Transcript The Brain and the Senses

THE BRAIN AND THE
SENSES
SECTIONS 35-2 and 35-3
What were the divisions of the nervous
system?
• Central Nervous System
a. Brain and Spinal Cord
b. Interprets all information from sensory
nerves and sends responses to the motor
nerves.
• Peripheral Nervous System
a. Sensory nerves – 5 senses, picks up stimuli
and sends to CNS.
b. Motor nerves – voluntary or involuntary,
carries out response sent by CNS.
Neuron types: Sensory,
Interneurons, Motor
The Brain
• Consists of mainly interneurons
• Five main structures:
1. Cerebrum – largest section, intelligence, learning and
judgment. All voluntary activities.
2. Cerebellum – coordination of voluntary
movements.
3. Brain Stem – controls vital functions for life
4. Thalamus – Relay station for incoming sensory info.
5. Hypothalamus – Controls hunger, thirst, fatigue, body
temperature.
Comparing Human, Dog and Rat Brains
Cerebrum
• Two hemispheres
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connected by the corpus
callosum
Four Lobes:
Frontal – movement,
problem solving, rational,
personality
Parietal – sensations and
perceptions
Occipital – vision
Temporal – hearing,
language, memory
Functions of the Cerebrum
Brain Stem
Three sections:
1. Midbrain
2. Pons
3. Medulla Oblongata
–regulates heart
rate, blood
pressure,
respiration,
coughing, sneezing,
vomiting,
swallowing
Spinal Cord
• Thick rope of interneurons
• Main communication line to brain
• 31 pairs of spinal nerves
• Herniated disc – swelling of
intervertebral discs, pinches spinal
nerves
Paralysis is when movement in
lost. Depends on where the
cord/nerve is injured.
Reflexes
Rapid, automatic
responses to specific
stimuli.
Their purpose is to
preserve homeostasis.
Only a few neurons are
needed.
Why do doctor’s test
reflexes?
What is the advantage
of having reflexes?
THE SENSES
Section 35-4
The Senses
• Part of the PNS – sensory division
• Five types of sensory receptors:
1. Pain receptor
2. Thermoreceptor
3. Mechanoreceptor
4. Chemoreceptor
5. Photoreceptor
• 5 organs for sensory perceptions
Where in the body are these receptors located and what
type of stimulus do they respond to?
The Skin
1. Touch and
Pressure
(mechanoreceptors)
- Light and strong
receptors
2. Temperature
(thermoreceptors)
- Warm and cold free
nerve endings
3. Pain Receptors
(nociceptors)
- Respond to all types of
stimuli
The Eye
• Rods and cones are the
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photoreceptor cells
Located in the retina
Rods – peripheral and low
light vision
Cones – color vision and
greatest acuity
Optic nerve sends signals
to brain; no photoreceptors
Where are all the parts of the
eye? Their functions?
The Ear
• Mechanoreceptors are ciliated
cells
• Function: hearing and balance
• Hearing comes from cochlea
- vibrations in air are conducted
to the: tympanum to ossicles to
cochlea to auditory nerve
to brain
• Balance come from semicircular canals
- bending or rotating of head
moves fluid in canals
Eustachian tube –
equalizes pressure,
connects with throat
Smelling
Chemoreceptors – stimulated by chemicals
Olfactory cells – sensory cells for smell
Low threshold (only a few molecules needed to detect)
Watery mucus lines cells to act as solvent.
Olfactory bulb sends impulses to olfactory cortex region
of brain.
• Anosmia – loss of sense of smell
• Helps with taste perception.
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Taste
• Chemoreceptors – picks up chemical
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stimuli
Molecules must be dissolved in a solvent
to activate receptors.
Saliva is the solvent!
Taste receptors are called “gustatory
cells”
Gustatory cells found in taste buds all
over tongue/mouth
• So, a single taste bud has many gustatory cells.
• 5 main tastes: salty, sweet, sour, bitter,
umami