A&P - Ch. 13 notes

Q: What do mechanoreceptors respond to?

A: Physical force, such as touch and blood pressure.

Q: What do thermoreceptors respond to?

A: Temperature changes.

Q: What do photoreceptors respond to and where are they located?

A: Light; located in the retina.

Q: What do chemoreceptors respond to?

A: Specific molecules or ions (they bind and activate the receptor); involved in taste, smell, and fluid chemistry.

Q: What do nociceptors detect?

A: Harmful stimuli (pain).

Q: What are exteroceptors?

A: Sensory receptors that respond to external stimuli.

Q: What are interoceptors?

A: Sensory receptors that detect internal stimuli (e.g., blood pressure, internal organ sensations).

Q: What are proprioceptors?

A: Receptors located in muscles, tendons, and ligaments that detect stretch and body position.

Q: What distinguishes general senses from special senses?

A: General senses are non-localized and widespread; special senses have dedicated structures (e.g., taste receptors on the tongue).

Q: Is touch a general or special sense?

A: General sense.

Q: What are nonencapsulated receptors and where are they found?

A: Free nerve endings without protective structures, found in epithelial and connective tissues.

Q: What are Merkel cells, and what do they detect?

A: Nonencapsulated, exteroceptive mechanoreceptors that detect light pressure. They adapt slowly and are located in the basal epidermis (stratum basale).

Q: What do hair follicle receptors detect, and how do they adapt?

A: They detect movement of hair and are rapidly adapting mechanoreceptors.

Q: What are encapsulated receptors?

A: Receptors enclosed in connective tissue that help refine the stimulus.

Q: What are tactile corpuscles (Meissner’s corpuscles) sensitive to?

A: Light touch and low-frequency vibration. They are rapidly adapting and concentrated in hairless skin (e.g., palms, fingertips).

Q: What are lamellar corpuscles (Pacinian corpuscles) sensitive to?

A: Deep pressure, stretch, and high-frequency vibrations. Found in the dermis.

Q: What do muscle spindles detect?

A: They are proprioceptors that sense muscle stretch and length.

Q: What do tendon organs detect?

A: They are proprioceptors that sense tendon stretch, acting as a protective mechanism during muscle contraction.

Q: What is the basic organization of sensory input to perception?

A: Receptor → neural circuit → perception (awareness from frontal/prefrontal cortex).

Q: What is specificity in sensory receptors?

A: Each receptor responds only to a specific type of stimulus (e.g., photoreceptors respond only to light).

Q: What is a receptive field?

A: The area or range of stimuli a sensory receptor can detect.

Q: What is adaptation in sensory receptors?

A: A decrease in sensitivity to a constant stimulus over time.

Q: What are tonic receptors?

A: Receptors that do not adapt; they continuously send signals.
Examples: Proprioceptors, Nociceptors.

Q: What are phasic receptors?

A: Receptors that adapt quickly to a constant stimulus.

Q: What is projection in sensory processing?

A: The concept that specific receptors always activate the same region in the cortex, leading to consistent perception.

Q: What is perceptual detection?

A: The ability to detect that a stimulus occurred, often requiring multiple receptors.

Q: What is magnitude estimation?

A: Perception of the intensity of a stimulus.

Q: What is spatial discrimination?

A: The ability to identify the exact location of a stimulus.

Q: What is feature abstraction?

A: Recognizing specific features (e.g., texture, shape) of a stimulus.

Q: What is quality abstraction?

A: Differentiating between submodalities within a sense (e.g., bitter vs sweet in taste).

Q: What is pattern recognition?

A: The ability to recognize familiar patterns, such as a face or melody, using memory.

Q: What does the presence of potassium (K⁺) ions outside of a cell indicate?

A: It suggests cellular damage, triggering pain responses via receptor activation.

Q: What are the two types of nerves based on origin?

A: Cranial nerves (from the brain) and spinal nerves (from the spinal cord).

