The Special Senses And Integrative Functions Of The Nervous System, -…
The Special Senses And Integrative Functions Of The Nervous System
anatomy and histology of the special and general sensory organs
Middle Vascular Tunic: Choroid (vascularized), ciliary body (muscular, lens adjustment), and iris (controls light entry).
Inner Nervous Tunic: Retina (photoreceptors, bipolar cells, ganglion cells for detecting light and transmitting signals to the brain via the optic nerve).
Outer Fibrous Tunic: Sclera (dense connective tissue layer) and cornea (transparent, innervated structure).
Sclera: Three layers of dense connective tissue (episclera, stroma, lamina fusca), providing structural support.
Cornea: Transparent structure with stratified, non-keratinized corneal epithelium, collagen-rich corneal stroma, and a single-layer corneal endothelium.
Choroid: Pigmented cells and capillaries, located between the sclera and retina.
Ciliary Body: Composed of ciliary muscle, processes, and epithelium, responsible for lens shape adjustment.
Iris: Controls light entry, made up of two pigmented cell layers and two muscle layers.
Retina: Includes photoreceptor, bipolar, ganglion cells, as well as horizontal, amacrine, and Müller cells.
Outer Ear: Includes the pinna and external auditory canal, featuring keratinized stratified squamous epithelium.
Middle Ear: An air-filled cavity housing ossicles, round window, oval window, and Eustachian tube, lined with non-keratinized stratified squamous epithelium.
Inner Ear: Contains the cochlea with the organ of Corti for sound detection, and the vestibule and semicircular canals with specialized sensory epithelium for detecting head movement.
The tongue is a muscular organ in the oral cavity with three parts: the apex, body, and root.
It plays essential roles in swallowing, speech, and taste, with moisture provided by salivary glands.
The tongue is covered by stratified squamous epithelium with varying keratinization.
It consists of interlocking muscles, connective tissue, glands, fatty tissue, lingual papillae, and lymphoid follicles.
Three main types of papillae are fungiform, filiform, and circumvallate.
Tongue muscles include extrinsic and intrinsic muscles responsible for shape changes.
The nasal cavity connects to the outside through the nostrils.
It's divided into two spaces by the nasal septum.
Nasal turbinates increase surface area.
The roof is olfactory mucosa, and the rest is respiratory mucosa.
Four pairs of paranasal sinuses exist: frontal, ethmoid, maxillary, and sphenoid.
The nasal vestibule has keratinized stratified squamous epithelium.
Deeper, it changes to pseudostratified columnar ciliated epithelium with goblet cells.
The olfactory part is less vascular.
Sinonasal cavities are lined by pseudocolumnar epithelium.
the major functions of the nervous system: sensation, integration, and response
Sensation is a fundamental function of the nervous system.
It gathers information about the internal and external environment.
The "big five" senses - taste, smell, touch, sight, and hearing - are crucial for this.
Sensation involves perceiving changes or stimuli in the environment.
Inputs like flavors, odors, touch, vision, and hearing are processed for further action.
Integration in the nervous system is like the brain's decision-making center.
It processes sensory information, incorporates past experiences, and determines appropriate actions.
Occurs in the central nervous system (CNS) - the brain and spinal cord.
Involves comparing, combining, and sometimes remembering sensory data.
The outcome is the coordination of signals sent through motor neurons to control muscles and glands.
Response is the phase where the nervous system translates information into actions.
It involves instructing effector organs like muscles and glands to carry out actions.
Signals for these actions are sent from the central nervous system (CNS) to effector organs through the peripheral nervous system's motor branch (PNS).
This phase converts decisions from integration into physical responses.
different types of sensory receptors
Chemoreceptors detect chemicals and are found in the nose (smell) and tongue (taste).
Mechanoreceptors respond to mechanical forces and are found in the skin (touch and pressure) and inner ear (balance and movement).
Thermoreceptors react to temperature changes and detect hot and cold sensations on the skin.
Photoreceptors detect light and are located in the eyes, particularly in the retina for vision.
can also be classified by their structure
Free Nerve Endings are basic and found in the skin and moist body parts, detecting pain, temperature changes, and pressure.
Encapsulated Nerve Endings are nerves wrapped in a protective layer, including Meissner's corpuscles, Pacinian corpuscles, and Ruffini endings, and they sense touch, pressure, and vibrations.
Specialized Receptor Cells are unique cells found in the eyes, ears, nose, and taste buds, like photoreceptor cells, hair cells, and olfactory receptor cells, serving distinct functions related to seeing, hearing, smelling, or tasting.
sequence of events in a simple sensory receptor–motor response pathway
Stimulus is the initial change or signal in the environment, detected by sensory receptors, which can be chemoreceptors, thermoreceptors, mechanoreceptors, or photoreceptors.
Receptor functions like a switch, detecting the stimulus and converting it into an electrical signal.
Sensory Neuron, also known as afferent neurons, acts as an information highway, transmitting the electrical signal to the central nervous system (CNS), which comprises the brain and spinal cord.
Integration takes place within the CNS, where the brain processes the information and makes decisions based on the message received.
Motor Neuron, or efferent neurons, carries the brain's message to the next step.
Effector, like a worker, receives the message and performs the instructed action, such as muscles moving your body or glands producing substances like sweat or tears.
Response is the visible reaction or outcome of the process, where you respond to the initial stimulus, like moving your hand away from something hot or experiencing your mouth watering when smelling delicious food.