A&P 1 - Unit 4 Study Guide

List the components of the nervous system (Ch.12)

• Brain

• Spinal Cord

• Nerves

• Ganglia

List the primary tissue of the nervous system (Ch.12)

Nervous tissue

What functions do neurons accomplish? (Ch.12)

• Collect information (receptors receive stimuli)

• Process and evaluate information

• Initiate response to information (effectors)

List the two functional divisions of the nervous system (Ch.12)

• Sensory nervous system

• Motor nervous system

Describe the epineurium, perineurium, and endoneurium (Ch.12)

Epineurium - Outermost layer of dense irregular connective tissue - protects, supports the entire nerve

Perineurium - dense irregular connective tissue layer that wraps around each fascicle- this layer supports blood vessels (nerves are vascularized)

Endoneurium - areolar connective tissue, more delicate covering, electrically insulates individual axons.

Define ganglion (Ch.12)

is a cluster of neurons cell bodies within the PNS

List the two types of cells that compose nervous tissue (Ch.12)

(1) Neurons, (2) Glial cells

Describe dendrites and axon (Ch.12)

Dendrites - Short, tapering processes branching from the cell body

Axon - single process emanating from the cell body

Define anterograde transport (Ch.12)

Movement of materials from the cell body toward to synaptic knobs

(antero = down)

Define retrograde transport (Ch.12)

Movement of materials from synaptic knobs towards the cell body

(retro = up the axon)

Describe the functional classes of neurons (Ch.12)

• Sensory neurons (afferent neurons)

  • Input

  • Unipolar

• Motor neurons (efferent neurons)

  • Output

  • Multipolar

• Interneurons (association neurons)

  • Communicates between sensory and motor neurons

  • Receives, process, and integrate

  • Multipolar

List the two types of synapses (Ch.12)

1) Chemical synapse

2) Electrical synapse

Define presynaptic neuron (Ch.12)

Signal producer - releases neurotransmitter

Define postsynaptic neuron (Ch.12)

Signal receiver - Binds neurotransmitter

Define glial cells/ their function (Ch.12)

1. Define: Glial cells, also known as neuroglia, are smaller than neurons and found in both the central nervous system (CNS) and peripheral nervous system (PNS).

2. Function:

   • They protect and support neurons.

   • Glial cells create a structural framework and guide neurons to their correct locations during development.

   • Account for half the volume of the nervous system

List the four types of glial cells (Ch.12)

• Astrocytes

• Ependymal cells

• Microglia

• Oligodendrocytes

Which type of glial cells are the immune cells of the nervous system? (Ch.12)

Microglia - Replicate in response to infection (Phagocytic activity)

Know what glial cell work with blood capillaries to form the choroid plexus (Ch.12)

Ependymal cells

Define myelination, which glial cells go through process of myelination (hint: there is one for the CNS and one for the PNS) (Ch.12)

Myelination - The process by which part of an axon is wrapped in myelin

• Neurolemmocytes in the PNS

• Oligodendrocytes in the CNS

Order the steps of axon regeneration (Ch.12)

1. Axon is severed

2. The proximal portion of each severed axon seals off and swells. The distal portion of axon and myelin sheath degenerates; the neurilemma survives.

3. Neurilemma and endoneurium form a regeneration tube

4. Axon begins to regenerate and remyelination occurs

5. Innervation to effector is restored

Define pumps (Ch.12)

Maintain specific concentration gradients by moving substances against their concentration gradient

Define channels (Ch.12)

Provide means for substances to move down their concentration gradient

Name the components of the receptive, initial, conductive, and transmissive segment (Ch.12)

Receptive segment (dendrites and cell body)

• Chemically gated cation channel, Chemically gated K+ channels, and chemically gated CL- channel

Initial segment (axon hillock)

• Voltage-gated Na+ channel, voltage-gated K+ channel

Conductive segment (axon and terminal extensions - but not synaptic knobs)

• Voltage-gated Na+ channel, voltage-gated K+ channel

Transmissive segment (synaptic knobs)

• Ca2+ channels and Ca2+ pumps

List the characteristics for neurons at rest (Ch.12)

• Ion concentration gradients exists for K+, Na+, and Cl- across the plasma membrane along the entire neuron

• A Ca2+ concentration gradient exists at the synaptic knob.

