1. What is the function of: ▪ Cone cells? ▪ Rod cells? 2. The perceived pitch of a sound is...
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Transcript of 1. What is the function of: ▪ Cone cells? ▪ Rod cells? 2. The perceived pitch of a sound is...
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:▪ Cone cells? Color▪ Rod cells? Light
2. The perceived pitch of a sound is dependent on… ?wavelength (λ)
1. What is the difference between perception and sensation?
Chapter 50Campbell Biology – 9th Edition
The location and function of several types of sensory receptors
How skeletal muscles contractCellular events that lead to muscle
contraction
Mechanoreceptors: physical stimuli – pressure, touch, stretch, motion, sound
Thermoreceptors: detect heat/coldChemoreceptors: 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
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.
Eye
Infraredreceptor
Some migrating animals, such as these beluga whales, apparently sense Earth’s magnetic field and use the information, along with other cues, for orientation.
ReceptionReception: receptor detects a stimulus SensationSensation = action potentials reach
brain via sensory neurons
PerceptionPerception: information processed in brain
Outer earMiddle
ear Inner ear
Pinna Auditorycanal
Tympanicmembrane
Eustachiantube
Middleear
Stapes
Incus
Malleus
Skull bones
Semicircular canals
Auditory nerve,to brain
Tympanicmembrane
Ovalwindow Round
window
Cochlea
Eustachian tube
Auditory nerve
Tympaniccanal
Cochlea duct
Organ of Corti
Vestibularcanal
Bone
To auditorynerve
Axons ofsensory neurons
Basilarmembrane
Hair cells
Tectorialmembrane
Semicircular canals
Flowof endolymph
Vestibular nerve
Nerve fibersVestibule
Utricle
Saccule
Ampulla
Flowof endolymph
Cupula
Body movement
Hairs
Haircell
Cornea
Ciliary body
Suspensoryligament
Iris
Pupil
Aqueoushumor
Lens
Vitreous humor
Central artery andvein of the retina
Optic disk(blind spot)
Fovea (centerof visual field)
Opticnerve
RetinaChoroidSclera
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
Optic nerve
Tobrain
Cone
Photoreceptors
Retina
RodNeurons
Pigmentedepithelium
Bipolarcell
Amacrinecell Horizontal
cellOpticnervefibers
Ganglioncell
Hydrostatic: fluid held under pressure in closed body compartment Hydra, nematodes, annelids
Exoskeletons: hard encasements on surface of animal Insects, mollusks, crustaceans
Endoskeleton: hard supporting elements buried within soft tissues Human bony skeleton
Shouldergirdle
Scapula
Clavicle
Sternum
SkullAppendicularskeleton
Axial skeleton
Key
Rib
Humerus
Vertebra
Radius
Examplesof joints
Fibula
Ulna
Tibia
Pelvicgirdle
Carpals
Phalanges
Metacarpals
Femur
Patella
TarsalsMetatarsalsPhalanges
Ulna
Pivot joints allow us to rotate our forearm at the elbow and to move our head from side to side.
Ulna
Hinge joints, such as between the humerus and the head of the ulna, restrict movement to a single plane.
Humerus
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.
Head ofhumerus
Scapula
Radius
Bicepscontracts
Human
Tricepsrelaxes
Forearmflexes
Bicepsrelaxes
Tricepscontracts
Forearmextends
Extensormusclerelaxes
Flexormusclecontracts
Grasshopper
Extensormusclecontracts
Flexormusclerelaxes
Tibiaextends
Tibiaflexes
Muscles always contractMuscles work in antagonistic pairs
to move parts of body
Bundle ofmuscle fibers
Single muscle fiber(cell)
Plasma membrane
Nuclei
Muscle
Myofibril
Dark band
Sarcomere
Z lineLightband
I bandTEM
A band I band0.5 µm
M lineThick filaments(myosin)
SarcomereH zoneZ line
Thin filaments(actin)
Z line
Attached to bones by tendons
Types of muscle: smooth (internal organs) cardiac (heart) Skeletal (striated)
1 long fiber = single muscle cell Each muscle fiber =
bundle of myofibrils, composed of:▪ Actin: thin filaments▪ Myosin: thick filaments
Sarcomere
0.5 µm
Z HA
Relaxed muscle fiber
I
Contracting muscle fiber
Fully contracted muscle fiber
Z lines – border I band – thin actin filaments A band – thick myosin
filaments
Sarcomere
0.5 µm
Z HA
Relaxed muscle fiber
I
Contracting muscle fiber
Fully contracted muscle fiber
1. Sarcomere relaxed: actin & myosin overlap
2. Contracting: Muscle fiber stimulated by
motor neuronmotor neuron Length of sarcomere is
reduced Actin slides over myosin
3. Fully contracted: actin & myosin completely overlap
Sliding-filament model: thick & thin filaments slide past each other to increase overlap
(Note: Filaments do NOT shorten!)
Ca2+ releasedfrom sarcoplasmicreticulum
MitochondrionMotorneuron axon
Synapticterminal
T tubule
Sarcoplasmicreticulum
Myofibril
Plasma membraneof muscle fiber
Sarcomere
Ca2+CYTOSOL
Ca2+
SR
PLASMAMEMBRANET TUBULESynaptic cleft
Synaptic terminalof motor neuron
ACh
Myosin-binding sites blocked.
Myosin-binding sites exposed.
Tropomyosin Ca2+-binding sitesActin Troponin complex
Myosin-binding site
Ca2+
Thin filaments
Thick filament
Thin filament
Thick filament
Myosin head (low-energyconfiguration)
Cross-bridgebinding site
Myosin head (high-energy configuration)
Actin
Cross-bridge
Myosin head (low-energy configuration)
Thin filament movestoward center of sacomere.
Hydrolysis of ATPHydrolysis of ATP by myosin by myosin cross-bridge formed cross-bridge formed thin thin filament pulled toward center of sarcomerefilament pulled toward center of sarcomere
Speed of muscle contraction:Speed of muscle contraction:•Fast fibers – brief, rapid, powerful contractions•Slow fibers – sustain long contractions (posture)
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)