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108 Cards in this Set
- Front
- Back
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Define consciousness |
Awareness of environment and oneself |
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What are the two components of consciousness and what part of the brain is responsible. |
1. Content: Memory, perceptions, attention - Cereberal cortex
2. Level: Awake, Alert, Asleep - Brain stem |
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What type of axons are responsible for inhibition of postural muscles during REM sleep |
Reticulospinal neurons send post synaptic inhibtition to postural muscles during REM sleep |
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What part of the brain does the ascending arousal system arise from? |
Brain stem |
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Describe the effects of the following on arousal:
Noradernergic neurons Sertonoergic neurons Dopaminergic neurons Histamine Cholinergic neurons |
1. Noradernergic neurons - from locus ceruleus, and contain cortical attention
2. Serotonergic neurons - from the ralphe nuceli, failure of arousal in low Co2 condition if you have SIDS
3. Dopaminergic neurons - reward based learning, involved in addiction
4. Histamine - anti-histamine cause drowsiness
5. Cholindergic neurons - Parkinsons disease |
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What role do the neurons of the ascending arousal system play in the CNS |
- They have projections to nearly all parts of the CNS!
- They modulate conscious states by acting as neuromodulators that alter membrane potential of the thalmo-cortical and cortical neurons
**Depolarization is needed to be awake, so get closer to threshold - wake up easier |
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Define coma and give two causes |
Coma = prolonged unconsciousness with no response to stimuli
Two causes: 1. Bilateral lesion of the rostral brainstem = severs the arousal pathways
2. Bilateral lesions of the cereberal cortex = can occur due to hypoxia or hematoma (blood clot produces pressure and damages the cereberal cortex) |
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Where does the lesion in Locked in syndrome occur?
What parts are destroyed, what is still intact? |
Lesion in the mid pons area - below the arousal system
Destroyed: Descending limb and speech motor pathways
Intact: Forebrain and oculomotor cranial nerve
They are able to interact with external world only via eye movements! |
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Give 4 features of Persistent vegetative state |
1. Usually due to forebrain damage (hypoxia) 2. Chronic (long term) 3. Partial arousal - eye movement, saccades, moaning, swallowing 4. Wake cycles occur in sleep but no outward signs of consciousness |
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Describe Adrian Owens research and how it relates to vegetative patients |
- Used an fMRI and asked patients simple ye/no questions
If answered yes - imagine playing tennis, activated motor areas in brain
If answered no - imagine walking through home, activated hippocampal place area
15% of patients could direct blood flow to areas showing that they are conscious. next step is to get an EEG recording |
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List two properties of a primary evoked potential of the sciatic nerve (somatosensory) |
1. It has a short latency of only 20ms as compared to visual which has 80 - since an additional 60ms needed to get out retina (GPCR)
3. Only recorded over somatosensory cortex is the electrode is placed on the cereberal cortex |
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List 3 points about primary evoked potential. -what it measures -where do currents arise -what its not |
1. Measurement of voltage changes on an oscilloscope
2. Results from the summation of extracellular currents associated with post synaptic potentials
3. it is NOT due to local currents associated with Action potentials |
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Describe the 3 types of waves and the conditions associated with them |
1. Synchronized alpha waves - 8-12 Hz, meditative state
2. synchronized delta waves - 1-2Hz, nonREM sleep
3. Awake or Mental arithemetic - 13-30Hz , desynhcronized beta waves
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What are the origins of the electric currents associated with an EEG |
1. summation of post synaptic potentials in cortical neurons located in the neocortex especially the pyramidal cells
2. Not due to local currents associated with EEG
3. Associated with location of epileptic focus, tumor, diagnosis of sleep disorder and as a brain machine interface
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What causes Sleep? Why is it neccessary? |
1. Sleep is not just a decrease in neural activity. Interplay of many brainstem components of the ascending arousal system
- Some neurons actually increase their activity in REM and awake state - in a cyclic fashion
2. No consensus of why sleep. But ideas like memmory consolidation, energy conservation, recalibration and resotrative |
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What is the limbic system? Where is it located? What are 4 things it is associated with? |
1. Limbic system is a ring of phylogenetically primitive cortex around the brain stem and its interconnecting structures
2. Limbo = border, limbic system = rostral border
3. It is is concerned with -emotion -motivation -behavior -memmory
It is essential!
