BIO 180 - Human Anatomy and Physiology I - Unit V Notes

ANS (Autonomic Nervous System)

• Functions: Regulates involuntary functions such as heart rate, digestion, and breathing.

• Divisions:

  • Sympathetic (Thoracolumbar):

    • Originates from thoracic and lumbar regions of the spinal cord.

    • Effects: Prepares the body for "fight or flight" responses.

    • Neurotransmitters: Primarily norepinephrine (noradrenaline).

    • Ganglia: Paravertebral (sympathetic chain) and prevertebral (collateral).

  • Parasympathetic (Craniosacral):

    • Originates from the brainstem and sacral region of the spinal cord.

    • Effects: Promotes "rest and digest" functions.

    • Neurotransmitters: Acetylcholine.

    • Ganglia: Terminal (intramural).

Ganglia

• Paravertebral (Sympathetic Chain):

  • Cervical, thoracic, lumbar, and sacral regions.

  • Located near the vertebral column.

• Collateral/Prevertebral:

  • Celiac, superior mesenteric, inferior mesenteric, aorticorenal, and renal.

  • Located anterior to the vertebral column.

• Terminal/Intramural:

  • Ciliary, pterygopalatine, submandibular, and otic.

  • Located near or within the walls of the organs they innervate.

• Adrenal Medulla:

  • Specialized neuroendocrine gland.

  • Releases epinephrine (adrenaline) and norepinephrine directly into the bloodstream during sympathetic activation.

Autonomic Tone & Biofeedback

• Autonomic Tone:

  • Baseline level of activity in the autonomic nervous system.

  • Maintains balance between sympathetic and parasympathetic activity.

• Biofeedback:

  • Technique that allows individuals to gain some conscious control over autonomic functions.

Memory

• Types of Memory:

  • Short-Term Memory:

    • Temporary storage of information.

    • Limited capacity.

  • Long-Term Memory:

    • Permanent storage of information.

    • Large capacity.

  • Fact (Declarative) Memory:

    • Storage of factual information.

  • Skill (Procedural) Memory:

    • Storage of how to perform tasks.

• Secondary vs. Tertiary Memories:

  • Secondary Memories: Recallable long-term memories.

  • Tertiary Memories: Long-term memories that are very resistant to being forgotten.

• Memory Engrams:

  • Physical or chemical changes in the brain associated with memory storage.

• Conversion of Short-Term to Long-Term Memory:

  • Time varies but repetition and emotional significance enhance conversion.

• Brain Areas Associated with Memory:

  • Hippocampus, amygdala, cerebral cortex.

Sleep

• Types of Sleep:

  • Deep Sleep (Slow-Wave Sleep):

    • Characterized by slow brain waves and reduced physiological activity.

  • REM (Rapid Eye Movement) Sleep:

    • Characterized by rapid eye movements and dreaming.

• Typical Sleep Cycle:

  • Cycles through different stages of sleep, including deep sleep and REM sleep, multiple times per night.

• States of Consciousness:

  • Varying levels of awareness and responsiveness.

• Sleep Intervals:

  • Stages of sleep are divided into intervals.

• Reticular Activating System (RAS):

  • Brainstem network that regulates wakefulness and sleep-wake transitions.

General Senses

• General vs. Special Senses:

  • General Senses: Widely distributed throughout the body (e.g., touch, temperature, pain).

  • Special Senses: Localized to specific organs (e.g., vision, hearing, taste, smell, equilibrium).

• Sensation vs. Perception:

  • Sensation: Detection of stimuli by sensory receptors.

  • Perception: Interpretation of sensory information by the brain.

Detection of Stimuli

• Receptor Specificity:

  • Sensory receptors are specialized to detect specific types of stimuli.

• Receptive Fields:

  • Area monitored by a single sensory receptor.

• Tonic Receptors:

  • Slowly adapting receptors that continue to respond as long as the stimulus is present.

• Phasic Receptors:

  • Rapidly adapting receptors that respond strongly to changes in stimuli but quickly decrease their response.

• Adaptation:

  • Peripheral Adaptation: Decreased response of sensory receptors to a constant stimulus.

  • Central Adaptation: Decreased perception of a stimulus due to changes in the brain.

Types of Pain

• Fast Pain:

  • Sharp, localized pain transmitted by A-delta fibers.

• Slow Pain:

  • Dull, diffuse pain transmitted by C fibers.

• Phantom Pain:

  • Pain perceived from a body part that is no longer present.

• Referred Pain:

  • Pain perceived at a location different from the site of the stimulus.

Sensory Receptors

• Exteroreceptors: Detect external stimuli.

• Interoceptors: Detect internal stimuli.

• Proprioceptors: Detect body position and movement.

• Types of Receptors:

  • Nociceptors: Pain receptors.

