UNIT 5 REVIEW GUIDE - NERVOUS SYSTEM 1) State the 3 functions of the nervous system. 1) sensory 2) integration 3) motor output 2) Briefly describe the general function(s) of each of the following neuron types: a) SENSORY NEURONS: detect a stimulus b) INTERNEURONS: processing; integration c) MOTOR NEURONS: send message to effector (muscle cell, gland cell) 3) What conditions must be met in order for neurons to repair themselves? 1) PNS neuron only 2) cell body must be intact 3) cell membrane (neurilemmal) must be intact 4) no scarring 4) Sketch a typical NEURON in the space below. Label the following structures: cell body dendrites axon nodes of Ranvier neurotransmitters nucleus myelin sheath synaptic end bulb vesicles direction of impulse (as an arrow) 1 glial cell axon terminal 5) How is the function of neurons different than the function of neuroglial cells? neurons transmit information/messages with action potentials; neuroglial cells support neurons but do not actually pass the electrical message 6) State the function of each of the following neuroglial cell types: oligodendrocytes: makes myelin in the CNS astrocytes: forms blood brain barrier between capillaries (small blood vessels) and brain neurons Schwann cells: makes myelin in the PNS
7a) List & briefly describe the four events (what ion is moving & in what direction) that occur to create an ACTION POTENTIAL. 1) Resting potential: neuron cell is at approximately -70 mv. Na + & K + gates are both closed so no ion movement 2) Depolarization: stimulus at the dendrites increase the membrane potential to -55mV in the cell body and as a result, has crossed the thresh hold to fire an action potential; at the beginning of the axon, Na + gates open and Na + rushes into the cell; cell becomes more positive on the inside 3) Repolarization: K + gate opens & Na + gate closes; K + moves out of the cell and this decreases the membrane potential inside the cell (it becomes more negative as the positive charges leave the cell) 4) Undershoot: K + gate is slow to close so more K + leaves the cell (Na + gate still closed); cell becomes even more negative **Refractory time period: time between action potentials when the Na + /K + pump resets the ion concentrations (Na + pumped back out & K + pumped back in; uses ATP) and the Na + gate is reset 7b) ) Draw and label a graph of the four phases of an action potential. 7c) What returns a neuron to its resting state (membrane potential)? Sodium-potassium pump 8a) What is the resting potential of a neuron and what is the threshold potential? Resting: -70mV Threshold: -55mV 8b) What is meant by an all-or-none response? An action potential is either going to fire or not fire; if the membrane potential reaches -55mV, an action potential WILL occur 9a) What is the purpose of MYELIN (i.e. the MYELIN SHEATH)? Speed up the electrical impulse (acts kind of like insulation to keep electrical charge/depolarization inside axon) 9b) What is saltatory conduction & what type of neurons does it occur on? Saltatory conduction is when the action potential appears to jump down the axon from node of Ranvier to node of Ranvier. It only occurs on myelinated neurons. 9c) Where are action potentials generated on myelinated neurons? At the very beginning of the axon and at each Node of Ravier. 9d) Why does an impulse travel faster in saltatory conduction? There are fewer action potentials needed to get down the axon of myelinated neurons.