Q: What do motor (efferent) nerves do?

A: They carry signals away from the CNS to effectors (muscles or glands).

Mnemonic for functions:
S = Sensory, M = Motor, B = Both

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CN I – Olfactory

Q: What is the function of the olfactory nerve?

Smell

CN I – Olfactory

Q: What’s unique about CN I's pathway?

A: Bypasses the thalamus, and is exposed to the external environment.

CN I – Olfactory

Q: What is anosmia?

A: Loss of smell, often due to damage to CN I.

CN II – Optic

Q: What is the pathway of the optic nerve?

A: Retina → Optic canal → Optic chiasma → Thalamus → Visual cortex (occipital lobe)

CN III – Oculomotor

Q: What muscles does the oculomotor nerve control?

A: 4 of 6 extrinsic eye muscles, iris (pupil constriction), ciliary body (lens focus).

CN III – Oculomotor

Q: Where does it originate and exit?

A: Starts in ventral midbrain, exits via superior orbital fissure.

CN IV – Trochlear

Q: Which muscle is innervated by the trochlear nerve?

A: Superior oblique muscle (eye rotation).

CN IV – Trochlear

Q: Where does it originate and exit?

A: Dorsal midbrain → Superior orbital fissure

CN V – Trigeminal

Q: What is the function of the trigeminal nerve?

A: Facial sensation and mastication (chewing).

CN V – Trigeminal

Q: What are its 3 main branches?

A: Ophthalmic (cornea), Maxillary, Mandibular (chewing muscles).

CN VI – Abducens

Q: What muscle does the abducens nerve control?

A: Lateral rectus muscle (eye abduction).

CN VI – Abducens

Q: Where does it originate and exit?

A: Inferior pons → Superior orbital fissure

CN VII – Facial

Q: What are the motor functions of the facial nerve?

A: Facial expressions, parasympathetic control of lacrimal, nasal, and salivary glands.

CN VII – Facial

Q: What are the sensory functions?

A: Taste (sweet, salty, sour, bitter) from anterior 2/3 of the tongue.

CN VIII – Vestibulocochlear

Q: What does the vestibulocochlear nerve do?

A: Hearing and balance from the inner ear.

CN VIII – Vestibulocochlear

Q: Does the vestibulocochlear have a motor function?

A: Yes, limited motor to protect inner ear by adjusting sensitivity.

CN IX – Glossopharyngeal

Q: What are its motor functions?

A: Swallowing, salivary gland activation, regulation of blood chemistry via carotid body.

CN IX – Glossopharyngeal

Q: What are its sensory functions?

A: Taste and touch on the posterior 1/3 of the tongue and throat.

CN X – Vagus

Q: What are its motor functions?

A: Swallowing and parasympathetic control of heart, lungs, and viscera.

CN X – Vagus

Q: What are its sensory functions?

CN XI – Accessory

Q: What muscles does the accessory nerve innervate?

A: Neck and shoulder muscles (e.g., trapezius, sternocleidomastoid).

CN XI – Accessory

Q: Does it have a sensory component?

A: Minor proprioception from those muscles.

CN XII – Hypoglossal

Q: What does the hypoglossal nerve control?

A: Tongue movements essential for speech, chewing, and swallowing.

Q: What is Cranial Nerve I? (Name, function, sensory/motor)

A: Olfactory – Smell – Sensory

Q: What is Cranial Nerve II? (Name, function, sensory/motor)

A: Optic – Vision – Sensory

Q: What is Cranial Nerve III? (Name, function, sensory/motor)

A: Oculomotor – Eye movement (4/6 muscles), pupil constriction, lens shape – Motor

Q: What is Cranial Nerve IV? (Name, function, sensory/motor)

A: Trochlear – Eye movement (superior oblique muscle) – Motor

Q: What is Cranial Nerve V? (Name, function, sensory/motor)

