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SENSES & NERVOUS SYSTEM (SENSES (Types of receptors based on stimulus…

- - - - Stimulus origin is internal organs
    - - Stimulus origin is muscles (including tendons), ligaments and joints.
    - - Stimulus comes from environment.
        
        Located: skin, special senses.
  - - - Noxious / dangerous - pain
    - - Touch, pressure, vibration, stretch
        
        Baroreceptor - measure blood pressure
    - - Sensitive to chemicals
        
        Air / Saliva (water)
        
        In blood - Ca ++, K+, Na+, CO2, O2
    - - Sensitive to light
    - - Cold and warm receptor
  - - - Three tunics of eye
        
        Vascular layer - choroid
        
        Nourishes the other layers.
        
        Deeply pigmented.
        
        Absorbs lights & prevents scattering.
        
        Choroid continuous with ciliary body - muscle that changes the shape of the lens.
        
        Neural layer (inner layer) - retina
        
        Photoreceptors.
        
        Axons coverage to form optic nerve.
        
        Fibrous layer
        
        Cornea - clear
        
        Allows lighting into eye.
        
        Involved with focusing light on retina.
        
        Sclera - white
        
        Dense connective tissue
        
        Protective.
        
        Anchor for muscle - extrinsic eye muscles.
      - Rods & Cones
        
        Rods
        
        Many - sensitive to light.
        
        Cones
        
        Fewer - Allow us to see color, best in bright light.
      - Lens
        
        Posterior to iris.
        
        Focuses light on retina.
      - Iris
        
        Anterior to lens
        
        Intrinsic muscle - sphincter muscle - dilate / constrict.
      - Optic disc
        
        "Blind spot" - no photoreceptors.
      - Macula lutea
        
        Precise posterior pole.
      - Fovea centralis
        
        At center of macula lutea.
        
        Location of clearest vision.
      - Cavities (segments)
        
        Posterior segment
        
        Largest cavity.
        
        Filled with vitreous humor.
        
        Gel-like.
        
        Support retina and lens.
        
        Helps maintain normal pressure.
        
        Anterior segment
        
        Posterior chamber - from iris to posterior chamber.
        
        Anterior chamber - from iris to cornea.
        
        Filled with aqueous humor: nourishes the lens & cornea + maintain normal intraocular pressure.
    - - Path of light
        
        Light --> cornea (focus) --> pupil --> lens (focus) --> (posterior segment - vitreous humor) --> retina.
      - Path of nerve impulses
        
        Retina --> optic nerve --> optic chiasm(a) --> optic tract --> midbrain --> thalamus --> primary visual cortex in occipital lobe.
  - - - Widespread, free nerve endings.
    - - Localized receptors - Head region - Specialized receptors.
  - - - Roof of nasal cavity.
        
        Pseudostratified columnar epithelium with olfactory sensory nervous.
    - - Olfactory receptors --> olfactory sensory neuron within the olfactory bulb --> olfactory tract --> limbic system --> primary olfactory cortex in temporal lobe.
  - - - Tongue, inner cheeks, posterior wall of pharynx, epiglottis.
        
        Epithelial cells - gustatory.
    - - Transmit information from tongue to brain.
        
        3 cranial nerves connected to brain, do NOT go through spinal cord: Facial Nerve (VII), Glossopharyngeal Nerve (IX), Vagus Nerve (X).
    - - Cranial nerves --> medullar oblongata --> thalamus --> gustatory cortex in the insula.
  - - - Tympanic membrane (ear drum).
        
        Auditory ossicles - cochlea - liquid filled.
    - - Receptor epithelium for hearing.
        
        Both the vestibular nerve + cochlea nerve go through internal acoustic meatus --> vestibulocochlear nerve (CN VIII).
        
        Cochlear branch of CN VIII --> medullar oblangata --> pons --> midbrain --> thalamus --> primary auditory cortex - in temporal lobe.
    - - Elastic cartilage.
        
        Auricle gather sound waves - amplify.
- - - - Brain
        
        Spinal cord.
    - - Receive, process incoming signals and respond.
  - - - Cranial nerves - attached to brain.
        
        Spinal nerves - attached to spinal cord.
        
        Ganglia - cluster / group of neuron cell bodies.
    - - Be sensitive to stimuli & send information toward the central nervous system.
  - - - Output to skeletal muscle.
    - - Input from skin, skeletal muscle, joints, limbs.
        
        Specials: Hearing, equilibrium, vision.
  - - - Autonomic motor
        
        Mainly to contents of ventral body cavity.
        
        Smooth muscles: digestive system, respiratory system, urinary system, reproductive system.
        
        Glands.
        
        Sweat glands.
        
        Arrector pili muscle of skin.
        
        Blood vessel wall.
        
        Cardiac muscle.
      - Autonomic (visceral) sensory
        
        Input from ventral body cavity contents.
        
        Specials: Taste and smell.
- - - - Simple cuboidal / columnar epithelium with cilia that keep cerebrospinal fluid (CSF) moving.
        
        Lining spaces filled with CSF called ventricles.
    - - Structurally supportive.
        
        Regulates exchange of materials in / out of neuron cell body.
    - - Phagocytes - removes microbes + damaged nerve tissue.
    - - Wrap their plasma membranes around 1 portion of several axon.
    - - Most numerous.
        
        Many processes that contact neurons _ capillaries (small blood vessels).
        
        Support neurons.
        
        Help maintain appropriate chemical environment.
    - - Wrap their plasma membrane around 1 portion of 1 axon.
- - - - Unipolar
        
        Bipolar - special sensory
        
        Cell bodies located in ganglia of PNS
    - - Between neurons in CNS
        
        Multipolar
        
        99.98% of all neurons.
    - - Multipolar
        
        Cell body in CNS --> muscle + glands