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Describe the 5 motivational states and their respective behavior |
1. Hunger (Feeding) 2. Thirst (drinking) 3. Rage/anger (defend yourself) 4. Sexual arousal (Mating) 5. Pain (avoidance) |
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List 3 things that can activate the rage/fear limbic response |
1. Rabies - virus attack limbic cortex, patients has bouts of fear and terror 2. Someone slaps you in the face - if they tell you beforehand you can supress response 3. Road rage- someonse cuts you off in road |
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List 4 components of Pain and the area of the brain located with it.
List an interesting consequence of damage in one of these areas. |
4 components 1. Location - Somatosensory cortex 2. Timing - Somatosensory cortex 3. Intensity - Somatosensory cortex 4. Emotion - Cingulate cortex
Damage of the singulate cortex results in sa patient that can feel pain but is not bothered by it
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List and Describe the 5 inputs and 5 ouputs of the Hypothalmus |
5 inputs 1. Circulating blood - info on osmolarity, gluc, Na+, fat/leptin 2. Limbic - information of the 5 motivational states 3. Retina - information of visual world 4. Thalmus - relays sensory information from somatosens 5. Medulla - relays sensory information from spinal cord
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5 output
1. Medulla --> spinal cord 2. Limbic system 3. Thalmus 4. Posterior pituitary (ADH, Oxytoxin) 5. Hypophyseal system - ANTERIOR pituitary (LH, FSH, ACTH)
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What is leptin? What is its role in obesity? |
1. Leptin is a hormone produced by adipose cells that signals fat storage to hypothalmus and induced decrease in hunger/feeding
2. Obese people may be insensitive to leptin or have a mutation in either the leptin gene or leptin receptor
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Describe simply the function of the hypothalmus |
1.Receive wide range of sensory information 2. Compare this information to a set point 3. Coordinate a response (autonomic, endocrine, or behavioral)
This works to maintain homeostasis and to coordinate behavioral response to motivation |
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List 7 major functions of the hypothalmus |
Regulation or coordination of the following
1. Body temperature 2. Blood pressure 3. Reproduction 4. Metabolism 5. Stress response 6. Fear/Threat/Rage response 7. Circadian
Most homeostatic mechanism follow a circadian rhythm Controlled by the 3 responses that hypothalmus uses - Autonomic, Behavioral, Endocrine |
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What are the effects of above midbrain lesions that removes everything but leaves the hypothalmus intact? |
An animal can still maintain homeostatic functions and reproduce |
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What were the issues with past brain lesion and stimulation experiments, and how do they relate to the hypothalmus? |
Though the hypothalmus is extremely small by mass, many ascending and descending pathways between the cerebral cortex and the brain stem pass through it.
Because of that, many lesion studies produced effect which werent caused by the location of the lesion rather the severing of an axonal pathway or cell group that went through the hypothalmus. Leading to missatribution of some functions to different parts of the brain |
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Give an example of how hypothalmic set points are used to maintain homeostatic conditions. |
Hypothalmus compares sensory information from blood circulation and sensory input and compares them to a set point. It can respond via: Autonomic, endocrine, and behavioral responses.
