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171 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Warm blooded animals are also known as ________ which means there body temperature remains in a narrow range. |
Homeotherms |
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What is the thermoneutral zone? |
The ambient temperature in which no body temperature adjustment is needed |
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What is critical temperature? |
Ambient temperature in which the body requires energy to maintain homeothermic conditions |
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What impact does hyperthermia (heat stress) have on cells? |
Cells can not function (enzymes and proteins denature). Generally fatal. |
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What impact does hypothermia (cold stress) have on cells and blood flow? |
Cells can survive freezing however blood thickens affecting blood circulation leading to respiration failure and death |
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In what 3 ways is heat produced by endotherms |
1. Metabolism 2. Growth and production 3. Exercise |
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Describe the 4 physical processes in which heat is released into the environment? |
1. Radiation - electromagnetic radiation is emitted and absorbed 2. Conduction - transfer through contact 3. Convection - transfer via moving air or water 4. Evaporation/ Condensation - Water absorbs energy to break its molecules apart - passive evaporation, sweating, panting, bathing |
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When extra heat is needed the body shivers to produce heat, how does the body produce heat when your muscles get tired of shivering? |
Non-shivering thermogenesis = - sympathetic nervous system secretes catecholamines increasing metabolism - thyroid hormones increase metabolism |
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Under normal conditions, metabolic heat is removed from the core via? |
Blood through the skin |
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How does the hypothalamus respond to heat? (4) |
1. Sympathetic vasoconstriction fibres slow down = vasodilation 2. Sympathetic activity for evaporative heat loss (panting/sweating) 3. Reduction of physical activity 4. Behavioural response: seeking shade or wind |
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What are the two basic ways in which your hypothalamus responds to cold? |
1. Reduction of heat loss 2. Production of heat |
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Cold fibres are much more numerous than warm fibres (T/F)? |
True |
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What role does aldosterone (hormone) play in the reduction of heat? |
An increase in aldosterone stimulates the reabsorption of Na+ and Cl- from sweat glands (sweating) |
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Why is hypothermia critical which newborns? |
They have little subcutaneous fat (brown fat) to keep them warm. |
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Which nervous systems are afferent and which are efferent, which use sensory nerve fibres and which use motor nerve fibres? |
The sensory system is both afferent and uses sensory nerve fibres The somatic and automatic systems are efferent and use motor nerve fibres |
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If a signal is afferent it travels to and from where? If it is efferent? |
Afferent: peripheral -> CNS Efferent: CNS -> peripheral |
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If info is traveling away from the cell body in a neuron it is traveling through which part of the neuron? If it is traveling towards the cell body? |
1. Axon 2. Dendrites |
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What are the three neuron categories and where are they primarily located? |
1. Multipolar: mainly in the CNS 2. Pseudounipolar: mainly in the PNS (small cell body, low integration, used mostly for transport) 3. Bipolar: mainly in sensory organs |
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What is the role of interneurons? |
Relay information between neurons in the CNS |
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What is the role of the specialized receptors called transducers in the nervous system? |
To convert stimuli to signal |
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What are the functions of glial cells? (5) |
1. Provide structural support to nervous tissue 2. Participate in myelin formation 3. Secrete glutamate: can modulate excitatory level of neurons (astrocytes) 4. Some posses phagocytic activity (microglia) 5. Supplies nutrients and oxygen to neurons via blood brain barrier |
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Grey matter corresponds to which part of the nerve cell? |
Cell body |
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What are ganglia? |
Clusters of sensory neuron cell bodies located outside of the CNS |
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What is the role of the myelin sheath? |
Works as an electric insulator around axons (transmission) of AP is faster in myelinated fibres |
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What is the function of nodes of Ranvier in the myelin sheath? |
Allows depolarization = transmission of action potential |
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What is the average RMP (resting membrane potential) in nerve cells? |
-70 to -90 mV |
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For membrane potential the inside of a membrane is negative relative to the outside. Relative meaning? |
The majority of the inside and outside of the cell is elctroneutral, it is the charges around the membrane that create the gradient |
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What 3 things maintain the RMP (resting membrane potential)? |