  • Photoreceptors: Light receptors.

  • Chemoreceptors: Chemical receptors.

  • Mechanoceptors: Mechanical receptors.

    • Tactile receptors (touch).

    • Baroreceptors/Osmoreceptors (pressure/osmolarity).

    • Proprioceptors (body position).

  • Thermoreceptors: Temperature receptors.

Specific Sensory Receptors

• Tactile Receptors:

  • Free Nerve Endings: Detect pain and temperature.

  • Root Hair Plexus: Detects movement of hair.

  • Merkel’s/Tactile Discs: Detects light touch and pressure.

  • Meissner’s/Tactile Corpuscles: Detects fine touch and vibrations.

  • Pacinian/Lamellated Corpuscles: Detects deep pressure and vibrations.

  • Ruffini/Bulbous Corpuscles: Detects sustained pressure and skin stretching.

• Proprioceptors:

  • Muscle Spindle Apparatus: Detects muscle stretch.

  • Golgi Tendon Organ: Detects muscle tension.

  • Joint Capsules: Detects joint position and movement.

• Chemoreceptors:

  • Hypothalamic Chemoreceptors: Detects changes in blood composition (e.g., glucose, oxygen).

  • Medulla Chemoreceptors: Detects changes in cerebrospinal fluid (e.g., pH, carbon dioxide).

• Baroreceptors:

  • Aortic Baroreceptors: Detects blood pressure in the aorta.

  • Carotid Baroreceptors: Detects blood pressure in the carotid arteries.

Homunculi

• Motor Homunculus:

  • Represents the cortical area responsible for motor control of different body parts.

• Sensory Homunculus:

  • Represents the cortical area responsible for sensory processing of different body parts.

  • Size indicates degree of sensitivity or motor control.

Sensory & Motor Tracts

• Sensory Tracts:

  • Posterior Columns:

    • Fasciculus gracilis and fasciculus cuneatus.

    • Carries fine touch, vibration, and proprioception.

  • Spinothalamic Tract:

    • Anterior (crude touch and pressure).

    • Lateral/Posterior (pain and temperature).

  • Spinocerebellar Tract:

    • Carries proprioceptive information to the cerebellum.

• Motor Tracts:

  • Corticospinal Tract:

    • Controls voluntary movement.

  • Corticobulbar Tract:

    • Controls muscles of the face, head, and neck.

  • Medial Pathways:

    • Vestibulospinal (balance).

    • Tectospinal (reflexive head movements).

    • Reticulospinal (arousal and motor control).

  • Lateral Pathways:

    • Rubrospinal (motor coordination).

Neurons

• 1st Order Neurons:

  • Sensory neurons that detect the initial stimulus.

• 2nd Order Neurons:

  • Relay sensory information to the thalamus.

• 3rd Order Neurons:

  • Relay sensory information from the thalamus to the cerebral cortex.

• Upper Motor Neurons (UMNs):

  • Originate in the cerebral cortex and descend to the spinal cord.

• Lower Motor Neurons (LMNs):

  • Originate in the spinal cord and innervate skeletal muscles.

Special Senses: Olfaction

• Olfactory Receptors:

  • Olfactory Glands (Bowman’s):

    • Produces mucus that dissolves odorants.

  • Olfactory Stem/Basal Cells:

    • Regenerate olfactory receptor cells.

  • Olfactory Epithelia:

    • Contains olfactory receptor cells.

  • Olfactory Cilia:

    • Hair-like structures that bind odorants.

  • Lamina Propria:

    • Connective tissue layer supporting olfactory epithelium.

  • CN I - Olfactory Nerve, Bulb, & Tract:

    • Transmits olfactory information to the brain.

Special Senses: Gustation

• Taste Buds:

  • Papillae:

    • Structures on the tongue that contain taste buds.

  • Gustatory Epithelial Cells:

    • Taste receptor cells.

  • Gustatory Hairs:

    • Microvilli that project into the taste pore and bind tastants.

  • Taste Pore:

    • Opening in the taste bud that allows tastants to enter.

  • Types of Lingual Papillae:

    • Filiform (no taste buds, texture).

    • Fungiform (taste buds).

    • Circumvallate (taste buds).

  • Types of Taste/Flavors:

    • Sweet, salt, sour, bitter, umami, and water.

Olfactory and Gustatory Pathways

• Olfactory pathway involves the olfactory receptors in the nasal cavity sending signals to the olfactory bulb, then to the olfactory cortex without passing through the thalamus.

• Gustatory pathway involves taste receptors on the tongue sending signals to the medulla oblongata, then to the thalamus, and finally to the gustatory cortex.

Special Senses: Vision - Accessory Structures of the Eye

• Accessory Structures:

  • Eyebrows/Lashes:

    • Protects the eyes from debris and sunlight.

