HAP LEC _ LAB MIDTERM PDF

HOMEOSTASIS 1. Releasing heat-sweat gland Homeo: same (vasoconstriction/vasodilation), muscle contraction Stasis: standing or status SENSATION...

HOMEOSTASIS 1. Releasing heat-sweat gland Homeo: same (vasoconstriction/vasodilation), muscle contraction Stasis: standing or status SENSATION 1. Nerve endings-thick skin vs thin skin Balancing act- to maintain a relatively constant internal environment STRUCTURES OF INTEGUMENTARY SYSTEM - SKIN Body systems are interdependent - ACCESSORY PARTS - They work together to maintain this stable - internal environment. LAYERS OF THE INTEGUMENTARY SYSTEM What is a set point? SKIN - Organ systems work together to keep within the - Largest organ of the body range around the set point. - Outer covering of the body Chemical reactions within cells work most effectively - Ectodermal in origin within a certain range of conditions. - Guards the underlying muscles, bones, Level at which a variable physiological state tends to ligaments and internal organs stabilize HYPODERMIS - Not fixed value - Subcutaneous layer - Dynamic - Innermost and thickest layer of the - Within the normal range integumentary system - Adipose tissue COMPONENTS: 2 MAIN LAYERS OF THE SKIN Stressor EPIDERMIS - Environmental change that signals the body - Outer layer Receptor - Stratified epithelium - Sensor that is sensitive to a stimulus DERMIS Control center - Inner layer - Receives and process information - Connective tissue Effector - Contains the accessory organs - Cell or organ that responds to the control center LAYERS OF EPIDERMIS Response 1. STRATUM CORNEUM - Change in the body to maintain homeostasis - Horny layer with: corneocytes and keratinocytes NEGATIVE FEEDBACK - For protection from: infection, dehydration, - Effective opposes or eliminates stimulus chemical and mechanical stress, desquamation - Results in a reversal of the direction of change 2. STRATUM LUCIDUM - Tends to stabilize a system correcting deviations - Clear layer from the set point - With keratinocytes filled with eleidin - BLOOD SUGAR REGULATION - Only in thick skin - REGULATION OF BODY TEMPERATURE 3. STRATUM GRANULOSUM POSITIVE FEEDBACK - Granula layer - Initial stimulus produces a response that - With keratohyalin granules exaggerates or enhances its effects 4. STRATUM SPINOSUM - Stimulus is promoted - Prickle cell layer - Amplifies the state or output of the system - Keratinization begins - The more there is, the more is added 5. STRATUM BASALE/GERMINATIVUM - SYSTEM-GIVING BIRTH - Basal layer - BLOOD CLOTHING - Deepest layer - Germinating layer INTEGUMENTARY SYSTEM - 3 cells: melanocytes, langerhans, merkel LAYERS OF DERMIS FUNCTIONS 1. Papillary layer PROTECTION - Thin, superficial layer 1. From microbes-oil glands - Full of blood vessels 2. As a barrier from harmful chemicals, UV - Forms dermal ridges/fingerprints radiation - (whirl, arch, double loops,simple loops) 3. From damages-abrasions, water loss 2. Reticular layer COVERING - Deeper layer 1. Largest system covers 1.5 to 2.0 m^2 of the - 80% entire body - Dense irregular connective tissue EXCRETION - With collagen fibers 1. Removal of wastes-sweat glands VITAMIN D SYNTHESIS CELLS IN THE DERMIS 1. Absorption of UV from the sun for liver and 1. Fibroblasts: differentiated cells of adult kidney connective tissue TEMPERATURE REGULATION 2. Macrophages: phagocytic cells 3. Mast cells: basophilic cells 4. WBC: inflammatory and immune response - 1st hair produced ACCESSORY PARTS - Hold the vernix caseosa CUTANEOUS GLANDS - Eating disorder 1. Sweat glands - teratomas - Sudoriferous glands 2. VELLUS HAIR - Secrete sweat - Peach fuzz 2. Oil glands - Short, fine colorless hair - Sebaceous glands - Thermal regulation body cooling - Secrete sebum - Cushing syndrome - To lubricate and waterproof the skin and hair 3. TERMINAL HAIR 2 TYPES OF SWEAT GLANDS - Thick, long and dark Eccrine sweat glands - Replaces the vellus hair - Merocrine sweat glands 4. ANDROGENIC HAIR - Excrete directly onto the surface of the skin - Body hair - Secretion: sweat-water - Growth is triggered by androgens - Clear and odorless SKELETAL SYSTEM - Functions: thermoregulation FUNCTION - Excretion 1. SUPPORT - Protection - Framework of the body - Apocrine sweat glands - Supports the entire body - Secrete into the hair follicle - Supports various organs and tissues - Odorless, oily fluid 2. PROTECTION - Modified apocrine sweat glands: ciliary glands - Thoracic basket (eyelid), ceruminous glands( ear), mammary glands - Skull or cranium (chest) - Vertebral column PIGMENT 3. MOVEMENT MELANOCYTE - Acts as levers for muscle - Cell producing skin color 4. MINERAL STORAGE MELANIN - Reservoir for minerals and adipose tissue - Skin pigment or color 5. HEMATOPOIESIS MELANOSOME - Blood cell production/formation - Organelle containing the melanin BONE CELLS ARRECTOR PILI 1. OSTEOBLASTS - Muscle attached to hair follicle - Bone builders - Causes goosebumps - Bone calcification NAILS - Periosteum & endosteum NAIL BEDS 2. OSTEOCYTES - Epidermis under the nail - Mature bone cells LUNULA 3. OSTEOCLASTS - White, half-moon shaped at the base of the nail - Bone eaters CUTICLES - Bone resorption - Eponychium - Endosteum - Epidermis covering the nail bed BONE RESORPTION HAIR - Digestion of bone matrix for normal growth, SHAFT development, repair and maintenance - Exposed part BONE MORPHOLOGY ROOT - Diaphysis - Covered part - Epiphysis FOLLICLE - Articular cartilage - Surrounds the root: living part BONE ANATOMY HAIR BULB (LONGITUDINAL SECTION) - Base: cell proliferation - Compact bone: outer bone and rigid HAIR PAPILLA - Spongy bone: inner bone and porous - Contains blood vessels and nerve endings (CROSS SECTION) LAYERS OF THE HAIR - Periosteum (outer surface ) INNER MEDULLA - Endosteum (inner surface) - Polyhedral cells - Resembles a sandwich - Pigment granules and air spaces - Bone marrow CORTEX BONE CLASSIFICATION - Elongated cells - Long bone - Pigment granules - Irregular bone CUTICLE - Flat bone - Outermost layer - Small bone - Thin, flat keratinized cells 4 TYPES OF HUMAN HAIR COMPARISON OF MALE AND FEMALE PELVIC BONES 1. LANUGO HAIR 1. CAVITY OF THE TRUE PELVIS - Fine, silky fetal hair FEMALE - Tilted forward BONE GROWTH - Broad 1. APPOSITIONAL GROWTH - Shallow - Formation of new bone on the surface of existing - Greater capacity bone increase in bone diameter MALE 2. ENDOCHONDRAL GROWTH - Less tilted forward - Formation of new bone on the epiphyseal - Narrow plate/ends of existing bone - Deep - Increase in bone length 2. BONE THICKNESS CONGENITAL ANOMALIES OF THE SKELETAL FEMALE SYSTEM - Lesser 1. SPINA BIFIDA( NATURAL TUBE DEFECT) - Smoother - Birth defect MALE - Improper formation of the vertebra - Greater 2. OSTEOGENESIS IMPERFECTA ( BRITTLE - Prominent markings BONE DISEASE) 3. ACETABULA - Skeleton does not ossify properly FEMALE - Often characterized by a blue coloration of the - Smaller white sclera of the eye. - Farther 3. ACONDROPLASIA MALE - Most common cause of dwarfism - Larger - Ossification does not occur properly - Closser METABOLIC BONE DISEASE 1. OSTEOPOROSIS( BRITTLE BONE) 4. PUBIS ANGLE - Generalized or localized deficiency of bone FEMALE matrix - Broader - Bones become lighter and fractured easier - More rounded 2. OSTEOPETROSIS (MARBLE BONE) MALE - Osteoclast malfunction decrease bone - More acute resorption - Overgrowth of bone denser and sclerotic bone BONE FORMATION 3. OSTEOMALACIA (BONE SOFTENING) - Reverse of osteoporosis OSTEOGENESIS - Abnormal decrease in bone density (BONE OSSIFICATION) - RICKETS in children TYPES OF OSSIFICATION 4. PAGET DISEASE ( OSTEITIS DEFORMANS) - INTRAMEMBRANOUS OSSIFICATION - Chronic disorder that