Chapter 17 Flashcards
Photopigments in rods
Rhodopsin
Rods and cones contain photopigments that absorb light which initiates the events that lead to this
Nerve impulse
Refraction
Bending
Know compartments of eye
Know compartments of eye
Tarsal plate
Fold of connective tissue that gives form to eyelids
Extrinsic eye muscles
Controls movement of eyeball itself
Palpebral muscles
Control eyelid movement (opening and closing eyes)
Two types of photoreceptors in retina
- Rods: see in dim light
- Cones: produce color vision
Axons of these exit at the optic (II) nerve
Fovea centralis
Area of highest visual acuity
Macula lutea
Exact center of retina
Optic disc
Point at which optic nerve exits the eyes (aka blind spot)
3 layers of eye
- Fibrous tunic
» Cornea: admits/refracts (bends) light
» Sclera: provides shape/protects inner parts - Vascular tunic
» Choroid: provides blood supply and absorbs scattered light
» Ciliary body: secretes aqueous humor/alters shape of lens for near or far vision
» Iris: regulates amount of light entering eye - Retina
» Pigmented layer
» Neural layer
Pathway for tears
- Lacrimal gland secretes tears into
- Excretory lacrimal ducts (distribute tears over surface of eye)
- Superior/inferior lacrimal caniliculi drains tears to
- Lacrimal sac, then drains tears into
- Nasolacrimal duct then drains tears into
- Nasal cavity
Function of lacrimal apparatus
Produces and drains tears
Keeps eyelids from sticking to ea. other
Row of sebaceous glands (tarsa;/Meibomian glands)
Keeps eyelids from sticking to ea. other
Row of sebaceous glands (tarsal/Meibomian glands)
Conjuctiva
Thin, protective mucous membrane that lines eyelids/covers sclera
Accessory structures of eyes
- Eyelids
- Eyelashes
- Eyebrows
- Lacrimal apparatus
- Extrinsic eye muscles
3 cranial nerves that carry impulses in the gustatory pathway
- Facial (VII): carries taste info from anterior 2/3 of tongue
- Glossopharyngeal (IX): carries taste info from the posterior 1/3 of tongue
- Vagus (V): carries taste info from taste buds on epiglottis and in the throat
Types of papillae
- Vallate
» Around 12
» 100-300 taste buds - Fungiform
» Scattered on tongue
» Around 5 tastebuds ea. - Follate
» In lateral trenches of tongue w/ taste buds
» Most degenerate in childhood - Filiform
» Have tactile receptors
» No tastebuds
» Incr. friction to make it easier for tongue to move food in mouth
Papillae
Elevations where taste buds on tongue are located
Three kinds of epithelial cells located in taste buds
- Supporting cells
- Gustatory receptor cells
- Basal stem cells
Where taste buds are located
- Tongue of YA
- Soft palate
- Pharynx
- Epiglottis
5 primary tastes
- Sour
- Sweet
- Bitter
- Salt
- Umami
Olfactory transduction
Binding of odorant molecule to an olfactory receptor protein
Lobe of cerebral cortex that contains the primary olfactory area
Cerebral cortex/cerebellum
Know pathway of nerve impulses from receptors to the primary olfactory area of cerebral cortex
Know pathway of nerve impulses from receptors to the primary olfactory area of cerebral cortex
Three types/functions of cells in olfactory epithelium
- Olfactory receptor cell: produce mucus used to dissolve odor molecules so transduction can occur
- Supporting cells: physical support, nourishment, and electrical insulation for olfactory receptor cells
- Basal cells: undergo mitosis to replace olfactory receptor cells
Location of olfactory epithelium
Inferior surface of cribriform plate (of ethmoid bone of skull) and extends along superior nasal concha
Where receptors are for general senses
Widespread in body (pain receptors, pressure receptors, etc.)
3 types of sensory receptors
- Free nerve endings of 1st order sensory neurons
- Encapsulated nerve endings of the 1st order sensory neuron
- Separate cells that synapse w/ first order sensory neurons
4 events in the process of sensation
- Stimulation of sensory receptor
- Transduction of stimulus: conversion of stimulus energy to neural energy
- Generation of nerve impulses: energy levels build up to where graded potential has propagated an action potential toward CNS
- Integration of sensory input: brain interprets input in cerebral cortex in CNS