Example: Sense cold temperature, compare to set point, initiate peripheral vasoconstriction (autonomic), thyroxine release (endocrine), move to a warmer climate, shiver (behavioral) |
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Describe two examples that alter the hypothalmic set point and the subsequent result they produce? |
1.Pyrogens (i.e interleukin) released from Bacteria may alter temperature set point resulting in fever. Results in paradoxical situation where you may be hot but still under the new high set point so you shiver and generate more heat
2. Lesion in the Ventral medial hypothalmus can lead to loss of apetitie control. Results is in a study force fed, starved rats both returned to normal weight after treatment ended, but VMH lesioned rats continue to gain weight and became obese
-- **this is feedback control, there is also feedforward |
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Describe feedforward control and its two advantages.
Give an example of feedforward control. |
Feedforward control involves intiation of a hypothalmic response (Autonom, Endo, Behav) even before there is a fluctuation in the set point.
Advantage 1.Increase the speed of the homeostatic response
Advantage 2. Minimize fluctuations in the variable. If the system works perfectly, might never have the variable change at all
Example: Wear shorts and T-shirt and enter a cold room. The skin receptors detect and send signal, and your body starts to shiver, or go to warm area. This happens before the body temperature drops below homeostatic level. Furthermore, just thinking about a cold room may activate some hypothalmic responses. |
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What part of the brain are feedforward endocrine reflexes thought to originate from |
Limbic cortex |
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Give one example of Autonomic nervous system |
Standing up after sitting for a long time. If no ANS then blood pools in leg and have 40% decrease in Cardiac output and faint.
If ANS is working then feedforward constriction of arterioles to push blood back up and avoid situation! |
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List the three ways through which the ANS maintains homeostatic conditions |
1. Cardiac muscle 2. Smooth Muscle (arteriole and enteric) 3. Glands (sweat, saliva etc.) |
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List 5 differences between ANS and the somatic nervous system. |
1. Control of internal (ANS) vs. externa (SomNS) environment
2. Largely involuntary (ANS) vs. voluntary (SomNS)
3. Some organs intrinsically active (Heart, gut) and ANS regulates vs. no intrinsically active
4. Dual innervation by both symp and parasym of some organs vs. no dual innervation
5. Deinnervation might not lead to atrophy (heart , gut) vs. it will lead to atrophy (SomNS) |
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List the 5 steps of the Autonomic Reflex arc |
1. Impulses are generated in sensory receptors: Mechanoreceptors (Gut, heart), Nociceptors, oxygen(carotid sinus) receptors
2. Information travels to the CNS via afferent nerves containing both paraNS and sympNS information
3. Information is processed at various levels of the CNS: Spinal cord, Brain stem, Hypothalmus, Cerebral cortex
4. Efferent parasym and symp information travels via efferent pathways to the visceral effectors (cardiac muscle, glands, and smooth muscle)
5. Preganglionic myelinated B fibers with cell bodies in the CNS travel down and make a synapse in the ganglia located outside the CNS (ventral), the post synaptic unmyelinated C fibers innervate the effector organ |
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Name 6 functional anatomical features of the ANS |
1. Adrenal medulla ---Preganglionic fibers innervate the adrenal medulla cells which release Epi(80%) and norepi(20%) into blood stream. ---Adrenal medulla can be thought of as a collection of postganglionic neurons that evolved to have a endocrine gland.
2. Distribution to the limbs ---Many post ganglionic sympathetic nerves reenter the spinal cord via the gray ramus and then are distributed to the organs such as piloerector, sweat glands, blood vessels
3. Antagonistic effect ---Many organs are innervated by both parasymph and symp nerves which often have antagonistic effects (Heart)
4.Only sympathetic effect ---Some organs are only innervated by the sympathetic nerve such as arteriole, adrenal medulla, piloerector, and sweat glands
5. Enteric Nervous system ---The enteric nervous system of the gut controls: gut motility, contraction and blood flow ---It can function independently of the CNS but is often innervated by symph and parasymp for modulation
6. Neurons in the enteric ---There are more neurons in the enteric (100mill) which is more than in the entire spinal cord |
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List 4 facts about the neurotransmitters and receptors in the Autonomics Nervous system |
1. All preganglionic fibers of the ANS secrete Ach and their receptors are all nictonic
2. All Parasympathetic post ganglionic fiber neurons secrete Ach (totally cholinergic system) and their receptors are muscarinic
3. Post ganglionic Sympathetic fibers can secrete Ach, Noerpi/epi and their receptors are either nicotinic, alpha/beta adrenergic respectively
4. The organs to which Ach is secreted onto by the postganglionic symp fibers are - vasodilation of skeletal muscle - Gut - Sweat glands |
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What is the name of the Scientict that discovered whether signalling across a synapse is either bioelectric or chemical in nature?
