Exam 4, Chapters 11-15

Know the functions of the nervous system.

• maintain body homeostasis with electrical signals

• sensation

• higher mental functioning

• emotional response

• activate muscles & glands

• sensory input & motor output

What are the functions of neuroglia cells: supporting cell of nervous system.

CNS	PNS
Astrocytes: facilitates formation of blood brain barrier, regulates extracellular environment of brain, anchors neurons and blood vessels in place, repairs damaged brain tissue	Satellite Cells: surround and support cell bodies
Microglial Cells: act as phagocytes
Ependymal Cells: line cavities, cilia circulate fluid around brain and spinal cord, some secrete this fluid	Schwann Cells: myelinate certain axons in PNS
Oligodendrocytes: myelinate certain axons in CNS

Describe myelin including functions, composition, and formation.

• composed of repeating layers of plasma membrane of neuroglial cell

• contain lipids unique to neurolemmocytes & oligodendrocytes

  • high lipid content makes myelin a great insulator

  • myelinated axons conduct action potentials faster than unmyelinated axons

• myelination - process of formation of myelin sheath by neurolemmocytes or oligodendrocytes

Define an action potential.

• uniform, rapid depolarization and repolarization of membrane potential of cell

• long-distance signals

 What are the 3 types of channels. Which substances use which channels?

1. Voltage-Gated Sodium and Potassium Ion Channels: open or close during AP to send signal to another cell

   1. located on axon which sends signals to other cells by generating & transmitting APs

2. Voltage-Gated Calcium Ion Channels: trigger exocytosis of synaptic vesicles

   1. located on axon terminal

3. Leak Channels & Na+/K+ Pump: generate resting membrane potential & maintaining ion gradients

   1. located on every part of neuron because resting membrane potential applies to entire neuron

What is a resting membrane potential? What is the charge inside the cell?

• voltage difference across plasma membrane of cell when not being stimulated

• about -70 mV

  • negative number because cell loses small numbers of positively charged potassium ions

Define depolarization, hyperpolarization, repolarization.

• depolarization - temporary increase in cell’s membrane potential; becomes less polarized as reaching 0 mV

  • Na+ enters

• hyperpolarization - change in membrane potential of excitable cell to a value more negative than its resting potential

• repolarization - movement of cell’s membrane potential back toward resting level after depolarization happened

  • K+ exits

Know what occurs at each phase of the action potential graph: resting state, depolarization, repolarization, hyperpolarization.

Resting → Depolarization → Repolarization → Hyperpolarization

What is meant by “all or none” in regard to action potentials.

action potential either happens completely or does not happen at all

Why are absolute refractory periods important?

• no additional stimulus is able to produce additional action potential

• creates limit to how many action potentials happen

 What are the functions of the dorsal root, dorsal root ganglia, and the ventral root?

• dorsal root - sensory input

• dorsal root ganglia - sensory cell bodies

• ventral root - motor output

Describe the 3 layers of meninges.

• dura mater - tough outer layer

• arachnoid mater - middle, CSF circulation

• pia mater - delicate inner layer

What are the functions of cerebrospinal fluid?

• cushioning

• protection

• nutrient & waste transport

What are the functions of the posterior, anterior, and lateral horns of the gray matter?

• posterior horn - receive sensory information

• anterior - sends out motor signals

• lateral - autonomic functions

 List the 4 major plexuses. What are the functions of the plexuses: cervical, brachial, lumbar, and sacral. Name at least one major nerve for each plexus.

1. Cervical (C1-C4) - innervates structures around head and neck

   1. phrenic nerve

2. Brachial (C5-T1) - innervates skin and muscles of upper limb

   1. axillary nerve, radial nerve

3. Lumbar (L1-L4) - innervates pelvis and lower limb

   1. obturator nerve, femoral nerve

4. Sacral (L4-S4) - innervates pelvis, gluteal region, and much of lower limb

   1. sciatic nerve

Know the 5 steps of a reflex arc.

1. Receptor - PNS detects

2. Sensory Neuron - delivers stimulus to CNS

3. Integration - CNS integrates stimulus

4. Motor Neuron - PNS delivers motor response from CNS to effectors

5. Effector - carries out response

What is the stretch reflex? Provide an example. Describe the withdrawal reflex and the crossed extensor reflex.

