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BIOA 2006 - Midterm 1 Review
1. Name the three different muscle types, what are their most important func- tions?: 1. Skeletal:
contractions to stabilize joints and move body. Multinucleate cells attached to bones by tendons. Voluntary contractions
2.Smooth: helps organ functions like digestion, blood vessels, airways. Spin-
dle-shaped, uninucleate cells found in walls tubes of organs (digestive tract, urinary bladder, uterus, blood vessels, parts of airways). Involuntary contractions regulate the resistance of the hollow organs.
3. Cardiac: alternating contractions and relaxations to circulate blood. Uninucleate cells and
branched or stellate in shape, intercalated disks, which allow action potentials to pass from cell-to-cell. Each individual muscle cell is NOT innervated.
2. How do the muscle types differ?: Skeletal is orderly striated and multi nucleate. Smooth is
smaller, uninucleate. Cardiac is uninucleate and intercalated.
3. Describe the structure of a skeletal muscle cell: -multinucleate
-striated -nuclei close to membrane -wide diameter (0.1mm), 30cm length.
4. Define Muscle fibre: A single, elongated cell that makes up the structural and functional unit
of skeletal muscle, made up of myofibrils and surrounded by the endomysium
5. Define myofibril: cylindrical structure within a muscle fiber, consisting of repeat- ing units
called sarcomeres
6. Myofilaments: actin and myosin in repeating arrangements of sarcomeres, giving striations
7. sarcomeres: The structural and functional unit of a myofibril. It is the repeating unit between
two Z lines and is composed of overlapping actin and myosin filaments
8. The sarcoplasmic reticulum is: a specialized endoplasmic reticulum in muscle fibres that stores
and releases calcium ions
9. Actin and myosin are: contractile proteins
actin: The thin filaments are composed of the protein actin myosin: The thick filaments are composed of the protein myosin
10. Order of muscle: Actin and myosin filaments<sarcomeres<myofilaments<my-
ofibril<muscle fibre<endomysium<fascicle<perimysium<muscle<epimysium
11. The sarcolemma is the: cell membrane of a muscle fiber
12. T-Tubules: Regularly spaced invaginations of sarcolemma that branch exten- sively
throughout the muscle fiber to help propagate APs
13. Actin is anchored to the: Z disc
14. Actin is: thin
15. Myosin is: thick
16. Describe the innervation pattern of skeletal muscle: -motor neuron releases Ach at
neuromuscular junction into synaptic cleft -binds to receptors on the sarcolemma, depolarizes muscle cell membrane. AP spreads through transverse tubules -releases ca++ from sarcoplasmic reticulum, changing the protein toponin-tropomy- posin, exposing myosin binding sites. -contraction
17. What is a motor unit?: a single motor neuron and all the muscle fibers it innervates
18. What is the neurotransmitter in neuromuscular synapses?: Ach, Acetyl- choline
19. Name the postsynaptic receptor in the neuromuscular synapses.: Nicotinic receptors
20. Describe the mechanism of filament sliding during muscle contraction: -
-Calcium released to cytoplasm, expose myosin binding site. -myosin binds actin, ATP breaks bond by binding to myosin -ATP hydrolyzed to ADP and and straightens head -myosin binds adjacent actin binding site and bends again (using energy stored from hydrolysis ADP), increasing overlap and shortening sarcomere -ADP released
28. Relate the various energy sources for skeletal muscle cells to different types of work (energy
requirements at different stages): -At rest: O2, FA, and glucose to make ATP via oxidative phosphorylation, aerobic. Creatine phosphate created -Maximum contraction: Creatine phosphate converted to creatine and ATP since oxidative phosphorylation not enough -continued strong contractions (1-2hrs): Oxi phos continues but cant meet demand. glycogen stores used in glycolysis (anaerobic), L acid produced -prolonged workout: glycogen stores depleted and returns to aerobic. Muscle re- duces metab to match supply of FAs and O2 in blood.
