Transcript cerebrum cerebellum brain stem pituitary gland hypothalamus

Nervous System
Nervous System
• The entire nervous system is composed of
nerves.
Nerves
While variable in size and
shape, all neurons have three
parts.
- Dendrites receive information
from another cell and transmit
the message to the cell body.
- The cell body contains the
nucleus, mitochondria and
other organelles typical of
eukaryotic cells.
- The axon conducts
messages away from the cell
body.
How do nerves work?
•
Neurons send messages electrochemically. This means that chemicals
cause an electrical signal.
•
Neurons must reach the threshold before a full action potential is fired. This
is an “all or none” principal. (The neuron either responds or it doesn’t).
How do nerves work?
• For communication between neurons to occur, an electrical impulse
must travel down an axon to the synaptic terminal.
• Communication of information between neurons is
accomplished by movement of chemicals across a
small gap called the synapse. Chemicals, called
neurotransmitters, are released from one neuron at
the presynaptic nerve terminal. Neurotransmitters
then cross the synapse where they may be accepted
by the next neuron at a specialized site called a
receptor.
Nervous System
Two major Systems
- Central Nervous
(brain and spinal cord)
- Peripheral Nervous
(all else not included in CNS,
mainly nerves)
Central Nervous System (CNS)
•
Brain
– composed of five parts:
•
•
•
•
•
•
cerebrum
cerebellum
brain stem
pituitary gland
hypothalamus
Spinal Cord
– The spinal cord runs along the dorsal side of the
body and links the brain to the rest of the body.
Vertebrates have their spinal cords encased in a
series of (usually) bony vertebrae that comprise the
vertebral column.
Cerebrum
• The cerebrum makes up 85% of the
brain's weight.
• The cerebrum is the thinking part of the
brain and it controls your voluntary
muscles.
Cerebellum
• Controls balance, movement, and
coordination (how your muscles work
together)
Brain stem
• In charge of all the functions your body
needs to stay alive, like breathing air,
digesting food, and circulating blood.
• Also, control your involuntary muscles
(work automatically) such as the heart and
stomach.
Pituitary gland
• Produce and release hormones into your
body.
• Regulates metabolism - breathing,
digesting food, and moving your blood
around.
Hypothalamus
• Regulates body temperature.
(about 98.6° Fahrenheit or 37° Celsius).
Spinal Cord
• The spinal cord is the main pathway
for information connecting the brain
and peripheral nervous system.
• The human spinal cord is protected by
the bony spinal column shown to the
left. The spinal column is made up of
bones called vertebrae. Although the
spinal column is somewhat flexible,
some of the vertebrae in the lower
parts of the spinal column become
fused.
Peripheral Nervous System (stuff
outside of the brain and spinal cord)
• Somatic NS
– You control most of this.
• Autonomic NS
– Controls organs
Somatic NS
• Responsible for coordinating the body
movements, and also for receiving
external stimuli.
• Regulates activities that are under
conscious control.
Autonomic Nervous System
• Sympathetic (Fight or flight)
• Parasympathetic (Rest and digest)
Sympathetic Nervous System
It is a nice, sunny day...you
are taking a nice walk in the
park. Suddenly, an angry
bear appears in your path.
Do you stay and fight OR do
you turn and run away?
These are "Fight or Flight"
responses. In these types of
situations, your sympathetic
nervous system is called into
action - it uses energy - your
blood pressure increases,
your heart beats faster, and
digestion slows down.
Parasympathetic
It is a nice, sunny day...you are
taking a nice walk in the park.
This time, however, you decide
to relax in comfortable chair
that you have brought along.
This calls for "Rest and Digest"
responses. Now is the time for
the parasympathetic nervous
to work to save energy - your
blood pressure decreases,
your heart beats slower, and
digestion can start.
The Autonomic Nervous System
Structure
Sympathetic Stimulation
Parasympathetic Stimulation
Iris (eye muscle)
Pupil dilation
Pupil constriction
Salivary Glands
Saliva production reduced
Saliva production increased
Oral/Nasal
Mucosa
Mucus production reduced
Mucus production increased
Heart
Heart rate and force
increased
Heart rate and force decreased
Lung
Bronchial muscle relaxed
Bronchial muscle contracted
Stomach
Peristalsis reduced
Gastric juice secreted; motility
increased
Small Intestine
Motility reduced
Digestion increased
Large Intestine
Motility reduced
Secretions and motility increased
Liver
Increased conversion of
glycogen to glucose
Kidney
Decreased urine secretion
Adrenal medulla
Norepinephrine and
epinephrine secreted
Bladder
Wall relaxed
Sphincter closed
Increased urine secretion
Wall contracted
Sphincter relaxed
Jamie McMullen can’t read thiss!
• Aoccdrnig to a rscheearch as an Elingsh
uinuervtisy, it deosn’t matter In what order
the ltteers in a word are, the only iprmoetnt
tihng is that frist and lsat ltteer is at the
rghit pclae. The rset can be a total mses
and you can still raed it wouthit porbelm.
Tihs is bcuseae we do not raed ervey
lteter by it slef but the word as a wlohe.
• Weird, isn’t it?