can result in enlarged and 1. FORMATION OF THE OSSIFICATION CENTER misshapen bones - Mesenchymal cells cluster and differentiate into BENIGN BONE TUMORS osteoblasts forming the ossification center 1. BONE CYST 2. BONE MATRIX SECRETION - Fluid-filled hole that develops inside a bone - Osteoblasts secret osteoid which becomes 2. OSTEOCHONDROMA ( calcified after few days, and forms the bon matrix OSTEOCARTILAGINOUS EXOSTOSIS) 3. TRABECULAE & PERIOSTEUM FORMATION - Cartilage-capped bony projections or outgrowth - Formation of the network of trabeculae on the surface of bones (exostosis) - Formation of periosteum by the condensation of 3. ENCHONDROMA the mesenchyme - Found inside the bones 4. COMPACT BONE FORMATION 4. OSTEOCLASTOMAS - Trabeculae thicken and fuse together - Giant cell tumor - Vascular tissue becomes red bone marrow 5. OSTEOID OSTEOMA - ENDOCHONDRAL OSSIFICATION - Tumor usually found in the femur or tibia 1. MATRIX CALCIFICATION MALIGNANT BONE TUMOR - Enlargement of chondrocytes 1. CHONDROSARCOMA - Calcification of the matrix - Malignant tumor of the cartilage 2. BONE FORMATION 2. OSTEOGENIC SARCOMA - Osteoblasts covering the cartilage - Highly malignant 3. OSSIFICATION CENTER FORMATION - Start in the ends of the bones where new bone - Penetration of blood vessels into the cartilage tissue form as a young person grows - Formation of the ossification center 3. EWING SARCOMA 4. BONE SHAFT FORMATION - Shows up primarily in 5-15 - Thickening of the bone shaft - Occurs in the diaphysis of long bones - Replacement of the cartilages near the 4. MULTIPLE MYELOMA (SWISS CHEESE epiphyses to bone shaft APPEARANCE) 5. FORMATION OF SECONDARY CENTERS OF - Cancer in the bone marrow, formed by malignant OSSIFICATION - CRAB - Secondary centers of ossification are formed by - Calcium elevation the osteoblasts - Renal impairment: increase in creatinine - Blood vessels invade the epiphyses - Anemia - bone : bone pain, lytic , fractures EXAMPLE 5. BONE METASTASES 1. Epiphyseal plate - Most common malignant bone tumor spreading 2. Vertebrosternal cartilage by means of the bloodstream or lymphatic vessels or by direct extension STRUCTURE - Results from primary tumor 1. BONY FUSION IF MINERAL IS REMOVED, BONE IS TOO BENDABLE. - Ossified joint IF COLLAGEN IS REMOVED, BONE IS TOO BRITTLE. SPECIFIC TYPE 1. SYNOSTOSIS ARTICULAR SYSTEM - No boundary existing FUNCTIONS EXAMPLES 1. Holds bones together 1. Metopic suture 2. Allows movement 2. Epiphysial line 3. Makes bone growth possible ARTICULAR CARTILAGE FUNCTION - Specialized connective tissue in diarthrodial 1. AMPHIARTHROSIS joints - Little movement - Reduces friction during joint movement STRUCTURE MENISCUS 1. FIBROUS - Thin fibrous cartilage between the surfaces of SPECIFIC TYPES some joints 1. SYNDESMOSIS - The knee - ligamentous BURSAE - Sacs filled with synovial fluid EXAMPLES - Reduce friction 1. Interosseous ligament - Shock absorber 2. Tibiofibular ligament SYNOVIUM - Synovial membrane STRUCTURE SYNOVIAL FLUID 1. CARTILAGINOUS - Synovia SPECIFIC TYPES - Reduces friction during joint movement 1. SYMPHYSIS TENDONS - Connection by pad of fibrous cartilage - Connect bone to muscle EXAMPLES LIGAMENTS 1. Pubic symphysis - Connect bone to bone 2. Intervertebral disks 3. Mandibular symphysis FUNCTION 1. DIARTHROSIS - Free movement STRUCTURE 1. SYNOVIAL JOINT - Surrounded by articular capsule and lined by synovial membrane CLASSIFICATION OF ARTICULATIONS SPECIFIC TYPES 1. PLANAR JOINTS FUNCTION - Flat or slightly curved bone surfaces 1. SYNARTHROSIS - Gliding movement side to side STRUCTURE EXAMPLE 1. FIBROUS - Sternoclavicular joint - Dense connective tissue (collagen fibers) - Vertebrocostal joint SPECIFIC TYPES - Intercarpal joints 1. SUTURE - Interlocking joints 2. HINGE JOINTS 2. GOMPHOSIS - Permits angular movement: like opening a door - Periodontal ligaments EXAMPLE EXAMPLE - Knee joint 1. Cranial suture - Elbow joint 2. Teeth and sockets - Ankle joint - Interphalangeal joint STRUCTURE 1. CARTILAGINOUS 3. PIVOT JOINTS - Joined by cartilage - Round surface - Monoaxial movement:rotation around SPECIFIC TYPES longitudinal axis 1. SYNCHONDROSIS EXAMPLE - Cartilaginous bridge between articulating bones - Atlanto-axial joint - Radio-ulnar joint 1. LYME DISEASE 4. SADDLE JOINTS - Caused by bites from an infected tick - 1 Saddle shaped bone, and 1 bone riding on the - Symptoms: red rash, burn, itch, hurt, grow an saddle bulls eye pattern, red with a white spot in the middle or - Biaxial movement: circumduction and opposition completely red, flue like symptoms, headaches, fatigue, and muscle and joint pain 5. CONDYLOID JOINTS 2. ANKLE SPRAIN - Oval-shaped bone fits into oval depression - Stretched, partially torn or completely torn ligaments at the ankle EXAMPLE - Most common is inversion injury, where the foot - Metacarpophalangeal joint is rotated inward - ANKLE SPRAIN TYPE 1: a mild sprain, it occurs 6. BALL AND SOCKET JOINTS when ligaments have been stretched or torn minimally - Ball fitting into a cup-like depression - ANKLE SPRAIN TYPE 2: it occurs when some EXAMPLE of the fibers of the ligaments are torn completely - Glenohumeral joint - ANKLE SPRAIN TYPE 3: most severe ankle sprain, it occurs when the entire ligament is torn and MOVEMENT there is great instability of the ankle joint. 1. GLIDING MOVEMENT 3. OSTEOARTHRITIS - Surfaces across each other - Degenerative joint disease 2. ANGULAR MOVEMENT - Aging, wear and tear FLEXION - Deterioration of cartilage produces bone spurs - Reduction of angle between the articulating - Restrict movement elements - Pain upon awakening disappears with EXTENSION movement - Increasing angle of the articulating elements 4. GOUTY ARTHRITIS HYPEREXTENSION - Uric crystals build up in joints-pain - Extension past the anatomical position - Waste products of DNA & RNA metabolism LATERAL FLEXION - Builds up in blood - Bending to the side - Deposited in cartilage causing inflammation and ABDUCTION swelling - Movement away from the longitudinal axis of the - Bones fuse body - Middle-aged men with abnormal gene ADDUCTION 5. RHEUMATOID ARTHRITIS - Movement back to the body's longitudinal - Autoimmune disorder position - Cartilage attacked 3. CIRCUMDUCTION - Inflammation, swelling & pain - Conical movement - Final step is fusion in joint - Complete circular movement 4. ROTATION ARTHROSCOPY - Pivotal - Examination of joint - Revolves around single axis - Instrument size of pencil 5. SUPINATION (PALM UP) - Remove torn knee cartilage 6. PRONATION (PALM DOWN) - Small incision only ARTHROPLASTY SPECIAL MOVEMENT - Replacement of joints 1. EVERSION - Total hip replaces acetabulum & head of femur - Twisting motion that turns the sole outward - Plastic socket & metal head 2. INVERSION - Knee replacement common - Twisting motion that turns sole inward 3. DORSIFLEXION - Flexing the ankle elevating the toes Functions of the Muscular System 4. PLANTAR FLEXION 1. Body movement Contraction of skeletal muscles is - Extending the ankle elevating the heels responsible for the overall movements of the body, such 5. OPPOSITION as walking, running, or manipulating objects with the - Moving in opposite directions hands. 6. ELEVATION - Moving part ion 2. Maintenance of posture Skeletal muscles constantly 7. DEPRESSION maintain tone, which keeps us sitting or standing erect. - Moving part in inferior direction 8. PROTRACTION 3. Respiration Muscles of the thorax are responsible for - Anteriorly moving a part at a horizontal plane the movements necessary for respiration 9. RETRACTION - Posteriorly moving apart at a horizontal plane 4. Production of body heat When skeletal muscles contract, heat is given off as a by-product. This released DISEASE heat is critical to the maintenance of body temperature.  