Exam 4 - Chapters 11 and 12 - A&P

Name and locate the ventricles of the brain

The brain contains four ventricles filled with cerebrospinal fluid. The lateral ventricles are in the cerebral hemispheres; the third ventricle is in the diencephalon; the fourth ventricle is between the brain stem and the cerebellum and connects with the central canal of the spinal cord.

Identify and describe the four major regions of the brain

1. Diencephalon - contains the epithalamus, thalamus, subthalamus and hypothalamus 2. Brain stem - midbrain, pons, and medulla oblongata 3. Cerebellum - a cortex covering white matter, as well as a ventricle filled with fluid 4. Cerebrum - largest part

Contrast the the characteristics and functions of neurons and neuroglia

1. Neurons - generate and send action potential 2. Neuroglia - glial cells, supports functions of the neurons

Describe the three basic functions of the nervous system

1. Sensory Input - sensory receptors detect change in external and internal environment 2. Integration -CNS receives input, interpret, decides on a change 3. Motor Output - signal goes to an effector (do-er) which is either a muscle or a gland

List the sequence of events that occur in the plasma membrane that generate an action potential (activities of sodium/potassium channels).

Action potentials are initiated by membrane depolarization which causes the opening of voltage-gated ion channels, which causes an influx of sodium into the cell. For nerve and muscle cells, sodium channels are opened, which produces the rapid upstroke of the action potential.

Classify neurons functionally

Afferent (sensory) neurons - afferent means toward, these neurons send signals toward the CNS Efferent (motor) neurons - efferent means away from, these neurons send signals away from the CNS Association (interneuron) neurons - receive information and make the appropriate response in the CNS

Describe how the cerebellum coordinates muscle movements by communicating with the motor cortex and the regions of the body while movements are occurring

As we make a movement the cerebellum is adjusting the movement. Most body movements require the coordination of multiple muscle groups. The cerebellum times muscle actions so that the body can move smoothly.

Explain the events of signal transmission at a chemical synapse

At a chemical synapse, an action potential triggers the presynaptic neuron to release neurotransmitters.

Contrast the different types of neuroglia in terms of function and location (CNS vs. PNS).

CNS Neuroglia 1. Astrocytes - most numerus, has the most jobs, they physically support neurons, maintain appropriate ion concentration, and help form memory, supply nutrients 2. Ependymal - ciliated cells, produce and circulate central spinal fluid 3. Microglia - deals with microbes, they are phagocytic cells, they engulf and digest pathogens and cellular debris, are trash men 4. Oligodendrocyte - responsible from myelination, means cell with a few branches (oli - few, dendro - branches), covers and wraps axons of neurons PNS Neuroglia Satellite cells - physically support neurons, maintain appropriate environment, like astrocytes Schwann cells - form myelin, one cell forms myelin of one axon, like oligodendrocytes

Describe the formation of the CSF and trace its circulatory pathway

CSF is formed in the cerebral ventricles

Describe the internal anatomy (cross-sectional) of the spinal cord and where major clusters of cell bodies are located

Central canal - contains CSF Dorsal root - contains afferent sensory axon Anterior root - contains efferent somatic motor fibers Dorsal root ganglion - contains cell bodies of afferent sensory neurons Lateral gray horn - cell bodies of visceral(autonomic) motor neurons Anterior gray horn - cell bodies of somatic motor neurons

Explain the formation and circulation of cerebrospinal fluid

Cerebrospinal fluid is produced in the choroid plexuses and is continuously circulated. CSF flows through the four ventricles and then flows between the meninges in an area called the subarachnoid space.

Compare the basic types of ion channels (mechanically, ligand, and voltage-gated), describe their locations on a neuron, and explain how they relate to graded potentials and action potentials.

Chemically gated - they key that opens these channels is a chemical eg. ACh receptors (Axon and Soma) Voltage gated - the key that opens these channels is a change in voltage eg. Calcium in sarcoplasmic reticulum (Axon) Mechanically gated - the key that opens these channels is physical distortion/bending eg. dendrites (Dendrites)

Describe the structures that protect the brain and how they do so

Cranium Meninges - some layers around spinal cord Blood-brain barrier - created by blood vessels that supply brain and prevent harmful substances from entering by tight junctions prevents passage of many substances from blood to brain lipid molecules can pass in general Cerebrospinal Fluid - created and circulated by ependymal cells

Predict the possible consequences of damage to any of the brain areas included in the above objectives

Damage to the frontal lobe of the brain can cause a range of symptoms, including motor weakness and behavioral problems. Damage to the cerebellum can lead to: 1) loss of coordination of motor movement (asynergia), 2) the inability to judge distance and when to stop (dysmetria), 3) the inability to perform rapid alternating movements (adiadochokinesia), 4) movement tremors (intention tremor), 5) staggering, wide based walking (ataxic gait)

Predict the consequences/effects of a drug or disorder that changes the activities of a given neurotransmitter

Drugs can alter the way people think, feel, and behave by disrupting neurotransmission, the process of communication between neurons (nerve cells) in the brain.

What are the three meninges?

