Nervous System: CNS, PNS, and Efferent Division

Central nervous system (CNS)

Comprises the brain and spinal cord

Peripheral nervous system (PNS)

Consists of nerve fibers

Enteric nervous system (ENS)

Refers to the nerve network of the digestive tract

Afferent neurons

Neurons responsible for carrying sensory information towards the CNS

Efferent neurons

Neurons that carry signals away from the CNS to muscles and glands

Internuerons

Neurons that facilitate communication between sensory and motor neurons

Astrocytes, oligodendrocytes, microglia, and ependymal cells

Types of glial cells in the CNS that provide physical, metabolic, and functional support to interneurons

Dura mater, Arachnoid mater, Pia mater

The three layers of the meninges that protect the brain and spinal cord

Brain stem (Midbrain, Pons, and Medulla)

Controls cardiovascular, respiratory, and digestive functions, regulates muscle reflexes, and the sleep-wake cycle

Cerebellum

Responsible for balance maintenance, muscle tone enhancement, and coordination of voluntary muscle activity

Diencephalon

Part of the forebrain that acts as a relay station for synaptic input, regulates basic sensations, motor control, thirst, and temperature

Cerebrum

Involved in sensory perception, voluntary movement control, language, muscle tone, and slow steady movements

Six

The number of structural layers in the cerebral cortex

Occipital lobe

Houses the visual cortex in the brain

Temporal lobe

Responsible for housing the auditory cortex, motivation, emotion, and memory functions

Parietal lobe

Responsible for the reception and perception of somatosensory input, speech understanding

Frontal lobe

Involved in voluntary motor movement, decision making, and planning

Motor Cortex

Responsible for voluntary movement

Somatosensory Cortex

Involved in feeling and sensation

Broca's area

Responsible for speech formation

Wernicke's area

Involved in speech understanding

Basal nuclei

Located deep within the cerebral white matter, plays a role in motor control and suppresses useless movements

Thalamus

Located at the wall of the third ventricle, acts as a sensory relay station and is involved in motor control

Hypothalamus

Located inferior to the thalamus, controls homeostatic functions like temperature and thirst

Limbic system

A ring of forebrain structures surrounding the brain stem, involved in emotion, feelings, moods, and physical reactions

Reticular formation

Regulates equilibrium, postural reflexes, and the overall degree of cortical alertness

Norepinephrine, dopamine, and serotonin

Neurotransmitters found in pathways for emotion and behavior

Short Term Memory

Immediately stored memory that can last for hours but may be forgotten if not transferred to long-term memory

Long Term Memory

Memory stored after repeated use, can last for years and takes longer to remember but can be retrieved

Working Memory

A complex type of short-term memory used for daily activities like reading comprehension, calculations, and logical reasoning

Retrograde amnesia

Inability to recall recent past events, often due to brain injury

Anterograde amnesia

Inability to consolidate memory into long-term memory for retrieval, often due to temporal lobe lesions

Brain stem

Consists of midbrain, pons, and medulla, regulates equilibrium, postural reflexes, and sleep centers

Spinal Cord

Extends from the brain stem, with specific types of neurons located in the dorsal, lateral, and ventral horns

Reflex arc

Involves sensory receptors, afferent and efferent pathways, an integrating center, and an effector organ

Spinal reflexes

Integrated by the spinal cord, such as removing a hand from a hot stove

Cranial reflexes

Subconsciously integrated by the brain, like pupil constriction due to light

Innate reflexes

Built-in unlearned responses

Conditioned reflexes

Learned responses, such as salivation to food smell

Somatic reflexes

Transmitted by motor neurons to skeletal muscles

Autonomic reflexes

Involve smooth muscle, cardiac muscles, and glands

Monosynaptic reflexes

Reflexes with only one synapse in the reflex arc

Polysynaptic reflexes

Reflexes with multiple synapses in the reflex arc

Photoreceptors, Mechanoreceptors, Thermoreceptors, Osmoreceptors, Chemoreceptors

Types of receptors sensitive to visible light, mechanical energy, heat/cold, changes in solute concentration, and specific chemicals respectively

Nociceptors

Sensory receptors sensitive to tissue damage

Visceral afferent

Carries subconscious input

Sensory afferent

Carries conscious input

Tactile receptors

Receptors like hair, Merkel's disc, Pacinian corpuscle, Ruffini endings, and Meissner's corpuscle

Pain categories

Mechanical, thermal, and polymodal nociceptors

Iris function

Varies pupil size and eye color

Lens function

Provides variable refractive ability

Ciliary muscle function

Regulates lens accommodation

Photoreceptors

Detect light stimulus and vary neurotransmitter release

Accommodation of the lens

Increases lens strength for near vision

Rods vs cones

Rods have high sensitivity; cones have high acuity and color vision

Anatomy of the ear

Includes external, middle, and inner ear

Organ of Corti

Contains inner and outer hair cells for hearing

Vestibular apparatus

Includes semicircular canals, saccule, and utricle

Primary taste sensations

Salty, sour, sweet, bitter, umami

Olfactory bulb glomeruli

Serve as smell file with multiple receptors activated

Autonomic nervous system

Involuntary branch with two-neuron chain

Sympathetic vs parasympathetic

Differ in origin and fiber lengths

Autonomic nerve pathways

Consist of preganglionic and postganglionic neurons

Receptors of the ANS

Cholinergic (nicotinic, muscarinic) and adrenergic (alpha, beta) receptors

Agonist vs antagonist

Agonists bind, antagonists prevent neurotransmitter binding

Dual innervation

Innervation of an organ by both autonomic branches

Motor neurons

Originate in CNS, stimulate muscle contraction with ACh

Neuromuscular junction

Where motor neuron axon terminals stimulate muscle contraction