4. ORIENTATION OF FASCICULI 5. Communication Skeletal muscles are involved in all - Rectus (straight) aspects of communication, such as speaking, writing, - Oblique (at an angle) typing, gesturing, and facial expression. 5. NUMBER OF HEADS - Biceps (two) 6. Constriction of organs and vessels The contraction of - Triceps (three) smooth muscle within the walls of internal organs and 6. FUNCTION vessels causes constriction of those structures. This - Abductor (away from midline) constriction can help propel and mix food and water in the - Adductor (toward midline) digestive tract, propel secretions from organs, and - Masseter (a chewer) regulate blood flow through vessels. 7. Heartbeat The contraction of cardiac muscle causes MUSCLE CONTRACTION the heart to beat, propelling blood to all parts of the body. Skeletal muscles contract and relax to mechanically move TYPES OF MUSCLES the body. Messages from the nervous system cause these muscle contractions. This contraction can be SKELETAL MUSCLE summarized in three steps: - Attached to bone (1) A message travels from the nervous system to the - Long,cylindrical muscular system, triggering chemical reactions. - Multiple, peripheral (2) The chemical reactions lead to the muscle fibers - Have striations reorganizing themselves in a way that shortens the - Voluntary muscle--that’s the contraction. - Move the whole body (3) When the nervous system signal is no longer present, CARDIAC MUSCLE the chemical process reverses, and the muscle fibers - Found in heart rearrange again and the muscle relaxes. - Branched 1. A Muscle Contraction Is Triggered When an Action - Usually single, central Potential Travels Along the Nerves to the Muscles - Have striations - Muscle contraction begins when the nervous - Involuntary system generates a signal. The signal, an impulse called - Heart contraction to propel blood through the an action potential, travels through a type of nerve cell body called a motor neuron. The neuromuscular junction is the SMOOTH MUSCLE name of the place where the motor neuron reaches a - Wall of hollow organs, blood vessels, and glands muscle cell. Skeletal muscle tissue is composed of cells - Spindle-shaped called muscle fibers. - Do not have striations - When the nervous system signal reaches the - Involuntary neuromuscular junction a chemical message is released - Compression of organs, ducts, tubes, etc. by the motor neuron. The chemical message, a neurotransmitter called acetylcholine, binds to receptors CHARACTERISTICS OF MUSCLES on the outside of the muscle fiber. That starts a chemical reaction within the muscle 1. Contractibility: ability of the muscle to shorten reducing 2. Acetylcholine Is Released and Binds to Receptors on distance between parts of its contents the Muscle Membrane - A multistep molecular process within the muscle 2. Excitability: ability to respond to a stimulus (similar to fiber begins when acetylcholine binds to receptors on the nerve tissue) muscle fiber membrane. The proteins inside muscle fibers are organized into long chains that can interact with each 3. Extensibility: ability of the muscles to be stretched other, reorganizing to shorten and relax - When acetylcholine reaches receptors on the 4. Elasticity: ability of a muscle to return to its original membranes of muscle fibers, membrane channels open length after stretching and the process that contracts a relaxed muscle fibers begins: Skeletal Muscle Anatomy - When the stimulation of the motor neuron 1. LOCATION providing the impulse to the muscle fibers stops, the - Pectoralis (chest) chemical reaction that causes the rearrangement of the - Gluteus (buttock) muscle fibers' proteins is stopped. This reverses the - Brachial (arm) chemical processes in the muscle fibers and the muscle 2. SIZE relaxes - Maximus (large) - Minimus (small) MUSCLE TONE - Major (larger of two muscles) - Minor (smaller of two muscles) Muscle tone: the constant tension produced by muscles - Longus (long) of the body over long periods of time. - Brevis (short) ❏ responsible for keeping the back and legs straight, 3. SHAPE the head held in an upright position, and the abdomen - Deltoid (triangular) from bulging - Quadratus (rectangular) ❏ depends on a small percentage of all the motor units - Teres (round) in a muscle being stimulated at any point in time, causing their muscle fibers to contract tetanically and out of phase - Assimilation with one another MAJOR FUNCTIONS: 1. Receiving sensory input. MUSCLE TONE ABNORMALITIES - Sensory receptors monitor numerous external 1. Low muscle tone (Hypotonia) and internal stimuli. We are aware of sensations from - Hypotonia, also known as a floppy baby some stimuli, such as vision, hearing, taste, smell, touch, syndrome, is a condition that involves low muscle tone pain, body position, and temperature. Other stimuli, such with reduced muscle strength. Hypotonia is not a specific as blood pH, blood gases, and blood pressure, are health sickness, but a possible sign of various disorders processed at a subconscious level. that affect muscle strength or motor nerve control by the 2. Integrating information brain. - The brain and spinal cord are the major organs ❏ can be genetic meaning that a child is born with Low for processing sensory input and initiating responses. The Muscle Tone or Hypotonia input may produce an immediate response, be stored as memory, or be ignored. ❏ central nervous system disorders and progressive 3. Controlling muscles and glands. neuromuscular disorders are the main cause of Low - Skeletal muscles normally contract only when Muscle Tone or Hypotonia stimulated by the nervous system. Thus, by controlling skeletal muscle, the nervous system controls the major ❏ Some of the medical conditions that may cause Low movements of the body. The nervous system also Muscle Tone or Hypotonia are: participates in controlling cardiac muscle, smooth muscle, Down syndrome and many glands. Muscular Dystrophy 4. Maintaining homeostasis. Cerebral palsy 2 - The nervous system plays an important role in Prader-Willi syndrome maintaining homeostasis. This function depends on the Myotonic dystrophy nervous system’s ability to detect, interpret, and respond Tay-Sachs disease to changes in internal and external conditions. In Symptoms: response, the nervous system can stimulate or inhibit the ❏ Muscle feeling extremely soft is a symptom of low activities of other systems to help maintain a constant muscle tone or hypotonia. internal environment. ❏ Difficulty extending the limb beyond what is normal. 