• Gated channels are closed

• There is an electrical charge difference across the plasma membrane (resting membrane potential)

Describe the all-or-none law (Ch.12)

• If threshold reached, action potential generated and propagated down axon without any loss in intensity

• If threshold not reached, (stimulus is subthreshold), voltage-gated channels stay closed, no action potential

Know the ions associated with depolarization and repolarization (Ch.12)

Depolarization: Na+ ions (sodium ions)

Repolarization: K+ ions (Potassium ions)

Contrast the absolute and relative refractory period (Which one cannot initiate another action potential, which one can) (Ch.12)

Absolute refractory period

• No stimulus can initiate another action potential (Cannot)

Relative refractory period

• Another action potential is possible (Can)

How does the diameter of an axon affect nerve signal velocity? (Ch.12)

• Nerve signal velocity is faster in axons with a larger diameter (less resistance)

How does myelination affect nerve signal velocity? (Ch.12)

• Nerve signals move more rapidly through myelinated axons compared to unmyelinated axons

List the four major regions of the brain (Ch.13)

1) Cerebrum

2) Diencephalon

3) Brainstem

4) Cerebellum

Define gyri (Ch.13)

Folds of the brain

Define sulci (Ch.13)

Shallow depressions between gyri

Define fissure (Ch.13)

deeper groves than sulci

Order the 4 steps of neurulation (Ch.13)

1. The neural plate develops the neural groove

2. The neural folds elevate and approach one another

3. The neural crest cells begin to pinch off from the neural folds and form other structures

4. Neural folds fuse to form the neural tube

List the structures that protect the brain (Ch.13)

• Bones of the skulls

• Meninges

• Cerebrospinal fluid (CSF)

• Blood-brain barrier

List the 3 cranial meninges

• Pia mater (Innermost)

• Arachnoid mater (middle layer; web-like)

• Dura mater (Outermost; toughest)

List the four ventricles (Ch.13)

• Cavities within the brain

• Lined with ependymal cells

• Contain cerebrospinal fluid

• Connect with each other and with spinal cord’s central canal

Describe the functions of the blood-brain barrier (Ch.13) (Slide 23)

• Regulates which substances enter brain’s interstitial fluid

• Helps prevent neuron exposure to harmful substances

  • Drugs, wastes, abnormal solute concentrations

  • Note: some drugs can pass and affect the brain (Ex: alcohol)

Describe the function of the corpus callosum (Ch.13)

Corpus callosum: largest tract providing connection between them

• Each hemisphere interacts with opposite sides of body

Describe the function of the primary motor cortex (Ch.13)

Primary motor cortex: located in precentral gyrus (somatic motor area)

• Controls skeletal muscle activity on opposite side of body

• The controlled body regions map as a motor homunculus

List the function and location of the primary somatosensory cortex (Ch.13)

Function: Receives somatic sensory information from Proprioceptors, touch, pressure, pain, temperature receptors

Location: in postcentral gyrus of parietal lobes

Describe the function and location of the primary visual and primary auditory cortex (Ch.13)

Primary visual cortex:

Location: within occipital lobe

Function: receives, processes, stores visual information

Primary auditory cortex:

Location: within temporal lobe

Function: receives, processes, stores auditory information

List the gland found in the epithalamus (Ch.13)

Pineal gland

What does the endocrine gland secrete? (Ch.13)

melatonin

List the seven functions of the hypothalamus (Ch.13)

1) Control of autonomic nervous system

2) Control of endocrine system

3) Regulation of body temperature

4) Food intake

5) Water intake

6) Sleep-wake rhythms

7) Emotional behavior

What component of the midbrain houses neurons that produce dopamine?

