A&P Midterm 1 Ch. 13 Study Guide PDF

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Summary

Nervous system and it's cells. How action potentials are initiated and how graded potentials change throughout an action potential. And how different neurotransmitter activate gated channels and their different effects on the brain. Professor: Bradley Buckley...

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Ch. 13 Know the gross anatomy and function of the spinal cord and spinal meninges ● Gross anatomy of spinal cord: 18 in long and 0.55 in wide ○ Cervical enlargement: controls head, neck, and upper limb ○ Lumbar enlargement: controls lower half of body ○ Dorsal root ganglion: cell bodies of sensory neurons ○ Spinal nerve: distal to dorsal ganglion form single “mixed” nerve ○ Meninges: ■ Dura mater (tough): Epidural space between the dura mater and vertebral column ■ Arachnoid mater (spider web) ● Squamous epithelial cells ● Arachnoid trabeculae: collagen and elastic fibers in web network ● Filled with CSF ■ Pia mater (delivers blood to and from spinal cord) ● Bound to neural tissue Understand the flow of information through the spinal cord and spinal nerves. ● Sensory neurons flow in from posterior root ○ Somatic into the posterior horn ○ Visceral into the lateral horn (lateral horn isn’t always present) ● Motor neurons flow out of anterior root ○ visceral flow from lateral horn ○ Somatic from anterior horn Understand the arrangement of white and gray matter in the spinal cord, including the role of each gray horn, and the ascending sensory pathways and descending motor pathways. ● White matter column aka funiculi where each posterior, lateral, and anterior have tracts (fasciculi) or bundles of axons. info transmission ○ Ascending tract: sensory info carried to the brain ○ Descending tract: motor info carried to the spinal cord ● Grey matter: nissl bodies around soma, info integration Know what kind of sensory information is being carried on each ascending tract, where decussation occurs, where synapses exist between first-, second- and third-order neurons (if a third-order neuron exists in that pathway). For the descending motor pathways, again, know where the signal originates, where it decussates, and where any synapses in the pathway exist. ● Types of receptors ○ Interoceptors (inside): Receive signals generated from inside the body. Ex: urge to pee

○ Exteroreceptors (outside): receives signals from outside the body. Ex: environmental temperature ○ Proprioceptors (both inside and outside): signals the sense of position. Example: sense of balance and position of body comes from inner ear ● Types of spinal nerves basic ○ First order neurons ■ Sensory stimulus enter spinal cord ■ Unipolar ■ Synapse (sends) sensory info to second order neurons ○ Second order neurons (in spinal cord) ■ Ascends towards brain stem/cerebellum of brain ■ Synapse to third order neuron ■ Decussation: cross over ● Example: pain sensation at left hand is crossed over and send to third order neuron at primary sensory cortex of opposite side ○ Third order neurons ■ Automatic side of brain ■ Emerges from thalamus ■ Relays signal from second neuron to parietal lobe of cerebrum (primary sensory cortex) ● Somatic sensory pathways (all 3 are ascending) ○ Posterior column pathway ■ Cuneate and gracile fasciculi ■ Sensations: fine touch, vibration, pressure, proprioception ■ 1st order neuron: enters spinal cord and ascends towards medulla oblongata of brain ● Synapse to 2nd order at medulla ■ 2nd order neuron: travels through midbrain ● Decussation: medial lemniscus of medulla ● Synapse to 3rd order at thalamus: thalamus filters out incoming sensory info by amplifying or inhibit signal ■ 3rd order destination: primary sensory cortex ○ Anterolateral system ■ Spinothalamic and spinoreticular tract ■ Sensations: Harsh pressure, touch, pain, and temperature ■ 1st order neuron: enters spinal cord ● Synapse to 2nd order at posterior gray horn of spinal cord (unlike posterior column pathway) ■ 2nd order neuron: head towards midbrain

● Decussation: anterior gray horn of spinal cord ● Synapse to third order at thalamus and destination is primary sensory cortex (like posterior column pathway) ○ Spinocerebellar pathway ■ How it’s different from the other two pathways ● No third order neuron or thalamus ● Info coming from this pathway can’t make it to primary sensory cortex, but to cerebellum instead ● May or may not decussate (if not, then there’s no cross over and the neuron just goes straight) ■ Sensations: proprioception (receptors at joints and tendons) ■ Made up of posterior and anterior spinocerebellar tract ■ 1st order neuron: enters spinal cord at both sides ● Synapse to 2nd order at spinal cord ■ 2nd order neuron: both posterior and anterior spinocerebellar tracts head through medulla oblongata and towards cerebellum ● Cerebellum: Receives info from both sides, so there’s coordinated 3D posture for balance. Example: one side of the brain hemisphere will receive info from both left and right side of body and vice versa for the other side of the hemisphere. Control practiced movements (piano etc) ○ Descending pathway: corticospinal tracts (lateral and anterior) ■ Motor command signals sent down from cortex of cerebrum to spinal cord out to PNS (motor pathways) ■ Tracts are clusters of axons inside CNS that controls conscious and reflex motor commands ■ Both lateral and anterior carry same motor commands, but in different tracts adjacent to each other ■ Directions ● Both tracts travel down towards midbrain ● Decussation: ○ medulla (85% decussate here): lateral tracts decussate ○ Spinal cord (15% decussate): anterior tracts ● Synapse (both tracts merge): lower motor neurons to skeletal muscles ● Medial pathways (all are descending) ○ Reticulospinal tracts: reticular activating system wakes up the brain, attention, and alert. No decussation

○ Vestibulospinal tracts: sometimes doesn’t decussate but when it does, it’s in the medulla ■ Originates in brainstem and travels down to spine ■ Inner ear, sense of equilibrium ○ Tectospinal tract: controls response to sight and sound. Decussates at midbrain (weird case) Know the major nerve plexuses and what parts of the body they serve, the names, locations and function of any specific nerves I’ve highlighted in class, and the different types of spinal reflexes. ● Plexus: interlaced cluster of nerves ● Types of plexus ○ Cervical ■ C1-C5 ■ Controls breathing (diaphragm), face, neck, and shoulder ■ Phrenic nerve ○ Brachial ■ C5-C8 and T1 ■ Controls upper limbs and hands ■ Axillary nerve, musculocutaneous nerve, median nerve, radial nerve, and ulnar nerve ○ Lumbar ■ L1-L4 and T12 ■ Controls lower limbs ■ femoral nerve ○ Sacral ■ L4-S4 ■ Sciatic nerve ● Types of spinal reflexes ○ Spinal reflexes ■ Innate vs acquired ■ Monosynaptic (1 synapse required for motor command in response to sensory input) vs polysynaptic (many synapses, majority of the case) ■ Conscious control over spinal reflexes ● Tracts descend from brain synapses on interneurons (where it can activate or inhibit motor neuron) ○ Ipsilateral reflex (same side): stretch reflex ■ Knee tap ■ Neurons travel towards single segment of spinal cord

○ Intersegmental reflex ■ Output response has multiple spinal cord segments involved, not just segment where sensory stimulus comes in ■ Ex: touching hot stove ● Signal motor commands could travel towards hand or brain ○ Contralateral reflex ■ Response on opposite side ■ Keeps body balanced ● Neural development test ○ Plantar reflex (toes pointed down): healthy descending track that’s not damaged. Inhibits babinski sign ○ Babinski sign (toes flex out) ● Encephalons ○ Telencephalon: cerebrum ○ Diencephalon (2): thalamus and hypothalamus ○ Mesencephalon: midbrain ○ Metencephalon: pons and cerebellum ○ Myelencephalon: medulla...