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197 Cards in this Set
- Front
- Back
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What is the nervous system divided into? |
the central nervous system and the peripheral nervous system |
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what makes up the CNS and the PNS? |
The CNS is the brain and spinal cord. The PNS are the cranial and spinal nerves |
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what are the two general types of cells of the nervous system? And what are their functions? |
1. Neurons- responsible for sending and receiving electrical impulses; conduct electrical impulses 2. Glial cells- they support neurons |
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what is the structure of a neuron and each of their functions? |
1. Cell Body- cluster in groups called nuclei in the CNS and ganglia in the PNS; is the metabolic center of cell 2. Dendrites- receive signals 3. Axon- conducts impulses, which initiate at the axon hillock; direction of impulse is AWAY from the cell body
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What is the Node of Ranvier? |
- is the area between the myelin sheaths on an axon - is critical for propagation of electrical signals - it is where are all ion channels and necessary resources are at to generate an AP |
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What are the different structural types of neurons? |
1. pseudounipolar- single short process that branches like a T to form 2 longer processes; only one axon 2. bipolar- have two processes, one on either end; has two axons 3. multipolar- several dendrites and one axon; is the most common types |
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sensory neurons? |
-are also called AFFERENT neurons -signals/impulses are from sensory receptors to CNS examples can be eyes and ears
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motor neurons? |
-are called EFFERENT neurons -signals/impulses are from the CNS to effector organs/muscles |
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associated neurons? |
-are also called INTERNEURONS -found WITHIN the CNS -integrate functions of teh CNS -are sometimes able to disperse signals to muscles while also sending signals to CNS to get more info |
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what are the two types of motor neurons? |
1. somatic- responsible for reflexes and VOLUNTARY control of skeletal muscles 2. autonomic- innervate INVOLUNTARY targets such as smooth muscle, cardiac muscle and glands - responsible for the SYMPATHETIC ("fire and flight") and the PARASYMPATHETIC ("rest and digest")
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what are nerves? |
- they are bundles of axons located OUTSIDE of the CNS - are composed of both sensory and motor neurons and are called mixed nerves |
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what is a tract? |
a bundle of axons INSIDE the CNS |
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what two types of supporting cells are found in the PNS? |
1. Schwann cells- form myelin sheaths around peripheral axons; gives axons in PNS their myelin sheath 2. Satellite cells- support cell bodies within the ganglia of the PNS |
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what are 4 types of supporting cells found in the CNS? |
1. Oligodendrocyes: form myelin sheaths around the axons of CNS 2. Microglia: migrate around tissue and phagocytize foreign and degenerated material 3. Astrocyes: regulate external environment of neurons 4. Ependymal cells: line ventricles of brain central canal of the spinal cord; secretes cerebrospinal fluid
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what is the importance of the myelin sheath on axons? |
- it behaves like duct tape, the insulation of an electrical signal - myelinated axons conduct impulses more rapidly due to insulating properties of the myelin sheath |
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what is the difference between oligodendrocytes and schwaan cells? |
- oligodendrocyes provide the myelin sheath for neurons in CNS; one can send extensions to several axons unlike schwaan cells; can form myelin sheath around many axons - schwaan cells provide myelin sheath in PNS; can only form myelin sheath around one axon
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what is the difference between white matter and gray matter in the CNS? |
WHITE= tissue covered in myelin GRAY= cell bodies and axons |
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What are the functions of Schwann cells in nerve conduction and nerve regeneration following injury? |
- when an axon in the PNS is cut, the severed part degernerates and a regeneration tube is formed by schwann cells - CNS axons NOT able to regenerate, perhaps due to the fact that myelin sheath provided by oligodendrocyes, not schwann cells |
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what are some general characteristics of astrocytes? |
