Chapter 13-15

Sensory Pathways

Afferent tracks bringing sensory information in, often involving conscious thought, particularly concerning skeletal muscles.

Motor Pathways

Efferent tracks taking information out, especially related to somatic nervous system functions and skeletal muscle contractions.

Sensory Receptor Function

To produce a signal, create an action potential, and spread it into the central nervous system for processing.

Postcentral Gyrus

Area of the cerebral cortex where somatic sensory information is processed, mapped by the “homunculus.”

Homunculus

Mapping on the cerebral cortex corresponding to where each body part sends its sensory information; areas are proportionate to the number of receptors.

Precentral Gyrus

Area of cerebral cortex (sensorimotor) where signals from the homunculus are initiated.

Thalamus

Relay center like “Grand Central Station” that directs sensory information to specific areas on the cerebral cortex.

General senses

Temperature, pain, touch, pressure, vibration and proprioception.

Proprioception

Sense of body position; awareness of where limbs and other body parts are in space.

Special senses

Smell, taste, vision, equilibrium, and hearing. Each has its own special sensory organ.

Receptor Specificity

Sensory receptors pick up target information, such as light touch, deep touch, or pain.

Receptive Field

Area monitored by sensory receptors; smaller fields allow for more precise localization.

Transduction

Conversion of a stimulus into an action potential, often involving membrane distortion that affects ion gates.

Adaptation

Reduction in sensitivity to a constant stimulus, allowing the brain to avoid sensory overload by filtering out unnecessary information.

Tonic Receptors

Slow-adapting sensory receptors that are always active. An example of this is pain receptors.

Phasic Receptors

Fast-adapting sensory receptors that are inactive unless stimulated. They provide information about the intensity and rate of change.

Exteroreceptors

Receptors providing information about the external environment.

Proprioceptors

Receptors that detect body positions. These are found in skeletal muscles and joints.

Enteroreceptors

Receptors that monitor internal conditions, such as stretch receptors and baroreceptors.

Nociceptors

Pain receptors that are sensitive to temperature extremes, mechanical damage, and dissolved chemicals.

Thermoreceptors

Receptors specialized for temperature sensation. These are found in the dermis, skeletal muscles, liver, and hypothalamus.

Mechanoreceptors

Receptors specialized for mechanical distortion of a cell membrane. These help detect stretch.

Chemoreceptors

Receptors that detect chemical concentration changes. Such examples could be o2 or co2 detections from the carotid artery.

Tactile Receptors

Touch receptors which include pressure and vibrations.

Baroreceptors

Mechanoreceptors that detect pressure or stretch in blood vessels, the digestive system, the respiratory system, and the urinary tract.

Muscle Spindles

Proprioceptors that monitor skeletal muscle length. This is used to detect the stretch on the muscle.

Golgi Tendon Organs

Proprioceptors that detect tension in tendons.

Chemoreceptors

Detect chemical changes such as too much CO2 and not enough O2 in the brain.

First Order Neuron

Relays signal from peripheral nervous system (PNS) to central nervous system (CNS).

Second Order Neuron

Interneuron in the central nervous system (CNS) that usually decussates (crosses over).

Third Order Neuron

Carries signal from the thalamus to the cerebral cortex for conscious awareness. Routes signal to homunculus mapping.

Spinothalamic Pathways

Ascending sensory pathways includes the anterior and lateral tracts.

Posterior Column Pathways

Ascending sensory pathways in the posterior spinal cord tracts. This carries fine touch, fine vibrations, and fine proprioception.

Spinocerebellar Pathways

Ascending sensory pathways that carry proprioceptive information to the cerebellum.

Cuneate Fasciculus

Posterior column pathway, carries sensory information and proprioception from the upper body.

Gracilis Fasciculus

Posterior column pathway, carries sensory information and proprioception from the lower body.

Anterior Spinothalamic Tract

Anterior spinal cord tract, carries crude touch and pressure.

Lateral Spinothalamic Tract

Lateral spinal cord tract, carries pain and temperature.

Afferent

Bringing signals/information to an area.

Efferent

Carrying signals/information away from an area.

Upper Motor Neuron

Motor neuron with its cell body in the central nervous system (CNS).

Lower Motor Neuron

Motor neuron with its cell body in the brain stem or spinal cord and axon extending into the peripheral nervous system (PNS) to innervate a motor unit in a skeletal muscle.

