Human Nervous System Overview

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Questions and Answers

Which of the following describes the role of the upper motor neuron?

It carries the message from the brain to the spinal cord. (correct)

It connects the brain to the skeletal muscle directly.

It initiates voluntary muscle contraction at the muscle fiber.

It receives signals from skeletal muscles to the brain.

What initiates the skeletal muscle contraction during voluntary movement?

Activation of excitatory cholinergic receptors by acetylcholine. (correct)

Inhibition of the lower motor neuron.

Direct stimulation of the skeletal muscle fibers by the brain.

Dopamine release at the neuromuscular junction.

Where does the motor pathway begin when sending a message to move a body part?

In the pre-central gyrus of the frontal lobe. (correct)

In the medulla oblongata.

In the skeletal muscle fibers.

In the spinal cord.

If a person decides to move their right arm, where does the message originate in the brain?

From the left hemisphere of the brain. Signup and view all the answers

What is the significance of the central sulcus in the motor pathway?

It separates the motor and sensory areas of the brain. Signup and view all the answers

Which cranial nerve is responsible for transmitting taste sensations from the anterior part of the tongue?

CN VII Signup and view all the answers

What is the primary role of the auditory ossicles in the ear?

To amplify vibrations from the tympanic membrane Signup and view all the answers

Which part of the eye contains photoreceptors responsible for detecting light?

Retina Signup and view all the answers

Where do chemoreceptors for taste send signals after being activated?

To the thalamus Signup and view all the answers

What fluid is found in the scala vestibuli and scala tympani of the cochlea?

Perilymph Signup and view all the answers

What is the main function of the semicircular canals in the vestibular apparatus?

To detect dynamic equilibrium Signup and view all the answers

Which special sense does not pass through the thalamus?

Smell Signup and view all the answers

What is the role of the ciliary body in the eye?

To hold the lens in place Signup and view all the answers

Which component of the outer ear collects and funnels sound waves into the head?

Pinna/auricle Signup and view all the answers

What type of receptors are responsible for detecting changes in sound vibrations?

Mechanoreceptors Signup and view all the answers

Which area of the brain is primarily responsible for producing speech?

Broca area Signup and view all the answers

What type of memory is characterized by retaining information for years or a lifetime?

Long-term memory Signup and view all the answers

Which area of the brain is involved in the storage of fact memory?

Hippocampus Signup and view all the answers

Which division of the autonomic nervous system is primarily active during stress?

Sympathetic division Signup and view all the answers

Which type of sensory receptor is responsible for detecting changes in temperature?

Thermoreceptor Signup and view all the answers

The process of converting stimuli into signals is known as what?

Transduction Signup and view all the answers

What type of memory involves the development of skills and is often referred to as muscle memory?

Implicit memory Signup and view all the answers

Which term describes the brain's ability to adjust sensory receptors after constant stimulation?

Adaptation Signup and view all the answers

What is the primary function of the hypothalamus in the autonomic nervous system?

Control homeostasis Signup and view all the answers

Which brain structure is mainly responsible for coordination and balance?

Cerebellum Signup and view all the answers

What is a characteristic of referred pain?

It occurs when damage is felt in a different part of the body. Signup and view all the answers

Where are the sensory receptors for pain primarily located?

In the skin and muscles Signup and view all the answers

Which of the following statements is true regarding short-term memory?

It is task-oriented and very brief. Signup and view all the answers

The arcuate fasciculus is responsible for connecting which areas of the brain?

Broca and Wernicke areas Signup and view all the answers

Study Notes

Somatic Nervous System

Controls motor pathways to skeletal muscles
Voluntary and conscious movements
Message originates in the frontal lobe's pre-central gyrus
Two neurons involved: upper and lower motor neurons
Upper motor neuron travels to medulla oblongata
Lower motor neuron connects to muscle fiber via medulla oblongata and spinal cord
Acetylcholine (Ach) stimulates excitatory cholinergic receptors, causing muscle contraction
Message originates on the opposite side of the brain relative to the affected body part (e.g., right arm movement initiated by the left brain)

Higher Brain Functions - Speech

Primarily lateralized to the left cerebral cortex
Wernicke area (parietal lobe): processes incoming sensory language
Receives input from visual and auditory cortices
Broca area (frontal lobe): responsible for motor commands for speech production
Arcuate fasciculus: connects Wernicke and Broca areas, resembling a stringy arch

Higher Brain Functions - Memory

Frontal cortex is crucial
Working memory: task-oriented, short-duration (e.g., GPS directions)
Short-term memory: lasts minutes to days (e.g., parking location)
Long-term memory: lasts years to a lifetime (e.g., first day of high school)
Consolidation: necessary for short-term memories to become long-term
Emotionally intense experiences more likely to consolidate