- is the most abundant glial cell in CNS - processes with end-feet associate with blood capillaries and axon terminals - are the personal assistants of CNS neurons as they can perform 5 or more functions at the same time |
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what are the functions of astrocytes? |
- take up K+ from extracellular environment to maintain ion environmnets - end-feet around capillaries so can take up glucose from blood for use by neurons to make ATP - needed for the formation of synapses in the CNS -take up neurotransmitters released from axon terminals of neurons |
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BLOOD BRAIN BARRIER |
-capillaries don't have pores between adjacent cells but joined by tight junctions - ASTROCYTES form blood brain barrier and determines what gets into brain - is when things coming out of capillaries have to be allowed into the brain by diffusion or active transport - nothing but blood gets into brain unless have special way of getting in |
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why do cells have electrical activity? |
- unequal distribution of charged molecules - semipermeable membrane and different permeabilities of charged molecules - diff conc in and outside of cell - diff amount of positive and neg charge on inside and outside of cell----known as MEMBRANE POTENTIAL, more negative inside than out |
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RESTING MEMBRANE POTENTIAL |
- have a resting potential of -70 mV due to large neg molecules inside cell, Na+/K+ pumps and differential permeabilit of membrane to ions - at rest, high conc of K+ inside cell and Na+ outside cell |
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what does being polarized mean? |
- neurons are polarized at rest - inside of cell is more negative than the outside |
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what is depolarization? |
- when the membrane potential inside cell increases EX: -70 going to -30 - it is when Na+ going in cell to make inside of cell more positive(becoming less negative) - depolarization = EXCITATORY |
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what is repolarization? |
when there is a return to resting potential |
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what is hyperpolarization? |
- when membrane potential inside cell decreases; becoming more negative EX: -70 to -90 - K+ leaving or Cl- are coming inside - hyperpolarization = INHIBITORY |
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ion gating in axons for K+ |
HAS 2 TYPES OF CHANNELS: 1. not gated (always open); sometimes called "leaky" K+ channels - leads to high permeability of K+ in cells because K+ can come and go 2. voltage- gated K+ channels - opens when a particular membrane potential is reached |
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ion gating in axons for Na+ |
- changes in membrane potential are controlled by changes in the flow of ions through channels - Na+ only have voltage-gated channels that are closed at rest - membrane is less permeable to Na+ at rest
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ALL OR NONE LAW |
-once threshold has been reached, action potential occurs - SIZE OF STIMULUS DOES NOT AFFECT SIZE OF AP OR AP DURATION - AP's all have same amplitude |
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coding for stimulus intensity |
- stronger stimulus will make AP happen more frequently - stronger stimulus also activates more neurons in a nerve...known as recruitment - cant alter strength/size but can change RATE of its firing |
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what are two types of refractory periods and its function? |
- refractory per occurs after an AP when neuron cant become excited again b/c AP can only inc in frequency to certain point 1. absolute - occurs during AP. Na+ channels are inactive 2. relative- when K+ channels are open; only a very strong stimulus can overcome this |
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ACTION POTENTIAL PROCESS |
1. membrane potential depolarizes to a certain point and reaches THRESHOLD POTENTIAL 2. Na+ (by voltage-gated Na+ channels) rushes in due to electrochemical gradient and membrane potential increases and becomes more positive 3. repolarization is reached and before Na+ closes, K+ voltage channels open 4. hyperpolarization occurs; voltage K+ channels remain open until resting potential is reached 5. after hyperpolarization, repolarization overshoots resting potential; voltage K+ channels not active as mp falls 6. Na+/K+ pumps reestablish resting potential |
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how is conduction in an unmyelinated axon? |
- conduction = SLOW because there is a lack of electrical insulation |
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What is salutatory conduction and what will happen to the rate of nerve conduction if you increase myelin around axons? |
- saltatory conduction is when AP's leap from one Nodes of Ranvier to another - this type of conduction helps impulses travel down an axon faster due to the myelin wrapped around the axon - increased myelin and fiber thickness means increased conduction |