1. Selective permeability (diffusion). 2. Na+/K+ pump (3 Na out 2 K in) 3. Large anions trapped in the inner surface of the membrane |
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Resting membrane potential is highly permeable to ___, but is barely permeable to ___, ___, and ___ resulting in _______ charges accumulating outside the cell |
1. K+ 2/3/4. Na+, Ca+, Cl- 5. Positive |
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Na+/K+ pump pumps __ Na+ out and __ K+ into the cell |
1. 3 2. 2 |
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The Na/K pump requires a lot of energy (T/F)? |
True, up to 40% of available ATP |
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Since neurons can store glucose and O2 the Na/K pump needs to be regulated as to not produce too much energy. (T/F)? |
False, neurons do not store glucose or O2 therefore a constant supply of Na+ and K+ ions are needed |
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Define an excitable cell |
Cells that are able to generate electrical impulses |
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Describe the process of creating AP in nerve cells. (5) |
1. Chemical, electrical, or physical stimulation induce change in membrane potential 2. Increase in Na+ permeability through gated channels 3. A rush of Na+ inside the cell causes polarity within the cell to switch (become positive) (depolarization) 4. Subsequent outflow of K+ returns potential to RMP (repolarization) 5. The depolarization wave moves along the membrane (action potential) |
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Describe the process of depolarization and repolarization within the cell. |
1. Depolarization needs to reach a threshold to provoke the opening of Na+ voltage gates channels 2. After ~0.5 ms the Na+ channels close 3. K+ voltage gated channels then open resulting in an outflow of K+ 4. K+ gated channels close more slowly and outflow of K+ continues after reaching the RMP = hyperpolariztion 5. Neurons cannot be re-stimulated until RMP is restored = refractory period 6. After AP, ions rejoin their respective compartments by diffusion and via Na+/K+ pump |
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How do myelinated axons differ from non myelinated axons? (4) |
1. Myelin prevents ion leakage 2. Current jumps from one node to another, called saltatory conduction 3. Velocity is increase 4. Less membrane is affected= less energy required to transport ions |
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What is nerve velocity dependent on? What is the range of its velocity? |
1. Dependent on the dissipation of current which is dependent on thickness of myelin and the diameter of the fiber 2. Ranges from 100 to 0.5 m/s and from 2500 to 250 impulses/s |
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Define a synaptic transmission |
Continuity of signal between a neuron and other neurons or muscle cells (neuromuscular synapse) |
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What is the cell membrane made up of to allow it to be a electric insulator? |
Phospholipids |
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Describe a neurotransmitter |
Molecules able to transmit information from a neuron by converting the electrical signal (AP) into a chemical signal |
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How many amino acids are in a neuropeptide |
3-40AA |
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What are the steps in neuromuscular synapse? (6) |
1. AP opens voltage gated Ca2+ channels 2. Ca2+ triggers exocytosis 3. Diffusion in the cleft 4. Binding to specific receptors 5. Ion channels open on post-synaptic membrane = depolarization 6. Neurotransmitter inactivated, termination of signal |
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Describe termination of transmission for small molecules (2) |
1. They are picked back up by presynaptic neuron via endocytosis and recycled for next time 2. Deactivated in the cleft by enzymes released by post-synaptic cell (Acetylcholine esterase) |
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What is the function of acetylcholine? |
A neuromuscular synapse transmitter |
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Describe the termination of transmission for neuropeptides (2) |
1. After binding to its receptor, can be internalized by post-synaptic cell via endocytosis and be degraded by cellular enzymes 2. It is broken down by extra cellular peptidase in the synaptic cleft |
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Why is it important to terminate a signal? |
Receptors can become desensitized |
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-Excitatory synapse = ____polarization = entry of ____ -Inhibitory synapse = ____hyperpolarization = entry of ___ and/or outflow of ___ |
1. De 2. Na+ 3. Hyper 4. Cl- 5. K+ |
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What are the tasks of the CNS? (3) |
1. Receives continuous flow of information 2. Analyzes and interprets the information 3. Sends commands to the body to maintain function of vital systems and organs and respond to the internal environment |
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What are the 3 layers of the meninges? |
1. Dura mater (outer): a thick a tough layer that supports the brain and forms the venous sinus which collects most of the blood from the brain 2. Arachnoid (middle) 3. Pia mater (inner): tightly attached to the neural tissue |
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Describe the flow of cerebrospinal fluid (CSF) (3) |
1. The CSF is produced by the choroid plexus 2. Td CSF diffuses from the 4th ventricle to the subarachnoid space and circulates around the brain and the spinal cord 3. The CSF in the brain is then drained into venous sinus before entering blood circulation.
