194.241 Past Exam 2016 PDF

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This is the past final exam used in the year 2016. I used these questions to produce my own practice answers when studying....

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1601/194.241 MAN/ALB Internal

Sc NSB ASR

MASSEY UNIVERSITY MANAWATU & ALBANY CAMPUSES EXAMINATION FOR 194.241 – PHYSIOLOGICAL CONTROL SYSTEMS

Semester One – 2016 _____________________________________________________ Time allowed: THREE (3) hours Answer ALL questions in Section A and Section B All 6 questions in Section A are of equal mark value (24 marks each). . Section A = 144 marks Section B = 36 marks Total marks = 180: Allow one minute per mark Answer Section A on the question paper directly in the space provided. There are 3 blank pages at the end of section A if you require more space. Please write your ID number on each page where it is requested. Answer Section B on the InspiroScan card provided INSPIROSCAN Ensure that your name and identification number are entered clearly on the InspiroScan Answer Form. Answers should be recorded directly on this form: Shade-in the entire circle surrounding the character (A-E) that best represents your chosen answer. If subsequent changes are required, cross through the original answer circle clearly with an X, before selecting an alternative. Use ballpoint pen (blue or black); pencil is not permitted. Please follow all instructions carefully on the InspiroScan Information Sheet provided, otherwise answers may not read correctly Answer all questions on Side A of the InspiroScan card. At the conclusion of the examination, please hand-in the complete InspiroScan Answer Form separately and the yellow Section A sheets.

Name: ______________________________ ID Number: __________________________

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Sc NSB ASR SECTION A

Question 1: a.

Describe, the roles of the following in the immune response: i.

Natural killer cells.

(3marks)

Kill or destroy infected cells by causing them to undergo programmed cell death. Natural killer cells have non-specific cellular and chemical defences. Harmful sunbstances or infected cells are often identified by surface carbohydrates which are unique to infectious organisms. Natural killer cells cause virus infected cells to die by programmed cell death (apoptosis). They wander in the blood monitoring MCH 1 levels on cells and kill cells that express low levels of MHC 1. Natural killer cells are small distict groups of large grnaular lymphocytes, which secrete potent chemicals that cause the infected cell to die and also produce an inflammatory reponce.

ii.

Complement proteins.

(3marks)

Are involved in destroying foreign substances in the blood, and also amplify all aspects of the inflammatory responce. They enhance the effectiveness of both the innate (non-specific) and adaptive (specific) immune responce. They kill bacteria and certain other types of cells but our own cells are immune to them. Complemen can be activated by either the classical, lectin, or alternative pathway.

iii. Major histocompatibility proteins (MHC-1 and MHC-2).

(3marks)

Are cell surface receptors that are essential in allowing the immune system to recognise foreign molecules. MHC molecules display proteins usually in healthy cells, but in infected cells they display foreign antigens which show the body that an immune responce should be initiated. MHC 1 = found on most nucleated body cells. MHC 2 = found on only certain types of antigen presenting immune cells such as macrophages and B lymphocytes

iv. Phagocytes.

(3marks)

Move around the body and engulf foreign cells, debris or infected/cancerous cells. A major part of the 2nd line of defence in the innate immunity. The major type is a macrophage. The surface of the phagocyte may ne covered with antibodies to help the infected cell adhere to it so the phagpcyte can engulph it by endocytosis. Macrophages secrete a lethal cocktail of chemicals that burn holes in bacterial walls.

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1601/194.241 MAN/ALB Internal B

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Identify the 4 major components of the cell cytoskeleton and describe their roles in cell function. (12 marks)

Microtubules = hollow tubes made of tubulin. Involved in chromosomal seperation and mitosis. Provide a surface for motor proteins to 'walk' along while transferring molecules or organelles to other regions of the cell. Maintain cel shape and organelle position. Are constantly assembling and disassembling depending on the cells needs at a specific time. Are present in cilia and flagella.

