates two neurons
(one’s axon from another’s dendrite)
• When the AP reaches the axon terminal,
synaptic vesicles release neurotransmitters.
• The neurotransmitters then travel across the
cleft and bind to the post synaptic receptor.
• This causes depolarization, and the AP
continues
• http://www.youtube.com/watch?v=tqvJZ1STL
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• http://www.youtube.com/watch?v=xysT9JD7i
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CNS
• Consists of:
– Brain: control center of the body
– Spinal Cord: 31 pairs of spinal nerves that relay
messages
– Meninges: Three protective layers of connective
tissue (Dura matter, Pia Matter, Arachnoid)
– Cerebrospinal fluid: acts as shock absorber to
protect the CNS, also allows exchange of nutrients
PARTS OF THE BRAIN!
• Cerebrum: largest portion of brain; two
hemispheres connected by corpus collusom;
each hemisphere is divided into lobes named
after the part of the skull that covers them.
• Cerebellum: Back of skull, coordinates and
balances action of muscles
Brain (cont’d)
• Brain Stem: Below cerebellum; consists of
pons, and MO. Controls involuntary functions
• Hypothalamus: Controls hunger, thirst, body
temp, anger, and fatigue.
• Thalamus: receives info from sense organs and
relays them to proper region of cortex.
Spinal Cord
• Relay station protected by vertebrae.
– What is a reflex?
• A quick automatic response to a stimulus.
• The body responds before the brain is
notified.
PNS
• 2 Types:
– Somatic: directs the voluntary contraction of
skeletal muscle
– Autonomic: controls involuntary muscles and
organs.
• Sympathetic: fight or flight response
• Parasympathetic: digestive functions
The Senses
• Sensory Receptor: neurons that react directly
to stimuli from the environment
– Pain: transmits pain from injuries & disease
– Thermo: nerve endings that sense temp
– Mechano: touch and pressure
– Chemo: sense chemicals, monitors taste and smell
– Photo: sense of light/found in retina
5 Senses
• Vision
• Hearing
• Smell
• Taste
• Touch