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What are the roles of Cerebrospinal fluid? (4) |
1. Provides nutrients to the CNS 2. Protection (shock absorber) 3. Ionic concentration ideal for optimum neuronal function 4. Blood-CSF barrier: at choroid plexus, uptake of nutrients and drugs into CSF |
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Cells, proteins, and amino acids are able to diffuse through the blood brain barrier (T/F) |
False, No cells or proteins are able to diffuse through the barrier, only small amounts of amino acids and liposoluble substance such as gases can diffuse |
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White matter is composed of what 3 kinds of myelinated fibers? |
1. Association fibers between parts of the cortex 2. Commissural fibers between the two hemispheres 3. Projection fibers: connect the cortex to other brain structures and the spinal cord |
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What functions are controlled by the basal nuclei within the brain? |
Control complex, semi-voluntary movements (walking, running) as it works in conjunction with the cortex and cerebellum. (In birds it also controls voluntary movements) |
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The cerebrum or cerebral cortex is composed of grey matter, what are its responsibilities? (2) |
1. Responsible for conscious experience of sensory input 2. It is the site of high nervous association |
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The cerebrum is marked by a high degree of educability, meaning? |
Its response to stimuli may change over time (aka learning) |
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The cerebellum contains grey matter in both its cortex and centre, what are the roles of the cerebellum? |
1. Its main role is to prevent distortion of intended movement (fine tunes movement) as it sends corrective signals via the thalamus to the cortex and spinal nuclei commanding the muscles. |
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What are the 3 structures that make up the diencephalon (inter brain), and what are their functions? |
1. Thalamus: relay station for sensory information, cerebellum and basal ganglia, and the cerebral cortex 2. Epithalamus: contains olfactory correlation centre and pineal gland 3. Hypothalamus: -produces neuropeptides that control the anterior pituitary. - produces neurohormones released by the posterior pituitary - principle regulator of autonomic nervous system; with the brain stem. |
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The brain stem contains large amounts of grey matter (T/F)?
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False, it contains large amounts of white fibres as it acts to convey messages from the brain to the spinal cord |
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What is the function of the mesencephalon portion of the brain? |
It acts as a visual reflex centre, receiving visual information. - controls eye movement - also acts as a auditory reflex centre (turn head for noise) * is large in birds and small in mammals |
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What is the function of the Pons and Medulla Oblongata portion of the brain? |
-Contains centre for postural reflexes -Controls respiratory movement - Medulla Oblongata is crucial for the control of: heart activity, blood pressure, and distribution of blood to organs |
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How many cranial nerve pairs are there? Which are the only purely sensory nerves that remain in the brain? |
There are 12 pairs Pair 1 and 2 (olfactory and optic) remain in the brain. |
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What cranial nerve is the most widely distributed nerve throughout the body? |
The Vagus nerve |
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Name these regions of the spine from head to tail Sacral Thoracic Cervical Coccygeal Lumbar |
Cervical, thoracic, lumbar, sacral, and coccygeal |
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What makes up white matter? What makes up grey matter? |
White matter: myelinated and unmyelinated nerve fibres (axons) Grey matter: contains cell bodies and dendrites |
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Label the diagram |
1. Ganglion 2. Dorsal root 3. Ventral root 4. White matter 5. Dorsal horn 6. Ventral horn 7. Grey matter 8. Central channel 9. Motor neuron (out) 10. Sensory neuron (in) |
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What are the 3 levels of CNS control of movement and what structures are in each |
1. Higher centres - cerebral cortex 2. Middle level - sensorimotor cortex - cerebellum - basal ganglia 3. Lower level -Spinal cord from which motor neurons exit |
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What are the 3 levels of CNS control of movement? |
1. Higher centres - cerebral cortex 2. Middle level - sensorimotor cortex - cerebellum - basal ganglia 3. Lower level -Spinal cord from which motor neurons exit |
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Define a reflex |
An automatic or unconscious response of effector organs to stimulus. It is involuntary and unvarying in response |