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why is conduction quicker in myelinated axons in comparison to unmyelinated? |
- are faster because AP's only focused at nodes of ranvier, where there is a high density of voltage-activated Na+ and K+ channels as well as Na+/K+-ATPase pumps - myelinated fibers = 100 meters/sec - unmyelinated = 1 meter/second |
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in the CNS, what does the synapse connect? |
- connection is between a neuron and another neuron |
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in the PNS, what does the synapse connect? |
- connects a neuron to a cell in a muscle or gland |
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Electrical Synapses |
- cells do not mostly transmit impulse by this type - can occur in smooth muscle and cardiac muscle cells - cells must be very close to each other and channels physically connect the two cells - are electrically coupled by gap junctions
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What is involved in a chemical synapse? |
- most cells transmit impulse by this type of synapse - most synapses involve a release of a chemical called a neurotransmitter from a presynaptic axon's TERMINAL BOUTONS - presynaptic and postsynaptic cells are held together by cell adhesion proteins |
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What is the mechanism by which synaptic vesicles containing neurotransmitters in terminal button of presynaptic neuron move toward the membrane facing cleft? |
1. when action potentials reaches axon terminals, voltage-gated Ca++ channels open at the terminal bouton 2. Ca++ binds to sensor protein in cytoplasm 3. Ca++ protein complex stimulates fusion and exocytosis of neurotransmiter - stimulation of calcium is done through activation of enzymes 4. greater frequency of action potential = more NT release into postsynaptic cell * OCCURS IN PRESYNAPTIC NEURON |
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how can these neurotransmitters cause excitatory post synaptic potentials (EPSP) or inhibitory post synaptic potentials (IPSP)? |
1. when neurotransmitter(ligand) diffuses across synapse, it binds to a specific receptor protein 2. when the ligand binds to a receptor, it results in the opening of ligand-gated ion channels 3. when ligand-gated ion channels open, MP depends on which ion channel opens - opening of Na+ or Ca++ channels = EPSP (is depolarized) * OCCURS IN POSTSYNAPTIC NEURON - opening of K+ or Cl- channels = IPSP (hyperpolarization) |
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what are the characteristics and functions of EPSP's and IPSP's? |
- EPSPs move membrane potential CLOSER to threshold - IPSPs move membrane potential FURTHER away from threshold - SUMMATION of these two detemines whether an AP will occur |
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are EPSPs and IPSPs the same as an AP? |
NO! aren't the same because EPSPs not "all or none"; are GRADED - if enough depolarization, an AP can be generated in postsynaptic neuron |
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What are some characteristics of Acetylcholine (ACh)? |
- most widely used NT - used in Autonomic Nervous system, where it can be inhibitory or excitatory, depending on receptor subtype of postsynaptic cell - in CNS is always EXCITATORY |
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What are two types of acetylcholine receptors on the postsynaptic neuron? |
1. Nicotinic= EXCITATORY 2. Muscarinic= INHIBITORY |
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How does acetylcholine (Ach) produce EPSP (Nicotinic Ach receptors) and IPSP (Muscuranic Ach receptors)? |
1. Nicotinic channels: open when ligand binds and lets diffusion of Na+ into and K+ out of postsynaptic cell. Inward flow of Na+ dominates, producins EPSP...which occurs at cell body and dendrites 2. Muscarinic channels: ACh linked to K+ channepl permeability through G-protein, which allows a chemical outside cell to initiate a change inside the cell (signal transduction) - ACh binds to muscarinic receptor, G-protein cascade results in opening of K+ channel causing hyperpolarization and thus IPSP |
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How is Ach action terminated? |
acetylcholinesterase (AChE) inactivates ACh, terminating its action - is located in cleft on the postsynaptic membrane |
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what is cAMP and its function? |
- is the most common second messenger for catecholamines - binding of catecholamine to its receptor activates G-protein to dissociate and send the alpha subunit to an enzyme called adeb=nylate cyclase which converts ATP to cAMP -cAMP activates protein kinase, whihc phosphorylates other proteins - an ion channel opens |
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what types of neural pathways are there? |
1. Divergence- one presynaptic neuron can form synapses with many postsynaptic neurons 2. Convergence- many different presynaptic neurons can synapse on one postsynaptic neuron |
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what is spatial summation?