Substantia nigra

What structure connects the third and fourth ventricles? (Ch.13)

Cerebral aqueduct

List the two nerves that has nuclei housed in the cerebral aqueduct (Ch.13)

1) Cranial Nerve III (Oculomotor)

2) Cranial Nerve IV (Trochlear)

Describe the function of the superior, middle, and inferior peduncles (Ch.13)

Superior cerebellar peduncles

• Connect cerebellum to midbrain

Middle cerebellar peduncles

• Connect cerebellum to pons (Transverse axons)

Inferior cerebellar peduncles

• Connect cerebellum to medulla oblongata (Tracts)

Describe the function of the hippocampus in the limbic system (Ch.13)

• Helps form long-term memories

• Neurogenesis (formation of new neurons)

Describe the function of the amygdaloid body (Ch.13)

Involved in many aspects of emotional memory, especially fear

Describe the functions of the olfactory bulbs, tracts, and cortex (Ch.13)

Process odors that can provoke emotions

Describe the types of studies done using an electroencephalogram (EEG) (Ch.13)

• Used in studies of sleep, brain lesions, coma, vegetative state

• Used to evaluate epilepsy: repeated seizures

Describe non-REM sleep (Ch.13)

Non-REM sleep: slower frequency brain waves

• Takes up about 75% of total sleep time

• Important for growth, rest, energy conservation, and strength renewal

• Divided up into substages with different EEG frequencies (delta, theta, etc.)

Describe REM sleep (Ch.13)

REM (rapid eye movement) sleep: brain is active, eyes move

• Takes up about 25% of total sleep time

• Memorable dreaming

• Considered important for consolidation of memories

Describe insomnia (Ch.13)

Difficulty in falling asleep or staying asleep

Describe the Wernicke area (Ch.13)

Interprets language

Be able to name the cranial nerves I-XII (Ch.13)

• Olfactory blub, termination of olfactory nerve (CN I)

• Optic nerve (CN II)

• Oculomotor nerve (CN III)

• Trochlear nerve (CN IV)

• Trigeminal nerve (V)

• Abducens nerve (CN VI)

• Facial nerve (CN VII)

• Vestibulocochlear nerve (CN VIII)

• Glossopharyngeal nerve (CN IX)

• Vagus nerve (CN X)

• Accessory nerve (CN XI)

• Hypoglossal nerve (CN XII)

Describe the two important functions of the spinal cord and spinal nerves (Ch. 14)

• Provide an essential structural and functional link (between the brain, the torso, and the limbs of the body)

• Spinal reflexe

What structure is formed from the tapering at the inferior end of the spinal cord? (Ch.14)

inferior end of the spinal cord tapers to form the conus medullaris

List the four continuous subdivisions of the spinal cord (Ch.14)

1. Cervical Part – continuous with the medulla oblongata

2. Thoracic Part

3. Lumbar Part

4. Sacral Part

Describe the cervical and lumbosacral enlargements (Ch.14)

• Cervical enlargement (Wide area in the cervical part)

• Lumbosacral enlargement (Wide area in the lumbar and sacral parts)

Describe the components of a mixed nerve (Ch.14)

• Contains both sensory and motor components

Each axon (sensory and motor) transmits information one-way

Where is the spinal cord housed? (Ch.14)

• The vertebral column houses the spinal cord

Be able to order the spinal cord meninges (Ch.14)

• Pia mater (innermost)

• Arachnoid mater

• Dura mater (outermost)

What is the dura mater composed of? What spaces are associated with it? (Ch.14)

• Composed of dense irregular tissue

Two spaces associated with Dura Mater

• Subdural space

• Epidural space

Describe the gray commissure (what it connects, what type of axons are present) (Ch.14)

• Forms a bar of gray matter connecting the two lateral sides of the gray matter

• Houses primarily unmyelinated axons

• Serves as a communication route between the left and right sides of the spinal cord