Intermediate filaments = made of keratin. Are not involved in the movement of organelles and molecules by 'rainway' lines like microtubules and microfilaments are. Are attached to cell junctions. Anchor the nucleus and other organelles in the cell. High tensile strength and pulling force for maintaining cell shape. Not used as a 'railway' for motor proteins to 'walk' along.

Microfilaments = made of actin. Are a part of the 'railway' line that allows motor proteins to move organelles and molecules to other regions of the cell. Maintains the cell shape by bracing and strengthening the cell surface. Are dynamic, and involved with cell division and muscle contraction.

Motor proteins = also called molecular moters, but are called motor proteins because they 'walk' along the cytoskeleton of the cell with what look like legs. They bind to and move along the cytoskeleton which is made up of microtubules, intermediate filaments, and microfilaments. They are powered by energy in the form of ATP and are made of proteins which bind to different filaments, move in differnet directions, and carry different cargo. Cargo is usually cellular organelles.

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Question 2:

ID Number:_____________

Part A a. Write an essay on the role of reflexes in the control of skeletal muscle contraction. (12 marks) Skeletal muscle is controlled by the somatic nervous system which is a division of the motor nervous system. This is to do with voluntary control of skeletal muscles with signals and conduction of impulses from the CNS to the effector organ which is the skeletal muscle. The somatic nervous system functions in movement by changing body position to perform a desired act, posture by maintaining the body position, and coordination by controlling the pattern and sequence of muscle contraction in complex movements. The efector organs which exert the effect are the skeletal muscle fibres which are innervated by Alpha motor neurons in the spinal cord and cranial morot neurons. Alpha motor neurons deliver impulses to the PNS which allow it to exert the effect. They are locate in the spinal neves which emerge from the spinal cord to innervate skeletal muscles for movement and posture. They are also located in cranial nerves emerging from the brain stem which are involved in facial expressions and chewing. Motor neurons in the spinal cord are called the lower motor neurons which may serve 1 or more skeletal muscles. This makes up a motor unit; a moto nerve and all of the skeletal muscles that it innervates. Recruitment of more motor units allows an increase in contractile force. Areas of the body that need more fine tuned movements have smaller motor units and areas of the body that have larger units and less precise movements can have larger motor units with more skeletal muscles.

Reflexes have a reflex arc of sensory receptor > sensory neuron > integration centre > motor neuron > effector organ/skeletal muscle. The integration centre is either the spinal cord or the brain, with the spinal cord alone being used to the most basic functions. For simple reflexes, the sensory neuron synapses directly with the motor neuron at the spinal cord level which requires no input from the brain (monosynaptic pathway). In an integrated responce, sensory neurons may synapse with one or more interneurons which can be excitatory or inhibitory to promote or prevent muscle contraction. The spinal cord can solely control some basic movements but the brain is always supervising and will intervene when necessary as it is the higher centre. More complex reflexes are controlled at the brain stem level, and the finely coordinated movements are controlled by the brain (posture). There are three levels of motor control which are the segmental level, projection level, and precommand level. Segmental level = consists of reflexes and the spinal cord segmental circuits that control autonomic movemnts which are involuntary. Projection level = controls the segmental level and consists of direct (pyramidal) and indirect (extrapyramidal) pathways. The indirect pathways consist of upper motor neurons which descend from the brain stem to the spinal cord. The direct pathways consist of motor neurons which descend from the motor cortex to the spinal cord. Precommand level = involves neurons in the cerebellum, basal nuclei and premotor cortex. Allowd planning of movements, determining the necessary sequance of events, and monitoring activity to make adjustments. Precommand level > projection level > segmental level.

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Part B Answer ONE of the following questions: b.

Compare and contrast the parasympathetic and sympathetic divisions of the autonomic nervous system. (12 marks)

c.