Brief explanation of experiment |
Otto Lewi
Put two healthy hearts in a beaker. Stimulate one and then remove fluid and put that fluid in the other heart containing beaker - that heart beats.
Must be chemical in fluid - that chemical was Ach |
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List 5 feature of Autonomic Nervous transmission and how it compares to the Somatic transmission |
1. The nicotinic receptor on the NMJ is strcturally different than the one at the ANS ganglion (blocked by different receptors)
2. However, both nicotonic recepotors in both systems produce a FAST EPSP
3. Ach can act on both nicotinic and muscarinic receptors (PNS post). Muscarinic is a slower mechanism producing slow EPSP via GPCR metabotropic
4. Alpha/Beta adrenergic, Muscarinic are all metabotropic GPCR receptors. Ach at the ANS ganglia produces a slow depolarization via closing of the K+ channel --> slow depolarization
5. There are different receptor subtypes - Muscarinic (5), adrenergic alpha (4), beta (3) - research finds specific antagonist
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Describe cotransmission and give an example |
Cotransmission is the simulatenous release of Ach and Ne in order to get both long term and short term effects.
example: Ach at the ANS ganglia - Nicotinic receptor = fast EPSP (10-50ms) - Muscarinic receptor = slow EPSP (100ms) - Peptidergic receptor = really slow (minutes)
Nicotinic fire action potentials. Muscarinic modulate excitability and peptidergic may modify gene expression
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What is a varicosity and give an example |
Bulbous enlargement of postganglionic ANS fibers in the enteric nervous system through which a variety of transmitters are released and diffuse onto surrounding smooth muscle.
Can have a variety of effects depending on receptor
Example of cotransmission |
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What are the two subtypes of adrenergic Beta receptors and what are their functions. |
1. Beta 1 = Cardioacceleration - increase HR (more affected by epi) 2. Beta 2 = Bronchodilation |
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What are the 2 differences of adrenal medulla transmitter release as compared to normal post synaptic |
1. Lasts longer (endocrine) 2. Has a greater affect on the heart (Beta 1 prefer epi which is 80% release from adrenal medulla but ratio switches in normal ANS post gang)
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Two reasons why the epipen is useful for anaphylatic shock treatment |
Two symptoms of anaphylatic shock are decreased blood pressure and bronchoconstriction
Epi acts on BETA receptors preferentially rather than norepi. And the two beta receptor effects are : cardioacceleration and bronchodilation |
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Describe what is sympathetic tone, its advantage and one example. |
Sympathetic tone is a tonic discharge by the sympathetic tone usually at 1 AP/s - full activation is 20 AP/s (somatic is 500 AP/s)
Advantage is that nerve can both increase and decrease activity of the effector organ
Example: Innervated arterioles are normally kept at 1/2 of diameter (1 AP/s) and can be constricted (20 AP/s) or dilated (0 AP/s)
**some basal tone comes from adrenal medulla secretions |
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What is shy-drager syndrome and list 4 symptoms associated with it |
Progressive degenerative disorder inovolving atrophy of many systems including ANS
1. Orthostatic hypotension (drop in BP when standing ) 2. Loss or bladder/urinary control 3. Impotence 4. Reduced sweating (loss of heat control) |
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List the 5 type of channels found in the ANS, the type of depolarization they cause and which drug inhibits them!!! |
