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Assignment 2 – (50 marks) I started the adjustment. it wasn’t well articulatedQ.1. Briefly describe the three categories of levers, an example of each and if eachone works at an advantage or disadvantage. (3 marks)Ans: Categories of Levers which are categorized according to the position of the fulcrum,effort, and loadA first class lever: In this, the fulcrum is the effort and the load it is called as the firstclass lever such as Scissors. A first class lever can produce either a mechanical advantageor disadvantage depending on whether the efforts or load is closer to the fulcrum.Second class lever: The fulcrum and the effort are called as a second class lever when theload is between them such as in a wheelbarrow. The second class lever operates at amechanical advantage because the load is always closer to the fulcrum than the effort. Third class leveler: When the effort is between the fulcrum and the load it is the thirdclass lever as in Forceps. Third class level operates at the mechanical disadvantagebecause the effort is always closer to the fulcrum than the load.Categories of Leverswhich are categorized according to the position of the fulcrum, effort and loadA first class lever If the fulcrum is between the effort and the load it is called as the firstclass lever. Eg Scissors. A first class lever can produce either a mechanical advantage ordisadvantage depending on whether the efforts or load is closer to the fulcrum.Second class leverIf the load is between the fulcrum and the effort it is called as secondclass lever. Eg. a wheel barrow. Second class lever operate at mechanical advantagebecause the load is always closer to the fulcrum than the effort. Third class levelerIf the effort is between the fulcrum and the load it is the third classlever. Eg. Forceps. Third class level operate at the mechanical disadvantage because theeffort is always closer to the fulcrum than the load. . Q.2. Name and describethe locations and actions of the muscles typically used inbreathing. (4 marks) Wrong answerAns: The floor of thoracic activity is formed by a diaphragm which contracts during inhalation ofair so that size of thoracic activity increases and the air pressure inside lungs decreases. The external intercostals that are found between the ribs cause the lateral and anteroposterior expansion of thorax. The decline in air pressure draws the air inside. diaphragm ,external intercostal, internal intercostalThe scalenes a shrugging muscle helps the inhalation by lifting sternum and upper ribs.After proper inhalation, the internal intercostals between ribs pull back the bones in the oppositedirection of movement during exhalation to decrease the size of the thoracic cavity anddiaphragm relaxes causing the pressure reversal and exhalation of the air. . external intercostalswhichr and se in air pressure draws Name: Diaphragm Locations and Actions: Diaphragm originates on the xiphoid process of the sternum, the inferiorsix ribs and their costal cartilages, and the lumbar vertebrae and their intervertebral discs and the1| Page
twelfth rib. The external intercostals are between the ribs. During active inhalation, they expandthe rib cage laterally, anteriorly and posteriorly.Name: ScalenesLocations and Actions: locatedin the front on either side of the throat, just lateral to the sternocleidomastoid. This muscle lifts the sternum and the upper ribs during active inhalation. Inactive exhalation, the muscles of the abdominal wall--rectus abdominis, internal and external obliques and transverse abdominis--contract, raising abdominal pressure. This raises the diaphragm, raising pressure in the lungs and expelling air.properiintercostals between ribion to decrease of the thoracic cavity. The diaphraratin to form nd decreass thoracic cavity. Briefly answer to the following questions: (4 marks)Q.3.a).Describe four ways drugs can modify the effects of neurotransmitters. It saiddescribe and not list. Not detailed with properties and characteristics missingAns: Followings are the ways where drugs can modify the effects of neurotransmitters.1) Stimulating or inhibiting their synthesis, drugL‐dopa is used beacuse it is a precursorof dopamine. For a limited period of time, takingL‐dopa boosts dopamine production inaffected brain areas.2) Enhancing or blocking their release, Amphetamines promote release of dopamine andnorepinephrine. Botulinum toxin causes paralysis by blocking release of acetylcholinefrom somatic motor neurons.3) Activating or blocking their receptor, An agent that binds to receptors and enhances ormimics the effect of a natural neurotransmitter is anagonist. Isoproterenol is a powerfulagonist of epinephrine and norepinephrine. It can be used to dilate the airways during anasthma attack. An agent that binds to and blocks neurotransmitter receptors isanantagonist.Zyprexa, a drug prescribed for schizophrenia, is an antagonist of serotoninand dopamine.4) Stimulating or inhibiting their removal For example, cocaine produces euphoria—intensely pleasurable feelings—by blocking transporters for dopamine reuptake. Thisaction allows dopamine to linger longer in synaptic clefts, producing excessivestimulation of certain brain regions. .The drugs can modify the effect ofneurotransmitters by various ways i.e., they can be agonist or antagonist. Antagonisteffect can be observed through blocking the effect of neurotransmitter, such as Curareblocks acetylcholine which is needed for the functioning of skeletal muscles. Agonisteffect is to increase the effect of neurotransmitters, as an example Neostigmine is anorganophosphate insecticide and chemical nerve agent which deactivates the enzymewhich breaks the acetylcholine and thereby increasing the effect of acetylcholine, causingtwitching and paralysis of muscle because of too much neurotransmitter around. Theother ways by which drugs can modify effects of neurotransmitters is by reducing itsactivity like by α-methyl-paratyrosine blocks the synthesis of dopamine causing stressand depression while amphetamine improves the synthesis of dopamine causing anxiety.Q.3.b).Describe the three ways neurotransmitters can be removed. Had to redo this oneAns: 2| Page