Dura mater "Tough mother" - outermost layer, thin dense irregular tissue, made of mostly collagen Arachnoid mater "Spider mother" - intermediate layer, collagen fibers in a weblike fashion Pia mater "Tender mother" - innermost layer, delicate, aids in production of CSF

What are the thee spaces in the spinal cord?

Epidural space - Epi = above, adipose tissue Subdural space - Sub=below, where dura mater and arachnoid mater are Subarachnoid space - where CSF is

Distinguish between excitatory and inhibitory postsynaptic potentials

Excitatory postsynaptic potentials (EPSP) bring the neuron's potential closer to its firing threshold. Inhibitory postsynaptic potentials (IPSP) change the charge across the membrane to be further from the firing threshold.

Identify the three main regions of the brain stem and describe the functions of each

Extends from diencephalon and spinal cord, in charge of survival reflexes and involuntary functions Midbrain - extends from diencephalon to the pons, contains sensory and motor tracts: Superior Colliculi - tracking, scanning (visual reflexes) Inferior Colliculi - startle reflex Pons - "bridge" between midbrain and medulla, contains many sensory and motor tracts, cluster cells (nuclei) that control the rhythm of breathing, transition between inhalation and exhalation Medulla Oblongata - extends from decussation of pyramids (crossing of tracts) Cardiac center - regulates heart rate and blood pressure Respiratory center - regulates breathing, rate of breathing, reflexes for vomiting, swallowing, sneezing, coughing, hiccupping

Compare and contrast graded potentials and action potentials in terms of size, direction of change, location of occurrence, and function.

Graded Potentials: Short distance com. Small (generally a few to tens of mV) They are hyperpolarizing or depolarizing Occur in the cell body before the axon hillock A hyperpolarization or depolarization event may simply produce a graded potential Action potentials: Long distance com. Large (~100mV) They are depolarizing and reverse the membrane potential Occurs down an axon away from the body A large enough depolarization event can lead to the production of an action potential

Contrast hyperpolarizing and depolarizing graded potentials and predict whether they are excitatory or inhibitory

Hyperpolarization is when the membrane potential becomes more negative. The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization. Examples: Opening of channels that let K+ out of the cell or CL- in Depolarization is when the membrane potential becomes less negative. The opening of channels that let positive ions flow into the cell can cause depolarization. Example: Opening of channels that let Na+ into the cell

Predict the potential consequences of damage to a particular part of the spinal cord based upon your knowledge of the anatomy and physiology

If the dorsal root was damaged, then it would damage the sensory neurons and the sensory tract so information would be impeded on getting to the brain, and if the ventral root was damaged, then it would damage the motor neurons and the motor tracts and signals would be impeded on carrying out actions in the body

Describe the general flow of information through the spinal cord

Information flows through the spinal cord by tracts, sensory tracts that are ascending towards the brain that sensory signals travel on, and motor tracts that are descending away from the brain that motor signals travel on towards the appendicular skeleton

Describe what is meant by membrane potential and how it is maintained.

Membrane potential - difference in charge of ions from one side of membrane to another, like voltage stored in batter Membrane potential is maintained by ion channels that keep the positive and negative charges appropriately balanced (like a battery with a positive and negative side)

Define neuron, describe its important structural components, and relate each to a functional role

Neurons are special cells that generate and send nerve impulses/action potentials (they do not divide quickly) Dendrites: Treelike extensions from the beginning of a neuron that receive information from other neurons and transmit electrical stimulation to the Soma (Cell body)> Soma (Cell Body): Where signals from dendrites are joined and passed on. Maintain the cell and keep neuron functional Axon: Elongated fiber that extends from cell body to terminal endings and transmit neural signals. Some have fatty substance called myelin which acts as an insulator and makes it faster Axon Hillock: Located at the end of the Soma and controls the firing of the neuron. If total strength of signal exceeds threshold, an action potential will occur Axon Terminal: Located at the end of the neuron and are responsible for sending a signal to other neurons and it contains a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons.

Define neurotransmitter and explain the functions of each that we covered

Neurotransmitters are chemical messengers in the body. Their job is to transmit signals from nerve cells to target cells. Acetylcholine - excitatory neurotransmitter, opens Na+ (sodium) channels at the NMJ Norepinephrine - excitatory, 'feel good' neurotransmitter Dopamine - excitatory and inhibitory, 'feel good' neurotransmitters Serotonin - sleep, mood, migraines

Describe the structure and functions of the cerebellum

Posterior to medulla and pons, ataxia, maintains all motor and peripheral equilibrium: Flocculonodular lobe - equilibrium and balance Anterior Posterior lobe - fine motor coordination Cerebral Cortex - motor area initiates signals to the muscles Preceptor Receptors - tell cerebellum what movement in the muscles is occurring Primary Motor Area - tells cerebellum planned movement

Explain how action potentials are generated and propagated along neurons.

Propagation: spread of an action potential. When an action potential is triggered and causes sodium channels to open, this change in voltage causes it's neighbor's channels to open up, which causes it's neighbors to open, and it's neighbors etc. and the action potential propagates down the entire axon through this process

Describe the membrane potential of a cell in millivolts and in terms of how the charges are separated.