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What are the 5 fundamental components of a reflex? |
1. Sensory cells (receptors) 2. Sensory nerve fibres 3. Coordinating centre (CNS) 4. Motor nerve fibres 5. Effectors (muscle of gland cells) *in this order |
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Describe the process of somatic reflex arcs in 5 steps |
1. Receptors transduce the environment (heat, cold, stretch) and convert energy into AP 2. Sensory (afferent) nerves conduct AP from the receptor outside of the spinal cord and bring it in via the dorsal roots 3. CNS synapse occurs 4. Motor (efferent) nerve carries AP from CNS to target (effectors) organs via ventral root 5. Target organ responds (I.e knee jerk, scratching) |
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Changes in tendon length is detected by which organ and how does it respond? (5) |
Golgi organ 1. Muscle contracts 2. Pulls tendon 3. Squeezes receptor 4. Sensory nerve contracts with an inhibitory interneuron in spinal cord 5. Inhibits motor neurons serving the same |
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Changes in muscle length is detected by what spindles and how do they respond? (3) |
By muscle spindles 1. Muscle stretch activated spindle 2. Sensory nerve makes excitatory synaptic contact with motor neurons serving the same muscle (extrafusal fibers) 3. Muscle shortening |
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Describe the actions taking place if your arm was forced down from a 90 degree resting position and you then returned it to that resting position |
1. Biceps stretch 2. AP in sensory neuron enters spinal cord 3. Activated bicep motor nerve and via interneuron inhibits tricep motor nerve 4. Biceps contract while triceps relax, restoring posture |
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What is the role of the autonomous nervous system? |
Controls body function without conscious thought (I.e: smooth muscle, cardiac muscle, glands, and reflex. |
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Autonomic nervous system is mainly controlled by a positive feedback loop (T/F)? |
False, a negative feedback loop |
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How many neurons are in the peripheral circuit of motor nerve fibres and what are they? |
2 vs. The 1 in somatic nerve fibres Preganglionic nerve has a cell body in the CNS with axon that innervates a second neuron, the postganglionic nerve |
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What are the major divisions of the autonomic nervous system and what do they affect? (3) |
1. Sympathetic: is activated during stress (demanding activities) where preganglionic neurons originate in the thoracic or lumbar vertabra and send axons to sympathetic ganglia which parallel spinal cord 2. Parasympathetic: which is most active during rest, where preganglionic neurons originate in the brain or sacral part of spinal cord and send axons to ganglia near or within effector organs 3. Enteric nervous system: Associates with parasympathetic |
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What is the function of some preganglionic fibres in the SNC that extend to the adrenal Medulla (adrenal glands)? |
Stimulate secretion of epinephrine and norepinephrine into circulation |
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What is the function of some preganglionic fibres in the SNC that extend to the adrenal Medulla (adrenal glands)? |
Stimulate secretion of epinephrine and norepinephrine into circulation |
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What is the function of post ganglionic fibres? |
Short axons that direct connection with specific organs (no branching off) with no enhancement by hormones=selective action |
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All peripheral nerve fibres with their cell body in CNS use what organic chemical? |
Acetylcholine (ACh) |
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Describe the two different acetylcholine receptors |
1. Nicotinic: are responsible for preganglionic synapses for neuromuscular functions (skeletal muscle not ANS) and is ionotropic = part of an ion channel 2. Muscarinic: are in target organs of the parasympathetic system it is separate from the ion channel and requires intracellular second messenger to activate target cell. Depending on messenger it can be stimulators or inhibitory *slower and more prolonged effect than nicotinic |
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What are the two receptors of adrenaline and noradrenaline and what are their functions? |
1. a-adrenergic: a1 =increase Ca a2 = decrease in cAMP -usually constriction of smooth muscles (vascular) 2. B-adrenergic: B1 and B2 = increase in cAMP - is the main form in the heart which increases contraction strength and rate also responsible for relaxation of smooth muscle |
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What inhibitor causes hypertension? |
B-adrenergenic blocker (Proranolol) which decreases heart rate (B1) |
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Which inhibitor causes asthma? |
B2-adrenergic agonist (salbutamol) = bronchodilatoin |
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What are the functions of Atropine? (4) |