With the aid of a diagram describe the hierarchical organisation seen in somatic motor control of muscle contraction. (12 marks)

The parasympathetic and sympathetic divisions of the autonomic nervous system. The autonomic nervous system is to do with the involuntary visceral motor actions of the nervous system, it is opposite to the somatic nervous system which controls the voluntary movement of the skeletal muscle. Both of these systems are a part of the motor (efferent) division of the peripheral nervous system. The diagram below shows how the whole nervous system is divided. The autonomic nervous system contains the sympathetic and parasympathetic divisions which often have opposing effects. These systems usually counterbalance each other and wach visceral organ has connections to both systems but the effects are antagonistic/opposite. Their effects are either stimulatory or inhibitory, unlike the SNS which is always stimulatory. Sympathetic nervous system - mobilises the body during activity = to do with the 'fight or flight' responce - deals with exercise, escape, excitement, emergency, embarrassment, stress - neurotransmitter = ACh (pre) and NE (post), act on smooth muscle/cardiac muscle/glands/organs - lightly myelinated preganglionic axon has cell body in CNS and synapses with ganglion or the adrenal medulla - nonmyelinated postganglionic axon has cell body in galnglion and then synapses with the effector organ - pregangloinic axon is shorter than the postganglionis axon - more complex and innervates more organs than the parasympathetic nervous system division - increases the metabolic rate of cells, raises blood glucose levels (glucagon), mobilises fat as an energy source, and increases mental alertness - increases heart rate, breathing rate, muscle blood flow, and dilation of pupils (to be ready for the unexpected, far vision) - skin is cold and may be sweaty - inhibits activities that are not essential for the immediate survival of the individual such as digestion and defecation (done by the parasympathetic division) - preganglionic axons synapse with paravertebral ganglia in the 'gutters' of the vertebra, or collateral ganglia which are outside of the paravertebral column - long lasting and diffuse effects (NE is inactivated more slowly than ACh) Parasympathetic nervous system - performs maintenance activities and conserves energy = to do with the 'rest and digest' responce - deals with digestion, defaecation, diuresis - neurotransmitter = ACh, act on smooth muscle/cardias muscle/glands/organs - lightly myelinated preganglionic axon has cell body in CNS and synapses with ganglion - nonmyelinated postganglionic axon has cell body in ganglion and synapses with effector organ - preganglionic axon is longer than the postganglionic axon - is dominant when the individual is resting, completes activities that can be put on hold when the body is in danger - blood pressure, heart rate, and respiratory rates are low - gastrointestinal activity is high - skin is warm - pupils are constricted and lenses adapted to focus on close objects - short lived and highly localised control Autonomic nerves release neurotransmitters when signalled to from varicosities which are like beads on a chain that surround smooth or cardiac muscle. Whether the effect will be stimulatory or inhibitory is determined by the type of receptor that is present. The two types of receptors are muscarinic receptors and nicotinic receptors. Muscarinic receptors can have a stimulatory or inhibitory effect and are located on the effector organ. Nicotinic receptors are only stimulatory and are located on all postganglionic neurons and hormone producing cells of the adrenal medulla. These two receptors are called colinergic receptors because they bind with ACh. Adrenergic receptors bind with adrenaline or noradrenaline. Alpha and Beta receptors have different binding effects for the two hormones. Alpha receptors bind more strongly with noradrenaline than adrenaline, and Beta receptors bind equally to adrenaline and noradrenaline. Both divisions are usually active at the same time but one predominates depeding on what the body needs or is doing at the time. Divisions may also have a cooperative effect. The sympathetic division alone usually controls the smooth muscle in blood vessels, the sympathetic system constricts blood vessels to increase blood pressure and dilates blood vessels to reduce blood pressure. The parasympathetic division usually dominates the heart and smooth muscle of the digestive tract. The somatic nervous system is different to the autonomic nervous system in that it only has one neuron, only uses ACh as the neurotransmitter, acts on skeletal muscles, and its effects are always stimulatory.

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Question 3:

a. Define the term motor unit with respect to skeletal muscle. Explain how motor unit recruitment is size-dependent. (5 marks) A motor unit is a neuron and all the muscle cells/fibres that it innervates/stimulates. The more skeletal muscle fibres presen in a morot unit, the more skeletal muscle fibres can be recruited. Recruitment is the activation of more motor units as the load on the muscle increases. The more fibres working to move a muscle, the stronger the cotraction and resulting movement will be. Recruitment refers to the activation of additional motor units to to deal with an increase in contractile strength. Organs that undergo finer movements will have motor units with fewer skeletal muscles, but more neurons per set number of skeletal fibres. This means that more motor units need to be recruited to increase the effect of finer movements than with larger movements using motor units that have more skeletal muscle fibres.

b.