Declarative/Explicit Memory

Retention of facts
Hippocampus (temporal lobe): stores factual memories
Amygdala (temporal lobe): processes emotions, sharing pathways with the hippocampus
Strong emotions enhance memory retention

Procedural/Implicit/Reflexive Memory

Development of skills (e.g., riding a bicycle)
Essentially muscle memory
Involves the cerebellum (coordination) and premotor cortex (voluntary motors)
Includes conditioned reflexes (e.g., Pavlov's dog)

Autonomic Nervous System

Controls involuntary visceral functions (e.g., cardiac muscle, smooth muscle, glands, adipose tissue)
Primarily unconscious, but sometimes conscious awareness (e.g., experiencing anxiety)
Three neurons needed to send a signal to an internal organ:
- Upper motor neuron from hypothalamus/medulla oblongata, entering grey matter (lateral horns)
- Lower motor neuron (pre-ganglionic) from lateral horns to ganglia
- Post-ganglionic LMN from ganglia to the visceral organ
Divided into:

Parasympathetic Division

"Rest and digest" system
Craniosacral division (cranial and sacral nerves)
Maintains homeostasis
Terminal ganglia near the target organs
Releases acetylcholine (Ach) for stimulation

Sympathetic Division

"Fight-or-flight" response
Thoracolumbar division (thoracic and lumbar nerves)
Generates energy (ATP)
Chain ganglia linked together
Involves the adrenal glands, secreting adrenaline/epinephrine
Uses adrenergic receptors

Sensory System Integration

Sensation: Feeling arising from a stimulus
Sensory receptors detect changes & undergo transduction (convert stimuli into signals)
Classification by Stimuli: chemoreceptors, nociceptors (pain), thermoreceptors, mechanoreceptors, photoreceptors

Classification by Structure

Free nerve endings: exposed nerve endings
Corpuscles: nerve endings enclosed in connective tissue

Sensory Adaptation

Receptors adjust to constant stimulation, causing them to become less responsive

General Senses

Receptors located throughout the body (skin, muscles, joints, viscera)
Pathway: receptor → spinal nerve → spinal cord → thalamus → cortex (parietal lobe's postcentral gyrus)
First, second, and third-order neurons are involved in the pathway
Decussation: crossing over of sensory pathways
Homunculus: representation of body parts on the postcentral gyrus

Somatic Senses

Touch and pressure: mechanoreceptors (corpuscles, free nerve endings)
Temperature: thermoreceptors (free nerve endings)
Pain: nociceptors (free nerve endings)
- Acute (fast, sharp, localized)
- Chronic (slow, general, aching)
- Referred (pain projected to an area other than the source)
Proprioception: sense of body position (muscle spindles, Golgi tendon organs)

Visceral Senses

Internal organs
Conscious and unconscious sensations
Mechanoreceptors and chemoreceptors

Special Senses

Receptors located only in the head
Pathway: receptor → cranial nerve → brain

Smell (Olfaction)

Chemoreceptors in olfactory organs (nasal cavity)
Unique: does not pass through the thalamus
CN I → frontal and temporal lobe to process smell

Taste (Gustation)

Chemoreceptors in taste buds (papillae on tongue)
CN VII (facial) and CN IX (glossopharyngeal) → thalamus → insula
Primary taste sensations: salty, sweet, umami, sour, bitter

Hearing (Auditory)

Mechanoreceptors in cochlea (inner ear)
Outer ear: pinna, external auditory canal, tympanic membrane
Middle ear: Eustachian tube, auditory ossicles (malleus, incus, stapes), oval window
Inner ear: cochlea, perilymph, endolymph, hair cells, round window
CN VIII (cochlear branch) → midbrain → thalamus → temporal lobe

Balance (Equilibrium)

Mechanoreceptors in vestibular apparatus (inner ear)
Vestibule (static balance), semicircular canals (dynamic balance)
CN VIII (vestibular branch) → brainstem & cerebellum → thalamus → parietal lobe

Sight (Vision)

Photoreceptors (rods and cones) in the retina (inner eye)
Accessory organs: eyebrows, eyelids, eyelashes, extraocular muscles, lacrimal glands
Outer tunic: cornea, sclera
Middle tunic: choroid coat, iris, lens, ciliary bodies
Inner tunic: retina (rods, cones, bipolar cells, ganglion cells), macula lutea, fovea centralis, optic disc
Humors: aqueous humor (anterior cavity), vitreous humor (posterior cavity)
CN II (optic nerve) → optic chiasm → thalamus → occipital lobe

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Description

This quiz covers the essential functions of the somatic nervous system and higher brain functions, particularly related to motor control and speech. It examines how messages travel from the brain to muscles and the areas of the brain responsible for speech production and processing. Test your understanding of these crucial neurological concepts.