Chapter 9

Explain why myelin sheath covering an entire axon (w/ no nodes of Ranvier) would inhibit conduction of an impulse.

Myelin sheath covering an entire axon would inhibit conduction of an impulse bc action potentials occur at the nodes where the exposed axon membrane has Na+ and K+ channels.

Define plexus, and locate the major plexuses of the spinal nerves.

Network of interlaced nerves or blood vessels; cervical, brachial, lumbosacral, intercoastal

Match the cranial nerves to the body functions that they affect. (More than one nerve pair may correspond to the same structure or function.) PP 1. Olfactory nerves (I) 2. Optic nerves (II) 3. Oculomotor nerves (III) 4. Trochlear nerves (IV) 5. Trigeminal nerves (V) 6. Abducens nerves (VI) 7. Facial nerves (VII) 8. Vestibulocochlear nerves (VIII) 9. Glossopharyngeal (IX) 10. Vagus nerves (X) 11. Accessory nerves (XI) 12. Hypoglossal nerves (XII)

Olfactory nerves (I)- sense of smell Optic nerves (II)- vision Oculomotor nerves (III)- eye movements Trochlear nerves (IV)- eye movements Trigeminal nerves (V) Abducens nerves (VI)- eye movements Facial nerves (VII)- Taste, facial expressions, secretion of tears and saliva Vestibulocochlear nerves (VIII)- Hearing and equilibrium Glossopharyngeal (IX)- Tongue movements and swallowing Vagus nerves (X)- Tongue movements and swallowing Accessory nerves (XI)- Muscles of the larynx, pharynx, soft palate, SCM, and trapezius muscles Hypoglossal nerves (XII)- Tongue movements and swallowing

Define hemisphere dominance.

One side of the cerebrum controls the ability to use and understand language

Describe the components of a reflex arc and their functions.

Receptors detect a certain type of change. The receptor sends impulses along a sensory neuron into the CNS, where it is integrated, in some cases by an interneuron. Commands are then transmitted by a motor neuron to the effector, which carried out the reflex.

List three body functions the reflexes control. (multiple are listed)

Reflexes control the rhythm and rate of the heart, help regulate blood pressure, control our breathing rate, coughing, sneezing, yawning, and swallowing

. List two ways in which the CNS controls autonomic activities.

Regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal.

List the general functions of the nervous system.

Sensory input (detect internal and external changes), integration and processing

Describe how sensory, motor, and mixed nerves differ.

Sensory nerves carry impulses to the CNS, motor nerves carry impulses from the CNS to muscles or glands, and mixed nerves perform both functions.

Distinguish among sensory neurons, interneurons, and motor neurons.

Sensory- (afferent neurons) conduct impulses from peripheral body parts into the brain or spinal cord Interneurons- (association/internuncial neurons) lie entirely within the brain or spinal cord Motor- (efferent neurons) are multipolar and conduct impulses out of the brain or spinal cord to effectors

Locate the sensory, association, and motor areas of the cerebral cortex, and describe the general functions of each.

Sensory-In multiple lobes of the cerebrum; Receive and interpret impulses from sensory receptors Association-Spread throughout the 4 lobes; Perform complex integrative functions, receive and send information to multiple areas of the cortex via association fibers. Motor- Primarily found in the frontal lobe; initiate impulses to skeletal muscles

Explain how the spinal nerves are classified and numbered.

Spinal nerves are grouped by the level at which they arise. They are named according to their spinal level: cervical (c1-4), thoracic(T1-11), lumbar(L1-5/S1-4), sacral ( S1-5) or coccygeal (one pair)

Explain the relationship between the CNS and the PNS.

The CNS is the brain and the spinal cord and the PNS is nerves found throughout other parts of the body

Distinguish between the ascending and descending tracts of the spinal cord.

The ascending tracts carry sensory information from the body, like pain, up the spinal cord to the brain. Descending tracts carry motor information, like instructions to move the arm, from the brain down the spinal cord to the body.

The structure that connects the cerebral hemispheres is the _____.

The corpus callosum

Relate the lobes for the cerebral hemispheres to the skull bones.