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occurs due to convergence of signals onto a single postsynaptic neuron - all of EPSPs and IPSPs are added together at axon hillock |
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What is temporal summation? |
is due to successive waves of neurotransmitter release from same neuron |
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what is synaptic plasticity? |
- repeated use of neuronal pathway may strengthen or reduce synaptic transmission in the pathway - when repeated stimulation inhances excitability, is called long-term potentiation |
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what is postsynaptic inhibition? |
produced by inhibitory neurotransmitters such as glycine and GABA - hyperpolarizes postsynaptic neuron and makes it less likely to reach threshold voltage at axon hillock
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What is presynaptic inhibition? |
sometimes a neuron synapses on the axon of a second neuron, inhibiting the release of excitatory neurotransmitter from the second neuron |
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what are the three primary vesicles of the brain? |
1. forebrain 2. midbrain 3. hindbrain |
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what are the secondary vesicles of the forebrain? |
1. telencephalon 2. diencephalon |
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what makes up the telecephalon? |
the cerebral hemispheres (hemispheres make up cerebrum) |
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what makes up the diencephalon? |
the thalamus and hypothalams |
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what is the secondary vesicle of the midbrain? |
mesencephalon |
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what makes up the mesencephalon? |
the midbrain |
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what are the secondary vesicles of the hindbrain? |
1. metencephalon 2. myelencephalon |
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what makes up the metencephalon? |
pons and cerebellum |
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what makes up the myelencephalon |
medulla oblongata |
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What part is considered to be rudimentary part of brain? |
BRAIN STEM |
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true or false: Almost all neurons are present at time of birth |
TRUE |
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Why does our brain continue to grow? Is it because we are getting more neurons? |
it continues to grow because of glial cells, NOT because we are getting more neurons |
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what are some characteristics of the adult brain? |
- weights 1.5 kg - 90% glial cells make half of the weight - receives 20% of blood flow to the body - needs constant supply of oxygen and glucose
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how is the brain protected? |
1. CRANIUM -skull and vertebral column 2. MENINGES - 3 protective membranes (dura, arachnoid, and pia mater) provide nourishment; is between skull and brain tissue 3. CEREBROSPINAL FLUID - provides cushioning 4. BLOOD BRAIN BARRIER - guards against chemical fluctuation and potential pathogens |
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what are the characteristics of the cerebrum? |
- derived from telencephalon - LARGEST portion of brain!!! - consists of a right and left cerebral hemisphere
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what connects the right and left cerebral hemispheres? |
corpus callosum |
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what are the 5 lobes of the cerebrum and their functions? |
1. frontal (front of brain)- voluntary motor control of skeletal muscles and higher intellectual processes 2. parietal (top of brain)- somatesthetic interpretations; understanding speech and formulating words to express thoughts 3. tempora(side of brain)l- process auditory input 4. occipita (back of brain)l- processes visual imput 5. insula(inside of brain)- memory and integration of other cerebral activities from other lobes |
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what separates the frontal and parietal lobes? |
central sulcus |
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the central sulcus separates frontal and parietal lobe. what are its two forms? |
1. precentral gyrus- located in FRONTAL LOBE and responsible for motor control 2. postcentral gyrus- located in PARIETAL LOBE and responsible for somatesthetic sensation; responsible for sensory info such as touch, temperature,etc... |
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where is the precentral gyrus located and its function? |
- frontal lobe - used for motor control
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where is postcentral gyrus located and its function? |
- parietal lobe - used for sensory |
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what are mirror neurons and its function? |
- found in frontal and parietal lobes - is able to mimic activity that we don't physically do but are able to mentally do - physically and mentally doing something uses the same amount of neurons |
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what is cerebral laterization? |
- is the idea that right hemisphere of brain controls left hemisphere of brain and vice versa |
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How do left and right cerebral hemispheres communicate and what are their functional specialties? |
- the cerebral hemispheres communicate through the corpus callosum - LEFT HEMI= language, speech, writing, logical thought, analytical and objective - RIGHT HEMI= visual tasks, intuitive, thoughtful, subjective, emotional
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what are the two areas in the brain that are involved with language? |
1. Broca's Area 2. Wernicke's Area |
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where is Broca's area located and what is its function? |
- located in left inferior frontal gyrus - controls motor aspects of speech - Broca's Aphasia (defect)= can't articulate speech; person knows what to say, but can't say it - can't physically make muscles to speak words - chewing and etc... are okay; only production of speech affected! |