The Pyramidal System

The corticospinal tract system, which carries voluntary motor signals. Decussation at the medulla is an important function.

Medulla

Important for nuclei for visceral sensory, tied to cardiovascular and respiratory centers.

Cerebellum

Responsible for the sense of muscle position. and also improves action that improves with practice.

Adult Human Brain

Contains 97% of the body's neural tissue.

Cerebrum

reasoning, your conscious decision making, things like that that we're gonna find

Diencephalon

Includes the Thalamus. Top of the brain stem.

Midbrain

Pineal gland, superior colliculi, inferior colliculi. It kinda makes this little chunk below the thalamus

Pons

first big bulge on the underside

Medulla

last bulge before this narrows right across from the cerebellum

Longitudinal Fissure

split down the middle of the two brain hemispheres

Commissural fibers

Fibers that cross and join the two hemispheres of the cerebrum

Corpus Callosum

band of commissural fibers. Top to the lateral ventricle.

Gray Matter

Accumulations of cell bodies

White Matter

Accumulation of axons

Gyrus

Upheavals

Sulci

Valleys

Cerebellum

coordinates our somatic motor patterns

Diencephalon

Top of the brain stem, it includes the thalamus

Hypothalamus

Controls the pituitary gland

Thalamus

The major relay station

Midbrain

Process sight, sound, and associated reflexes

Pons

Connects our cerebellum to our brain stem, and it does somatic and visceral motor control

Medulla

It relays information, but it regulates all these autonomic things.

Pineal gland, superior colliculi, inferior colliculi, pons & medulla

major players in your midbrain

Sagittal Sinus

These are where we can put things back, back into venous circulation from our brain circulation.

Cerebral Spinal Fluid

The fluid that travels in the ventricles

Ependymal Cells

These secrete your cerebral spinal fluid

Where the fourth ventricle goes

Apertures, Subarachnoid space & Central Canal

Apertures

These are just little channels that let it go around into the subarachnoid space and then down the central canal.

Cauda Equina

Bottom of the spinal cord

Arachnoid Villi

Finger like things

Meninges

anchor and protect the brain

Dura Mater

inner fibrous layer and an outer fibrous layer

Periosteal Layer

anchors it to the cranial bones

Meningeal Layer

it's right up next to the arachnoid meninges.

Pituitary Gland

Major endocrine hormone. It secretes more hormones than any other gland in the body.

Dural Folds

Area that those big thick folds of dura mater that go into some of our deeper fissures of the brain.

Falx Cerebri

It goes right down the longitudinal fissure right here, right between my two halves of my cerebrum.

Tentorium Cerebelli

it folds in right here between the cerebrum and the cerebellum, and it's the one I said. It kinda makes a tent over the top of the cerebellum

Falx Cerebelli

Pole that goes right into the cerebellum.

Blood Brain Barrier

We don't let everything come into the brain circulation. Right? It has to come through special areas. The cells that control that are the astrocytes at the choroid plexus of the brain.

Cerebrovascular Accident (CVA)

basically where we have something that interferes with blood supply.

When we bleed and stapled our cells together so things can't leak between the cells.

Tight junctions

Ependemial Cells

Secrete cerebral spinal fluid

CSF produced a day

500 milliliters

Cauda Equina

Bottom of the spinal cord

Cervical Segments

We have eight segments to the spinal cord in the cervical area.

Cervical Enlargement

Area towards the bottom of the cervical vertebrae where we see big branches coming off to innervate the upper limbs.

Thoracic Section

12 thoracic segments.

Lumbosacral Enlargement

Area at the bottom of the thoracic part of the spinal cord where we see big bundles of nerves coming off.

End of Spinal Cord

The spinal cord ends between L1 and L2.

Conus Medullaris

Triangular cone shape at the very tip of the spinal cord.

Cauda Equina

Spinal nerves that branch off to innervate the legs and buttocks.

Filum Terminale

Single, thin filament that goes from the conus medullaris to the coccyx, anchoring the spinal cord.

Myelin

Fatty sheath around axons that gives white matter its color.

Dendrite

Receiving end of a signal at a neuron.

Axon

Part of the neuron that flows away from the cell body and carries the message.

Ventral Horns

Anterior horns of the spinal cord.