• stretch reflex - monosynaptic reflex triggered by muscle stretch producing automatic contraction of muscle to counter stretch

  • knee-jerk

• withdrawal reflex - polysynaptic reflex initiated by painful stimuli triggering withdrawal of affected body part

  • touch hot object

• crossed extension reflex - polysynaptic reflex that occurs concurrently with withdrawal reflex triggering extension of limb on opposite of body from painful stimulus

  • maintain balance when pulling away from stimuli

Know the names. numbers, and functions of the 12 cranial nerves. (CH 12)

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1. Olfactory - sense of smell; SENSORY

2. Optic - vision; SENSORY

3. Oculomotor - eye movement, pupil control; MOTOR

4. Trochlear - eye movement (looking down and moving eyes toward/away nose); MOTOR

5. Trigeminal - sensation in face, mouth, and head; chewing muscles; BOTH

6. Abducens - lateral eye movement; MOTOR

7. Facial - facial expression, salivation, taste; BOTH

8. Vestibulocochlear - hearing, balance; SENSORY

9. Glossopharyngeal - salivation, taste, swallowing; BOTH

10. Vagus - digestion, blood pressure, heart rate, breathing; BOTH

11. Accessory - head & shoulder control; MOTOR

12. Hypoglossal - tongue movements, speech, swallowing; MOTOR

Identify the 4 parts of the brain along with major functions.

1. Cerebrum - higher mental functions

   1. five lobes

2. Diencephalon - primary relay & processing center for sensory information and autonomic control

   1. thalamus, hypothalamus, epithalamus, subthalamus

3. Brainstem - connects brain and spinal cord; regulates involuntary bodily processes

   1. midbrain, pons, medullar oblongata

4. Cerebellum - balance

Know the 4 ventricles and where each is found. What fills the ventricles?

• hollow cavities filled with cerebrospinal fluid

1. Right Lateral Ventricle - in right cerebral hemisphere

2. Left Lateral Ventricle - in left cerebral hemisphere

3. Third Ventricle - in diencephalon

4. Fourth Ventricle - in hindbrain

Define the blood-brain barrier. Which substances are allowed to pass through the barrier? (remember, large molecules such as proteins and urea are unable to enter)

• keeps cerebrospinal fluid & brain extracellular fluid separate from blood, protecting brain from certain substances in blood

• prevents substances (large, polar molecules) in blood from gaining access to cells of brain

• allow water, oxygen, carbon dioxide, and non-polar lipid-based compounds to pass

• allow glucose, amino acids, and ions to pass if there are protein channels or carriers

Know the functions of the brain stem (midbrain, pons, medulla) and the cerebellum.

1. midbrain - processes & routes visual and auditory stimuli to thalamus, mediates reflexes

2. pons - regulate breathing & sleep/wake cycle

3. medulla - regulate many autonomic functions (heart rate, blood pressure, respiration)

4. cerebellum - coordinates ongoing voluntary movement to reduce motor error; balance, coordination

Understand these structures of the diencephalon: thalamus, hypothalamus, limbic system, pineal gland. What are their functions?

1. thalamus - controls sensory information entry into cerebral cortex

2. hypothalmaus - regulates autonomic nervous system, sleep/wake cycle, thirst & hunger, body temperature

   1. processes ADH and oxytocin

   2. controls secretion from anterior pituitary gland

3. limbic system - emotions, memory

4. pineal gland - sleep

What are the functions of the basal nuclei? Which diseases may affect this area?

• group of nuclei in cerebrum that function in movement (initiate voluntary motion)

• (1) caudate nucleus, (2) putamen, (3) globus pallidus

• Parkinson's Disease - movement difficult to initiate & difficult to end once started

  • tremor, minimal face expression 

• Huntington's Disease - jerky, involuntary movement

  • degeneration of basal nuclei

Differentiate between “left brain” and “right brain”. Define lateralization.

• left - logic/language

• right - creativity/spatial skills

• lateralization - division of labor between the hemispheres

Define: concussion, contusion, subdural hemorrhage, and cerebral edema, paralysis, parasthesias, paraplegia, and quadriplegia.

• concussion - mild brain injury

• contusion - brain tissue bruising

• subdural hemorrhage - bleeding between dura and brain

• cerebral edema - swelling; buildup of excess fluid in brain

• paralysis - loss of motor function

• parasthesias - loss of sensation

• paraplegia - paralysis of legs

• quadriplegia - paralysis of all limbs

Know the functions of the lobes of the brain (frontal, parietal, temporal, occipital, insula).

