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Copy of AP Bio- Physiology 8: Sensation, Integration, Response

8 of 11 of my Physiology Unit. Image Credits: Biology (Campbell) 9th edition, copyright Pearson 2011, & The Internet. Provided under the terms of a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. By David Knuffke.
by

Jed Doyle

on 18 February 2014

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Transcript of Copy of AP Bio- Physiology 8: Sensation, Integration, Response

Sensation
Integration
Response
What is Sense?
Touch
Sound
Sight
Chemicals
Other Senses
How To Respond?
Muscle Structure
Human Skeleton
Muscle Function
Other Skeletons
Movement
The Nervous System
The Brain
Function
Structure
?
Big Questions:
How do nervous systems help animals coordinate and control their physiology?

How is the structure of the brain related to its functions?

Why do most responses in animals rely upon the skeletal/muscular system?
Compare the major sensory apparati used by mammals and other animals.

Explain the relationships between the major divisions of the mammalian nervous system.

Explain the relationships between the major divisions of the human brain

Explain the causes of nervous system disruptions and how disruptions of the nervous system can lead to disruptions of homeostasis.

Explain how the skeletal-muscular system functions at the system and cellular levels.

Explain the sliding filament model of muscle contraction

Explain the causes of sensory and motor system disruptions and how those disruptions can affect homeostasis
Make Sure You Can
Any Questions?
Why Can We Run So Fast?
Fundamentally,
sensation
requires three things:

1. A
stimulus
must be detected by a
sensory receptor
.
2. The sensor must translate the stimulus into a nervous signal (an action potential).
3. The signal must be interpreted by the
central nervous system
(the
brain
).

All sensory apparatus have these three things in common!!!
The sensory receptor is either:
the first ("
afferent
") neuron in the signaling pathway

or it regulates the afferent neuron through
neurotransmitter
release.
Touch sensations are mediated by receptors in the
skin
.

There are many kinds of receptors in the skin:
temperature receptors
pain receptors
pressure receptors
hair movement receptors.

These are what people mean by
"
nerve endings
".
Since action potentials are binary, the
spatial
and
temporal
pattern of signals is what determines the sensation
Sight is mediated by
photoreceptors
in specialized organs ("
eyes
")
Sound is mediated by receptors that vibrate in response to sound waves
Eyespots in Planaria
Very primitive.

The planarian brain drives movement as long as light is shining on either
eyespot
(
ocellus
).

This causes
negative phototaxis
(movement away from light).

The ocellus only allows light from above to interact with neurons
The Vertebrate Eye
Light is focused by a
lens
onto the
retina
lining the back of the eyeball.

The retina translates light into nervous signals.

Information from each eye is routed to both
hemispheres
of the brain
Rods
interpret the presence/absence of light
Cones
respond to different wavelengths of light
Schematic of retina
Compound Arthropod Eye
Each eye contains many individual
facets
.

Each facet has one fixed
lens
and one
photoreceptor
UV illumination of some flowers suggests adaptation for arthropod pollinators
The Mammalian Ear
The
ear
consists of a canal to direct soundwaves, and a series of bones and organs that interpret those waves as heard sound.

Much of hearing is due to
hair cells
that line the
cochlea
and vibrate at particular frequencies.

These vibrations stimulate afferent neurons.
Hair cells and ear anatomy are also involved in the detection of
spatial positioning
of the body and subsequently balance
Normal hearing range occurs over a logarithmic scale of frequencies, with lower frequency vibrations being interpreted as lower pitch sounds.
Arthropod hearing is typically mediated by
tympanic membranes
on the the forelegs of the organism
Chemoreception
in animals is mediated through taste and smell

Most animals sense the environment predominantly through chemoreception
Taste
Smell
Taste is mediated by
taste buds
in the
tongue
Taste buds interpret different molecules as different tastes

"Food" tastes "good"
Genetic variance is demonstrated to be responsible for differences in taste preferences.
Smell is interpreted when molecules ("
odorants
") interact with receptors on the cell membranes of chemoreceptors that protrude from the
olfactory bulb
of the brain.

Human sense of smell is vastly less pronounced than that of typical mammals.

