Chapter 12-14 Study Guide

Four types of brain waves and when they appear

1. Alpha Waves: occur when people are awake and resting with their eyes closed; they disappear during sleep 2. Beta Waves: appear when the nervous system is active; during periods of sensory input and mental activity 3. Theta Waves: occur during emotional stress 4. Delta Waves: occur during sleep in adults and in awake infants

Protection of the spinal cord

1. Bone (vertebrae) 2. Connective Tissue (meninges) 3. Fluid (cerebrospinal fluid)

Four major parts of the brain

1. Brainstem 2. Cerebellum 3. Diencephalon 4. Cerebrum

What are the parts of a neuron and their functions

1. Cell Body: contains typical cellular organelles 2. Dendrites: receiving or input portions 3. Axon: output portion propagates nerve impulses toward target cell (another neuron, a muscle fiber, or a gland)

Names of the four main plexuses, the spinal nerves that make them up, and the body areas they serve

1. Cervical Plexus: arises from C1-C4 spinal nerves and supplies the skin and muscles of the head, neck, superior portion of the shoulders and chest, and diaphragm 2. Brachial Plexus: large, complex plexus arising from C5-T1 spinal nerves and providing almost the entire nerve supply to the shoulders and upper limbs 3. Lumbar Plexus: arises from L1-L4 spinal nerves and supplies part of the abdominal wall, the external genitals, and part of the lower limbs 4. Sacral Plexus: arises from L4-S4 spinal nerves and supplies the buttocks, perineum, and lower limbs

Two types of propagation of action potentials and their differences

1. Continuous Conduction: Step-by-step depolarization and repolarization 2. Saltatory Conduction: Occurs along myelinated axons due to the uneven distribution of voltage-gated channels

Layers of protection of the brain

1. Cranial bones 2. Cranial meninges (Cranial dura mater is composed of 2 layers) 3. Cerebrospinal fluid

How neurotransmitters are removed from the synaptic cleft

1. Diffusion 2. Enzymatic degradation 3. Uptake into cells

Three layers of meninges

1. Dura mater: tough outer layer 2. Arachnoid mater: middle layer 3. Pia mater: inner layer

Two types of synapses and their differences

1. Electrical Synapses: Action potentials conduct directly between the plasma membranes of adjacent neurons through gap junctions 2. Chemical Synapses: Presence of a synaptic cleft, a space filled with interstitial fluid that nerve impulses cannot cross

Three parts of the brainstem

1. Medulla Oblongata 2. Pons 3. Midbrain

Functional regions of the three parts of the brainstem

1. Medulla Oblongata: Heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing, hiccupping 2. Pons: Relays nerve impulses related to voluntary skeletal muscle movements from cerebrum to cerebellum 3. Midbrain: Conveys motor impulses from the cerebrum to the cerebellum and spinal cord, sends sensory impulses from the spinal cord to the thalamus, and regulates auditory and visual reflexes

Components of a reflex arc

1. Sensory receptor 2. Sensory neuron 3. Integrating center 4. Motor neuron 5. Effector

What are Two the branches of the Autonomic Nervous System and their function?

1. Sympathetic: fight-or-flight responses 2. Parasympathetic: rest-or-digest responses

Three parts of the diencephalon and their functions

1. Thalamus: located superior to the midbrain and contains nuclei that serve as relay stations for all sensory impulses (except smell) to the cerebral cortex; sends information from cerebellum to motor cortex of cerebrum and plays a role in maintenance of consciousness 2. Hypothalamus: found inferior to the thalamus, has four major regions, controls many body activities, and is one of the major regulators of homeostasis 3. Epithalamus: lies superior and posterior to the thalamus and contains the pineal gland; the pineal gland secretes melatonin and the habenular nuclei are involved in olfaction

Three factors resulting in a resting membrane potential

1. Unequal distribution of ions across the plasma membrane and the selective permeability of the neuron's membrane to Na+ and K+ 2. Most anions cannot leave the cell 3. Na+/K+ pumps

Meaning of spinal reflex

A reflex is a fast, involuntary, unplanned response to a particular stimulus.

Difference between afferent, efferent, and inter neurons

Afferent, or sensory, neurons convey information to the CNS. Efferent, or motor, neurons convey action potential from the CNS. Interneurons are found in the CNS between afferent and efferent neurons, and they process or integrate sensory information and elicit motor response.

Meaning of threshold as it relates to action potentials

An action potential, or nerve impulse, occurs when depolarization reaches a certain level termed the threshold.