Nicotinic (skeletal muscle) - ionotropic, fast EPSP, blocked by d-Tubocurarine and alpha Bungarotoxin
Nicotinic (ANS ganglia) - ionotropic, fast EPSP, blocked by Hexamethonium
Muscarinic (ANS ganglia AND Parasymp organs), metabotropic, GPCR, slow IPSP/EPSP. Blocked by Atropine. WOrks by modifying K+ and Ca2+ channel conductance slow conductance
ALpha adrenergic - Norepi favorable, same mechanism as above! 4 subtypes. Blocked by phenotlamine
Beta adrenergic - Epi favorable - same mechanism as above! 3 subtypes. Blocked by Propanalol
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List one condition associated with overuse of the Epi-pen |
Cardiac arrest since heart is greatly affected by epi and over stimulated cardioacceleration is bad |
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Name three things the cardio system distributes and 1 thing it regulates. |
Transport Oxygen and nutrients TO body Transports CO2 and Waste TO environment Transports Hormones/clotting factors antibodies TO body
Regulates body temperature |
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Which circulatory system is the heart part of? *wink* |
Heart is not part of either circulatory system (systemic or pulmonary) since circulatory refers ONLY TO BLOOD VESSELS |
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Name two places in the cardiovascular system that contain valves? |
Valves are found in the HEART and in the VEINS |
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Are the following circulatory system in series or parallel
Systemic Pulmonary |
Systemic = Parallel except (Renal and Digestive) Pulmonary = Series only |
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Name two advantages of having the systemic circulation in parallel |
1. Individual control of blood flow to specific organs - Must decrease blood flow to one to increase to other
2. Decreases resistance to blood flow - Which in turn decreases pressure required and workload on the heart
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Arrange the following systems from lowest to highest in terms of blood volume distribution.
- Systemic arteries - Systemic Veins - Heart + pulmonary system - Capillaries |
(Lowest) - Capillaries - Systemic arteries - Heart+Pulmonary - Systemic veins (Most) |
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List all 4 valves found in the heart and their location |
1. Right (AV) valve = Tricuspid 2. Left (AV) valve = Bicuspid aka. MITRAL VALVE 3. Aortic valve 4. Pulmonic valve = pulmonary SEMILUNAR valve |
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Describe during which period (systole/diastole) does each valve close? And why? |
1. The Left and right AV valve close - AND the semilunar and aortic valve OPEN during SYSTOLE because pressure in ventricle increases
2. The Aortic and Pulmonic valve CLOSE during diastole due to MOMENTARY BACKFLOW OF BLOOD IN AORTA/ PUlmonary artery |
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Name two similiarities and 4 differences between skeletal muscle and cardiac myofibers |
Similarities: 1. Striated 2. Contain acting and myosin for sliding filament
Differences 1. Myofubers Branch and Recombine but each is one CELL w individual sarcolemma 2. 1/3 of their volume is mitochondria 3. More efficient (80%) at extracting oxygen from blood 4. Intercalated disk joining cells in series |
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Is the cardiac muscle a functional syncitium or a structural syncitium? WHy? |
Cardiac muscle is a functional syncitium, because when one cell gets excited they all do as well due to cell to cell interconnection propagation of AP |
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Name the two seperate funtional syncitium in the Heart and what they are seperated by?