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where is Wernicke's area and what is its function? |
- located in left superior temporal gyrus - controls comprehension and understanding of works - info about written words send by occipital lobe - wernicke's aphasia= rapid speech with no meaning; says words/sentences that don't make sense |
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what is the process of speech production? |
word comprehension starts in wernicke's area and is then sent to broca's area so can form/articulate words |
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what does the limbic system consist of ? |
- hypothalamus - amygdala - hippocampus
-in telencephalon |
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what is short term memory? |
can last for seconds or hours; has limited capacity and fades quicklY; changes are QUANTITATIVE - has pre-existing neurons |
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what is long term memory? |
attained by active rehearsal, has large capacity and takes longer to retreive; involves permanent changes in neurons - differences are QUALITATIVE, different proteins are made, new synapses established |
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Where is short term memory consolidated into long term memory |
the hippocampus |
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what are dendritic spines? |
involved for storing long term memory! - are made by production of new proteins in neurons -spines will enlarge and change shape |
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what is the amygdala important for? |
- fear memories - involved if memory has an emotional component |
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what is retrograde amnesia? |
cant remember something before traumatic event |
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what is anterograde amnesia? |
can't remember future events after traumatic event |
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what is the epithalamus? |
- located in diencephalon - contains pineal gland, which secretes melatonin |
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what is the thalamus? |
- relay center where most sensory info is passed to cerebrum - crude awareness of sensations and reinforces motor control -part of telencephalon |
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what is the hypothalamus important for? |
- important for maintaining homeostasis and regulating autonomic nervous system - helps with regulation of body temp, sleep and wakefulness, emotions, etc... - SERVES AS LINK BETWEEN NERVOUS SYSTEM AND ENDOCRINE SYSTEM BY THE PITUITARY GLANDS!! -part of telencephalon |
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What is the relationship between hypothalamus and anterior pituitary gland? |
hypothalamus produces regulatory hormones that control the anterior pituitary gland, therefore linking the nervous and endocrine systems - oxytocin and vasopressin produced in hypothalamus and stored in posterior pituitary |
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what is the midbrain important for? |
alot of motor coodination and visual and auditory reflexes occur here! |
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where are pons and cerebellum located and its functions? |
- located in hindbrain and in metencephalon vessicle 1. CEREBELLUM= second largest structure; needed for motor learning and the proper timing and force required to move limbs in a specific task; influences motor coordination through inhibition on motor cortex 2. PONS= connects fibers from medulla to midbrain and cerebellum; - contain nuclei for cranial nerves - helps when we sleep so our organ system is still working |
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what is medulla oblongata important for? |
- is the place where nerve cells cross from one side of body to other (decussation) - is why right side of brain can control left side of body |
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What is the reticular activating system (RAS)? |
- it helps us fall asleep by tuning out sensory stimuli - when we wake up, we are alert to sensory stimuli - includes pons and reticular formation of midbrain
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Where does the decussation take place? |
medulla oblongata |
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what type of matter is the dorsal horn and ventral horn? |
gray |
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what type of neurons does the ventral horn consists of? |
motor neurons |
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what type of neurons does the dorsal horn consists of? |
sensory neurons |
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what are spinal nerves? |
they are all mixed nerves that separate near the spinal cord into a dorsal root carrying sensory fibers and ventral root carrying motor fibers |
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what two branches of systems can motor neurons (efferent) be divided into? |
autonomic and somatic motor system |
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how many neurons does the somatic neuron consists of? if have more than one, name them and its functions |
they have cell bodies in spinal cord and ONE neuron that travels from spinal cord to effector cell, which are skeletal muscles -goes directly from CNS to effector
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how many neurons does autonomic motor system consists of? if have more than one, name them and its functions |
- they have TWO sets of neurons in the PNS 1. PREGANGLIONIC- cell body in gray matter of spinal cord - travels from spinal cord and synapses at autonomic ganglion - usually myelinated 2. POSTGANGLIONIC- from autonomic ganglion, goes out to smooth mucles, cardiac muscles, or glands and synapses there - usually unmyelinated |
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what is the function of the autonomic nervous system? |
- controls involuntary functions - influences heart rate, digestion, respiratory rate, perspiration, pupil dilation, etc... - effectors are cardiac and smooth muscles and glands |
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what are the functions of somatic motor neurons? |