A B C 9e) What causes an action potential to travel down an axon? In other words, what causes a new action potential at Node C when there is an action potential at Node B? The depolarization that occurs at Node B travels down the axon to the right to initiate a new action potential at the next Node of Ravier- Node C. 10) How is a stimulus of greater intensity produced as compared to a stimulus of lesser intensity: more stimulus leads to a greater frequency (number) of action potentials 11) List the events that occur at a SYNAPSE for an action potential (impulse) to be transmitted from the presynaptic neuron to the postsynaptic neuron. depolarization reaches the synaptic bulb (aka axon end terminal bulb) this causes the vesicles to fuse with the neuron s membrane neurotransmitters then spill into the synapse neurotransmitters diffuse across the synaptic cleft & binds to the appropriate receptor in the postsynaptic cell s membrane this initiates a new action potential in the next neuron 12a) What is a NEUROTRANSMITTER? A chemical messenger between cells 12b) List the neurotransmitters in the human body from your notes & their function. 1) ACh: stimulates skeletal muscle contractions 2) dopamine/serotonin: affect sleep, mood, attention, learning 3) endorphins: decrease the perception of pain 4) epinephrine/norepinephrine: attention & mental focus, cognition 5) histamine: promotes alertness (released in hypothalamus) 13a) Label the following information on the drawing below: there are synaptic end bulbs from 2 different neurons synapsing with the dendrites of a 3 rd neuron which is at rest. Synaptic end bulb #1 releases neurotransmitters that cause a -5 mv change inside the cell body and synaptic end bulb #2 releases neurotransmitters that cause a +25mV change inside the cell body. 13b) Will there be an action potential generated in neuron #3? YES! How do you know? Charge is -50mV; crossed threshold of -55mV
14a) List the four major regions of the brain & their general function: 1) CEREBRUM: thinking/decision making; personality; memory; main integration 2) CEREBELLUM: coordinates where your body is in space & time; major muscular coordination 3) BRAIN STEM: vital reflexes for homeostasis (coughing, sneezing, vomiting, breathing) 4) DIENCEPHALON: homeostasis (hunger, thirst, body temp), biological clock, relay center 14b) Differentiate between the function of the motor cortex & somatosensory cortex. The somatosensory cortex receives sensory information (such as pressure, touch, pain, temperature) to be processed. The motor cortex sends commands to skeletal muscles for voluntary movement. 14c) Which of the 4 major brain regions are the motor cortex and somatosensory cortex found in? Both are found in the cerebrum. 14d) What side of the body does your left hemisphere control? Right side 14e) What does this model (homunculus) tell you in regards to the motor & somatosensory cortex? There is a lot of motor cortex and somatosensory cortex dedicated to hands/fingers and the lips. 15a) State the location of the CORPUS CALLOSUM. Joins left & right hemispheres of the brain 15b) What is its function? Help integrate information from right & left sides of the body 16) Describe the location AND functions of CEREBROSPINAL FLUID. > Location: around the brain & spinal cord > Functions: cushion, protect, nourish brain & spinal cord cells 17) On the diagram below, label the: -occipital lobe -CEREBELLUM -hypothalamus -midbrain -frontal lobe -medulla oblongata -corpus callosum -thalamus -parietal lobe -pons -pituitary gland -spinal cord -temporal lobe FRONTAL LOBE PARIETAL LOBE CORPUS COLLOSUM HYPOTHALAMUS PITUITARY TEMPORAL LOBE OCCIPITAL LOBE THALAMUS MID BRAIN PONS CEREBELLUM MEDULLA OBLONGATA T SPINAL CORD
18) Complete the following chart of the various parts of the brain: Brain Structure (or region) State major brain region unless the structure is a major brain region. If it is, then describe location in the brain. Function(s) Thalamus diencephalon relay center (that sorts out & transmits sensory information to and from cerebrum) Hypothalamus diencephalon controls many important brain activities, most involved with homeostasis; control ANS body temperature pituitary gland and production of hormones regulates emotion (such as feelings of rage, aggression, pain, and pleasure) regulates behavioral patterns such as those related to sexual arousal regulates eating and drinking regulates circadian rhythms Pineal Gland diencephalon secretes melatonin which promotes sleepiness and contributes to setting the body s biological clock Optic chiasma diencephalon Region where the right and left optic nerves cross each other before entering the brain; this allows objects from each visual field to be processed together (also gives depth perception) Midbrain Brain stem receives and sends sensory information that coordinates eye movements/head movements to respond to stimuli Pons Brain stem regulates breathing centers in the medulla oblongata Medulla oblongata Brain stem Considered the most vital part of the entire brain for keeping us alive! controls involuntary reflexes like breathing heart and blood vessel activity swallowing vomiting sneezing digestion Frontal lobe cerebrum Reasoning; planning; emotions; problem solving; part of the speech process; movement Parietal lobe cerebrum perception of sensory stimuli; orientation Temporal lobe cerebrum Perception & recognition of auditory stimuli; memory; speech Occipital lobe cerebrum Visual processing Cerebellum Back/bottom of brain Coordinates muscles to produce movement; regulate posture & balance