WHy is it important to have two syncitias rather than one large one? |
1. Ventricular Syncitium 2. Atrial Syncitium
They are seperated by the atrioventricular ring
Advantage of two syncitias is that it allows for atrial contraction a short time ahead of the ventricular contraction |
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Which type of channel in the Cardiac cycle is BOTH ligand and Voltage gated? By which ligands? |
The Na+ funny channel required for nodal cell depolarization is voltage gated (closes at threshold) and ligand gated (enhanced by sympathetic stimulation and Beta adrenergic agents. SUPRESSES by vagal stimulation) |
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Name the three factors and the channels that lead to a unstable resting membrane potential of the self excitable cells |
1. Increased permeability of sodium through funny channel
2. Increased calcium permeability through the t-type calcium channel
3. Additional calcium through SOME l-type calcium channels
3. decreaSING POTASSIUM permeability (decreases as potential becomes more positive)
---All of this during diastole only---- |
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What is the maxium negativity of a excitable/conducting cell vs. ventricular fiber respectively. |
1. Excitable/Conducting cell = -60 2. Ventricular fiber = -90 |
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Name two things that can alter the rythmic generation of Action potentials from the SA node |
1. Changing the slope of the pacemaker potential
2. Changing the degree of hyperpolarization |
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Which 2 channels contribute to TWO phases of the excitable cell action potential (SA nodal) |
1. Potassium channel contributes to both the prepotential (decreases conductivity progressively) and the repolarization (increases conductivity)
2. The l type channels contributes to prepotential (SOME L TYPE OPEN) and to the depolarization (all L type open) |
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Name the bands that conduct the action potential from SA node to the left atrium and the three bands that conduct it to the AV node |
1. From right to left : Anterior interatrial myocardial band
2. From SA to the AV node = Anterior, Middle and Posterior interNODAL pathway |
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What would happen if the conduction velocity of the ATRIA became the same as or slower than that of the AV node. |
1. The atria would not have complete time to contract before the ventricle did - this could lead to backflow and also less blood being pumped by the ventricle to the body |
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Which electrocardiogram interval DECREASES as the HEART RATE increases? and What does it represent? |
1. The P-R interval decreases as Heart rate increases and it represents the conduction time form SA to AV node and the atrial depolarization. |
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Name two factors of an Action potential in the heart that determine how rapid its conduction is down the fiber |
1. Rate of change of potential during depolarization
2. Amplitude of the Action potential
**hence NOdal AP are slow response AP ** |
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What is responsible for the Absolute refractory period and the relative refractory period in the ventricular muscle AP? |
1. ARP = Inactivation of sodium channels 2. RRP = Efflux of potassium through potassium channel |
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List the ions responsible for each phase of the ventricular muscle Action Potential |
1. 0 phase - Rapid depolarization - VG Na+ channel 2. 1 phase - Rapid repolarization - VG K+ channel and VG Cl- channel and Na+ close
3. 2 Phase - Plateau phase - VG Cl- Close and VG l-type Ca2+ open
4. 3 Phase - Restoration of Resting Membrane - VG Ca2+ eventuall close, K+ does not
5. 4 Phase - Resting Membrane potential - (-90mV) K+ close
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List the 4 sources of calcium during excitation contraction coupling in the heart |
1. VG slow L-type calcium channel for ECF calcium (aka. DHP) **no longer a voltage sensor like in skeletal now a voltage activated ***
2. Na+/Ca2+ (NCX) bidirectional exchanger for ECF calcium (dependent on conc. gradient and membrane potential)
3. ECF Calcium induced calcium release from the SR (aka. Ryanodine)
4. Intracellular calcium induced calcium release from the SR |
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Name three mechanisms for REMOVING intracellular calcium from the sarcoplasm of heart after contraction |
1. Membrane (sarcolemma) bound Ca2+ ATPase 2. Sarcoplasm Reticulum bound Ca2+ ATPase 3. The NCX switches direction (3 Na+ for 1 Ca2+) |
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What are the 2 role of extracellular calcium in cardiac excitation contraction coupling. Why is it necessary? |
1. Raise Intracellular calcium levels during contraction (contributes very little)
2. Maintain Intracellular free calcium stores over the long run
It is essential due to its second role, without which contraction CANNOT OCCUR |
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Why are tetanic contraction not possible in cardiac muscle fiber |