5. Establishing and maintaining mental activity. ❏ In cases of children with low muscle tone or hypotonia, - The brain is the center of mental activity, there will be symptoms of delay in achieving gross motor including consciousness, memory, and thinking. skills and problems with feeding. ❏ Shallow breathing is yet another symptom seen in Three principle functions: children with Low Muscle Tone or Hypotonia. - SENSORY INPUT (nervous system senses the spider ❏ Children with Low Muscle Tone or Hypotonia also have on your leg) symptoms of an underactive gag reflex. - INTEGRATION (your nervous system processes the input, and decides what should be done about it) 2. Excessive muscle tone - MOTOR INPUT (your hand shakes off the spider, it's a - (Hypertonia) Muscle hypertonia is an increase in response that occurs when your nervous system the rigidity of muscle tone and reduced capacity of the activates certain parts of your body) muscle to stretch brought by injury to the CNS (central nervous system) or spinal cord causing disruptions in the SPECIAL SENSES nerve pathways in charge of muscle tone. This takes two Developmental Aspects of the Special Senses forms: spasticity, which is a type of stiffness related to Formed early in embryonic development uncontrolled reflexes, and rigidity, a stiffness not Eyes are out growths of the brain associated with reflexes. All special senses are functional at birth DIFFERENCE OF HYPOTONIA VS HYPERTONIA A. The Senses HYPERTONIA General senses of touch (Tactile) - Stiff limbs Temperature - thermoreceptors (heat) - High muscle tone Pressure - mechanoreceptors (movement) - Difficulty moving\ Pain - mechanoreceptors - Muscle spasms HYPOTONIA Special Senses - Floppy limbs Smell - chemoreceptors (chemicals) - Low muscle tone Taste - chemoreceptors - Difficulty standing Sight - photoreceptors (light) - Instability Hearing - mechanoreceptors Equilibrium - (balance) mechanoreceptors NERVOUS SYSTEM The Eye and Vision 70 percent of all sensory receptors are in the eyes FUNCTIONS Each eye has over a million nerve fibers - Communication Protection for the Eye - Coordination Most of the eye is enclosed in a bony orbit: - Orientation 1. Lacrimal (medial) 2. Ethmoid (posterior) light from getting in, has melanin) 3. Sphenoid (lateral) Modified interiorly into two structures 4. Frontal (superior) 1. Ciliary body – smooth muscle (contracts to adjust the 5. Zygomatic and maxilla (inferior) shape of the lens) 2. Iris- pigmented layer that gives eye color (contracts to Note: A cushion of fat surrounds most of the eye adjust the size of the pupil- regulates entry of light into B. Accessory Structures of the Eye the eye) Eyelids ➔ brush particles out of eye or cover eye. Pupil – rounded opening in the iris Eyelashes ➔ trap particles and keep them out of the eye. H. Sensory Tunic (Retina) Conjunctiva Contains receptor cells (photoreceptors) ➔ Membrane that lines the eyeliids ○ Rods ➔ Connects to the surface of the eye– forms a seal. ○ Cones ➔ Secretes mucus to lubricate the eye. Signals leave the retina toward the brain through the Lacrimal Apparatus optic nerve ○ Lacrimal gland - produces lacrimal fluid Signals pass from photoreceptors via a two neuron ○ Lacrimal canals - drains lacrimal fluid. chain Lacrimal sac ○ Bipolar neurons and Ganglion cells ➔ provides passage of lacrimal fluid towards nasal cavity. Visual Pigment Nasoclacrimal duct a. Rhodopsin – visual purple, in high concentration in ➔ Empties lacrimal fluid into the nasal cavity. RODS ○ Composed of opsin and retinal (a derivative of vitamin C. Function of the Lacrimal Apparatus A) protein. Properties of Lacrimal Fluid ○ When light hits the protein it “bleaches”- turns yellow Dilute salt solution (tears) and then colorless. It straightens out and breaks down Contains antibodies into opsin and retinal. 1. Fight antigens- foreign substance I. Neurons of the Retina and Vision 2. Lysozyme (enzyme that destroys bacteria) Protects, moistens, and lubricates the eye Rods Empties into the nasal cavity ○ Most are found towards the edges of the retina ○ Allow dim light vision and peripheral vision (more D. Extrinsic Eye Muscles sensitive to light, do not respond in bright light) Muscles attach to the outer surface of the eye ○ Perception is all in gray tones Produce eye movements When Extrinsic Muscles Contract.... Cones Superior oblique = eyes look out and down ○ Allow for detailed color vision Superior rectus = eyes looks up ○ Densest in the center of the retina Lateral rectus = eyes look outward ○ Fovea centralis – area of the retina with only cones Medial rectus = eyes look inward ○ Respond best in bright light Inferior rectus = eyes looks down Inferior oblique = eyes look in and up No photoreceptor cells are at the optic disk or blind spot E. Structure of the Eye J. Cone Sensitivity The wall is composed of three tunics: There are three types of cones 1. Fibrous tunic - outside layer. Different cones are sensitive to different wavelengths 2. Choroid - middle layer ○ red - long 3. Sensory tunic - inside layer ○ green - medium ○ blue - short F. The Fibrous Tunic Color blindness is the result of lack of one or more cone Sclera type White connective tissue layer Seen anteriorly as the “white of the eye” K. How do we see colors? Semi-transparent To see any color, the brain must compare the input from different kinds of cone cells – and then make other Cornea comparisons as well. Transparent, central anterior portion The lightning-fast work of judging a color begins in the Allows for light to pass through (refracts, or bends, light retina, which has three layers of cells. Signals from the slightly) red and green cones in the first layer are compared by Repairs itself easily specialized red-green “opponent” cells in the second The only human tissue that can be transplanted without layer. fear of rejection These opponents' cells compute the balance between red and green light coming from a particular part of the visual G. Choroid Layer field. Other opponent cells then compare signals from Blood-rich nutritive tunic blue cones with the combined signals from red and green Pigment prevents light from scattering (opaque- blocks cones.  Blind Spot L. Colorblindness If the image is focused at the spot where the optic disk An inherited trait that is transferred on the sex is located, nothing will be seen chromosomes (23rd pair) - sex-linked trait. There are no photoreceptors – nerves and blood Comes from a lack of one or more types of color vessels pass through this point. receptors. Occurs more often in males. T. Visual Pathway Most are green or red or both and that is due to lack of Photoreceptors of the retina red receptors. Optic Nerve Another possibility is to have the color receptors Optic nerve crosses at the optic chiasma missing entirely, which would result in black and white Optic tracts vision. Thalamus (axons from optic radiation) M. Colorblindness Test Plates Visual cortex of the occipital lobe Ishihara Chart U. Eye Reflexes Internal muscles are controlled by the autonomic N. Lens nervous Biconvex crystal like structure system Held in place by a suspensory ligament attached to the ○ Bright light causes pupils to constrict through action of ciliary body radial (iris) ciliary muscles Refracts light greatly ○ Viewing close objects causes accomodation External muscles control eye movement to follow O. Internal Eye Chamber Fluids objects – Aqueous humor voluntary, controlled at the frontal eye field Watery fluid found in chamber between the lens and Viewing close objects causes convergence (eyes cornea moving Similar to blood plasma medially) Helps maintain intraocular pressure Provides nutrients for the lens and cornea SENSE OF HEARING Reabsorbed into venous blood through the canal of A. The Ear Schlemm Houses two senses ○ Hearing (interpreted in the auditory cortex of the Vitreous humor temporal lobe) Gel-like substance behind the lens ○ Equilibrium (balance) (interpreted in the cerebellum) Keeps the eye from collapsing Lasts a lifetime and is not replaced Receptors are mechanoreceptors Different organs house receptors for each sense P. Lens Accomodation Auricle Helps collect sound waves traveling through the air Light must be focused to a point on the retina for and directs them into the external acoustic meatus. optimal vision. B. Anatomy of the Ear The eye is set for distance vision (over 20 feet away) The ear is divided into three areas 20/20 vision - at 20 feet, you see what a normal eye ○ Outer (external) ear would ○ Middle ear see at 20 feet (20/100 - at 20, normal person would see ○ Inner at 100) C. The External Ear The lens must change shape to focus for closer objects Involved in hearing only Structures of the external ear