Describe the composition and function of white matter (Ch.14)

• White matter - (primarily composed of myelinated axons)

• Functions to relay nerve signals

What is a conduction pathway? (Ch.14)

• Conduction Pathway - (Series of neurons that relay nerve signals between the brain and a specific part of the body)

Distinguish between sensory (ascending) and motor (descending pathways) (Ch.14)

• Sensory pathways (ascending pathways)

Include sensory neurons that relay sensory input from sensory receptors to the brain

• Motor pathways (descending pathways)

Includes series of motor neurons that relay motor output from the brain to its effectors

List the two categories of general sense receptors (Ch.14)

• Somatosensory receptors

• Visceral sensory receptors

Function of the medial lemniscal pathway (Ch.14)

• Uses a chain of neurons to communicate with the brain about specific stimuli in the skin or joints

List the nerve plexuses in the body (Ch.14)

• Cervical plexuses

• Brachial plexuses

• Lumbar plexuses

• Sacral plexuses

Distinguish between somatic and visceral reflexes. (Ch.14)

Somatic reflexes involve skeletal muscles as the effector

visceral reflexes (autonomic) involve cardiac muscle, smooth muscle, or a gland as an effector

Identify an innate or acquired reflex (Ch.14)

An innate reflex is a reflex you are born with, and an acquired reflex is a learned after birth

Define the somatic nervous system (slide 2) (Ch.15)

• Includes processes that are perceived or controlled consciously

• Includes both a sensory and motor portion

What structures control reflexive skeletal muscle activity? (slide 3) (Ch.15)

controlled by brainstem and spinal

What is the function of the cerebellum? (Ch.15)

coordination of skeletal muscle movements

Define the autonomic nervous system (Ch.15)

• Includes processes regulated below the conscious level
• Motor system only
• Initiate and transmit nerve signals from the CNS to cardiac muscle, smooth muscle, glands
• Responds to input from visceral sensory components (note* - visceral sensory are not ANS components)

Describe the overall function of the autonomic nervous system (Ch.15)

• Maintain homeostasis (constant internal environment)
• Regulates heart rate, blood pressure, body temperature, sweating, digestion

Are motor neurons of the somatic nervous system myelinated? What do they release? (Ch.15)

• Are myelinated (faster propagation)

• Always release acetylcholine

Describe the function of the preganglionic and postganglionic neuron. (Ch.15)

Preganglionic axon:

• extends from the cell body and exits in either a cranial or spinal nerve... axon projects into an autonomic ganglion where it synapses.

Postganglionic axon:

• extends from the cell body to the effector

Function of the hypothalamus, brainstem, and spinal cord (Ch.15)

Hypothalamus
• Integration and command center for autonomic functions; involved in emotion
Brainstem
• Contains major ANS reflex centers
Spinal Cord
• Contains ANS reflex centers for defecation and urination

Describe the function of the parasympathetic and sympathetic nervous system (Ch.15)

Parasympathetic division
• Functions to maintain homeostasis when at rest

Sympathetic Division
• Maintain homeostasis during exercise, times of stress or emergency

Know the effectors innervated and their function of CN X. (Ch.15)

• Heart – decreases heart rate

• Bronchi/bronchioles – constricts to decrease airflow

• GI tract – increases movements of contents

• Pancreas – releases insulin into the blood

• Liver – stimulates glycogenesis

• Gallbladder – releases bile

List the effectors innervated by the pelvic splanchnic nerves (Ch.15)

Effectors innervated
• Distal portion of large intestine and rectum
• Urinary bladder
• Distal part of the ureters
• Most of the reproductive organs

List the organ systems affected by the sympathetic division (Ch.15)

• Cardiovascular system

• Respiratory system

• Reproduction system

• Nervous system

• Urinary system

List the two types of cholinergic receptors (Ch.15)

• Nicotinic

• muscarinic