The mechanical response of the muscle starts right after the depolarization of the muscle and lasts for 300 milliseconds. It occupies MOST of the Absolute refractory period and by the time ARP ends, it has already relaxed 75%. |
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At the end of which phases is the EDV and ESV found respectively? |
EDV = Atrial systole ESV = Protodiastole |
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During which phase of the CARDIAC cycle is the T wave (repolarization of atrial muscle) found? |
The T wave is found during the rapid ejection phase |
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During which phase of the cardiac cycle do pressure lines cross BUT WITH NO VALVE CLOSURE? And why? |
During protodiastole when ventricles begin to relax, there is less blood to push against so the pressure falls but no valve closure since blood is still moving due to considerable inertia. |
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During which phase do each of the heart sound occur and what is the reason? |
The first heart sound "lub" occurs during isovolumetric contraction when the AV valve closes
The second heart sound "dub" occurs during Isovolumetric relaxation when either the pulmonic or aortic valve close
The reason for both noises is revereberation of blood due to sudden block of blood flow reversal |
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What is Cardiac output matched to? **What factor controls cardiac output level** |
Cellular demand for oxygen. |
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How does the output of the right ventricle compare to the cardiac output of the left ventricle? Same, higher, lower? |
The right ventricle recieves all the blood coming back and contracts at roughly the same time so its output is nearly the same at 5L |
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During rest blood FLOW to the brain, kidney and liver is very high. List why for each organ. |
Liver - High metabolic demand
Brain - Remove Co2, provide nutrient and prevent pH getting too low
Kidney - Maintain proper blood composition
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Why can highly trained endurance athlete increasecardiac output to 40L/min as compared to 20L/min for untrained? |
Highly trained endurance athletes can vary their STROKE VOLUME to a greater extent in addition to increasing Heart rate by a higher factor to acheive max output. |
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Name the 3 places in the body onto which the sympathetic post ganglionic neurons secrete Ach |
1. Sweat glands 2. Piloarrector muscles 3. Blood vessel of skeletal muscle - vasodilator
***PREGANGLIONIC fibers secrete Ach onto adrenal medulla |
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What is the difference between an INOtropic effect and a CHRONotropic effect? |
1. Chronotropic effect = affects HR 2. Inotropic effect = affects force of contration |
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Name the two mechanisms through parasympathetic stimulation slows down Heart Rate |
1. Increasing permeability of K+ (hyperpolarization)
2. Slowing the opening of L-type Calcium channels (decrease slope of pacemaker)
*similiar at AV node and AP conduction * |
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What is ventricular escape? |
Given a STRONG stimulation from the vagus nerve the SA node pulse generate and/or AP transmission to AV node can be completely stopped. If this occurs, the purkinje system will take over to maintain ventricular contraction but at a lower HR |
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Describe the mechanism by which the sympathetic system increases HR/ conduction time and increases force of contraction in the heart |
1. Sympathetic Beta 1 stimulation increases Na+ permeability through funny channels and quickens the opening of the L-type calcium channels.
The sodium and calcium increase pacemaker slope and the increased calcium increases contractability of the myocardial cells |
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List 3 reasons related to ventricular sarcomeres that explain why increased EDV leads to increase SV |
Preload leads to stretching of the fibers which leads to the following
1. Increased cross bridge formation 2. Increased entry of ECF Ca2+ 3. Increased affinity of troponin to calcium |
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What is Frank-Starling law of the heart? |
The greater the extent of filling during diastole the greater the ejection during systole. |
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Draw the Frank-Starling curve for the heart and its 2 variations (SNS and PNS innervation) |
http://kobiljak.msu.edu/cai/psl501/graph1.jpg |
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Name three ways to increase EDV (venous return to heart) |
1. Muscle pump (dynamic exercise) 2. Respiratory pump (drop in intrathoracic pressure) 3. ANS (venoconstriction to push blood back) |
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What part of the systemic circulation causes the greatest resistance to flow and hence the highest drop in pressure? |
The arteriole system - which accounts for about 50% of TPR |
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What is PULSE pressure. What are the two things that affect it? |
Pulse pressure is the difference between systolic pressure (120 normally) and the diastolic pressure (80).
