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Ch. 50 Bio Teaching Lesson Presentation

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Lauren Eller

on 27 April 2010

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Transcript of Ch. 50 Bio Teaching Lesson Presentation

Chapter 50: Sensory and Motor Mechanisms 50.1 Sensory Receptors Sensory Pathway Reception Transduction Transmission Perception Amplification Types of Sensory Receptors Mechanoreceptors Chemoreceptors Electromagnetic Receptors Thermoreceptors Pain Receptors 50.2 Mechanoreceptors Invertebrates Gravity Sound Mammals Hearing Equilibrium 50.3 Sensory Receptors and taste and smell Taste in Mammals Smell in Humans 50.4 Vision Invertebrates Vertebrates The Eye Sensory Transduction in the eye Visual Information Processing 50.5 Muscle Function Vertebrate Skeletal Muscle The "Sliding-Filament Model of Muscle Contraction The role of calcium and regulatory protiens Nervous Control of Muscle Tension Types of Skeletal Muscle Fibers Oxidative Glycolytic Fast-Twitch Slow-Twitch 50.6 Skeletal Systems and Locomotion Types of Skeletal Systems Hydrostatic Exoskeleton Endoskeleton Types of Locomotion Swimming Locomotion on Land Flying Energy Costs of Locomotion Sensory Receptors detect:
External stimuli: heat, light, pressure, chemicals
Internal stimuli: blood pressure, body postion Extreme sensitivity Magnitude varies with strength of stimuli Magnitude of receptor potential controls the rate at which action potientals are produced ie. colors, smells, sounds, tastes:
constructions perceived by the brain Note: action potential triggered by light has the same properties as an action potential triggered by air vibrating in the ear.
Thus, we distinguish sensory stimuli solely by where in the brain the action potential arrives. Secondary Adaptation -strengthing of stimulus energy during transduction -a decrease in responsiveness so we are not constantly aware of feeling every piece of clothing on our body -a sensory cell has a single type of receptor specific for a particular stimulus -mechanical energy: pressure, touch, strech, motion, sound Ex. crayfish, knee-jerk reflex Ex. Osmoreceptors: detect solute concentration of blood and stimulate thirst
Ex. Receptors for Specific molecules: glucose, oxygen, carbon, ect The antennae of nale sildworn moths are covered with sensory hairs with chemoreceptors that are highly sensitive to the female sex pheromone. Ex. Snakes(infrared receptors)
Beluga Whales use magnetic field for orientation -detect heat and cold
Cayenne peppers taste "hot" b/c they trigger the same sensory receptors as do hot soup and coffee. -or nociceptors - organs that sense gravity and maintain equilibruim Statocytsts -just grains of sand In experiments in which statoliths were replaced with metal shavings, researchers "tricked" crayfish into swimming upside down by using magnets to pull the shavings to the upper end of the statocysts. A tuning fork vibrating at the same frequency as that of a female's wings will by itself attract males Insect Ears=tympanic membrane Sensory reception by hair cells. When you tilt your head, otoliths press on the hairs protruding into the gel Gustation(taste)
Olfaction(smell) -the detection of chemicals called tastants Sweet, Sour, Salty, Bitter, and Umami(Savory) Note: Any region of the tounge can detect any of the five types of taste: taste maps of tounge are incorrect!! Individual taste cells expresses a single receptor tupe and transmit action potentials to the brain representing only one of the five tastes. Sensory cells are nuerons Signal Transduction Pathways Humans have over 1,000 odorant receptor (OR) genes(about 3% of all our genes) Ex. Ocellus (most invertebrates)
-a light detecting organ that is stimulated by light Here, the planarian's brain directs the body to turn until the sensations from the two ocelli are equal and minimal, causing the animal to move away form light. 1. Light detecting Organs 2. Image Forming Eyes Ex. Compound Eyes(mostly insects)
-ommmatidias detect light from a ting portion of the visual field
Helps detect movement
Excellent color vision
See into ultraviolet(UV) range Ex. Single-Lens Eyes(jelly fish, spiders)
pupil, iris
like camera lens that moves forward and backward and expands o r contracts in diameter Single-Lense Eyes(differ from Lense-Eyes of Invertebrates b/c they have much more complex eye structures)
Remeber, it is the brain that truly "sees"! Glaucoma, a condition in which increased pressure in the eye damages the optic nerve, occurs when the ducts are bloked and cannot drain the aqueous humor. Glaucoma leads to vision loss and sometimes blindness. For instance, Humans and other mammals focus by changing the shape of the lens.
Close objects: lens becomes spherical
Distant objects: lens flattens Rods-
sensitive to light
do not distinguish color
enable us to see at night Cones-
provide color vision
three types(different sensitivity across the visible spectrum):red, green, or blue optimal light responses Forvea contains high density of cones(approx. 15,000/sq. millimeter 1. Rod Cells Hperpolarizes the photoreceptor; creates receptor potential II. Cone Cells photopsin-red, green, or blue- are formed from binding of retinal to three distinct opsin protiens
Absorption spectra overlap: why we see other colors Light must pass through several layers of neurons to reach the photoreceptors Bear in mind:
Muscle contraction requires energy
Muscle extention occurs only passively (attached to bones) Striated muscle-
the regular arrangment of filaments creates a pattern of light and dark bands -the basic contractable unit of the muscle Thick filaments(myosin) The myosin head binds ATP and hydrolyzes it into ADP Each of the 350 heads of a thick filament form and reform about 5 cross-bridges per second Creatine phosphate and glycogen provide the energy need for repetitive contractions Tropomyosin-
covers the myosin -binding sites along the thin filament, preventing actin and myosin from interacting When Ca2+ accumulates in the cytosol, it binds to the troponin complex, causing the proteins bound along the actin strands to shift positions and expose the myosin-binding sites Sensory Input
Motor output Can regulate the strength of muscle contractions muscle fibers it activates at a given instand and be selecting large or small muscle fibers.
In Amyotophic lateral sclerosis (ALS) or Lou Gehrig's disease, motor nuerons in the spinal cord and brainstem degenerate causing paralysis of skeletal muscle fibers When the rate of stimuli is high enough that mucle fibers cannot relax in between contractions, it is called tetanus Rely on aerobic respiration
make use of a steady energy supply
uses a large amount of myoglobin(oxygen storing protein) Relies on glycolysis as their primary source of ATP
Fatigue more readily Ex. Poultry and Fish: Dark meat Ex. Poultry and Fish: Light(White meat) brief, rapid, powerful contractions
Ex. Eye and hand(exclusively fast-twitch) long contractions
Did you know?
If a muscle is used repeatedly for activities requiring high endurance, some fast glycolytic fibers can develop into fast oxidative fibers Antagonistic pair-
two muscles that have coopertive functions -fluid held under pressure
type of skeleton in most flatworms, nematodes, ect Crawling by peristalsis(a type of movement produced by rhythmic wabes of muscle contractions passing from front to back Ex. calcium carbonate(bivalves, ie. clams)
Ex. live chitin(arthropods, ie. lobsters) Arthropods must shed their skeletons(molt) Animals must overcome friction and gravity Friction is the major problem>
sleek, fusiform(torpedo-like) shape Gravity is major problem>
powerful muscles and strong skeletal support Gravity=biggest problem, obviously!
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