  • Eyelids:

    • Lateral and medial canthus, tarsal glands.

    • Protects and lubricates the eye.

  • Conjunctiva:

    • Lines the eyelids and covers the anterior surface of the eye.

  • Lacrimal Apparatus:

    • Lacrimal glands, lake, puncta, canaliculi, caruncle, nasolacrimal duct.

    • Produces and drains tears.

  • 6 Extrinsic Eye Muscles:

    • Controls eye movement.

Structures of the Eye

• Fibrous Layer:

  • Sclera (white of the eye).

  • Cornea (transparent anterior portion).

• Vascular Layer/Uvea:

  • Choroid (blood-rich layer).

  • Ciliary Body (controls lens shape).

  • Iris (controls pupil size).

  • Pupil (opening in the iris).

• Inner/Neural Layer/Retina:

  • Ora Serrata (serrated edge of the retina).

  • Pigmented Layer (absorbs light).

  • Neural Layer (contains photoreceptors).

  • Photoreceptors (rods and cones).

  • Bipolar Cells.

  • Ganglion Cells.

  • Optic Disc (blind spot).

  • Macula Lutea (area of high visual acuity).

  • Fovea Centralis (area of sharpest vision).

  • Lens (focuses light).

  • Anterior Segment/Cavity:

    • Anterior Chamber.

    • Posterior Chamber.

    • Aqueous Humor.

    • Canal of Schlemm (drains aqueous humor).

  • Posterior Segment/Cavity:

    • Vitreous Humor.

Events Converting Light into Neural Signal

• Photoreceptors:

  • Rods (black and white vision).

  • Cones (color vision).

• Photopigments:

  • Light-sensitive molecules in photoreceptors.

• Retinal:

  • Light-absorbing molecule in photopigments.

• Phototransduction:

  • Process by which light is converted into an electrical signal.

• Accommodation:

  • Adjustment of the lens to focus on objects at different distances.

• Refraction:

  • Bending of light as it passes through the cornea and lens.

• Adaptation:

  • Adjustment of the eye to changes in light intensity.

• Color Vision (Cones) vs. Black and White Vision (Rods):

  • Cones: Color vision in bright light.

  • Rods: Black and white vision in dim light.

Visual Pathway

• Optic disc → optic nerve (CN II) → optic chiasm → lateral geniculate nuclei → optic radiation → occipital lobes

Special Senses: Hearing - Structures of the Ear

• Outer Ear:

  • Auricle/Pinna (collects sound waves).

  • External Auditory/Acoustic Canal/Meatus (transmits sound waves).

  • Ceruminous Glands (produces earwax).

• Middle Ear:

  • Tympanic Membrane (eardrum).

  • Oval and Round Window (membranes connecting middle and inner ear).

  • Malleus, Incus, Stapes (ossicles that transmit vibrations).

  • Auditory Tube (Eustachian tube, equalizes pressure).

  • Tensor Tympani (muscle that dampens loud sounds).

  • Stapedius (muscle that dampens loud sounds).

• Inner Ear:

  • Bony Labyrinth (outer bony shell).

  • Membranous Labyrinth (inner membrane-bound tubes).

  • Perilymph (fluid between bony and membranous labyrinths).

  • Endolymph (fluid within membranous labyrinth).

  • Vestibule (saccule, utricle - balance).

  • Semicircular Canals (anterior, posterior & lateral - balance).

  • Cochlea (hearing).

  • Macula (sensory receptor for static equilibrium).

  • Semicircular Duct (contains endolymph).

  • Ampulla (swelling at the end of semicircular canal).

  • Crista Ampullaris (sensory receptor for dynamic equilibrium).

  • Cupula (gelatinous structure covering hair cells).

  • Scala/Ducts:

    • Cochlear Duct (Scala Media).

    • Vestibular Duct (Scala Vestibuli).

    • Tympanic Duct (Scala Tympani).

  • Vestibular Membrane.

  • Basilar Membrane.

  • Organ of Corti (contains hair cells).

  • Hair Cells (sensory receptors for hearing).

  • Spiral Ganglia.

Terms Related to Sound

• Frequency:

  • Number of sound waves per second (measured in Hertz).

• Pitch:

  • Perception of frequency.

• Volume/Intensity:

  • Amplitude of sound waves (measured in decibels).

• Resonance:

  • Amplification of sound waves.

Auditory and Equilibrium Pathways

• Auditory pathway involves sound waves causing vibrations in the tympanic membrane, which are transmitted through the ossicles to the oval window, creating pressure waves in the cochlear fluid that stimulate hair cells in the organ of Corti, leading to electrical signals sent to the auditory cortex.

• Equilibrium pathway involves hair cells in the vestibule and semicircular canals detecting changes in head position and movement, sending signals to the vestibular nuclei and cerebellum to coordinate balance and posture.