Influenced by: 1. stroke volume (directly proportional) 2. Compliance (inversely proportional)
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If someone has extremely high PULSE pressure. What is a possible condition they could have and why is it causing high pulse pressure? |
1. They could have artherosclerosis which leads to rigidity of the aorta (less compliance) and subsequent high pulse pressure |
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What are the two equations for Mean arterial pressure ? |
MAP = Diastolic pressure (80) + 1/3 (Pulse pressure)
MAP = CO X TPR |
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What is the equation for measuring the RATE PRESSURE PRODUCT AND WHAT DOES IT MEASURE? |
Rate pressure product = Systolic Pressure + HR It is a measure on the workload of the heart |
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what are the two factors affecting blood flow |
1. Force opposing flow (vascular resistance) 2. Force causing flow (pressure difference) |
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What are the two equations for measuring Blood FLOW? |
1. (P2-P1)/ R ; where R is resistance 2. (P2-P1) X r^4 ; where r is the radius of vessel |
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What are the 5 assumptions of the posieulle equation |
1. Straight, unbranched, cylindical, constant radius, and non pulsatile |
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Describe the composition of each blood vessel layer (intima, media, adventitia) |
1. Intima = endothelial cells 2. media = circularly arranged ELASTIN and SMOOTH MUSCLE 3. Adventitia = Connective tissue only
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Which type of vessel contains the most ELASTIN in its media and which vessel contains the most SMOOTH MUSCLE in its media. |
Most elastin = Aorta
Most smooth muscle = Artery |
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List the 3 regulatory mechanisms for controlling blood supply through the vessels |
1. Local control (autoregulation) - myogenic - metabolic 2. Humoral control 3. Nervous control |
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Describe the Bayliss effect |
Blood vessel stretch due to increased pressure in the capillary
Leads to opening of ion channels which depolarize and open calcium channels (GRADED PROCESS NO ACTION POTENTIAL OCCURS)
This calcium entry causes contraction and reduction of pressure after the arteriole (capillary) and the increase in pressure before arteriole (artery) |
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Describe the difference between ACTIVE hyperaemia and REACTIVE hyperaemia |
Active hyperaemia occurs during exercise when cells release more VDM's resulting in local vasodilation
REactive hyperaemia occurs after a moment of occlusion of ischaemia when there is a buildup of VDM and when occlusion removed, there is a transient higher than normal blood flow through tissue |
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List the 4 Vasoconstrictor hormones of the humoral regulation system |
Acronym: Never Eat Violet Apples
N = Norepi/EPi E = Endothelein V = Vasopressin A = Angiotensin 2 |
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List the 2 effects of Angiotensin 2 in terms of regulating blood pressure |
1. Causes peripheral vasoconstriction 2. Increase synthesis of Norepi from nerve endings which leads to more vasoconstriction |
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List the 6 vasodilator agents. *Hint: Think acronym * |
Acronym: Never eat poison after Hot breakfast
N = NO2 (NOT NOREPI, IT DOESNT BIND TO BETA 2 RECEPTORS)
E = Epinepherin
P = Prostaglandins
A = Atria naturetic factor ( ANF)
H = Histamine
B = Bradykinin |
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Name the two locations where the High pressure mechanoreceptors are located in the heart. And also the two locations where LOW pressure mechanoreceptors are located. |
1. High pressure = Carotid Sinus and Aortic arch 2. Low pressure (volume) = Atrial walls and junction between vein and atria |
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Name the two hormones released in response to stimulation of low pressure (volume) receptors in the heart |
1. ADH release from hypothalmus 2. Angiotensin 2 release indirectly from sympathetic release of renin from Juxtaglomerular |
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What is the main recieving station for afferents from the baroreceptors
*Hint: located in medulla * |
The solitary tract nucleus in the medulla of brainstem |