1. Muscular receptor blocker 2. Dilation of pupils (eye exam) 3. Inhibits contraction of lower GI tract 4. Reduces mucus production in respiratory tract |
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Arteries bring blood from the heart, veins bring blood to the heart (T/F)? |
True |
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What are the major functions of the CVS? (7) |
1. Transport O2/CO2 from and to the lungs and tissue 2. Transport of nutrients 3. Transport of waste 4. Transport of heat 5. Transport of hormones 6. Carrying immune cells 7. Stabilize internal environment (buffer: pH, ions, ect) |
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What are the two layers of the pericardium, the connective tissues that surround the heart? |
They prevent over-sizing (over stretching) of the heart |
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Label the heart |
1. Superior vena cava 2. Interatrial septum 3. Right AV valve 4. Inferior vena cava 5. Pulmonary vein 6. Right ventricle 7. Pulmonary and aortic valves 8. Interventricular septum 9. Aorta 10. Pulmonary artery 11. Left atrium 12. Pulmonary vein 13. Pulmonary trunk 14. Left ventricle 15. Left AV valve |
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What is myocardium? |
The muscle tissue of the heart wall |
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What is the role of the two atria in the heart? |
Mainly serve as blood reservoirs but also help transfer blood to the ventricles |
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What is the role of the two ventricles in the heart? |
To propel blood into systemic and pulmonary circulation |
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Label this cross section of the heat |
1. Tricuspid valve 2. Bicuspid valve 3. Fibrous ring 4. Aortic valve 5. Pulmonary valve |
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Which valves in the heart are Atrio-ventricular and which are semilunar? |
AV valves: 1. Bicuspid 2. Tricuspid Semilunar valves: 1. Aortic 2. Pulmonary |
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Blood volume is equal in both sides of the heart (T/F)? |
True |
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Blood volume is equal in both sides of the heart (T/F)? |
True |
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1. Ventricle relaxed= _____ pressure= AV valves ______ 2. Ventricles fool= _____ pressure= AV valves _____ 3. Ventricles contract= pressure ______ than arterial pressure= aortic and pulmonary valves _______ 4. Ventricle emptied= pressure back down= all valves _______ |
1. Lower, open 2. Higher, closed 3. Higher, open 4. Closed |
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How do small arteries (arterioles) control blood pressure so far from the heart? |
Via the tone of the vessels smooth muscle allows for contractions to take place |
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Venules collect blood from where? |
Capillaries |
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Describe the basic workings of the pulmonary system |
Heart/lungs loop oxygenated blood -has relatively low pressure, low resistance and highly distensible |
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Describe the basic workings of the systemic system |
Is the distribution of oxygenated blood and nutrients throughout the whole body -high pressure and high resistance |
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What are the 5 physical phases of he cardiac cycle, in order? |
1. Diastole (relaxation/filling) 2. Atrial contraction (push blood into ventricles 3. Isovolumic contraction 4. Ejection phase (systole) 5. Isovolumic relaxation *then back to top |
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What are the two types of muscle cells that make up the myocardium? |
1. Contractile cells: 99% of the cell, require AP to contract 2. Autorhythmic cells: are modified non-contractile cells that are concentrated in specific regions of the heart -they spontaneously generate action potential *=pacemaker |
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Describe the function of the Sino-Atrial (SA) node in the heart |
It is the command centre, it controls contraction of the heart) -rhythmical self excitation |
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Describe the function of the Atrio-Ventricular (AV) node |
Has autorhythimic ability but it's pace is slower than SA so it is under SA control -It is the gateway for electrical conduction between atria and ventricles |
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What is the role of the bundle of His and Purkinje fibres in the heart? |
To help quickly propagate electrical activity from the AV node to the rest of the ventricles |
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What are the roles of the electrical systems in the heart? (2) |
1. Maintain appropriate heart rate 2. Coordinate contraction of atria and ventricles |
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What is the sequence of excitation within the heart? (4) |
1. SA node self excitation (generation of APs) 2. APs propagate through atria=atria contraction 3. AV node activated by AP wave , transmit electrical activity to the bundle of His and Purkinje fibres 4. Electrical activity propagate through ventricles = ventricular contraction |