Types of neuroglial cells, what they do, and where they're located (CNS or PNS)

CNS= astrocytes, oligodendrocytes, microglial cells, and ependymal cells o Astrocytes: wrap cellular processes around blood capillaries contributing to the blood-brain barrier o Oligodendrocytes: form the myelin sheath around CNS neurons o Microglial cells: phagocytes cleaning up cellular debris, microbes, and damaged tissue o Ependymal cells: lining the brain's ventricles and the spinal cord's central canal; produce cerebrospinal fluid which protects and nourishes the brain and spinal cord · PNS= Schwann cells and satellite cells o Schwann cells: encircle PNS axons forming myelin sheaths; the entire cell wraps around the axon o Satellite cells: surround cell bodies of neurons of PNS ganglia; provide support and regulate exchange of materials between neuronal cell bodies and interstitial fluid

Function of the voltage-gated Na+ channels and voltage-gated K+ channels in membrane depolarization and repolarization

Depolarizing Phase: Once the membrane has depolarized to threshold, voltage-gated Na+ channels open rapidly resulting in an inrush of Na+ which causes the depolarization from -55mV to +30mV. Each voltage-gated Na+ channel has two separate gates, an activation gate and an inactivation gate. In the resting state, the inactivation gate is open, but the activation gate is closed (Na+ can't move through). At threshold, the channels go into the activated state where both gates are open and Na+ inflow begins. · Repolarizing Phase: Shortly after the activation of the voltage-gated Na+ channels open, the inactivation gates close. Now the channel is in an inactivated state. Now the voltage-gated K+ channels open. The stop of Na+ inflow and the start of K+ outflow repolarizes the membrane (brings it from +30mV back to -70mV)

Difference between Action Potentials and Graded Potentials

Graded potentials are small deviations in the resting membrane potential. It occurs in response to the opening of a mechanically-gated or ligand-gated ion channel. An action potential is a sequence of rapidly occurring events that decrease and ultimately reverse the membrane potential and eventually restore it to the resting state.

Difference between myelination in the CNS and PNS

In the PNS, Schwann cells wrap many times around a small section of axon, forming up to 100 layers of plasma membrane encircling the axon. This is the myelin sheath. Outside these layers is the Schwann cell's cytoplasm and nucleus, called the neurolemma, which aids in regeneration if axon is injured. · In the CNS, there is no neurolemma since oligodendrocytes form their myelin sheath with cellular processes. This results in very limited regrowth after injury.

Types of ion channels in neurons

Leak channels randomly alternate between open and closed. K+ channels are much more numerous than Na+ channels. Ligand-gated channels respond to a ligand binding to a receptor. Mechanically-gated channels respond to mechanical vibration, pressure, or stretching stimuli. Voltage-gated channels open in response to changes in membrane potential (voltage).

How signals are transmitted at chemical synapses

Nerve impulse opens voltage-gated Ca++ channels allowing Ca++ to flow into the cell; the increase in Ca++ triggers exocytosis of synaptic vesicles filled with neurotransmitters; neurotransmitters diffuse across the synaptic cleft to bind with receptors on the postsynaptic side; binding od neurotransmitter to its receptor (ligand-gated ion channel)results in ions flowing across the membrane; flow of ions changes the voltage across the membrane; this change in membrane voltage is a postsynaptic potential, which may hyperpolarize of depolarize.

Spatial and temporal summation

Spatial Summation: progressively larger numbers of primary afferent (presynaptic) neurons are activated simultaneously, until sufficient neurotransmitter is released to activate an action potential in the spinal cord (postsynaptic) neuron · Temporal Summation: converts a rapid series of weak pulses from a single source into one large signal

What makes up the CNS and PNS?

The CNS (central nervous system) is made up of the brain and spinal cord. The PNS (peripheral nervous system) is made up of the cranial and spinal nerves.

Meaning of plexus

The anterior rami of spinal nerves form networks with neighboring spinal nerves

Basal nuclei (corpus striatum) and its function

The basal nuclei are paired masses of gray matter in each cerebral hemisphere. It helps regulate initiation/termination of movements as well as subconscious contractions of skeletal muscles.

Oxygen and glucose requirements of the brain

The brain utilizes about 20% of the body's oxygen and glucose supply

Cerebellum and its functions

The cerebellum occupies the inferior and posterior aspects of the cranial cavity. evaluates how well movements initiated in the motor areas of the cerebrum are carried out, but when the movements are not carried out correctly, the cerebellum sends feedback to the cerebral cortex to smooth out and coordinate the movements; functions in the maintenance of normal muscle tone, posture, and balance.

Location of the epidural space and subarachnoid space and what it contains

The epidural space is located between the dura mater and the wall of the vertebral canal, cushion of fat and connective tissue. The subarachnoid space is between the arachnoid mater and pia mater and contains CSF.

