Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
NU01 [al] The Nernst equation represents the potential at which:
A. Electrical neutrality exists B. Concentration of ions on each side of membrane equal C. Potential at which there is no net movement of ions D. (?Balance of chemical & electrical forces?) E. Both sides are equiosmolar |
ANSWER C
|
|
|
NU02 [g] Shivering that is ?mediated by the hypothalamus:
A. . . ? . . muscle spindle to increase tone B. . . ? . . via red nucleus C. . . ? . . rhythmic stimulation of anterior horn cells D. Activation of shivering centre in brainstem |
ANSWER A
* primary motor centre for shivering is located in the posterior hypothalamus, near the wall of the 3rd ventricle. * normally inhibited by heat centre of hypothalamus * excited by cold signals from skin/spinal cord. * when excited, signals are sent bilaterally down brain stem, then lateral columns of spinal cord, and on to anterior horn motor neurons. * signals are nonrhythmic. they cause increase in muscle tone, which is thought to trigger feedback oscillation of the muscle spindle stretch reflex mechanism, causing shivering. Addition: Mechanisms activated by cold * Increase heat production * Shivering * Hunger * Increased voluntary activity * Increased secretion of norepinephrine and epinephrine * Decrease heat loss * Cutaneous vasoconstriction * Curling up * Horripilation (goose bumps - no apparent useful purpose) Mechanisms activated by heat * Increase heat loss * Cutaneous vasodilation * Sweating * Increased respiration * Decrease heat production * Anorexia * Apathy and inertia |
|
|
NU03 [hopq] Transection of a motor nerve leads to:
A. Muscle fibre hypertrophy B. Increased/decreased RMP C. Increased receptors D. Increased spontaneous muscle activity |
Answer D
Denervation of muscle causes: * Muscle Atrophy * Denervation hypersensitivity to circulating Ach – foetal γ subunit is up regulated over muscle cells other than the motor end plate. * Muscle fibrillations * Note: fasciculations are related pathological discharge of motor neurons. Ganong Ed21 p76 |
|
|
NU05 [j] The setpoint in temperature regulation controls the body's response to
changes in temperature. The location of sensory receptors which regulates the setpoint is: A. Anterior hypothalamus B. Posterior hypothalamus C. Spinal cord D. Skin E. Great veins |
Poorly worded question
Sensory receptors (sensors)in the body temperature control system are located in the skin, deep tissues, spinal cord, extrahypothalamic portions of the brain and the the hypothalamus itself - each contributing 20% of information for integration by the hypothalamus. The posterior hypothalamus "regulates" the set point for thermoregulation, it sends efferents to control shivering The anterior hypothalamus sends efferents to control sweating and vasodilation (remember when hot you fan yourself from the front:anterior) |
|
|
The efferent limb of thermoregulation comes from
A. ? B. ? C. Anterior hypothalamus D. Posterior hypothalamus E. ? |
Again poor question
Anterior send efferent for hot : ei sweating and vasodilation Posterior sends efferent for cold : shivering and vasoconstriction |
|
|
NU06 [k] Chemoreceptor trigger zone:
A.Both D2 and 5-HT3 receptors B. ?(something about motion sickness) C. Stimuli from blood and CSF D. ? E. ? |
ANSWER A
CTZ -located : bilateral set of centers in the brainstem lying under the floor of the fourth ventricle. -outside BBB -sense chemicals in blood and CSF -Seratonin 5HT3, Histamine H1, Muscarinic, Opiods, Dopamine D2 and other toxins -afferents from vestibular apparatus via CN8 -efferent to Vomiting Centre Vomiting centre -located bilaterially -dorsal part of lateral reticular formation in medulla -close proximity to respiratory and vasoactive centre -afferents from a. gut chemo and stretch receptors via vagal and sympathetic nerves b. cortex c. limbic system -efferents to coordinate vomiting a. respiratory muscles via vagus, hypoglossal, glossopharyngeal, trigeminal, facial nerves b. abdominal and diaphragm muscles via spinal nerves (motor) |
|
|
NU07 [mn] (“Question about Pain” ?details)
A. Substance P acts on pain receptors B. Any peripheral stimuli can activate pain receptors C. Dull and sharp pain travel via the same fibres D. ? E. A delta & C fibres act on the same receptor |
ANSWER A
|
|
|
NU08 [m] Cerebrospinal fluid (CSF):
A. Production is 150 ml / day B. Volume is 50 ml C. Produced by choroidal blood vessels and ependymal cells D. ? E. ? |
ANSWER C
