Muscle Tissue, Nervous System, and Special Senses Practice Flashcards

A comprehensive set of vocabulary flashcards covering muscle tissue types and functions, nervous system divisions and anatomy, and the structures of the eye and ear based on the lecture notes.

Percentage of adult body weight composed of muscle

$40\%$–$50\%$

Skeletal Muscle Count

The muscular system contains approximately $700$ skeletal muscles.

Sphincters

Circular muscle bands that contract and relax to regulate the passage of material and allow for voluntary expulsion of feces and urine.

Joint

The location where two bones meet.

Excitability (Muscle)

The characteristic of being responsive to nervous system stimulation via neurons secreting neurotransmitters that bind to muscle cells.

Conductivity

An electrical change traveling along the plasma membrane, typically initiated in response to neurotransmitter binding.

Contractility

The ability for the muscle to shorten when contractile proteins within muscle cells slide past each other.

Elasticity

The property that allows a muscle to return to its original length after contraction due to protein fibers acting like compressed coils.

Extensibility

The lengthening of a muscle cell, such as the extension of the triceps brachii during elbow flexion.

Fascicles

Organized bundles into which muscle cells (fibers) are packed.

Epimysium

The outermost surface layer of dense irregular connective tissue that surrounds the whole skeletal muscle.

Perimysium

The middle layer of dense irregular tissue surrounding the fascicles; contains extensive blood vessels and nerves.

Endomysium

The deepest, innermost connective tissue layer made of delicate areolar connective tissue that electrically insulates each muscle fiber.

Tendon

A cordlike structure composed of dense regular connective tissue that attaches muscle to bone, skin, or another muscle.

Aponeurosis

A thin, flattened sheet of dense irregular tissue that connects muscle to muscle.

Deep fascia

A sheet of dense irregular connective tissue external to the epimysium that separates individual muscles and binds together those with similar functions.

Superficial Fascia

Located superficial to deep fascia and composed of areolar and adipose connective tissue; separates muscles from the skin.

Central nervous system (CNS)

Anatomical subdivision consisting of the brain and spinal cord.

Peripheral nervous system (PNS)

Anatomical subdivision consisting of nerves and ganglia.

Nerve

A bundle of nerve fibers (axons) wrapped in fibrous connective tissue.

Ganglion

A knot-like swelling in a nerve where neuron cell bodies of the PNS are concentrated.

Sensory (afferent) division

The functional division of the PNS that carries signals from receptors to the CNS.

Visceral sensory division

Carries signals from the viscera such as the heart, lungs, stomach, and urinary bladder.

Motor (efferent) division

Carries motor commands away from the CNS to effectors like glands and muscles.

Visceral motor division (Autonomic system, ANS)

Carries signals to glands, cardiac muscle, and smooth muscle; lacks voluntary control.

Sympathetic division

The part of the ANS that stimulates and prepares the body for action (fight or flight).

Parasympathetic division

The part of the ANS that has a calming effect on the body for relaxation.

Enteric plexus

Located within the digestive tract wall to enable coordination and communication.

Secretion (Neurons)

The release of a neurotransmitter when a signal reaches the end of an axon to stimulate the next cell.

Interneurons

Functional class of neurons that lie entirely within the CNS, process information, and make decisions; they account for about $90\%$ of all neurons.

Lipofuscin

A pigment inclusion in neurons resulting from the degradation of organelles by lysosomes.

Dendrites

The most numerous neurites, resembling tree branches, which serve as primary sites for receiving signals from other neurons.

Axon hillock

A mound on one side of the neurosoma where the axon originates.

Axon terminal (terminal bouton)

A bulbous ending at the end of terminal arborization that forms a synapse with the next cell.

Meninges

Three membranes (dura mater, arachnoid mater, and pia mater) surrounding the brain and spinal cord for protection and structural framework.

Gray matter

Dull-colored tissue containing neuron cell bodies and dendrites; it lacks myelin.

White matter

Bright, pearly white tissue consisting of axon bundles; color is due to the presence of myelin.

Conjunctiva

A specialized stratified squamous epithelium that lubricates and moistens the eye; subdivided into ocular and palpebral layers.

Lysozyme

An antibacterial enzyme found in lacrimal fluid that helps prevent bacterial infection.

Lacrimal puncta

Two small openings in each lacrimal caruncle that drain fluid into the lacrimal sac.

Sclera

The "white" of the eye; composed of dense irregular connective tissue that provides shape and serves as an attachment site for extrinsic muscles.

Cornea

A convex transparent structure forming the anterior one-sixth of the fibrous tunic.

Vascular tunic (Uvea)

The middle layer of the eyeball containing the choroid, ciliary body, and iris.

Retina

The internal layer of the eye wall consisting of an outer pigmented layer and an inner neural layer.

Auricle

The funnel-shaped, visible part of the external ear supported by elastic cartilage.

Tympanic Membrane

The eardrum; a delicate sheet that vibrates when hit by sound waves and partitions the external and middle ear.

Auditory ossicles

The three smallest bones in the body: the malleus, incus, and stapes.

Bony labyrinth

Spaces within the temporal bone containing the cochlea, vestibule, and semicircular canals.

Endolymph

Fluid found within the membranous labyrinth that is similar to intracellular fluid.

Perilymph

Fluid found between the bony labyrinth and the membranous labyrinth that is similar to interstitial fluid.