The frontal lobe forms the anterior part of each cerebral hemisphere. The parietal lobe is posterior to the frontal lobe and separated from it by the central sulcus. The temporal lobe lies below the frontal and parietal lobes and is separated from them by the lateral sulcus. The occipital lobe forms the posterior part of each cerebral hemisphere and is separated from the cerebrum by a shelflike extension of the dura mater.

Describe the functions of the cerebellum.

The is responsible for fine-tuning motor movements and coordination. All trial and error learning tasks, like riding a bicycle are stored in the cerebellum and fine-tuned.

Define limbic system, and explain its functions.

The limbic system is connected structures in the brain that produce emotions; controls emotional experience and expressions such as fear, anger, and pleasure

Distinguish between preganglionic and postganglionic neurons.

The main difference between preganglionic and postganglionic neurons is that preganglionic neurons are the neurons that arise from the central nervous system and supply the ganglia whereas postganglionic neurons are the neurons that arise from the ganglia and supply the tissues.

Distinguish between the sympathetic nervous system and parasympathetic divisions of the ANS.

The parasympathetic nervous system restores the body to a calm and composed state and prevents it from overworking. The sympathetic nervous system, on the other hand, prepares the body for fight and flight response.

The _____ period ensures that action potentials progress in one direction toward the axon terminal.

The refractory period

What is the longest nerve?

The sciatic nerve

Distinguish between the somatic nervous system and the autonomic nervous system.

The somatic nervous is involved in conscious activities. The autonomic nervous system mediates unconscious activities.

Describe the structure of a spinal nerve.

The spinal nerves are relatively large nerves that are formed by the merging of two nerve roots: a sensory nerve root and a motor nerve root. Sensory nerve roots emerge from the back of the spinal cord and the motor nerve roots from the front of the spinal cord.

Explain the relationship between threshold potential and an action potential.

The threshold potential is a stimulation level that must be achieved to elicit an action potential and an action potential is a sequence of electrical changes in part of a nerve cell or muscle cell exposed to a stimulus of threshold or greater; an impulse

Describe what happens to the body when the reticular formation receives sensory impulses, and what happens when it does not receive stimulation.

When sensory impulses reach the reticular formation, it responds by activating the cerebral cortex into a state of wakefulness. Without this stimulation, the cortex remains unaware of stimulation and cannot interpret sensory information to carry on thought processes, resulting in sleep.

"Facilitation in a neuronal pool" refers to _____.

When the neurons are more excitable for incoming situations than before; may cause neuron to release additional/more neurotransmitters in response to a single impulse.

Distinguish between a sulcus and a fissure.

a sulcus is a shallow groove and a fissure is a deep groove.

The part of the diencephalon that regulates hunger, weight, water and electrolyte balance, sleep and wakefulness, temperature, arterial blood pressure, heart rate, production of substances that stimulate the pituitary gland, and movement and secretion in areas of the digestive tract is the _____. a. Thalamus b. Pineal gland c. Infundibulum d. Hypothalamus

c. Hypothalamus

Match the neurotransmitter to its description. 1. Biogenic amine 2. Acetylcholine 3. Neuropeptide 4. GABA a. Short chain of amino acids b. A modified amino acid c. An amino acid d. Stimulates skeletal contraction

1. Biogenic amine- b. A modified amino acid 2. Acetylcholine- d. Stimulates skeletal contraction 3. Neuropeptide- a. Short chain of amino acids 4. GABA- c. An amino acid

Match the neuron part to its description. (1) Dendrite (2) Axon (3) Cell body A cell that processes and sends information One of the usually several cells that receive information The roundest part of a neuron

1. Dendrite- B. one of the usually several cells that receive information 2. Axon- A. a cell that processes and sends information 3. Cell body- C. the roundest part of a neuron

Match each layer of meninges to its description. 1. Dura mater 2. Arachnoid mater 3. Pia mater

1. Dura mater- B. The tough, outermost layer, mostly connective tissue 2. Arachnoid mater- C. The lacy membrane, lacking blood vessels, sandwiched between the other two layers 3. Pia mater- A. The thin, innermost layer, containing blood vessels and nerves

Know these functional classifications: 1. Sensory 2. Interneurons 3. Motor

1. Sensory- Stimulus is coming towards the body; afferent, unipolar 2. Interneurons-Brain, spinal cord, multipolar, nuclei; the "freeway"- connects two parts together 3. Motor- Movement, efferent, multipolar; does something (ex: takes hand off of stove when hot)

Describe the structure of the spinal cord.