Defn: "The cerebrospinal fluid (CSF) is located within the ventricles, spinal canal, and subarachnoid spaces. Numbers Vol : total 150ml, 75ml in ventricles, 75ml around spine -500ml/days or 21ml/hour -ICP 5-15mmHg -biochemistry Na 147 active transport NaKATPase K 2.9 Mg 2.2 Ca 2.3 Cl 113 HCO3 25.1 PCO2 50 pH 7.3 Osmo 290 Little protein (20g/L) 60% of plasma glucose facilitated transport, saturated above 15mmol/L Function: 1. cushions the brain and reduces effective weight (boeyancy) 2. regulates brain extracellular fluid 3. allows for distribution of neuroactive substances 4. "sink" that collects the waste products produced by the brain, no lymph system 5. protective role as buffering for any rise in ICP by CSF translocation Production: 500ml/day constant! 70% choroid plexi of lat, 3rd and 4th Ventricles 30% endothelial cells lining capillaries of brain Circulation: foramens of Magendie and of Luschka into the subaracoid space of the brain and spinal cord Absorption varies depending on ICP 90% arachnoid villi 10% directly into cerebral venules. |
|
|
NU09 [opq] Which ONE of the following is characteristic of type A nerve fibres:
A. Nociception B. Slower conduction than C fibres C. Myelinated D. Substance P E. Sensory only F. Do not carry pain sensation |
ANSWER C
|
|
|
NU10 The sharp initial pain associated with injury is transmitted by:
A. Unmyelinated C fibres. B. Unmyelinated Aδ fibres. C. Nerve fibres with a conduction velocity of approximately 15 m/s. D. Nerve fibres which project to the anterior horn and the spinothalamic tract. E. Nerve fibres with a diameter of less than 2 µm |
ANSWER C
From Kam, Aδ fibres result in short-lasting, pricking-type pain. 1. Myelinated 2. Conduction velocity 10 - 30 m.sec-1 12-30m/s from Ganong p142 3. Axon diameter 2-5 µm 4. Cell body in Dorsal Root Ganglion (laminae I and V) |
|
|
Pre-ganglionic sympathetic fibres pass to the
A. otic ganglion B. carotid body C. ciliary ganglion D. coeliac ganglion E. all of the above |
ANSWER D
preganglion sympathetic fibres -celiac ganglion T5-T12 -superior mesenteric T10-12 -inferior mesenteric L1-L3 Preganglionic parasympathetic -Ciliary ganglion -spenopalantine ganglion -submacillary ganglion -otic ganglion All from midbrain and medulla -pelvic nerve S2-4 end on short postganglionic neurons located on or near visceral surfaces |
|
|
Postganglionic sympathetic nerve fibers originate from:
A. Carotid body B. Nervi erigentes C. Otic ganglion D. Coeliac plexus E. None of the above |
A = FALSE Carotid Body - structure with chemoreceptors and rich sinusoidal blood supply. Efferents via Glossopharygeal
B = FALSE Nervi Erigentes - pelvis sphlanchic nerves which are parasympathetic fibers from anterior primary rami of S2, S3 and sometimes S4 C = FALSE Otic Ganglion - assoc with CN V, has motor, sensory, sympathetic and parasympathetic fibers. The Sympathetic fibers are Postganglionic fibers ORIGINATING from the Superior Cervical Ganglion. D = TRUE Coeliac Plexus is the largest sympathetic plexus. It recieves pre-ganglionic fibers from the spinal segments, some of which pass through the plexus without synapsing and end in the adrenal medulla. The rest synapse within the plexus, Therefore Post ganglionic fibers originate within the plexus |
|
|
PH04 In a healthy person lying quietly on his back, the intracranial pressure (referred to the level of the interventricular foramen) is in the range:
A. 0-5 cmH2O B. 5-15 cmH2O C. 15-30 cmH2O D. 2-3 mmHg E. 15-18 mmHg |
Answer B
|
|
|
PH22
Normal pCO2 of CSF? (In mmHg) A. 36 B. 40 C. 44 D. 48 E. 52 |
ANSWER E
|
|
|
PH23
Cerebral blood flow changes by how much per mmHg change in pCO2? A. 0.4% B. 1% C. 4% D. 10% E. 12% |
ANSWER C
|
|
|
PH36 [Mar93] [Aug93] [Aug99]
In a normal person, cerebral blood flow is increased by: 1. Administering propofol 2. Head-down position 3. Systolic increase from 100 to 130mmHg 4. Increase in arterial pCO2 to 60 mmHg |
ANSWER D
|
|
|
PH44 [Apr99]
Spinal cord perfusion pressure: A. Equal to mean distal aortic pressure minus CVP B. ?Has same control as cerebral autoregulation C. Increased pCO2 >60mmHg increases cord blood flow D. Thoracic aortic surgery decreases perfusion pressure because of decreased CVP E. Different blood flow (mls/100g/min) compared to brain due to differences in proportion of grey & white matter |
ANSWER B and C
|
|
|
Can04-7 Which has the same median value in plasma and CSF
A. pH B. osmolality C. Cl D. K E. Glucose |
ANSWER B
CSF lower pH 7.3 higher Cl 124 low K 2.9 60%glucose 40g/L protein Osmo equal |
|
|
Can04-40 Regarding pain transmission, which is TRUE?
A. A-delta fibres are responsible for slow component or burning pain B. C fibres are responsible for fast component or localized pain C. A-delta and C neurons contain a wide variety of neurotransmitters D. A-delta and C neurons are only found centrally (in spinal cord) E. Substance P is the only neurotransmitter in pain pathways |
ANSWER C
|
