Chapter 50 ppt max chandler ii[1]
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Transcript of Chapter 50 ppt max chandler ii[1]
Chapter 50Sensory and Motor Mechanisms
Sensory Pathway
• Sensory Receptions: Detection of a stimulus by sensory cells or sensory receptors.
• The sensory receptors transfer the physical and chemical stimulus to a membrane potential, this process is known as transduction.
• Transduction triggers transmission, which is the conversion of membrane potential to action potentials which is then sent to the CNS.
• Perception is the final step and it is when the action potential is interpreted by the brain and perceived either as sound, color, smell or taste.
Fig. 50-2
Slight bend:weakstimulus Stretch
receptor
Mem
bran
epo
tenti
al (m
V)
Axon
Dendrites
Strong receptorpotential
Weakreceptorpotential
Muscle
–50
–70M
embr
ane
pote
ntial
(mV)
–50
–70
Action potentials
Action potentials
Mem
bran
epo
tenti
al (m
V)
Large bend:strongstimulus
Reception
Transduction
0
–70
0
–70
1 2 3 4 5 6 7
Mem
bran
epo
tenti
al (m
V)
Time (sec)
1 2 3 4 5 6 7Time (sec)
Transmission Perception
Brain
Brain perceiveslarge bend.
Brain perceivesslight bend.
1 23
4
1
2 3 4
0
0
Sensory Pathway
Types of Receptors:Chemoreceptors, Electromagnetic Receptors, Thermoreceptors, Pain Receptors
Hearing Through Mechanoreceptors
• Humans have a tympanic membrane which is a hair covered membrane in the ear that receives sounds and transmits them to the brain.
• Where sound vibrations enter the ear they travel through the cochlear duct and the vibrations are converted to pressure waves. This information is taken to the brain and two things are analyzed from the pressure waves, volume and pitch.
Fig. 50-8
Hair cell bundle froma bullfrog; the longestcilia shown areabout 8 µm (SEM).
Auditorycanal
EustachiantubePinna
Tympanicmembrane
Ovalwindow
Roundwindow
Stapes
Cochlea
Tectorialmembrane
Incus
Malleus
Semicircularcanals
Auditory nerveto brain
Skullbone
Outer earMiddle
ear Inner ear
Cochlearduct
Vestibularcanal
Bone
Tympaniccanal
Auditorynerve
Organ of Corti
To auditorynerve
Axons ofsensory neurons
Basilarmembrane
Hair cells
Taste and Smell
• Taste is detected by taste buds on a mammals tongue.
• Taste buds have receptors that can read only one taste, when a receptor accepts its respective molecule it attaches it to a protein that then sends it through a pathway to a sensory neuron that interprets the taste of the molecule.
Fig. 50-15
Olfactorybulb
Odorants
Bone
Epithelialcell
Plasmamembrane
Odorantreceptors
Odorants
Nasal cavity
Brain
Chemo-receptor
Cilia
Mucus
Action potentials
Taste and Smell
Electromagnetic Reception(Seeing)• Different Types of Eyes– Compound eyes are found in insects and crustaceans
and consist of up to several thousand light detectors called ommatidia
– Single-lens eyes are found in some jellies, polychaetes, spiders, and many molluscs
– Vertebrate Eye; the eye ball, detects color and light, but the brain assembles the information and perceives the image
Fig. 50-17
Rhabdom
(a) Fly eyes
Crystallinecone
Lens
(b) OmmatidiaOmmatidium
PhotoreceptorAxons
Cornea
2 m
m
Use of Photoreceptors
• In vertebrates the eye detects color and light, but the brain assembles the information and perceives the image.
• Absorption of light by retinal triggers a signal transduction pathway that hyperpolarizes(increases in polarity) the photoreceptors , causing them to release less neurotransmitters. Synapses transmit information from photoreceptors to the brain.
• Rods are light-sensitive but don’t distinguish colors(peripheral vision).
• Cones distinguish colors but are not as sensitive to light.
Fig. 50-18
Opticnerve
Fovea (centerof visual field)
Lens
Vitreous humorOptic disk(blind spot)
Central artery andvein of the retina
Iris
RetinaChoroidSclera
Ciliary body
Suspensoryligament
Cornea
Pupil
Aqueoushumor
Microfilaments and Macrofilaments Underlie our Muscles
• Myosin heads (thick muscle filaments) bind to myofibrils (thin muscle filaments) forming cross-bridges.
• When the myosin heads are energized by ATP a cycle starts that causes the myosin heads to bend and slide over the myofibrils, this process contracts the muscle.
• Cardiac muscle, only within the heart, are electrically connected striated muscle cells.
Fig. 50-26
Z
Relaxedmuscle
M Z
Fully contractedmuscle
Contractingmuscle
Sarcomere0.5 µm
ContractedSarcomere
Skeletal Systems
• Skeletal muscles provide movement by contraction of the muscle pulling against the skeleton.
• Types– Hydrostatic Skeleton: Found in most flatworms,
nematodes and annelids, consists of fluid under pressure in a closed body compartment.
– Exoskeletons: Found in most molluscs and arthropods, are hard coverings deposited on the surface of an animal.
– Endoskeletons: Found in sponges, echinoderms, and chordates, are rigid supporting elements embedded with an animal’s body.
Energy Costs
• Animals that specialize in swimming spend less energy per meter traveled than any other type of locomotion for an animal their size.
Fig. 50-37
Body mass (g)
Running
Swimming
Flying
Ener
gy c
ost (
cal/
kg•m
) 102
103
10
1
10–1
10–3 1061
RESULTS
Assessment Questions1) Which part of the eye specializes in peripheral vision?• A) cones• B) sclera• C) choroid• D) rods2) Which form of locomotion is best per meter traveled, for animals?• A) running• B) driving• C) swimming• D) flying3) Which of the following sensory receptors is correctly paired with its category?• A) Rod- electromagnetic receptor• B) Hair cell- chemoreceptor• C) Myofibrils- electromagnetic receptor• D) Thermoreceptors – Pain Receptors