29. How does muscle fatigue arise?: From prolonged muscle activity
- Increased levels of Pi
- Changes in ion flux, eg., reduced release of Ca 2+ from SR and altered conduction of AP's
- Psychological factors
- Not due to lactic acid build up
30. What is the benefit of muscle fatigue?: prevents rigour (the inability to break myosin-actin
bonds due to lack of ATP). Fatigue in the muscles decreases ATP use, keeping some to prevent rigour -energy conservation -prevents overuse -endurance improvement
31. Which are the two main subgroups/types of smooth muscle? What are the differences between
them?: multi-unit and visceral. -Multi unit: separate cells, allowing distinct control =, like of the iris -visceral: more common, forms sheets, bound by gap junctions which conduct APs
32. Compare the innervation patterns of visceral smooth muscle and multi-unit smooth muscle: Multi
unit muscle is individual innervated. Visceral muscle is inner- vated as a whole by spreading AP's through gap junction from the ANS. The ANS nerve termini have varicosities to release NT's
over several cells. Visceral muscle also has an unstable membrane potential, causing spontaneous depolarization and contraction
33. Which properties does cardiac muscle have in common with skeletal muscle and smooth muscle
respectively?: -like skeletal: has striations, but not always parallel, both have actin and myosin, careful regulation of Ca++ for all three types of muscles. -Like smooth: uninucleate, involuntary, spontaneous depolarization
34. The CNS has the: brain and spinal cord
35. the PNS (peripheral) has: cranial and spinal nerves branching from the brain and the spinal
chord to the periphery
36. A sensory neuron is a: specialized cell that transmits information from sensory receptors to
the CNS
37. A motor neuron is a: specialized cell that transmits from the CNS to muscle or glands
38. A target cell is a: muscle or gland that receives motor neuron signals, causing contraction or
gland secretions
39. Integrating centers are: located in the CNS and serve to process and integrate information
from sensory neurons
40. Effector cells are the cells that: carry out the response dictated by the integrat- ing center. In
the nervous system, these are often muscle cells or gland cells.
41. The subdivisions of the PNS: 1. Sensory system (sensory nerve fibres and sensory cells)
2.Somatic motor system (motor nerve fibres and skeletal muscle)
3.Autonomic NS (sympathetic and parasympathetic and endocrine)
42. The glial cells of the CNS: -Ependymal cells
-oligodendrocytes -astrocytes -microglia
43. The glial cells of the PNS: Schwann cells and satellite cells
44. The structure of a neuron:
AP, -55mV
52. Depolarization is the process of: changing membrane potential to less nega- tive and more
positive, driven by the influx of sodium
53. Repolarization is the process of: returning a neuron to its resting membrane potential after
depolarization, driven by the closing of VG sodium channels and the opening of VG potassium channels
54. The absolute refractory period is when: an AP cannot be stimulated due to the temporary
inactivation of VG Na channels
55. The relative refractory period: usually follow the absolute refractory period and can produce
and AP if the stimulus is particularly strong
56. What is an excitatory postsynaptic potential (EPSP)?: Uses excitatory NTs to receptors and
results in opening of ion channels (influx of Na) causing a slight depolarization in the postsynaptic membrane. Promotes APs
57. What is an inhibitory postsynaptic potential (IPSP)?: Inhibiting the action potential in the
post-synaptic membrane. Neurotransmitter binding causes slight hyperpolarization of the post-synaptic cell membrane.
58. Briefly describe the embryological development of the central nervous system in vertebrates:
The CNS develops as a hollow tube/ neural tube. The posterior end becomes the spinal cord and the anterior end becomes the brain, with three pouches: the hindbrain, midbrain, and forebrain.
59. The fore brain is aka, and contains the: aka the prosencephalon
cerebrum (telencephalon) and diencephalon (thalamus and hypothalamus)
60. The midbrain is called the: Mensencephalon
61. The hindbrain is aka and contains the: rhombencephalon pons, medulla
oblongata, cerebellum
62. The brain stem constitutes of: midbrain, pons, and medulla
63. Plasticity is the ability of the brain to: adapt to varying conditions. And this goes beyond
conventional learning and it refers to emotional processing and memory as well
64. Developmental learning is: early experiences and their influence on the devel- opment of
synapses.