A: Trigeminal – Facial sensation, chewing – Both

Q: What is Cranial Nerve VI? (Name, function, sensory/motor)

A: Abducens – Eye movement (lateral rectus muscle) – Motor

Q: What is Cranial Nerve VII? (Name, function, sensory/motor)

A: Facial – Facial expressions, taste (anterior 2/3 tongue), salivary/lacrimal glands – Both

Q: What is Cranial Nerve VIII? (Name, function, sensory/motor)

A: Vestibulocochlear – Hearing and balance – Sensory

Q: What is Cranial Nerve IX? (Name, function, sensory/motor)

A: Glossopharyngeal – Taste (posterior 1/3 tongue), swallowing, salivation, blood chemistry – Both

Q: What is Cranial Nerve X? (Name, function, sensory/motor)

A: Vagus – Parasympathetic control of heart/lungs/viscera, swallowing, visceral sensation – Both

Q: What is Cranial Nerve XI? (Name, function, sensory/motor)

A: Accessory – Shoulder and neck movement (sternocleidomastoid, trapezius) – Motor

Q: What is Cranial Nerve XII? (Name, function, sensory/motor)

A: Hypoglossal – Tongue movement (speech, chewing, swallowing) – Motor

Q: Are spinal nerves sensory, motor, or both?

A: Both afferent (sensory) and efferent (motor).

Q: What does the dorsal root of a spinal nerve carry?

A: Sensory (afferent) fibers.

Q: What does the ventral root of a spinal nerve carry?

A: Motor (efferent) fibers.

Q: Where are sensory neuron cell bodies located?

A: In the dorsal root ganglion.

Q: What kind of nerve is a spinal nerve?

A: Short and mixed (contains both sensory and motor fibers).

Q: What do spinal nerves split into after exiting the spinal cord?

A: Rami (anterior and posterior), which are mixed.

Q: What does the posterior ramus innervate?

A: Skin and muscles of the back.

Q: What does the anterior ramus innervate?

A: Anterior/lateral body wall and limbs.

Q: What connects spinal nerves to the sympathetic nervous system?

A: Rami communicantes.

Q: What is a plexus?

A: A network of interconnecting spinal nerve fibers.

Q: What is the function of the cervical plexus?

A: Innervates skin of the neck (cutaneous nerves).

Q: What does the phrenic nerve innervate?

A: The diaphragm.

Q: What condition is linked to phrenic nerve damage?

A: Respiratory paralysis.

Q: What area does the brachial plexus serve?

A: The upper limb.

Q: What does the axillary nerve innervate?

A: Deltoid and teres minor muscles.

Q: What does the musculocutaneous nerve innervate?

A: Biceps and other anterior arm muscles.

Q: What does the median nerve control?

A: Forearm and thumb muscles.

Q: What does the radial nerve control?

A: Wrist extensor muscles.

Q: What does the ulnar nerve control?

A: Hand muscles; known as the "funny bone."

Q: Which nerves serve the forearm?

A: Median, radial, and ulnar nerves.

Q: What area does the lumbar plexus supply?

A: Anterior thigh and lower abdomen.

Q: What does the femoral nerve innervate?

A: Quadriceps and hip flexors.

Q: What does the obturator nerve innervate?

A: Thigh adductor muscles.

Q: What area does the sacral plexus serve?

A: Posterior thigh and lower leg.

Q: What is the largest nerve in the body, and what does it branch into?

A: Sciatic nerve; branches into the fibular and tibial nerves.

Q: What does the coccygeal nerve control?

A: Sensation around the tailbone.

Q: What are dermatomes used for in clinical practice?

A: To determine nerve blocks for anesthesia.

Q: What are motor endings for skeletal muscles called?

A: Neuromuscular junctions (NMJs).

Q: What are motor endings at visceral effectors called?

A: Synapses en passant.

Q: What neurotransmitter is released at the NMJ?

A: Acetylcholine (ACh).