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What effect do sympathetic fibres have on reaching threshold potential in order to generate AP? What about parasympathetic fibres? |
Sympathetic: reduce the time required to reach threshold = faster pace. Parasympathetic: prolong the time required to reach the threshold = slower pace |
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The heart can be considered a "functional syncytium" meaning what? |
Contraction will follow the all or nothing rule *This is do to the gap junction |
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How does AP in contractile cells differ from autorhythmic cells? How do they differ from skeletal muscle AP? |
1. Stable resting membrane potential (no drift) 2. Cardiac muscle AP is much longer as is its refractory period which means that cells can't be restimulated until contraction is over |
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What are the 5 phases of AP from contractile cells? |
1. Resting membrane potential 2. Rapid depolarization due to influx of Na+ in the cell 3. Short phase of repolarization; loss of K+ from cell 4. Plateau phase - influx of Ca2+ into the cell 5. Repolarization phase - outward movement of K+ from the cell |
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With the gap junction all cells contract at once (T/F)? |
True |
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Describe the 5 steps of calcium stimulated calcium release for contraction |
1. Depolarization 2. Voltage-gated Ca2+ channels open 3. Ca2+ entry induces avalanche of Ca2+ release from sarcoplasmic reticulum (10 fold increase) 4. Large increase of intracellular Ca2+ triggers contraction 5. Ca2+ is pumped back in its pre-stimulation compartment |
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What effects does the sympathetic system have on heart contractions? (4) |
1. Stimulates heart rate -stimulates the firing of SA node - stimulates velocity of AV node conduction 2. Increases the contraction force - increases the release of Ca2+ from sarcoplasmic store 3. Reduces the contraction time - increases the speed of Ca2+ transport (reduces plateau length) 4. Actions mediated by epinephrine/norepinephrine on B-adrenergic receptors present in all cardiac cells |
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What effects does the parasympathetic system have on the control of heart contractions? (2) |
1. Decreases the heart rate - reduces the firing of the SA node - decreases the velocity of AV node conduction (longer delay) 2. Actions mediated by binding of acetylcholine on muscarinic receptors in autorhythmic cells - increase K+ permeability - hyperpolarization increase time required to reach AP threshold |
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What is an electrocardiogram (ECG) used for? |
It measures heart membrane potential throughout the cardiac cycle |
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What is an electrocardiogram (ECG) used for? |
It measures heart membrane potential throughout the cardiac cycle |
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What are the 3 ECG standard waves? |
1. P-wave: depolarization of aorta 2. QRS wave: depolarization of ventricles 3. T wave: repolarization of the ventricles |
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What is the most practical electrode configuration when using an ECG? |
The base-apex lead configuration: one lead on the left chest, second over neck *produces normal rate and rhythm |
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In an ECG diagram how are each of these measured? 1. Heart rate 2. Contraction force 3. Rhythm |
1. Measure the interval between cycles 2. Measure amplitude of waves 3. Measure the intervals between each wave |
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Bradycardia is a condition in which heart rate is (slower/faster)? Tachycardia is a condition is which heart rate is (slower/faster)? |
1. Slower 2. Faster |
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Bradycardia is a condition in which heart rate is (slower/faster)? Tachycardia is a condition is which heart rate is (slower/faster)? |
1. Slower 2. Faster |
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When looking at a ECG chart you notice an abnormally long P-Q interval, what could cause this? |
AV conduction problem |
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What are ectopic beats in the heart? |
Action potential generated independently of the SA node, which results in extracontraction |
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What causes the lub noise from the heart? What causes the dub? |
Lub: closing of AV valve Dub: closing of semilunar, aortic, and pulmonary valve |
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What does each colour represent? |
Green: ECG reading Orange: heart sound Purple: aortic pressure Pink: left ventricle pressure Blue: left atrial pressure Red: left ventricle volume |
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What happens when the aortic valve opens during ventricular contraction? (3) |
1. Rapid flow of blood 2. Increased arterial pressure 3. Aorta elasticity absorbs some of the pressure (temporarily stores energy) |
