Lecture AP Biology Chapter 50 Sensory and motor mechanisms

This chapter distinguish between the following pairs of terms: sensation and perception; sensory transduction and receptor potential; tastants and odorants; rod and cone cells; oxidative and glycolytic muscle fibers; slowtwitch and fasttwitch muscle fibers; endoskeleton and exoskeleton.

1 What is the function of: ▪ ▪ Cone cells? Rod cells? The perceived pitch of a sound is dependent on… ? What is the difference between perception and sensation? What is the function of: ▪ ▪ 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 The location and function of several types of sensory receptors  How skeletal muscles contract  Cellular events that lead to muscle contraction       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  Reception: Reception receptor detects a stimulus  Sensation = action potentials reach brain via sensory neurons  Perception: Perception information processed in brain Middle ear Inner ear Outer ear Stapes Middle ear Incus Semicircular canals 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 Utricle Saccule Nerve fibers 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 Amacrine cell Optic nerve Ganglion fibers cell Cone Rod Horizontal cell Bipolar cell Pigmented epithelium  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 Key Axial skeleton Appendicular skeleton Shoulder girdle Sternum Rib Humerus Vertebra Radius Ulna 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 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 Tarsals Metatarsals Phalanges Radius Pivot joints allow us to rotate our forearm at the elbow and to move our head from side to side   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 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) Sarcomere  Skeletal (striated)  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 (actin) ▪ Myosin: thick filaments Z line H zone Z line  Sarcomere 0.5 µm Z H A Sarcomere Relaxed muscle fiber Contracting muscle fiber Fully contracted muscle fiber I    Z lines – border I band – thin actin filaments A band – thick myosin filaments 0.5 µm Z H A Sarcomere Relaxed muscle fiber I 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 NOT shorten!) Motor neuron axon Mitochondrion Synaptic terminal T tubule Sarcoplasmic reticulum Myofibril Plasma membrane of muscle fiber Ca2+ released from sarcoplasmic reticulum Sarcomere Synaptic terminal of motor neuron Synaptic cleft T TUBULE PLASMA MEMBRANE SR ACh Ca2+ CYTOSOL Ca2+ 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)      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) ... (λ) What is the difference between perception and sensation? Chapter 50 Campbell Biology – 9th Edition The location and function of several types of sensory receptors  How skeletal muscles contract... organs) Light Z line band Dark band  cardiac (heart) Sarcomere  Skeletal (striated)  long fiber = single muscle cell  Each muscle fiber = bundle of TEM 0.5 µm I band A band I band myofibrils, composed... skeleton Key Axial skeleton Appendicular skeleton Shoulder girdle Sternum Rib Humerus Vertebra Radius Ulna Skull Examples of joints Head of humerus Scapula Clavicle Scapula Ball -and- socket joints, where