• frontal - planning, motor, complex mental functions

• parietal - processing & integrating sensory information, attention

• temporal - hearing, language, memory, emotions

• occipital - vision

• insula - deep lobes of cerebrum; have functions relating to taste and to viscera

Know the general function of the autonomic nervous system.

• controls homeostatic responses of organs of many other systems

• controls involuntary movement (heartbeat, breathing)

• sympathetic nervous system and parasympathetic nervous system

Differentiate between the sympathetic NS and the parasympathetic NS. (See the 7 sympathetic responses and the 5 parasympathetic responses)

• Sympathetic: fight or flight; speeds body functions up (heart rate, respiratory rate, dilate pupils, increase glucose)

1. heightened mental alertness

2. increased metabolic rate

3. reduced digestive and urinary functions

4. energy reserves activated

5. increased respiratory rate and respiratory passageways dilate

6. increased heart rate and pressure

7. sweat glands activated

• Parasympathetic: rest and digest; slows things down (decreases HR, RR, increases digestion and elimination)

1. decreased metabolic rate

2. decreased heart rate and blood pressure

3. increased secretion by salivary and digestive glands

4. increased motility and blood flow in digestive tract

5. urination and defecation stimulation

Know the location of the ANS.

• Sympathetic: T1-L2

• Parasympathetic: Cranial and sacral regions

Know the functions of the following (some repeated information)

• Medulla: vital center: regulates cardiac, vasomotor, respiratory system

• Hypothalamus: regulates visceral functions, temperature, hunger, thirst, water, electrolyte balance Understand the important role of the hypothalamus “center of ANS activity” 

• Limbic: controls emotional responses and feelings.

What is meant by “dual innervation” in regards to sympathetic and parasympathetic NS.

• SNS & PNS work together to maintain balance ensuring body’s needs are met

• organs innervated by neurons from both systems

• SNS becomes dominant & trigger effects to maintain homeostasis & PNS to regulate same organs and preserve homeostasis

Differentiate between the general senses and the special senses.

• general - touch, pressure, pain, temperature; skin, various organs & joints

  • receptors: sensory neuron endings

  • stimuli transmitted through cranial and spinal nerves

• special - vision, sound, taste, smell, balance; eyes, ears, nose, mouth

  • receptors: mostly specialized cells

  • stimuli transmitted only through cranial nerves

Why is perception of pain important? What is referred pain? Provide several examples.

• perception of pain warns of damage

• referred pain - pain that originates in organ is perceives as cutaneous pain due to sensory impulses from two regions following common nerve pathway to brain

  • heart attack → anterior chest wall & left arm

  • diaphragm → shoulder/back

  • kidney stones → lower back

Describe the olfactory nerve pathway.

• receptors → olfactory bulb → tract → temporal cortex

1. Axons of olfactory neurons carry olfactory stimuli to olfactory bulb in CNS.

2. An olfactory stimulus travels from olfactory bulb to primary olfactory cortex in temporal lobe.

Describe the visual pathway. Include the basic eye and nervous structures: the eye: cornea, iris, pupil, retina, lens, anterior cavity, aqueous humor, posterior cavity, vitreous body; optic nerve, optic chiasm, optic radiations, thalamus, occipital cortex.

1. The retina of each eye detects visual stimuli from portions of the right and left visual fields.

2. Some visual stimuli cross at the optic chasma so that all stimuli from the right visual field are processed by the left hemisphere, and stimuli from the left visual field by the right hemisphere.

3. Visual stimuli travel from the thalamus to the primary visual cortex in the medial portion of the occipital lobe.

37. Describe the hearing pathway: include structures of the ear and nervous system: auricle, external acoustic meatus, tympanic membrane, auditory ossicles (malleus, incus, stapes), auditory tube, bony labyrinth (vestibule, semicircular canals, cochlea, perilymph), membranous labyrinth (endolymph), hair cells, otoliths, vestibulocochlear nerve, thalamus, temporal lobe.

1. Action potentials propagate through axons of the cochlear portion of the vestibulocochlear nerve to the cochlear nuclei at the medulla-pons junctions.

2. Axons from the cochlear nuclei synapse on the superior olivary nucleus in the pons.

3. Auditory stimuli are then sent to the inferior colliculus of the midbrain. 

4. The auditory stimuli are relayed to the medial geniculate nucleus of the thalamus.

5. The thalamus stimulates neurons of the primary auditory cortex in the superior portion of the temporal lobe.

Differentiate between static and dynamic equilibrium.

• static - ability to maintain balance when the head & body are not moving

• dynamic - ability to maintain balance when head & body are moving