1) By degrading with enzymes in synaptic terminals; certain neurotransmitters areinactivated through enzymatic degradation example acetylcholinesterase monoamineoxidase which is the fastest way2) Uptake by cells. Many neurotransmitters are actively transported back into the neuronthat released them (reuptake) or are transported into neighboring neuroglia(uptake)..example astrocyte uses excitatory amino acid transporter 2 (EAAT2) to removeglutamate3) By diffusion: Some of the released neurotransmitter molecules diffuse away from thesynaptic cleft .example Nitric oxide which is not stored in synaptic vessels and diffuses assoon as it is produced.Q.3.c).Describe the two conditions that allow maintenance of the resting membranepotential in excitable cells. An attempt but not well detailedAns: The two conditions that allow maintenance of resting membrane potential is:a)Electrical gradient which causes the membrane to become more positive outside andmore negative inside.b) concentration gradient through which ions move from high concentration area to loweroneUnequal distribution of ions in the ECF and cytosol.A major factor that contributes to theresting membrane potential is the unequal distribution of various ions in extracellular fluid andcytosol.The resting membrane potential is determined by three major factors: (1) unequaldistribution of ions in the ECF and cytosol, (2) inability of most anions to leave the cell,and (3) the electrogenic nature of the Na+/K+ATPases.Voltage differential on each side of the membrane andNeurotransmitter receptors on the post-synaptic cell of a neuromuscular synapseQ.3.d).Briefly describe what causes the depolarizing phase. Same with 3cAns: When membrane potential of axon reaches the threshold, Na+ voltage-gated ionchannels open and Na+ flows inside the axon to rest along the inner surface of axonmembrane, causing it to depolarize from -55mV to +30mV. As the depolarization occursmore Na+ voltage gated channels open, causing a positive feedback mechanism. Na+ K+pumps to expel the Na+ out of the cell quickly to maintain a low Na+ content inside thecell. When a depolarizing graded potential or some other stimulus causes the membrane of theaxon to depolarize to threshold, voltage‐gated Na+channels open rapidly. Both theelectrical and the chemical gradients favor inward movement of Na+, and the resultinginrush of Na+causes the depolarizing phase of the action potential. Voltage gated Na+ channels open rapidly then both the electrical and chemical gradientsfavor the inward movement of Na+. The inward rush of Na+ causes depolarization phaseof the action potential.3| Page
Q.4.Answer to the following questions: Wrong and incomplete answer; asked foranatomy not anatomy and physiology. Meaning the External physical structure,function not included, grey matter is internal.Q.4.a).Describe the gross external anatomy of the spinal cord. (3 marks)Ans: still incompleteThe spinal cord is the cylinder of nerve tissue within the vertebral canal which is thicklike a finger and oval in shape. The length of the adult spinal cord ranges from 42 to 45cm (16–18 in.). Its diameter is about 2 cm (0.75 in.)The vertebral column grows faster than the spinal cord so in an adult the spinal cord onlyextends to L1. Elongation of the spinal cord stops around age 4 or 5, but growth of thevertebral column continues. Two conspicuous enlargements can be seen. Thecervical enlargement is the superior enlargement which extends from the fourthcervical vertebra (C4) to the first thoracic vertebra (T1). Thelumbar enlargement, the inferior enlargement which extends from the ninth to thetwelfth thoracic vertebraConus medullaris is where the spinal cord terminates as a tapering, conical structure,which ends at the level of the intervertebral disc between the first and second lumbarvertebrae (L1–L2) in adults.Filum terminale is the non‐nervous fibrous tissue of the spinal cord that extendsinferiorly from the conus medullaris to the coccyx.Spinal nervesTheposterior (dorsal) rootand rootletsTheanterior (ventral) rootand rootletsIt extends through the spinal column from the foramen magnum to L1.31 spinal nerve pairs originate from thoracic, cervical, sacral and lumbar areas of thecord. All segments of cord arise to a spinal nerves pair. Medullary cone (conus medullaris) = tapered tip of cordCervical (brachial plexus) nerve and lumbar enlargements (providing nerves to thelumbar and sacral plexus)The equine cauda stem from the conus medullaris and the lumbar enlargement, these arethe L12 - S5 nerve roots (resembles a horse tail).Spinal Cord – Gross Anatomy Structure • Long and cylindrical • 42cm in length and 1.8cm thick • Has two enlarged portions o Cervical enlargement (C4 and T1) Receives sensory inputfrom the upper limbs Sends motor output to the upper limbs Lumbar enlargement (T9 and T12) Receives sensory input from the lower limbs Sends motor output to the lower limbs Ends in a cone-shaped structure called the conus medullaris from where a fibrousextension of the pia, filum terminale, and mater extends inferiorly to anchor the cord tothe coccyx 4| Page
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