65. Sensitive period: Life stages when experiences have a higher than normal influence on brain
development (examples: learning patterns and social behaviour)
66. Critical period: Life stages when experience is required to direct development in a certain
way (example: binocular vision development)
67. The meninges: three layers of connective tissue in which the brain and spinal cord are
wrapped -pia mater -arachnoid -dura mater
68. What are the functions of cerebrospinal fluid (CSF)?: -Provide the ionic environment for
neuronal functions -Provide physical and chemical protection for the CNS
69. What is the blood-brain barrier?: highly selectively permeable and protectively layer between
blood and CSF. Made of of endothelial cells like a normal blood vessel, but have tight junctions to restrict diffusion. The end of astrocytes often surround BV's in the brain and help signal endothelial cells to form the tight junctions of the BBB
70. What is the function of the blood brain barrier: maintains a stable environ- ment for CNS,
preventing toxins, pathogens and more from entering. allows glucose, water, oxygen, lipid sol substances, some drugs.
71. what are the effector cells in the somatic reflex: skeletal muscle cells
72. what are the effector cells in the autonomic refelxes: smooth muscle, cardiac muscle, and
glands
73. Draw the anatomy of the spinal cord: The spinal cord has dorsal and ventral horns of grey
matter, from which extend the dorsal and ventral roots. The dorsal root contains afferent axons from the PNS to the CNS. The ventral root contains motor axons from the CNS to effector cells
74. What is the function of the cerebrum: contains two hemispheres and be- comes the
neocortex in higher mammals. Contains the primary cortices for:
85. V
oluntary motor movement controlled by: Relay to cortex, reward, emotions, memory controlled by: : Voluntary motor movement: Basal ganglia. Relay to cortex, reward, emotions, memory: Limbic system
86. what is the basal ganglia: a group of nuclei, and therefore gray matter, that lie in the
subcortical white matter, considered part of the limbic system
87. The limbic system includes: hippocampus, amygdala, thalamus & hypothala- mus
88. What are other terms for the sympathetic and parasympathetic nervous system?:
Sympathetic nervous system: Fight or flight system. parasympathetic nervous system: Relax and recovery system
89. If an animal is faced with danger, how is the sympathetic nervous system affected?: 1) release
of stress hormones (adrenaline (epinephrine and norepineph- rine) and cortisol),
2) dilation of pupils,
3) increase heart rate and respiration rate,
4) increase blood flow to skeletal muscle,
5) inhibit less important systems (immune system, digestive system and reproduc- tion
system)
90. Describe the effects of increased activity of the parasympathetic nervous system. Anatomical
and functional differences between the sympathetic and parasympathetic divisions of the autonomic nervous system: SYMPATHETIC -fight/flight -glanglia close to spine -pre ganglionic NT = acetylcholine -post ganglionic NT = epinephrine and norepinephrine PARASYMPATHETIC -relax/digest -ganglia closer to target -pre and post ganglionic fibres=Ach
91. Define membrane potential: the electrical charge or voltage difference that you find across the
cell membrane of all cells. At rest, it is around -70 mV
92. K+ concentration: higher inside the cell
93. Na+ concentration: higher outside
94. Cl- concentration: higher outside the cell
95. Ca++ concentration: higher outside
96. Protein - concentration: higher inside
97. What ion is the cell membrane most permeable to at rest?: most permeable to potassium ions
(K+), due to the presence of potassium channels in the cell membrane.
98. What are the three factors that determine resting membrane potential? (-70 mV): -concentration
gradients and active transport processes -Selective permeability of the cell membrane -Electrical charges of ions
99. What is the Na+ -K+ pump?: actively transports three sodium ions out of the cell and two
potassium ions into the cell against their respective concentration gradients
100. What is its significance for the membrane potential?: 1. Generates electric charge
across membrane - 'electrogenic' so net negative charge around the mem- brane
- Prevents cell swelling - the negatively charged proteins & nucleic acids in the cell would tend to pull positive ions into cell along with water.
101. What is homeostasis?: Automatic response to a stimulus or stress (deviation from
setpoint) to help return the system to its 'set-point'
102. What are the three main systems for communication between cells?: a. Neural reflex
(e.g. thermoregulation) b. Endocrine reflex (e.g. blood glucose) c. Neuroendocrine reflex (e.g. "fight or flight response" to dangers)
103. What are the five components of the homeostatic reflexes?: -stimu- lus/stress
-receptors: sensory neurons that detect specific stimuli that connect to CNS -control/integration centre: neural centre or endocrine gland with an efferent pathway that maintains parameter at set point -effectors- muscular organs (contract) or glands (secrete)
-Creatine kinase reaction