Smell is important for taste as well, as odorants are released into the nasal cavity when food is chewed.
There are many examples of senses that are present in other animals but are absent in humans
Many reptiles have infared radiation receptors
Bats and cetaceans use
sonar
systems
The
lateral line
system in fish detects energy signatures (currents, sound, etc) in water
Many insects have chemoreceptors on their antennae which are particularly sensitive to mating pheromones
Evolutionary Progression of Nervous System complexity.
Nerve net
: No CPU
Development of
Central Nervous system
, &
Brain
Cephalization
of sensory organs.
Human Nervous System
Major divisions:
Central
vs.
Peripheral
Afferent
vs.
Efferent
Autonomic
vs.
Motor
Parasympathetic
vs.
Sympathetic
Reflex
Actions Do Not Require CNS Processing (only relay)

Why?
Fundamentally, the Brain consists of
Glial cells
(
astrocytes
)
100 billion
neurons
- perhaps 500 trillion synapses
one neuron
EMG of Cerebral Cortex
Brainbow staining of neurons
One Glial Cell
Development of the human brain
Like an onion!
Gray matter
= cell bodies, nerve terminals, dendrites
White matter
= axons
The Brain Has Specific Sections
Diencephalon
:
Seat of Endocrine Control
Medulla/Pons
- Autonomic System
Cerebellum
- Balance, coordination
Cerebrum
- "Higher order" functions
Different cerebral regions participate in different functions
2 "
hemispheres
" of the brain
Human vs. Avian Brain
Somatosensory
&
Motor Cortexes
route from/to different regions of the body.
Different Regions of the Brain Are Active for different tasks
Dolphins sleeping one hemisphere at a time
fMRI showing word-related brain activity
Amygdala
-
involved in emotional response
Nucleus Accumbens
-
involved in reward response
Lots of "Black Boxes" left:
Learning/Memory?
Roughly: The more used a synaptic pathway is, the more firm that pathway becomes
Synapses are
plastic
(meaning "flexible")!
Long Term Potentiation
: A lasting synaptic connection.
Mental Illness
Roughly: Disruptions in normal neurotransmitter release and reuptake contributes to mental illness.
Likely an issue with Neuron excitement - role of serotonin is no longer clear.
Some mental illnesses seem to have a genetic component.
Much better understanding & treatment than 50 years ago!
Roughly: It is still hard to predict the effect that brain damage will have on an individual.
Brain Damage?
Phineas Gage:
lived for 12 years following this injury
Though his personality changed drastically
Alzheimer's Disease
: Associated with destructive protein plaques in the brain.
Is it "brain damage"?
Evidence of neural stem cells in a mouse hippocampus.
Plasticity!
Major animal Response:
Muscle!
3 Kinds:
Skeletal
- voluntary motion
Smooth
- lines organs, involuntary
Cardiac
- heart, independent
Only skeletal is under conscious control!
Muscle cells do two things:
Contract
Relax
That's it!
Skeletal muscles are arranged in "
antagonistic
" pairs.
Extensor
&
Flexor
Typical Muscle Structure:
Each
muscle
is bundle of
muscle fibers

Each fiber is a bunch of
multinucleated cells.

Each cell has a collection of
myofibrils

Each myofirbril is packed with
actin
(
thin
) and myosin (
thick
) fillaments, arranged in "
sarcomeres
"
Muscle fiber (nuclei in blue)
Muscle fiber (nuclei in purple)
The "
Sliding Fillament
" Model
ATP is hydrolyzed to move myosin between active (high energy) and inactive (low energy) conformations

Active: Myosin bonds to actin (forming a "
cross bridge
") and pulls it towards the middle of the sarcomere.

Inactive: Myosin remains attached to actin until ATP hydrolysis occurs again.

"
Sliding fillament
": Actin and myosin slide past each other.
Calcium ions must be present in the sarcomere, and bonded to
tropomyosin
for myosin to bond to actin.

Calcium is stored in a region of the sarcomere called the "
sarcoplasmic reticulum
"
The nervous system interfaces with muscle tissue at modified synapses called "
neuromuscular junctions
".

The release of
Acetylcholine
into the NMJ is responsible for calcium ion release into the sarcomere.

"
Motor neruons
" terminate at NMJ's
A motor neuron and its NMJ's are called a "
motor unit
"
Total muscle contraction ("
Tetanus
") is only initiated when enough motor units are activated ("
twitch summation
")
Stonefish venom induces involuntary tetanus.
Wear your Flip Flops!
The human skeleton is an
endoskeleton
made of
bone
tissue.
During early life, bones grow.

Bones are awesome!
Living Bone is constantly broken down and reformed by populations of bone stem cells.

Some bone tissue ("
marrow
") is also the site of blood cell production.
Joints
: Connections between bones.
All Vertebrates have
endoskeletons
.
Advantage: Internal-grows with the organism
Disadvantage: Interntal- soft flesh on top
Annelids have a
hydostatic skeleton.

No Bones (good for squishiness)

Structure is maintained by internal pressure.
Animals have three options
Fly

Run

Swim
There are energy considerations
Arthropods and molluscs have
exoskeletons
("
shells
")
Advantage: Protects all soft tissue beneath.
Disadvantage: Doesn't grow with the organism, must be periodically shed ("
molting
")
Chitin!
Calcium Carbonate!
Microscopic image of human cerebral cortex showing the delineation between gray matter and white matter.
I'ma get my molt on
Full transcript