Q. Myopia ○ Pinna (auricle)- collects sound Nearsightedness, or myopia is the difficulty of seeing ○ External auditory canal- channels sound inward objects at a distance. The External Auditory Canal ○ Myopia occurs when the eyeball is slightly longer Narrow chamber in the temporal bone- through the than usual from front to back. external auditory meatus ○ This causes light rays to focus at a point in front of the Lined with skin retina, rather than directly on its surface. Ceruminous (wax) glands are present ○ Concave lenses are used to correct the Ends at the tympanic membrane (eardrum) R. Hyperopia D. The Middle Ear or Tympanic Cavity Hyperopia (farsightedness) Air-filled cavity within the temporal bone Light entering the eye focuses behind the retina. Only involved in the sense of hearing Hyperoptic eyes are shorter than normal. Two tubes are associated with the inner ear Hyperopia is treated using a convex lens. ○ The opening from the auditory canal is covered by the tympanic membrane (eardrum) S. Images Formed on the Retina ○ The auditory tube connecting the middle ear with the throat (Eustacian tube)  Allows for equalizing pressure during yawning or Function of Maculae: swallowing ○ Movements cause otoliths to bend the hair cells This tube is otherwise collapsed (gravity moves the “rocks” over and pulls the hairs) Bones of the Tympanic Cavity Dynamic Equilibrium Three bones span the cavity Whole structure is the ampulla ○ Malleus (hammer) Crista ampullaris – receptors in the semicircular canals ○ Incus (anvil) ○ Tuft of hair cells ○ Stapes (stirrip) ○ Cupula (gelatinous cap) Action of angular head movements Vibrations from eardrum move the malleus ○ The cupula stimulates the hair cells These bones transfer sound to the inner ear ○ Movement of endolymph pushes the cupula over and E. Inner Ear or Bony Labyrinth pulls the hairs Also known as osseous labyrinth- twisted bony tubes ○ An impulse is sent via the vestibular nerve to the Includes sense organs for hearing and balance cerebellum Filled with perilymph I. Chemical Senses - Taste and Smell Vibrations of the stapes push and pull on the Both senses use chemoreceptors membranous ○ Stimulated by chemicals in solution oval window, moving the perilymph through the cochlea ○ Taste has four types of receptors The round window is a membrane at the opposite end ○ Smell can differentiate a large range of chemicals to relieve pressure. Both senses complement each other and respond to many of the same stimuli A maze of bony chambers within the temporal bone ○ Cochlea J. Olfaction - The Sense of Smell ○ Scala Vestibuli - upper chamber Olfactory receptors are in the roof of the nasal cavity ○ Scala Tympani - lower chamber Neurons with long cilia ○ Vestibule Chemicals must be dissolved in mucus for detection ○ Semicircular canals Impulses are transmitted via the olfactory nerve Interpretation of smells is made in the cortex (olfactory F. Organ of Corti area of temporal lobe) Located within the cochlea Receptors = hair cells on the basilar membrane K. The Sense of Taste Gel-like tectorial membrane is capable of bending hair Taste buds house the receptor organs cells Location of taste buds Endolymph in the membranous labyrinth of the cochlear ○ Most are on the tongue duct flows over it and pushes on the membrane) ○ Soft palate Cochlear nerve attached to hair cells transmits nerve ○ Cheeks impulses to auditory cortex on temporal lobe L. The Tongue and Taste G. Mechanisms of Hearing The tongue is covered with projections called papillae Vibrations from sound waves move tectorial membrane ○ Filiform papillae – sharp with no taste buds (pass through the endolymph fluid filling the membranous ○ Fungifiorm papillae – rounded with taste buds labyrinth in the cochlear duct) ○ Circumvallate papillae – large papillae with taste buds Hair cells are bent by the membrane Taste buds are found on the sides of papillae An action potential starts in the cochlear nerve The signal is transmitted to the midbrain (for auditory M. The Structure of Taste Buds reflexes and then directed to the auditory cortex of the Gustatory cells are the receptors temporal lobe) Have gustatory hairs (long microvilli) Continued stimulation can lead to adaptation (over Hairs are stimulated by chemicals dissolved in saliva stimulation to the brain makes it stop interpreting the Impulses are carried to the gustatory complex (pareital sounds) lobe) by several cranial nerves because taste buds are found in different areas H. Organs of Equilibrium ○ Facial nerve Receptor cells are in two structures ○ Glossopharyngeal nerve ○ Vestibule ○ Vagus nerve ○ Semicircular canals Sweet receptors Equilibrium has two functional parts ○ Sugars ○ Static equilibrium- in the vestibule ○ Saccharine ○ Dynamic equilibrium- in the semicircular canals ○ Some amino acids Static Equilibrium Sour receptors Maculae – receptors in the vestibule ○ Acids ○ Report on the position of the head Bitter receptors ○ Send information via the vestibular nerve ○ Alkaloids Anatomy of the maculae: Salty receptors ○ Hair cells are embedded in the otolithic membrane ○ Metal ions ○ Otoliths (tiny stones) float in a gel around the hair Umami cells ○ Glutamate, ○ aspartate (MSG, meats) Fibrous Skeleton of the Heart Functions: THE CARDIOVASCULAR SYSTEM 1. Structure support - firm base of the heart valves and The cardiovascular system is a closed system of the openings of great vessels. heart 2. It anchors the cardiac muscle. and blood vessels. 3. An electrical insulator. ○ The heart pumps blood into blood vessels ○ Blood vessels circulate the blood to all parts of the Chambers of the Heart body, to ALL cells. Atrium (R & L)—receive blood Functions: each atria extends into a smaller, external chamber ○ to deliver oxygen and nutrients to all body cells, called ○ transport enzymes and hormones, and an auricle ○ to remove carbon dioxide and other waste products Ventricle (R & L)—inferior to the atria; expel blood out from the cells. of the heart Heart D. Chambers of the Heart The long axis is directed obliquely, leftward, downward, ATRIUM (R&L) and forward. receive blood Size of adult’s fist, weight < 1 pound each atria extends into a smaller, external chamber Adult heart called an auricle. ➔ 12 cm long from its base at the beginning root of the aorta to the left ventricular apex. VENTRICLE (R&L) ➔ 8 to 9 cm wide transversely. inferior to the atria; ➔ 6 cm thick anteroposteriorly. expel blood out of the heart MALE HEART Note: The chambers on the left are separated from the 0.43% of body weight chambers on the right by a septum (wall of cardiac 280 to 350 g, with an average of 300 g muscle) FEMALE HEART interatrial septum interventricular septum. 0.40% of body weight ○ interatrial septum 230 to 300 g, with an average of 250g ○ interventricular septum A. Location of the Heart Heart Chambers – Internal The heart is medial to the lungs, posterior to the 1. Interatrial septum – wall that separates atria sternum, 2. Pectinate muscles – internal ridges of myocardium in anterior to the vertebral column, and superior to the right atrium and both auricles (absorber) diaphragm. 