Myasthenia Gravis is a chronic autoimmune neuromuscular disease in which the number of acetylcholine (Ach) receptors is significantly reduced. Explain why these patients suffer from skeletal muscle fatigue compared to healthy people. (10 marks)

ACh is the neurotransmitter which travels across the synaptic cleft between the neuron and the muscle cell that it innervates. When there are less ACh receptors present on the scarolemma (muscle cell membrane), less ACh can be detected and so the signal for muscle contraction is less strong. Muscle fatigue is the decline in a muscles ability to generate force. This occurs in Myasthenia Gravis because nerve impulses are prevented from stimulating the muscles and so therefore their action is decreased and slowed. Ach moves across the synaptic cleft and binds to receptors on the sarcolemma which causes the opening of voltage gated sodium channels. This causes depolarisation and leads to generation of an action potential if the change in membrane potential is large enough. This causes the release of calcium from the scaroplasmic reticulum, which moves to bind to troponin which will cause a conformational change in tropomyosin and uncover the myosin head binding sites on actin. ACh receptors are called cholinergic receptors as the detect and respond to ACh. These receptors can either be muscarinic receptors or nicatinic recetors. Nicotinic receptors always stimulate but muscarinic receptors can either stimulate or inhibit.

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c.

Sc NSB ASR

Explain the “sliding filament model” of skeletal muscle contraction and describe 3 differences in the model when compared to smooth muscle cells. [9 marks]

Skeletal muscle compared to smooth muscle = Smooth muscle does not have the functional unit sarcomere that skeletal muscle does, it has filaments arranged diagonally to undergo a scrunching like contraction which is not straight like in skeletal muscle. = Smooth muscle does not have the troponin binding protein which calcium binds to on skeletal muscle to cause a conformational change in tropomyosin and uncover the myosin head binding sites on actin. = Smoth muscle has much more actin than myosin, and MLCK is required to activate myosin by phosphorylation. 1. Calcium binds to the troponin protein complex and causes a conformational change in trypomyosin which leads to i moving away from the myosin beinding sites on the actin filament. 2. Myosin heads bind to the actin filament (cross bridge formation) and Pi is lost which initiates the power stroke that moves the actin filament over the mysoin filament to bring the two Z disks closer together. 3. ADP is lost which allows another ATP molecule to attach and cause breaking of the cross bridge formation so actin and the myosin head are seperated. 4. ATP is hydrolysed to ADP and Pi which caused a conformational change in the mysoin head called cocking, which positions it to attach to the actin binding site closer to the Z disk than its previous binding site. 5. The myosin head binds to the next actin binding site and they cycle starts again. This process happens very fast and allows rapid contraction of skeletal muscles and therefore rapid movement of the body This allows the actin filaments to slide over the myosin filaments and hense the name 'sliding filament model'.

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Question 4: a.

ID Number:_____________

Name the three filtration barriers that substances leaving the plasma must pass through before entering Bowman’s space AND briefly describe their function. (6 marks)

Capillary epithelium = the capillary that the plasma will leave is only one cell thick and has fenistrations which are like small pores that allow passage of most small molecules or atoms. Basment membrane = the basement membrane is selectively permeable. Visceral layer of Bowmans capsule = this layer of the Bowmans capsule is comprised of podocytes which have foot like projections. Molecules aiming to get into the Bowmans space must move between these foot like prohections. The spaces between podocytes are called filtration slits.

b.

Name and discuss the three different pressures that operate at the filtration membrane allowing net filtration to occur. (6 marks)

Plasma hydrostatic pressure = is the pressure of the fliud in the capillaries which pushes molecules into the urinary space. Glomerular hydrostatic pressure = is the pressure of the fluid in the urinary space which pushes molecules bac towards the capillary. Blood colloid osmotic pressure ...