19) How is the function of Broca s area different than Wernicke s area? Broca's area is the motor speech area and it helps in movements required to produce speech. Wernicke's area, which is located in the parietal and temporal lobe, is the sensory area. It helps in understanding speech and written words. 20a) Outline the functional differences between the SYMPATHETIC and the PARASYMPATHETIC divisions of the autonomic nervous system. Sympathetic nervous system: fight or flight response specific areas of your body are targeted by adrenaline (epinephrine) to increase glucose & oxygen in your blood and take away waste products of cellular respiration faster Parasympathetic system: rest & digest when your body is doing what it normally does at its normal pace; digesting food, making urine, etc 20b) What are the physiological effects of adrenaline in your body? Increased heart rate Dilation of blood vessels in skeletal and cardiac muscles Constriction of blood vessels in non-essential organs Dilation of respiratory airways Increased sweating Increased blood glucose levels 21) Why is the hypothalamus sometimes called the autonomic nervous center? Hypothalamus is in charge of so many involuntary actions that it can seem as if it runs the whole autonomic nervous system 22) Complete a flow chart showing the relationships within the nervous system using the following terms: Nervous System; Central nervous system (CNS); Sensory division; Motor division; Autonomic nervous system (ANS); Peripheral nervous system (PNS); Skeletal Motor Control; Parasympathetic division; Sympathetic division NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM SENSORY DIVISION MOTOR DIVISION SKELETAL MUSCLE CONTROL SYMPATHETIC DIVISION AUTONOMIC NERVOUS SYSTEM (ANS) PARASYMPATHETIC DIVISION 23a) What is a REFLEX? Involuntary/automatic response 23b) What is an advantage to a reflex? It is very fast & you can react to protect yourself more quickly.
24a) List the 5 steps/actions that occur during reflexes such as the knee-jerk reflex and the pupillary reflex. 1) receptor cell detects stimulus (i.e. stretch receptor in patellar tendon or light receptor in eye) 2) sensory neurons relay message to spinal cord (knee-jerk reflex) or brain stem (pupillary reflex) 3) interneurons process the information and send message to motor neuron to make the correction 4) motor neuron takes message to effector (quad muscles in knee-jerk or pupil muscles in pupillary reflex) 5) effector responds: quad muscle contracts to jerk leg/tibia up or both pupils constrict & become smaller 24b) What happened in the following reflex tests: Knee-jerk: tibia kicked up Pupillary: both pupils constricted Plantar flexion: toes curled 25) What happens in a stroke? Brain cells (neurons) do not get enough oxygen because a blood vessel is blocked or it ruptures and the brain cells die. (Symptoms: face drooping; difficulty with speech, weakness/numbness in arms or legs, unexplained dizziness, dimness in vision in one eye) 26) Briefly describe the main symptoms of the following conditions (from neurological conditions chart). Parkinson s Disease: symptoms such as tremors & stiffness of limbs, slowness of movement, impaired balance & coordination; caused by the death of specific neurons in the brain; appears is older people (around 60) Migraine: symptoms include throbbing head, nausea/vomiting, sensitivity to light/noise/odor; caused by swelling of the blood vessels around the head which result from stress or hormonal changes. Epilepsy: seizures and muscle spasms; caused by abnormal brain signals Schizophrenia: hearing internal voices, hallucinations, delusions, paranoia Huntington s disease: This condition causes degeneration of brain cells which leads to uncontrolled muscle movements & loss of intellectual faculties (genetically caused disease which doesn t appear until around age 40). Dementia: Symptoms include memory loss, difficulty performing tasks, problems with language, disoriented to time and place; loss of mental skills that result from changes in or damage to the brain (stokes, tumors, head injuries, Alzheimer s) Alzheimer s: Symptoms include memory loss, confusion, and difficulty learning & remembering new information; condition appears later in life and is caused by brain lesions or plaques that accumulate causing specific brain cells to die. Cerebral Palsy: symptoms- problems with body movement/muscle spasms & posture; a person is usually born with this neurological disorder and it is caused by damage/abnormalities in parts of the brain that control muscle movement. Multiple Sclerosis: symptoms include weakness, vision loss, and muscle spasms; myelin has been damaged by their body s own immune system (autoimmune disease) Meningitis (from notes p4): Symptoms include severe headache, sudden high fever, stiff neck, and nausea; caused by a viral or bacterial infection and results in the inflammation of the meninges & cerebrospinal fluid.