3. Interventricular septum – wall that separates ventricles Its distal end, the apex, points to the left, terminating at 4. Trabeculae carneae – internal ridges in both ventricles the (absorber) level of the 5th intercostal space. Coverings of the Heart E. Myocardial Thickness and Function Pericardium (Pericardial sac) Thickness of myocardium varies according to the 1. Fibrous pericardium - sac made of tough connective function tissue of the chamber 2. Double-layered serous membrane (Serous Atria are thin walled, deliver blood to adjacent ventricles pericardium): Ventricle walls are much thicker and stronger a. Parietal Pericardium - lines the interior of the fibrous ○ right ventricle supplies blood to the lungs (little flow pericardium. resistance) b. Visceral pericardium (epicardium) ○ left ventricle wall is the thickest to supply systemic ➔ covers the heart Circulation ➔ It is part of the heart wall. ➔ the innermost layer of the pericardium and the Thickness of Cardiac Walls outermost layer of the heart wall. ★ Myocardium of the left ventricle is much thicker than the right. NOTE: Serous fluid fills the pericardial cavity between parietal & visceral layers D. Developmental Aspects of the Heart Fetal heart structures that bypass pulmonary circulation Pericardial Layers of the Heart ○ Foramen ovale connects the two atria ○ Ductus arteriosus connects pulmonary trunk and the Heart Wall Aorta Epicardium (visceral pericardium ➔ outside layer of connective tissue on the surface of Atrial Septal Defect the heart. A hole between the two atria. Myocardium It occurs about 10% of children born with congenital ➔ thick wall of cardiac muscle. heart Endocardium defects. ➔ inner epithelial & connective tissue lining of heart Occurs during fetal lifed when partitioning process and valves. (during the formation of the heart chambers) does not occurs CENTRAL NERVOUS SYSTEM completely, leaving an opening in the interatrial septum. ➔ Composed of the main officers which are the brain ASD is large or moderately large then it will allow a and spinal cord large PERIPHERAL NERVOUS SYSTEM amount of blood to pass through the opening into the right ➔ Spinal nerves are primarily involved heart and the right ventricle and lungs will become ➔ Have afferent subdivision which brings forth sending overworked, and symptoms may be noted impulses on the office of the central nervous system Symptoms to what is the appropriate action, which can come ○ Delayed weight gain and poor growth from sensory stimuli or visceral stimuli. ○ Child tires easily, especially when playing ➔ Have efferent division where after coming from the ○ Fatigue central nervous system, there is an action coming ○ Excessive sweating from the somatic nervous system–where skeletal ○ Rapid breathing muscle are involved. ○ Poor feeding ○ Shortness of breath C. Functional Classification of Nervous ○ Frequent respiratory infections including pneumonia System Most children have no symptoms and seem healthy. SENSORY (AFFERENT) DIVISION The mixing of blood through the ASD produces an Consist of nerve fibers that conveys impulses to the overload of blood in the right heart (Usually well tolerated) Central Nervous System. Some of the atrial septal defects, if small enough, may ○ SOMATIC SENSORY FIBERS (soma = body) become smaller with time and even close spontaneously. ➔ Impulses from the skin, skeletal muscle, and joints Examples of Congenital Heart Defects ○ VISCERAL SENSORY FIBERS ➔ Impulses from the visceral organs F. Heart Valves MOTOR (EFFERENT) DIVISION GENERAL FUNCTIONS: Carries impulses from the Central nervous system to When a chamber wall contracts blood is pumped effector organs, muscle and gland. through Activate - bring about a motor response. a valve. Two Divisions: Any backflow increases pressure on the cusps and ○ Somatic Nervous System (Voluntary Nervous closes System) the valves. ➔ Allows conscious and voluntary control of AV valve closes during ventricular contraction; papillary skeletal muscle. muscles also contract pulling the chordae tendineae ○ Autonomic Nervous System (Involuntary Nervous which system) keep the valve cusps from prolapsing into the atrium. ➔ Regulares events that are automatic and ➔ Semilunar Valves Prevent backflow of blood into the involuntary (smooth and cardiac muscle) ventricles ➔ Aortic semilunar valve lies between the left ventricle D. Structures and Functions and SUPPORTING CELLS the aorta. Lumped together as NEUROGLIA ➔ Pulmonary semilunar valve lies between the right Nerve glue ventricle and pulmonary trunk Functions: NOTE: The valve cusps are held in place by chordae ○ Support tendineae (“heart strings”) which originate from papillary ○ Insulates muscles protruding from the inside of the ventricle wall ○ Protects V. THE NERVOUS SYSTEM ASTROCYTES 1. Master controlling (thought, action, and emotion) Star-shaped cells 2. Communication Most abundant and versatile neuroglia a. signalling device between body cell Numerous projections has swollen ends that clings to b. rapid and specific and cause immediate response. neurons (anchoring to nutrient and blood capillaries) *Endocrine system - release hormone; scond major Protect neurons from harmful substances in the blood controlling Control the chemical environment in the brain system. (potassium ions and neurotransmitters) Potassium A. Functions of the Nervous System ➔ the primary cation for muscular contraction; 1. Monitor changes - uses millions of sensory receptors ➔ active intracellular ➔ both internal and external (stimuli) Sodium ➔ SENSORY INPUT - gathered information ➔ a potent neurotransmitter 1. PROCESS and INTERPRETS - INTEGRATION ◆ Neurotransmitter helps passing of impulses ➔ Decision what should be done 2. EFFECT AND CAUSE - RESPONSE MICROGLIA ➔ Activating muscle or gland (EFFECTORS) Spider-like phagocyte MONITORS the health of nearby neurons B. Organization of Nervous System Eats the disposed debris (dead brain cells) and bacteria The Nervous System is divided into two: EPENDYMAL CELLS NODE OF RANVIER Glial cells (non-neurons) that line the central cavities of Gaps and indentions in between myelin sheath the brain and spinal cord Motor neurons cause muscle contractions and it is like a BEATING/MOVING CILIA control secretions from glands and organs controlling ➔ helps circulate cerebrospinal fluid and fills cavities. body functions. Froms protective cushion around the CNS. F. Types of Neurons OLIGODENDROCYTES NERVE RECEPTORS FLAT EXTENSION ↓ ➔ wraps around the nerve fiber producing MYELIN SENSORY NEURONS SHEATH. ↓ ◆ Myelin Sheath - fatty insulating covering. INTERNEURONS ↓ SATELLITE CELLS AND SCHWANN CELLS MOTOR NEURONS Schwann Cells ➔ Considered as the satellite cells. Interneurons are located entirely within the central ➔ Forms the myelin sheath around the nerve fibers nervous that are found in the PNS. system. They intercept the impulses from the sensory Protective and cushioning cell. neurons and transmit the signals to the motor neurons. E. Parts of a Neuron Neurons NERVE FIBERS ➔ “Nerve cells” There are no Schwann cells on nerve fibers in the ➔ The structural and functional units of the nervous central system nervous system, therefore damage to those nerve fibers ➔ Functions: is Conduct Impulses that enable the body to interact not reversible. with its internal and external environment. A bundle of nerve fibers is simply called ‘a nerve’. The tissues that support the nerve cells is called AFFERENT nerves conduct impulses to the central neuroglia. nervous system *The motor neurons usually have one axon and several EFFERENT nerves conduct impulses to the muscles, Dendrites organs, and glands. SYNAPSES CELL BODY “metabolic center” Nerve impulses are transmitted via branches called Transparent nucleus that contains nucelolus synapses. The synapses are connectors... hooking PROCESS dendrites and axons from one neuron to another. ARMLIKE or FIBER The number of synapses influences transmission. Length 3-4 feet (lumbar region of the spine to the great ○ That number can decrease with disease, lack of toe) stimulation, drug use, etc. Important neurotransmitters: DENDRITES ○ Monoamines short and unsheathed ○ Neuropeptides Conveys INCOMING messages toward the cell body. ○ Nitric Oxide