Transcript Chapter 48 Nervous Systems

1.
What is the function of:
▪
▪
Cone cells?
Rod cells?
2.
The perceived pitch of a sound is dependent
on… ?
3.
What is the difference between perception
and sensation?
1.
What is the function of:
▪
▪
2.
1.
Cone cells? Color
Rod cells? Light
The perceived pitch of a sound is dependent
on… ?
wavelength (λ)
What is the difference between perception
and sensation?
Chapter 50
Campbell Biology – 9th Edition
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The location and function of several types of
sensory receptors
How skeletal muscles contract
Cellular events that lead to muscle
contraction
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Mechanoreceptors: physical stimuli –
pressure, touch, stretch, motion, sound
Thermoreceptors: detect heat/cold
Chemoreceptors: transmit solute conc. info –
taste (gustatory), smell (olfactory)
Electromagnetic receptors: detect EM
energy – light (photoreceptors), electricity,
magnetism
Pain receptors: respond to excess heat,
pressure, chemicals
Eye
Infrared
receptor
This rattlesnake and other pit vipers have a pair of infrared
receptors, one between each eye and nostril. The organs
are sensitive enough to detect the infrared radiation
emitted by a warm mouse a meter away.
Some migrating animals, such as these beluga whales,
apparently sense Earth’s magnetic field and use the
information, along with other cues, for orientation.
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Reception: receptor detects a stimulus
 Sensation = action potentials reach brain
via sensory neurons
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Perception: information processed in brain
Middle
ear
Inner ear
Outer ear
Semicircular canals
Stapes
Middle
ear
Incus
Skull bones
Auditory nerve,
to brain
Malleus
Pinna
Tympanic
Auditory membrane
canal
Eustachian
tube
Tympanic
membrane
Oval
window
Cochlea
Round
window
Eustachian tube
Tectorial
membrane
Hair cells
Bone
Cochlea duct
Vestibular
canal
Basilar
membrane
Axons of
To auditory
sensory neurons nerve
Auditory
nerve
Tympanic
canal
Organ of Corti
Semicircular canals
Ampulla
Flow
of endolymph
Flow
of endolymph
Vestibular nerve
Cupula
Hairs
Hair
cell
Vestibule
Nerve fibers
Utricle
Saccule
Body movement
Sclera
Choroid
Retina
Ciliary body
Fovea (center
of visual field)
Suspensory
ligament
Cornea
Iris
Optic
nerve
Pupil
Aqueous
humor
Lens
Vitreous humor
Central artery and
vein of the retina
Optic disk
(blind spot)
Retina
Optic nerve
To
brain
Compound eyes: several
thousand ommatidia (light
detectors) with its own lens;
insects & crustaceans
Vertebrates:
 Rods: sense light
 Cones: color vision
 Rhodopsin: light-absorbing
pigment that triggers signal
transduction pathway that
leads to sight
Retina
Photoreceptors
Neurons
Cone Rod
Amacrine
cell
Optic
nerve Ganglion
fibers cell
Horizontal
cell
Bipolar
cell
Pigmented
epithelium
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Hydrostatic: fluid held under pressure in
closed body compartment
 Hydra, nematodes, annelids
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Exoskeletons: hard encasements on surface
of animal
 Insects, mollusks, crustaceans
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Endoskeleton: hard supporting elements
buried within soft tissues
 Human bony skeleton
Key
Axial skeleton
Appendicular
skeleton
Shoulder
girdle
Sternum
Rib
Humerus
Skull
Examples
of joints
Head of
humerus
Scapula
Clavicle
Scapula
Ball-and-socket joints, where the humerus
contacts the shoulder girdle and where the femur
contacts the pelvic girdle, enable us to rotate our
arms and legs and move them in several planes.
Vertebra
Radius
Ulna
Humerus
Pelvic
girdle
Carpals
Ulna
Phalanges
Metacarpals
Femur
Hinge joints, such as between the humerus
and the head of the ulna, restrict movement
to a single plane.
Patella
Tibia
Fibula
Ulna
Radius
Pivot joints allow us to rotate our forearm at the
elbow and to move our head from side to side.
Tarsals
Metatarsals
Phalanges
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Muscles always contract
Muscles work in antagonistic pairs to move
parts of body
Human
Grasshopper
Extensor
muscle
relaxes
Biceps
contracts
Biceps
relaxes
Triceps
contracts
Flexor
muscle
contracts
Forearm
flexes
Triceps
relaxes
Tibia
flexes
Extensor
muscle
contracts
Forearm
extends
Tibia
extends
Flexor
muscle
relaxes
Muscle
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Bundle of
muscle fibers
Single muscle fiber
(cell)
Attached to bones by tendons
Nuclei
Types of muscle:
Plasma membrane
Myofibril
 smooth (internal organs)
Light
Z line
band Dark band
 cardiac (heart)
 Skeletal (striated)
Sarcomere
1 long fiber = single muscle cell
 Each muscle fiber = bundle of
TEM
0.5 µm
I band
A band
I band
myofibrils, composed of:
M line
Thick filaments
(myosin)
▪ Actin: thin filaments
Thin filaments
▪ Myosin: thick filaments
(actin)
Z line
H zone
Sarcomere
Z line
0.5 µm
Z
H
A
Sarcomere
Relaxed muscle fiber
I
Contracting muscle fiber
Fully contracted muscle fiber
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Z lines – border
I band – thin actin filaments
A band – thick myosin filaments
0.5 µm
1.
2.
Z
H
A
Sarcomere
Relaxed muscle fiber
I
3.
Contracting muscle fiber
Fully contracted muscle fiber
Sarcomere relaxed: actin & myosin
overlap
Contracting:
 Muscle fiber stimulated by motor
neuron
 Length of sarcomere is reduced
 Actin slides over myosin
Fully contracted: actin & myosin
completely overlap
Sliding-filament model: thick & thin
filaments slide past each other to
increase overlap
(Note: Filaments do NOT shorten!)
Motor
neuron axon
Mitochondrion
Synaptic
terminal
T tubule
Ca2+ released
from sarcoplasmic
reticulum
Sarcoplasmic
reticulum
Myofibril
Plasma membrane
of muscle fiber
Sarcomere
Synaptic
terminal of
motor neuron
releases
acetylcholine
Muscle
fiber
depolarizes
Ca2+
released
Synaptic terminal
of motor neuron
Synaptic cleft
T TUBULE
PLASMA
MEMBRANE
SR
ACh
Ca2+
CYTOSOL
Ca2+
Initiate
sliding of
filaments
Tropomyosin
Ca2+-binding sites
Actin
Troponin complex
Myosin-binding sites blocked.
Ca2+
Myosinbinding site
Myosin-binding sites exposed.
Hydrolysis of ATP by myosin  cross-bridge formed  thin
filament pulled toward center of sarcomere
Thick filament
Thin filaments
Thin filament
Myosin head (low-energy
configuration)
Thick
filament
Thin filament moves
toward center of sacomere.
Actin
Myosin head (lowenergy configuration)
Cross-bridge
binding site
Myosin head (highenergy configuration)
Cross-bridge
Speed of muscle contraction:
•Fast fibers – brief, rapid, powerful contractions
•Slow fibers – sustain long contractions (posture)
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ALS (Lou Gehrig’s disease): degeneration of motor
neurons, muscle fibers atrophy
Botulism: block release of acetylcholine, paralyzes
muscles
Myasthenia gravis: autoimmune disorder, produce
antibodies to acetylcholine
Calcium deficiency: muscle spasms and cramps
Rigor mortis (after death): no ATP to break
actin/myosin bonds; sustained muscle contraction
until breakdown (decomposition)