31 segments with a pair of spinal nerves that each branch out and connect to the CNS; Your spinal cord is the long, cylindrical structure that connects your brain and lower back. It contains tissues, fluids and nerve cells. A bony column of vertebrae surrounds and protects your spinal cord. Your spinal cord helps carry electrical nerve signals throughout your body.

Describe the components of a neuronal pool.

A group of neurons with specific common functions

Distinguish between a reflex arc and a reflex

A reflex arc is the simplest response to a stimulus. A reflex is an automatic, subconscious response to stimuli inside or outside the body.

"All-or-none" response in impulse conduction means that _____. PP

All action potentials in neuron are of the same length

Explain how information passes from one neuron to another

An impulse reaches the synaptic knob at the end of an axon, synaptic vesicles release neurotransmitter molecules that diffuse across the synaptic cleft and bind to specific receptors on the membrane of the postsynaptic cell.

Distinguish between myelinated and unmyelinated axons.

An impulse traveling along a myelinated axon appears to jump from node to node, eventually to the axon terminal. Action potential movement along an unmyelinated axon is called continuous conduction, bc it flows uninterrupted along its entire length.

Match the types of neuroglia to their functions. Ependymal cells Oligodendrocytes Astrocytes Schwann cells Microglial cells Form a myelin sheath around peripheral nerves Phagocytize cellular debris and bacteria Line inner parts of ventricles and spinal cord Form scar tissue and regulate ion and nutrient concentrations in the CNS Form a myelin sheath around neurons in the CNS

C- Line inner parts of ventricles and spinal cord E- Form a myelin sheath around neurons in the CNS D- Form scar tissue and regulate ion and nutrient concentrations in the CNS A-Form a myelin sheath around peripheral nerves B- Phagocytize cellular debris and bacteria

6. Choose the correct sequence of events along an axon. Resting potentials are propagated along a stimulated axon, causing a very small action potential A threshold stimulus opens K+ channels and the ions disuse in, depolarizing the cell membrane. Then Na+ channels open, Na+ exits, and the cell membrane repolarize, generating an action potential that stimulates adjacent cell membrane, forming the impulse. A threshold stimulus opens Na+ channels and the ions diffuse in, depolarizing the cell membrane. Then K+ channels open, K+ exits, and the cell membrane repolarize, generating an action potential that stimulates adjacent cell membrane, forming the impulse. A threshold stimulus opens Na+ channels and the ions diffuse in, depolarizing the cell membrane. Then K+ channels open, K+ exits, and the cell membrane repolarize, generating an action potential that inhibits adjacent cell membrane, forming the impulse.

C. A threshold stimulus opens Na+ channels and the ions diffuse in, depolarizing the cell membrane. Then K+ channels open, K+ exits, and the cell membrane repolarize, generating an action potential that stimulates adjacent cell membrane, forming the impulse. (PAGE 233 PIC 9.1)

The general function of neurons is to _____, whereas the general functions of neuroglia are to _____.

Carry information/provide physical support, insulation, and nutrients to the neuron.

Describe 3 structures found in neurons that are also in other cell types, and describe the two structures that are unique to neurons.

Cell membrane- serves as a protector of the cell and transporter of nutrients inside the cell and transports toxic substances outside the cell. Mediates intracellular and extracellular activities of the cell. Mitochondria- serves as the energy provider of the cell in the form of Adenosine triphosphate (ATP), it also has its own DNA. Lysosomes- have a digestive enzymes that is responsible for degrading cellular waste products from outside of the cell. Golgi apparatus- acts as the packaging and process of proteins and lipids of the cell. Two structures unique to neurons: Axon and Dendrite

The part of the Schwann cell that contributes to the myelin sheath is the _____, and the part that contributes to the neurilemma is the _____.