AXON G. Nerve Properties Related to Function Generates nerve impulses and conducts then AWAY Irritability from the sell body ➔ able to respond to stimuli Conductivity AXON TERMINALS ➔ able to transmit electrical potential along the axon Contains hundred of tiny vesicles that contains chemical (neurotransmitter) H. Resting Membrane Potential Difference in charge between the inside and outside of SYNAPTIC CLEFT the cell tiny gap ○ Sodium in greater concentration outside Separates from the next neuron ○ Potassium in greater concentration inside Functional junction - SYNAPSE ○ Anions in greater concentration inside ○ Membrane permeability greater for potassium than MYELIN SHEATH sodium Whitish fatty material ○ Na+ Covers most long nerves / K+ pump moves sodium out, potassium in. Protects and insulates the fiber and increase the Sodium ion stays outside transmission rate of nerve impulses. ○ Outside of the membrane is polarized because of the sodium SCHWANN CELL Inside is the potassium “Myelinate” the cell axon outside the Central Nervous ○ Inside of the membrane is negative because of system potassium  The sodium because of the channel will open up and K. Reflexes the sodium will come in. Because it is now positive it will Rapid, predictable and involuntary response to stimuli allow for the opening of the channel leading forth for the Types of Reflexes potassium to go out. a. Somatic Reflex As the sodium comes in the are becomes polarized ➔ reflex that stimulate the skeletal muscle ○ The process is called depolarization b. Autonomic Reflex ➔ negative to positive; leading forth to positive ions ➔ Regulates the activity of smooth muscle (heart and to come in. gland), salivary reflex, pupillary reflex ➔ Regulates body function: Digestion, elimination, blood As the sodium channel opens the depolarization will pressure , sweating lead forth to the opening and the inactivation. ○ Inactivation allows the opening or going outside of the Reflexes Arc potassium ions making the inside of the membrane Reflexes occurs over neural pathways positive and negative outside. Involves both CNS and PNS structures Repolarization is when the potassium ions goes out of 5 elements: the membrane. ○ Sensory receptor (reacts to stimulus) ○ it is like a resting phase or another cycle where ○ Effector organ (stimulated organ) sodium will go out and potassium goes in. ○ Sensory neuron ○ Synapse (Interneuron) I. Generating Action Potentials ○ Motor neurons Voltage gated ion channels ○ Sodium channels open → sodium rushes in THE CENTRAL NERVOUS SYSTEM ○ Sodium channels close → stops inward flow of EMBRYONIC DEVELOPMENT sodium Central Nervous System - FIRST APPEAR AS A ○ Potassium channels open →potassium rushes out SIMPLE Net effect - Depolarization then Repolarization TUBE ○ Electrical flow created by ionic flow, not electron flow (NEURAL TUBE) 4th week –anterior end of neural tube Sodium (Na+ ) and Potassium (K + ) Pump begins to expand (Brain formation) Membrane bound proteins The rest of the neural tube (posterior) becomes the Utilizes ATP SPINAL CORD Maintains resting membrane potential Establishes sodium & potassium concentration CENTRAL NERVOUS SYSTEM gradients The central nervous system (CNS) consists of the brain and the spinal cord. J. Neuromuscular Junction The average length of a male spinal cord is 45 cm and Motor neuron cell body and dendrites in gray matter of for females, it is around 43 cm. spinal cord The spinal cord carries incoming and outgoing Axons extend to muscle messages between the brain and the rest of the body. Axon’s terminal end contains a synaptic knob Synaptic knob has synaptic vesicles containing A. Brain acetylcholine Two fistful of pinkish gray tissues Axon leaves spinal cord Wrinkled like a walnut with a texture of cold oatmeal Extends to skeletal muscle Weigh – over three pounds Terminal branches end in synaptic knob. BLOOD SUPPLY TO THE BRAIN The arteries deliver oxygenated blood from the heart to Motor Unit all the regions of the body. A single motor neuron and all of the muscle fibers The left and right internal carotid and vertebral arteries which it supply the brain. innervates. The blood is distributed throughout the brain via the Represents functional unit of movement. numerous branches of the circle of Willis. Ratio of muscle fibers to nerve relates to muscle’s Veins return deoxygenated blood to the heart. movement function. The largest vein in the brain is the venous sinus, located Motor End Plate between the two hemispheres of the brain. Area beneath the terminal branches of the axons It receives blood from the left and right superficial Contains acetylcholine receptor complexes cerebral veins of the cerebrum. Acetylcholine binding opens the receptor complex The blood is then drained via the left and right internal Cholinesterase degrades acetylcholine into acetate and jugular veins choline B. Regions of the Brain Tension Generating Characteristics The brain can be split into three regions All or None Law 1. Forebrain When a neuron reaches threshold it generates an 2. Brainstem action potential which is conducted the length of the axon 3. Cerebellum without any voltage change When the nerve fires, all the muscle fibers it innervates FOREBRAIN contract Consists of: 1. Cerebrum (Cerebral cortex and Basal ganglia) Wernicke’s area: 2. Corpus callosum ➔ Comprehension of written and spoken language 3. Diencephalon Primary olfactory cortex: 4. Limbic system ➔ Receives and processes olfaction signals Secondary auditory cortex: C. Cerebrum ➔ Processes auditory information and plays a role in The cerebral cortex is the surface of the cerebrum. speech perception LARGEST part of the brain (Taking up 7/8ths of the Visual association area: brain’s weight) ➔ Participates in object and pattern recognition Develops and grow Responsible for higher intellectual functions and OCCIPITAL LOBE conscious thought. Primary visual cortex: Made up of the cerebral cortex and the basal ganglia. ➔ Receives and processes visual signals from the The cortex contains around 16 billion neurons (cells opposite visual field via the thalamus that relay sensory information and motor commands as Secondary visual cortex: electric signals throughout the body). ➔ Interprets visual signals and contributes to visual In order for the cerebral cortex to fit inside the skull, the mapping cerebral cortex has folds. Tertiary visual cortex: ➔ Participates in object recognition and motion CEREBRAL CORTEX HEMISPHERES sensing Cerebral cortex consists of a left and a right hemisphere. Basal Ganglia (Basal Nuclei) ○ Left Deep within the white matter ○ responsible for language, calculation, Helps regulate voluntary motor activities sent to the comprehension, and writing. skeletal muscle ○ Right Influence body movement and muscle tone ○ responsible for creativity, visual, emotional, and artistic awareness. Gray and White Matter Each hemisphere controls the opposite side of the The brain and spinal cord of the central nervous system body. receive impulses, process the information, and respond with the appropriate action. LOBES OF THE CEREBRAL CORTEX Gray matter of the brain and spinal cord The cortex is also divided into 4 lobes that correspond ➔ consists of unsheathed nerve fibers (cannot be to the overlying bones of the skull. regenerated if damaged) in the cortex or surface layer. The white matter FRONTAL LOBE ➔ makes up the internal structure, and consists of Prefrontal association area: myelinated nerve fibers. ➔ Executive function (thought, cognition, planning, and personality) D. Corpus Callosum Premotor cortex: C-shaped structure that straddles the midline of the ➔ Planning movement brain. Supplementary