BIOS 252 Midterm Exam Essay Question and Answers
BIOS 252 Midterm Exam
BIOS 252
BIOS 252 Midterm Exam Essay Question and Answers (Latest Upgrade)
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Chapter 10 & 11
1. Identify and describe intracellular structures (organelles, myofilaments, ect.) of a muscle cell. Contrast skeletal, cardiac and smooth.
Epimysium – covers whole muscle belly; Perimysium – slightly thicker layer of connective tissue surrounds a bundle of cells called a fascicle; Endomysium – thin layer of tissue surrounding each cell; Muscle fiber – muscle cells are long, cylindrical & multinucleated; Sarcolemma – muscle cell membrane; T tubules – are investigations of the sarcolemma into the center of the cell; Myofibrils – muscel fibers filled with treads separated by SR; Myofilaments – are contractile proteins of muscle; Sarcoplasmic Reticulum (SR) – system of tubular sacs sotes Ca+2 in a relaxed muscle, release of Ca+2 triggers muscle contraction; Skeletal Muscle – attaches to bone, skin or fascia; striated, voluntary control of contraction, multinucleated; Cardiac – striated, involuntary control, uninucleated.
2. Describe all phases of twitch.
Latent phase – the time that elapses between the generation of an action potential in a muscle cell and the start of the contraction of the muscle.
Contraction phase – when the muscle contracts this starts after the latent phase ends with muscle tensions.
Relaxation phase – starts after muscle tension and continues until muscle contraction has ended.
3. Outline the sequence of physiological events of a twitch starting at the motor neurons and ending with movement.
4. Describe a neuromuscular junction and identify all major components.
Stimulus down axon terminal Excitability on synaptic cleft (releases Ca++) Ach moves down to synaptic end bulb and meets receptors, gated channel for Na+ Sodium creates an action potential that travels across the sarcolemma (plasma membrane) Action potential travels down the t-tubule which stimulates the SR to release Ca2+ Ache starts the update of Ach and the action potential fade away
5. Describe the connective tissue “packaging” of muscle.
6. Describe the major functions of the three types of muscles and the differences between them.
7. Describe how skeletal muscles acting across synovial joints function as a lever system. Discriminate between 1st class, 2nd class and 3rd class levers in the human body (provide an example of each)
1st class lever – Fulcrum (F) between the effort and the load (EFL), like a see saw. Few of these in the body. Example: atlanto occipital joint,
2nd class lever – The load is between the fulcrum and the effort (ELF), like a wheel barrow. This class lever is uncommon in the human body. Example: Standing on tip toes
3rd class lever – The effort is between the fulcrum and the load (FEL), the most common in the human body. Example: elbow joint
8. Differentiate between isotonic, isometric, eccentric and concentric contractions.
Isotonic – the tension, the force of contraction, developed in the muscle remains almost constant while the muscle changes its length. Used for body movements and moving objects. There are 2 types concentric and eccentric.
Isometric – The tension generated in not enough to exceed the resistance of the object to be moved, and the muscle does not changed its length. These contractions are important because they help maintain posture and supporting objects in a fixed position.
Eccentric – is when the length of a muscle increases during a contraction.
Concentric – is great enough to overcome the resistance of the object to be move, the muscle shortens and pulls on another structure such as a tendon, to produce movement and to reduce the angle at a joint.
9. Identify the muscles involved in relaxed and forced breathing and describe their role.
The Diaphragm – the most important muscle that powers breathing. It separates the thoracic and abdominal cavities. Contraction of the diaphragm causes it to flatten and increases verticle dimension of thoracic cavity. Resulting in inhalation. Relaxation of the diaphragm causes it to move superiorly and decreases vertical dimension of thoracic cavity resulting in exhalation.
External Intercostals – found in the superficial layer of the ribs from the rib above to the rib below. Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity, resulting in inhalation relaxation depresses ribs, and decreases anteroposterior and lateral dimensions of thoracic cavity, resulting in exhalation.
Internal Intercostals – occupy the superficial layer and their fibers run in an oblique direction interiorly and anteriorly from the rib above to the rib below. Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation
Chapter 12
1. Identify the anatomy of a neuron
2. Describe the functional and structural classification of neurons.
Functional Classification:
Sensory Function – sensory receptors detect internal stimuli such as an increase in blood pressure or external stimuli. This then carried into the brain and spinal cord through cranial and spinal nerves.
Integrative Function – nervous system process sensory information by analyzing it and making decisions for appropriate responses, this is known as integration.
Motor Function – once sensory information is integrated the nervous system may elicit an appropriate response by activating effectors (muscles and glands) through cranial and spinal nerves. Stimulation of the effectors causes muscles to contract and glands to secret.
3. Identify and describe the major divisions of the nervous system.
Central Nervous System (CNS) – Contains the brain and spinal cord
Peripheral Nervous System (PNS) – Cranial nerves (12 pairs), spinal nerves ganglia (3 pairs), enteric plexuses in small intestine, sensory receptors in the skin
- Somatic Nervous System (SNS) – Convey information to the CNS via somatic receptors in the head, body wall and limbs and motor neurons that conduct impulses from the CNS to skeletal muscles only. VOLUNTARLY
- Autonomic Nervous System (ANS) – Consists of sensory neourons that convey information to the CNS from autonomic sensory receptors, located primarily in visceral organs such as the stomach and lungs and motor neurons that conduct nerve impulses from the CNS to smooth muscle cardiac muscle and glands. INVOLUNTARY
- Enteric Nervous System – INVOLUNTARY
4. List and describe the function/location of all neuroglia cells
Astrocytes – star shaped cells form blood-brain barrier by covering blood capillaries , metabolize neurotransmitters, regulates K+ balance, provides structural support; Oligodendrocytes – most common glia cell type, each forms myelin sheath around more than one axon in CNS, analogous to schwann cells of PNS; Microglia – small cells found near blood vessels, phagocytic role ( clear away dead cells), derived from cells that also gave rise to macrophages & monocytes; Ependymal Cells -form epithelial membrane lining cerebral cavities & central canal, modify cerebrospinal fluid; Satellite Cells – flat cells surrounding neuronal cell bodies in peripheral ganglia; Schwann Cell – cells encircling PNS axons, each cell producing part of the myelin sheath surrounding an axon in the PNS
5. Explain how excitatory and inhibitory neurotransmitters work on the postsynaptic membrane and give one example of each.
6. Describe all steps of an action potential, including initiation by local potential.
Threshold is reached voltage regulated Na+ activation gates open ( K+ gates signals to open) Na+ rushes into cell (depolarization) Na+ inactivation gates close K+ finally open K+ rushes out of cell (repolarization) Na+ gates reset (activation gates closed, inactivation gates open) K+ gates told to close continued loss of K+ leads to hyperpolarization Na+/K+ pumps re-establish RMP
7. Understand the mechanism of IPSPs and EPSPs.
ESP- neurotransmitter Na+ channel depolarize channel goes closer to threshold making it excitatory
IPSP – neurotransmitter K+ channel hyperpolarize channel action potential more difficult post synaptic membrane inhibitory
Chapter 13
1. Describe the basic anatomy of a spinal cord section, indicating the functional significance of each area/major tract.
2. Explain the similarities and differences of a spinal withdrawal reflex and a crossed extensor reflex.
Similarities – excitatory synapses, polysynaptic reflexes, which contain sensory neurons, interneurons and motor neurons
Differences – spinal withdraw reflex – causes withdrawal of a part of the body in response to a painful stimulus ; cross-extensor reflex- causes a contraction of the muscle that extends joints in a limb opposite a painful stimulus [Show Less]