Limbic system and its function

The limbic system encircles the upper brain stem on the inner border of the cerebrum. It is responsible for emotions: anger, pleasure, pain, docility, affection, rage, and fear.

Know what the decussation of pyramids is and its result (left brain controls right side movement)

The point at the junction of the medulla and spinal cord where the motor fibers from the medullary pyramids cross the midline. The left hemisphere of the brain controls movement on the right side of the body.

Meaning of refractory period

The refractory period is the period of time after nerve impulse begins during which an excitable cell cannot generate another nerve impulse in response to a normal threshold stimulus.

Reticular Formation and its function

The reticular formation produces consciousness (alert, aware, and oriented), maintains attention and alertness, and awakens one from sleep.

Meaning of tract as it relates to the spinal cord

Tracts are pathways that carry information up and down the spinal cord between brain and body.

Difference between white matter and grey matter

White matter is composed primarily of myelinated axons. Grey matter is composed of unmyelinated axons, neuronal cell bodies, dendrites, and neuroglia.

Blood-brain barrier and its function

protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood into the brain

Cerebrospinal fluid: know its function, where it's produced, where it's contained

· CSF is produced by ependymal cells in networks of blood capillaries called choroid plexuses · CSF continuously circulates through cavities of the brain called ventricles · Functions of CSF: mechanical protection, chemical protection, and circulation

Definitions of gyrus, sulcus, and fissure as it relates to the cerebrum

· Gyrus: a ridge-like elevation found on the surface of the cerebral cortex · Sulcus: a depression or groove in the cerebral cortex · Fissure: a deeper groove; divides the right and left hemisphere of the cerebrum

Meaning of ipsilateral, contralateral, monosynaptic reflex arc, polysynaptic reflex arc, and reciprocal innervation

· Ipsilateral= same side · Contralateral= opposite side · Monosynaptic reflex arc= a single synapse between a sensory neuron and motor neuron · Polysynaptic reflex arc= involves one or more interneurons · Reciprocal innervation= neural circuit simultaneously contracts one muscle and relaxes its antagonists

Spinal nerves and their anterior roots, posterior roots, and spinal ganglion

· Most spinal nerves exit the spinal canal via intervertebral foramina and allow communication with specific regions of the body o 8 cervical, 12 thoracic, 5 lumbar, and 5 sacral · Anterior roots contain efferent (motor) neurons à outgoing · Posterior roots contain only afferent (sensory) axons à incoming o Each posterior root has a swelling known as the spinal ganglion which contains the cell bodies of sensory neurons

Meaning of cauda equina

· Nerves that exit the vertebral column inferior to L2 travel down the spinal column similar to wisps of hair. · "horse's tail"

Cranial nerve names, numbers, and functions

· Olfactory I: special sensory; functions in olfaction (smell) · Optic II: special sensory; functions in vision (sight) · Oculomotor III: motor, somatic, and autonomic; functions somatically in the movement of eyeballs and upper eyelid; functions autonomically by adjusting lens for near vision and constricts pupil. · Trochlear IV: motor and somatic; functions in the movement of eyeballs · Trigeminal V: mixed (sensory and motor); three branches (ophthalmic, maxillary, and mandibular); sensory function is sensations from scalp, face, and oral cavity; motor functions in control of muscles of mastification (chewing) and middle ear muscle · Abducens VI: motor; functions in the movement of eyeball · Facial VII: mixed (sensory and motor); sensory functions include taste, sensation from skin over external acoustic meatus; somatic motor functions include the muscles of facial expression; autonomic motor function includes secretion of tears and saliva · Vestibulocochlear VIII: special sensory; functions in hearing and equilibrium · Glossopharyngeal IX: mixed (sensory and motor); sensory functions include taste, monitors blood pressure and oxygen and carbon dioxide levels in blood, sensation from skin of external ear and pharynx; somatic motor function includes swallowing; autonomic motor function includes secretion of saliva · Vagus X: mixed (sensory and motor); sensory functions include taste, proprioception from throat and voice box muscles, monitors blood pressure and oxygen and carbon dioxide levels in blood; sensation from skin of external ear, sensation from thoracic and abdominal organs; somatic motor function includes swallowing, vocalization, and coughing; autonomic motor functions include motility and secretion of digestive canal organs, constriction of respiratory passageways, and decreases heart rate · Accessory XI: motor; functions in the movement of head and pectoral girdle · Hypoglossal, XII: motor; functions in speech, manipulation of food, and swallowing

Major functional differences between right and left cerebral hemispheres

· Right Hemisphere: emotional and artistic · Left Hemisphere: numbers, science, and analytical