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What happens when the aortic valve opens during ventricular contraction? (3) |
1. Rapid flow of blood 2. Increased arterial pressure 3. Aorta elasticity absorbs some of the pressure (temporarily stores energy) |
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What happens when he aortic valve closes during diastole? (4) |
1. No blood flowing from the ventricle 2. Energy stores during the stretching of the aorta is released 3. Allows blood flow to continue in vessels 4. Gradual decrease in arterial pressure |
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Heart rate X stroke volume = ?? |
Cardiac output |
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How do these three things affect heart rate? |
1. Sympathetic NS 2. Adrenal Medulla 3. Parasympathetic NS |
1. Increase 2. Increase 3. Decrease |
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How do these three things affect heart rate? |
1. Sympathetic NS 2. Adrenal Medulla 3. Parasympathetic NS |
1. Increase 2. Increase 3. Decrease |
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How do you determine the volume of blood ejected per contraction? |
End-Diastolic Volume (EDV) - End-Systolic Volume (ESV) |
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EDV or preload represents what? |
Volume of blood present in the ventricles at the end of diastole -Work imposed on the ventricles prior to contraction |
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EDV or preload represents what? |
Volume of blood present in the ventricles at the end of diastole -Work imposed on the ventricles prior to contraction |
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ESV or afterload represents what? |
Residual volume of blood contained in ventricle after systole -Impedance to ejection of blood from ventricles |
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Increase in EDV = decrease in stroke volume (T/F)? |
False an increase in EDV = and increase in stroke volume as EDV is the volume in the ventricles at the end of diastole |
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What is the Frank Starling laws of the heart (4)? |
1. As preload is increased, the contractility of the heart is increased which increases stroke volume 2. Increase stretch of cardiac fibres at onset of systole induces increase in contractility by enhancing binding of Ca2+ to troponin C 3. Under resting condition, EDV stretches cardiac muscle to sub-optimal levels 4. Stretching cardiac muscle beyond optimum does not occur (pericardium) |
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What is the main factor effecting Preload (EDV)? |
Venous return |
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What factors promote venous return and how? (4) |
1. Skeletal muscle pump: muscle contraction squeezes veins which pushes blood toward the heart 2. Respiratory activity: inspiration increases abdominal pressure = transfer to abdominal veins 3. Blood volume: increased blood volume = elevated venous return 4. Autonomic nervous system: veins contain smooth muscle innervated by sympathetic fibres= contraction |
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What factors affect afterload (ESV)? |
1. Resistance the ventricles encounter during ejection 2. During exercise, indirectly controlled by the heart contractility 3. During rest, main determinant is arterial vasomotor tone= Total Peripheral Resistance (TPR) |
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What are the 3 important factors involving blood vessels that effect blood pressure |
1. Diameter: large diameter= more blood 2. Elasticity: more elasticity means it can handle more volume 3. Contractility: smooth muscle tissue relies on the autonomic nervous system in order to move blood |
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How is flow calculated? (Equation) |
Flow (Q) = pressure difference (dP)/ Resistance (dR) |
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Pressure is higher in veins than arteries (T/F)? |
False, pressure is higher in arteries |
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Pressure is higher in veins than arteries (T/F)? |
False, pressure is higher in arteries |
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What factors affect resistance of blood flow? (3) |
1. Length of vessel 2. Radius of vessel (most important) -Resistance decreases by the 4th power of the radius 3. Viscosity of blood |
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Arteries have more continuos flow than veins (T/F)? |
True |
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During diastole the loss of blood pressure is much slower than the gain in pressure during systole, why is this? |
The aortic valve closure helps maintain blood pressure until the next heart beat |
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What factors influence the arterial pressure? |
1. Elasticity of the artery: low elasticity equals high pressure 2. Cardiac output 3. Respiration: during expiration, pressure increases 4. Resistance to blood flow 5. Blood volume (minimal effect because veins absorb the major effect) |
