ANS and Brain/Cranial Nerves Flashcards

Somatic:

- single neuron from CNS to effector

- No ganglia involved

- Afferent origin from skeletal muscles, joints, and skin

Autonomic:

- Two-neuron chain: preganglionic and postganglionic

- Uses ganglia (clusters of neuron cell bodies in the PNS)

- Afferent input from visceral organs (digestive, cardiovascular)

Sympathetic Division

- Origin: Preganglionic neurons in the lateral horns of spinal cord segments

- Function: Activated during exertion, stress, or emergency; prepares the body for intense physical activity

Parasympathetic Division

- Origin: Preganglionic neurons in the brainstream

- Function: Active during relaxed states. Promotes digestion, energy conservation, and bodily maitenance

Sympathetic Chain Ganglia

Collateral Ganglia

Adrenal Medulla

Paired and located near the spinal cord. They send messages to effectors in the thoracic cavity, head, body wall, and limbs

Unpaired and located anterior to the spinal column. They run to organs in the abdominal cavity and innervate visceral effectors in the abdominal pelvic cavity

Found on the kidney; instead of a direct nerve link, the adrenal medulla releases epinephrine and norepinephrine directly into the bloodstream

- These circulating hormones are distributed throughout the body to target organs

- Preganglionic neurons release Acetylcholine (ACh) which excites the chain ganglia

- Most postganglionic neurons release Norepinephrine (NE), which is usually excitatory but depends on the receptor at the target organ

Eye: Causes a dilation of the pupils

Salivary Glands: Mostly not excited; stimulation is more associated with parasympathetic activation

Cardiovascular and Respiratory Systems: Increases heart rate and respiration

Digestive Organs: Not excited or stimulated (resources are diverted away during "fight or flight"

Kidney and Bladder: Activity is dampened. The detrusor muscle of the bladder is relaxed, while the sphincter is contracted to prevent the release of urine

Reproductive Organs: Not in an excitatory mode

- The preganglionic neurons are located in the brain stem (with cranial nerves) and the sacral spinal cord. The preganglionic fibers are long because the ganglia are not adjacent to the spinal cord

- The ganglia (peripheral ganglia) are located within or right adjacent to the target organs

- The preganglionic neurons release acetylcholine (ACh), which is excitatory to the ganglia

- The postganglionic neurons also release ACH, which will usually be inhibitory, but depends on the receptor

Oculomotor: Innervates the levator palpebrae (lifts the eyelid)

Facial: Controls tear glands and salivary glands

Glossopharyngeal: Important for salivary gland innervation

Vagus: Responsible for about 75% of all parasympathetic outflow, much of it related to digestive function

Sacral Outflow: The preganglionic fibers form the pelvic nerves, which innervate pelvic organs

Eyes: Constriction of the pupils and a "drowsy" eyelid

Digestive System: Secretion of digestive glands, secretion of hormones promoting nutrient absorption, and increased smooth muscle activity along the digestive tract to move matter

Defecation: stimulation and coordination of defecation

Urination: contraction of the urinary bladder (the detrusor muscle) and relaxation of the urinary sphincter

Cardiovascular: reduction in heart rate and force of contraction

Respiratory: Constriction of the respiratory passageways

Reproductive: Sexual arousal

Innervated by both the sympathetic and parasympathetic systems (most vital organs)

- The two systems have opposite effects but work together to maintain homeostasis

Through various reflexes

Scalp

Epicranialaponeurosis: a broad, tendon-like sheath of dense connective tissue

Loose connective tissue

Periosteum: the outer fibrous layer covering the cranial bones

Cranium: bony skull

Meninges: three protective membrane layers

- Dura mater --> arachnoid mater ---(subarachnoid space containing CSF)---> pia mater

Cerebrum, Cerebellum, Diencephalon, Midbrain, Pons, medulla Oblongata

Largest part of the brain, responsible for higher functions.

- Hemispheres, longitudinal fissure, contralateral control, corpus callosum, cerebral cortex

Each cerebral hemisphere controls the opposite (contralateral) side of the body.

Separates the left and right cerebral hemispheres

A large bundle of white matter fibers deep within the longitudinal fissure that allows communication between the two hemispheres

The outer layer of the cerebrum, composed of gray matter (contains neuronal cell bodies)

- gyri = folds

- sulci = grooves

Primary Motor Cortex (Precentral Gyrus), Premotor Cortex, Prefrontal Cortex

Initiates voluntary skeletal muscle movement

Plans and coordinates complex movements

Responsible for executive functions, decision-making, and personality

Primary Somatosensory Cortex (Postcentral Gyrus), Somatosensory Association Area

Receives and processes sensory information from the body

Integrates and interprets sensory information

Visual Cortex, Visual Association Area

Processes visual information received from the eyes

Interprets visual stimuli

Auditory cortex, olfactory cortex, Gustatory cortex

Bundles of white matter that allow different regions within the same cerebral hemisphere to communicate

Inferior to the occipital lobe; integrates sensory input from proprioceptors, the visual system, and the auditory system to fine-tune motor commands

Connects the brain stem to the cerebrum. Divided into:

1. Epithalamus

2. Thalamus

3. Hypothalamus

Contains the pineal gland: an endocrine gland that secretes melatonin

Acts as the main relay station for sensory information. Nearly all input passes through the thalamus before being directed to the appropriate area of the cerebral cortex

Master control center for the autonomic nervous system and the endocrine (hormone system); regulates the release of hormones from the pituitary gland

Midbrain (Mesencephalon), Pons, Medulla Oblongata

Processes visual and auditory data and generates reflexive somatic motor responses; plays a key role in maintaining consciousness

Acts as a relay center, passing sensory information to the cerebellum and thalamus; point of origin for several cranial nerves

Contains autonomic centers that regulate functions; relay station for information traveling to the thalamus. Connects directly to the brain stem

Subcortical structures involved in the control of voluntary motor movements, procedural learning, and posture

- substantia nigra: produces dopamine

Strongly tied to the sense of smell and emotional states. Includes the hippocampus (memory formation), amygdala (emotion and memory), and parts of the thalamus and hypothalamus

fluid-filled cavities in the brain

-lateral ventricles, third ventricle, fourth ventricle

The largest, one per each cerebral hemisphere

Narrow Cavity in the diencephalon

Located between the brain stem and the cerebellum

Network of specialized ependymal cells that line the ventricles and produce cerebrospinal fluid

Lateral ventricles ---(interventricular foramen)---> third ventricle----(cerebral aqueduct)---> fourth ventricle ----(foramina in the roof of the fourth ventricle)---> subarachnoid space

Sensory; sense of smell

Sensory; Vision

Motor: controls 4 of the 6 extracurricular eye muscles and the levator palpebrae superioris (elevates eyelid)

Motor; Controls the superior oblique eye muscle (moves eye down and out)

Sensory: Sensation from the face

Motor: Muscles of mastication

Motor: controls the lateral rectus eye muscle (abducts the eye, moves it laterally)

Sensory: taste from the anterior 2/3 of the tongue

Motor: Muscles of facial expression

Sensory: hearing and balance/equilibrium

Sensory: taste from the posterior 1/3 of the tongue; monitors blood pressure in the carotid artery

Motor: Assists in swallowing

The longest cranial nerve/primary nerve of the parasympathetic nervous system

- Innervates visceral organs in the thorax and abdomen also important for speech and swallowing

Motor; innervates the sternocleidomastoid and trapezius muscles (neck and shoulders)

Motor; innervates the intrinsic and extrinsic muscles of the tongue, controlling tongue movement for speech and swallowing