motor area: Connects the two hemispheres to allow communication ➔ Planning limb and eye movement Broca’s area: between them. ➔ Speech production and language processing Gustatory cortex: E. Cerebral Cortex ➔ Receives and processes taste signals Consciousness, interpretation of sensation, speech, Primary motor area: memory, logical and emotional response, and voluntary ➔ Voluntary movement movement. Control Sensory pathways- CROSS pathways (left side of the primary somatic sensory area receives impulses from the PARIETAL LOBE right side of the body) Primary somatosensory cortex: Primary somatic sensory area: ➔ Processes tactile information (for the opposite side of ○ Recognize pain the body) ○ Coldness Secondary somatosensory cortex: ○ Light touch ➔ Processes tactile information (including pain Somatosensory association area: BROCA’S AREA (Speech area) ➔ Integrates sensory input (perceives temperature, Found in the base of the precentral gyrus. pressure, size, texture,and relationships between touched CORTICAL AREA INVOLVE IN SPEAKING objects F. Diencephalon PARIETAL LOBE The diencephalon refers to the thalamus and Auditory association area: hypothalamus. ➔ Interprets auditory information such as speech, music, Thalamus or other sounds ➔ the relay center for all sensory impulses except Primary auditory cortex: olfactory (sense of smell) and motor areas of the ➔ Interprets pitch and rhythm of sounds cortex.  Hypothalamus trochlear (CN04) nerves. Both help control eye ➔ regulates behavior , body temperature, water balance movement. , metabolism, any metabolic activities. ○ Attached to the pituitary gland, it also controls PONS hormonal secretions of this gland. Plays a role in regulating visceral (internal organ) LIMBIC SYSTEM (Emotional Visceral brain) – thirst , control. appetite, sex, pain and pleasure Connects the brain to the brain stem through tracts of white fibers that carry signals between them. DIENCEPHALON is the region of the brain that consists It houses pontine nuclei, which affect breathing rhythms of the: 1. Hypothalamus MEDULLA OBLONGATA 2. Thalamus Connects the rest of the brain to the spinal cord. 3. Epithalamus (main structure is the pineal gland). Controls involuntary functions of the respiratory, digestive, THALAMUS and circulatory system and contributes to hearing, Plays a role in learning and memory. balance, and taste. It consists of several nuclei that pass sensory The medulla plays a role in homeostasis, acting as the information autonomic reflex center for heart contraction, vasomotor to different regions of the cerebral cortex. control, respiratory rate and depth, as well as other Determines what sensory information is important reflexes such as swallowing, coughing, vomiting, and enough Sneezing to send to the cerebral cortex to allow for conscious awareness of the sensory input. Reticular Formation Diffused mass of gray matter extending the entire HYPOTHALAMUS length of the brain stem Regulates autonomic nervous functions, emotions, Neuron involve in motor control of the visceral organs behavior, food consumption, circadian rhythms, body Reticular Activating System (RAS) temperature. regulates behavior, water balance Plays a role in consciousness and wake and sleep ,metabolism, any metabolic activities cycle It also produces hormones that influence the pituitary Filter for the flood of sensory inputs that stream up the gland and regulate endocrine functions. spinal cord and brainstem daily At the base of the hypothalamus, the optic chiasm is Damage to RAS = COMA the crossing point of the optic nerves H. Cerebellum LIMBIC SYSTEM Large, cauliflower-like that project dorsally from under Located on the inner border of the cerebrum, above the the occipital lobe of the cerebrum diencephalon, forming a pair of rings between the two Second largest part of the brain. cerebral hemispheres. It contains nerve fibers that connect it to every part of It manages a range of emotions and contributes to the the central nervous system. processing of smell memory It coordinates voluntary and involuntary patterns of The limbic system consists of: movements. ○ Amygdala (memory and emotion) It also adjusts muscles to automatically maintain ○ Hippocampus (long term memory) balance, posture and equilibrium, cognitive functions ○ Mammillary body (smell memory) related to word association and puzzle solving. ○ Septal nucleus (feeling of pleasure) Considered to be a motor structure. (Even though ○ Cingulate gyrus (expressing emotions through motor commands do not directly come from the gestures) cerebellum, it modifies the commands to make the movements more accurate.) EPITHALAMUS Cerebellar damage leads to impairment in motor Forms the roof of the third ventricle control. Pineal gland – endocrine (melatonin) Choroid plexus I. Protector of the Nervous System ○ Knots of capillaries within each ventricle Nervous tissue is very soft and delicate ○ Form the cerebrospinal fluid Irreplaceable neurons are injured in the slightest pressure. G. Brain Stem The brainstem consists of 4 structures: MENINGES 1. Midbrain The brain and the spinal cord are vital to the human body 2. Pons (“bridge”) Meninges 3. Medulla oblongata ➔ set of protective connective tissue structures that surround the spinal cord and brain. MIDBRAIN The meninges consist of three layers: The midbrain contains nuclei, called colliculi, which ○ Dura mater is the outermost layer; control visual and auditory reflexes. ○ Arachnoid mater is directly underneath the dura Control visual reflexes and sense of hearing. ○ Pia mater is the innermost layer. It also contains nuclei for the oculomotor (CN03) and The brain and spinal cord are enclosed by 3 membranes,collectively known as the meninges 1. Dura Mater “Tough or Hard Mother” – doubled-layered membrane EPINEURIUM where it surrounds the brain TOUGH fibrous sheath that bound the bundle of ○ Periosteum (periosteal layer) fascicle. ➔ Attached to the inner surface of the skull ○ Meningeal layer A. Cranial Nerves ➔ Forms the outer most covering of the brain Composed of 12 pairs - serves the head and neck VAGUS nerve – extend to the thoracic and abdominal 2. Arachnoid cavities WEB LIKE ; (Arachnida: spider) Names are number according to the structures it Middle meningeal layer CONTROLS Threadlike extension span the subarachnoid space to MIXED NERVES - nerves carrying a SENSORY and attach to the innermost layer MOTOR fibers Sensory Functions: 3. Pia Mater ○ Optic nerve “Gentle mother” ○ Olfactory nerve Clings tightly to the surface of the brain and spinal cord ○ Vestibulocochlear nerve SPINAL CORD CRANIAL NERVE I: OLFACTORY NERVE The spinal cord has 31 segments: LOCATION ○ 8 cervical segments (C1-C8 vertebrae) In the nasal cavity and passes through each side of the ○ 12 thoracic segments (T1-T12 vertebrae) nose, terminating in masses of gray matter called the ○ 5 lumbar segments (L1-L5 vertebrae) olfactory bulbs. ○ 5 sacral segments (S1-S5 vertebrae) ○ 1 coccygeal segment. SENSORY The 44 cm long spinal cord is shorter than the spinal Transmits signals for smell column, so segments do not perfectly correspond to the vertebrae. TEST Each segment of the spinal cord, left and right pairs of Subject is asked to sniff and identify sensory and motor nerves aromatic substance (oil, vanilla, perfume) Branch out and connect to the peripheral nervous system. CRANIAL NERVE II: OPTIC NERVE Impulses travel back and forth to the brain and back to LOCATION the muscles. In the retina of each eye and terminates in the thalamus. From there, signals are VENTRICLES transmitted to the visual cortex. Networked ventricles that produce cerebrospinal fluid. This fluid moves between th