Cell membrane/Cytoplasm

Name the four major parts of the brain and describe their functions

Cerebrum- sensory and motor functions, higher mental functions; memory, reasoning, intelligence, Cerebellum-grey matter that coordinates voluntary muscular movements Brainstem- connects parts of the nervous system and regulates certain visceral activities Diencephalon-processes sensory information

Explain how cerebrospinal fluid is produced and how it functions.

Choroid plexuses secrete/produce CSF. CSF cushions the brain within the skull and serves as a shock absorber for the central nervous system, CSF also circulates nutrients and chemicals filtered from the blood and removes waste products from the brain.

Distinguish between convergence and divergence in a neuronal pool.

Convergence is when axons originating from different neurons lead to the same postsynaptic neuron. Divergence is th branching of axons, allowing impulses to transmit information to different regions

Distinguish between cranial nerves and spinal nerves.

Cranial nerves emerge directly from the brain while spinal nerves emerge directly from segments of the spinal cord

Neurotransmitters are synthesized in _____ and are stored in _____.

Cytoplasm/Synaptic knob

The parts of the brainstem are the _____, _____, and _____.

Midbrain, Pons, Medulla Oblongata

List the functions of the three parts of the brainstem.

Midbrain- Mostly composed of tracts of nerve fibers. Pons- A brain structure that relays information from the cerebellum to the rest of the brain. Medulla oblongata- Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion

Describe the general functions of the autonomic nervous system.

Motor portion of the peripheral nervous system that controls the viscera and operates without conscious effort

Distinguish among multipolar, bipolar, and unipolar neurons.

Multipolar- many processes and lies within the brain or CNS Unipolar-single process, function as a single axon, two branches one in the PNS and one in the CNS Bipolar-have only two processes, one is an axon and the other is a dendrite; in the ears, eyes, nose, PNS

Vomiting is controlled by _____. a. The reticular formation b. The medulla oblongata c. The midbrain d. The pons

b. The medulla oblongata

. Distinguish between excitatory and inhibitory actions of neurotransmitters.

Excitatory neurotransmitters open Na+ channels to allow Na+ to enter the axon; this causes depolarization, which brings the axon closer to the threshold potential and makes it more likely that an action potential will occur. Inhibitory neurotransmitters influence other types of ion channels, causing hyperpolarization. This makes the inside of the axon more negative, moving it farther from the threshold potential, and making it less likely that an action potential will occur

The unction of the basal unit is to _____.

Fine-tune voluntary movements, eye movements, cognition, and emotion

List the events that occur during an action potential.

First, Na+ channels open, often in response to a neurotransmitter, and Na+ ions enter the neuron, making the inside of the neuron less negative (or more positive (depolarization)). The neuron responds by opening K+ channels; K+ ions then diffuse out of the cell, restoring the more negative charge inside the cell (repolarization). After this, the membrane is returned to its resting state by the Na+/K+ pump, which restores the original concentrations of the ions on both sides of the membrane

Define synapse.

Functional connection between the axon terminal of a neuron and the dendrite or cell body of another neuron or the membrane of another cell type

Distinguish between ganglia and nuclei.

Ganglia- lie in the peripheral nervous system (PNS) Nuclei- exclusively within the central nervous system (CNS)

The effects of the sympathetic and parasympathetic autonomic divisions differ because _____.

In the sympathetic division, everything increases (heart rate, BP, blood flow) while blood flow to the skin and the digestive tract decreases. In the parasympathetic division, everything decreases (heart rate, BP, blood flow) while digestion and waste elimination are normal.

. Describe how ions associated with nerve cell membranes are distributed.

It is determined in part by pores or channels in those membranes. Some channels are always open, and others can be opened or closed. Channels can also be selective.

Explain how a membrane becomes polarized.

It occurs from an unequal distribution of positive and negative ions between sides of the membrane.

Explain what happens to neurotransmitters after they are released.

They are either decomposed or removed from the synaptic cleft.

Define resting potential.

This is when the neuron is at rest or inactive (-70mV)

Locate the ventricles of the brain.

Ventricles are chambers within the cerebral hemispheres and brainstem. They are all connected to each other and to the central canal of the spinal cord

The area of the brain that contains centers controlling visceral activities is the _____. a. Cerebrum b. Cerebellum c. Brainstem d. Diencephalon

d. Diencephalon