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What are the two levels of control of arteriolar resistance? |
1. Autoregulation: local mechanisms 2. Extrinsic control factor (neuro-hormonal) |
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Describe the two types of autoregulation of vascular resistance |
1. Metabolic regulation: responds to change in metabolism, thus blood requirement. - results in an increase of diameter which increases CO2, K+, and NO while decreasing pH 2. Myogenic (pressure) autoregulation: Vessels respond to changes in tone or stretch - Maintain the blood supply virtually unchanged even when pressure changes |
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Describe extrinsic regulation of vascular resistance |
Vasoconstrictive influences: -sympathetic stimulation on a-adrenergic receptors (B-adrenergic in the heart) - Angiotensin -Arginine vasopressin Vasodilatory influences: -Parasympathetic influences (vagus nerve) |
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During inspiration, P in the thoracic cavity (increase/decreases?) and P in the abdominal cavity (increases/decreases?) |
1. Decreases 2. Increases |
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What is the function of baroreceptors? |
They are stretch receptors that sense the stretching of arterial wall and are located in sensitive areas such as the aortic arch and carotid sinus |
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How do sensory fibres determine whether to increase or decrease AP frequency? |
Stretch increase of the fibre = increase in APs frequency Stretch decrease = decrease in AP frequency |
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What is the role of the cardiovascular centre in the Medulla on blood pressure? |
An integration centre that compares info to reference values |
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What happens to your blood pressure when you stand up from a lying position? How is this counterbalanced? |
- shift 500-700ml of blood from thoracic cavity to lower extremities which decrease venous return, CO, and BP 1. A decrease in arterial baroreceptors firing 2. This affects medullary cardiovascular centre 3. Which decrease parasympathetic activity while increasing sympathetic activity 4. This in turn increases cardiac output and peripheral resistance, normalizing arterial pressure |
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How do artial volume receptors regulate blood volume? |
They determine atrial wall stretch and regulate blood volume via: autonomic nervous system and neural input the controls thirst and secretion of hormones that alter renal handling of sodium and water |
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How do these hormones regulate BP? 1. Atrial natriuretic peptide (ANP)? 2. Renin 3. Antidiuretic hormone |
1. Increases sodium excretion 2. Synthesized in the kidney, it increases synthesis of angiotensin II (vasoconstriction) and Aldosterone (decreases sodium excretion. 3. Decreases water excretion by the kidney |
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What are metarterioles? |
They are a network that connects arterioles and capillaries They posses rings of smooth muscle tissue that can open and close on demand |
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Describe how each of these substances diffuse across the membrane 1. Lipid soluble substances 2. Water and lipid-insoluble molecules (Na+, Cl-, glucose, AAs) 3. Water and water soluble macro molecules |
1. Exchange freely across cell membrane 2. Most capillaries have pores or clefts that allow their transfer 3. Some capillaries fenestrated vesicles fuse to form large gaps across endothelial cell membrane |
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If a mass movement of water and dissolved substances is heading for interstitial flood it will be ________. If it is heading for intravascular fluid (blood) it will be _______ |
1. Filtrated 2. Absorbed |
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Net movement of fluid depends on what two pressures? |
1. Filtration (hydrostatic) pressure pushing fluid out 2. Osmotic (oncotic) pressure pushing fluid in |
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Net movement of fluid depends on what two pressures? |
1. Filtration (hydrostatic) pressure pushing fluid out 2. Osmotic (oncotic) pressure pushing fluid in |
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Hydrostatic pressure difference (increases/decreases) during arteriole dilation |
Has a higher start and finish than a normal situation but still decreases over all |
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What happens to hydrostatic pressure difference when arteriole constrict? |
It drastically decreases |
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Low protein in plasma = (increase/decrease) in osmotic pressure = fluid going (out/in) |
1. Decrease 2. Out |
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What are the 4 mechanisms responsible for edema formation (abnormal accumulation of interstitial fluid) |
1. Hydrostatic pressure in blood vessels 2. Interstitial protein concentration 3. Decrease in oncotic pressure 4. Obstruction of lymphatic vessels |
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