Resting membrane potential is approximately -70 millivolts

Describe the changes that would occur in membrane potential if a given ion channel opens.

Resting membrane potential is approximately -70 millivolts. At -55mv a graded potential triggers an action potential, which causes set of sodium channels to open and sodium rushes in (depolarization, more positive) then voltage-gated potassium channels open, allowing potassium to rush out of the cell down its electrochemical gradient (repolarization, more negative) These events rapidly decrease the membrane potential past -55 (hyperpolarization, most negative) then bringing it back towards its normal resting state.

Describe the structural and functional divisions of the nervous system

Sensory Input - signal received by the CNS Motor Output - signal put out by the CNS CNS - Central nervous system includes brain + spinal cord (where integration occurs), is constantly giving and receiving information PNS - Peripheral nervous system includes spinal nerves + receptors + 12 cranial nerves PNS has 2 divisions: PNS 1st division Sensory Division (in PNS) - carries sensory signals from receptors PNS 2nd division Motor Division (PNS) - responsible for voluntary functions Motor has 2 divisions: 1. Somatic division (in motor, PNS) - responsible for voluntary actions, namely skeletal muscle 2. Autonomic/Visceral division (in motor, PNS) - responsible for involuntary functions such as smooth and cardiac muscle) Autonomic has 2 divisions: Sympathetic division (in visceral, motor PNS) - fight or flight reflex, high alertness Parasympathetic division (in visceral, motor, PNS) - rest and digest, restoration

Explain how a neurotransmitter could be excitatory at some synapses and inhibitory at others.

Some neurotransmitters, such as acetylcholine and dopamine, can create both excitatory and inhibitory effects depending upon the type of receptors that are present.

Describe the location of the diencephalon, name its subdivisions, and the functions of the subdivisions

The diencephalon surrounds the third ventricle. It is comprised of the: Thalamus - the main relay station for impulses going to the cerebral cortex, routes signals like a computer switchboard, it is responsible for "editing" Hypothalamus - inferior to thalamus; inferior to the thalamus, sits on top of pituitary, contains many nuclei (cluster of cell bodies in the CNS) functions: 1. Integrates and coordinates autonomic nervous system 2. Bodies thermostat, fever 4. Secretes hormone Anti-Diarrheic Hormone (ADH) which conserves water, and Oxytocin which stimulates contractions, and milk letdown 5. It controls the pituitary gland 6. It controls biological clock-circadian rhythm Epithalamus - superior and posterior to the thalamus, consists primarily of: Pineal body - secretes hormone melatonin, makes you sleepy Habenular Nuclei - emotional responses to smell

Contrast the structure and function of electrical and chemical synapses provide examples of each in the body.

The key difference between chemical and electrical synapse is their method of transmitting signals; chemical synapse pass signals in the form of chemical molecules called neurotransmitters, while electrical synapse transmits signals in the form of electrical signals without the use of molecules. Chemical synapse: The synapse between axon and NMJ where Acetylcholine is released Electrical synapse: gap junction in cardiac muscle

Describe the importance of myelination of axons, and contrast continuous and saltatory conduction

The main function of myelin is to protect and insulate these axons and enhance the transmission of electrical impulses The key difference between saltatory and continuous conduction is that saltatory conduction is the propagation of action potential along myelinated axons while continuous conduction is the propagation of action potential along unmyelinated axons.

Describe the gross anatomical features of the spinal cord

The spinal cord: - extends from the medulla oblongata (in the brain stem) to L1 or L2 vertebra - About 42-25 cm long - 2 cm in diameter - 31 pairs of spinal nerves arise from cord - Contains enlargements - Cauda equina "Horse's tail"

Explain how the strength of the stimulus relates to action potential frequency

The strength of the stimulus is coded into the frequency of the action potentials that are generated. Thus, the stronger the stimulus, the higher the frequency at which action potentials are generated. The less strong the stimulus is, the less frequent the action potentials will be.

Describe the protective structures of the spinal cord

Vertebral column - runs through vertebral foramina of vertebrae Meninges - made of connective tissue, continuous meninges of brain CSF (cerebrospinal fluid) - shock absorber

Distinguish between white and gray matter, a nerve and a tract, and a nucleus and a ganglion

White matter - presence of myelinated axons where information is being transmitted in and out Grey matter - presence of unmyelinated axons where interpretation is occurring and choices are being made Nerve - a collection of nerve fibers (axons) in the peripheral nervous system Tract - a tract is a collection of nerve fibers (axons) in the central nervous system Nuclei - clusters of nerve cell bodies in the CNS Ganglia - clusters of nerve cell bodies in the PNS

Differentiate between the different types of sensory and motor neurons based on a description. (i.e. tell me that it is a somatic motor neuron based on the fact that it controls contraction of the biceps brachii...)

neuron carrying signal to skeletal muscle is a somatic motor nueron

Describe the location where an epidural injection would be given and where a lumbar tap procedure takes place

the subarachnoid epidural space between the spinal column and outer membrane of the spinal cord