- they control voluntary motion - effector organ is skeletal muscle |
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comparing somatic and autonomic motor systems, is there a presence of ganglia? |
somatic- NO GANGLIA autonomic- yes! cells bodies of postganglionic autonomic fibers located in paravertebral, pervertebral and terminal ganglia |
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comparing somatic and autonomic, what type of neuromuscular junctions do they have? |
-somatic has specialized motor end plate - autonomic has not specialization of postsynaptic membrane; all areas of smooth muscle ells contain receptor proteins for NTs |
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compating somatic and autonomic, are they exicitatory or inhibitory? |
somatic = ALWAYS EXCITATORY autonomic= INHIBITORY OR EXCITATORY |
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are somatic or autonomic fast conducting? |
somatic= FAST CONDUCTING autonomic SLOW CONDUCTION due to preganglionic fibers lightly myelinated and postganglionic not myelinated
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what is important about the autonomic ganglia? |
its location is a distinguishing feature between sympathetic and parasympathetic nervous system |
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what are the two systems of the autonomic nervous system and where do they originate? |
1. sympathetic- preganglionic originate from the thoracic and lumbar levels of spinal cord - synapses in sympathetic chain of ganglia 2. parasympathetic- preganglionic neurons originate in brain and sacral region of spinal cord; axons synapse to ganglia near or in effector organs |
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what are the characteristics/functions of sympathetic pre and post ganglionic neurons? |
1. preganglionic- are myelinated axons that exit spinal cord at ventral roots and diverge into WHITE RAMI COMMUNICANTS and then into autonomic ganglia at multiple levels 2. post ganglionic- are unmyelinated and form gray rami communicantes, which return to the spinal nerve and travel with other spinal neurons to their effectors
WHITE= ENTRY GRAY= EXIT POINT |
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why the sympathetic nervous system can have mass activation and parasympathetic system cannot? |
because preganglionic neurons can branch and synapse in ganglia at any level, there is divergence and convergents, which allws sympathetic division to act as a single unit through mass activation----important for fight or flight
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what is collateral ganglia and its importance? |
- they don't synapse in sympathetic chain of ganglia. - instead, form splanchnic nerves, which synapse in collateral ganglia - collateral ganglia include celiac, superior mesenteric and inferior mesenteric ganglia |
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what are the two parts of the adrenal glands? and why is adrenal gland considered a special case? |
cortex(outer) and medulla(inner) -considered a special case b/c it is formed as one structure bt can be 2 different glands |
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what are the functions of the cortex and medulla of the adrenal gland? |
1. cortex- secretes steroid hormones 2. medulla- intervated by sympathetic preganglionic neuron - secretes epinephrne into blood system - behaves like postganglionic sympathetic neuron...NT release of norepinephrine at synapse |
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do preganglionic neurons in the parasympathetic nervous system travel with somatic neurons in spinal neurons? |
no, sympathetic postganglionic neurons do |
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vagus nerve |
- cranial nerve X - provides major sympathetic innervation to thoracic and abdominal cavities - branches into several plexi and nerves - synapses with postganglionic nerves with effector organs - heart, lungs, esophogus, stomach, pancreas, liver, intestines - goes through all organs |
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what are the functions of the SYMPATHETIC nervous system? |
- activates body for "fight or flight" through RELEASE OF NOREPHINEPHRINE from postganglioni neurons and SECRETION OF EPINEPHRINE from adrenal medulla - increases heart rate and blood glucose levels
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what are the parasympathetic functions? |
- allows body to "rest and digest" through RELEASE OF ACETYLCHOLINE (ACh) from postganglionic neurons - slows heart rate, dilates visceral blood vessels, increases digestive activities
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does the sympathetic and parasympathetic nervous system release ACh from both the preganglionic and postganglionic neuron? |
- PARA releases ACh from pre and postganglionic neurons (ACh released during entire way) - SYMPATH releases ACh from preganglionic neurons but release NOREPINEPHRIN FROM POSTGANGLIONIC neurons |
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What are varicosities, synapse en passant? |
- are axons of postganglionic neurons that have various swellings valled varicosities that release neurotransmitter along length of axons, not just at the terminal ends - form "synapses en passant" in passing because dumps out NT as it moves through |
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what are complementary effects? |
- occurs when both divisions produce similar effects on same target, with some differences EX: salivary gland secretion- para stimulates secretion of watery saliva whereas sympath constricts blood vessels so secretion is thicker |
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what are cooperative effects? |
- when both divisions produce different effects that work together to promote a single action EX: erection and ejaculation- para causes vasodilation and erection; sympa causes ejaculation |
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Know how cholinergic receptors can be excitatory or inhibitory (nicotinic vs. muscarinic). |
1. nicotinic ACh receptors- depolarization causes excitation 2. muscarinic ACh receptors- produces parasympathetic nerve effects in heart, smooth muscles and glands - G-protein coupled reeptors - hyperpolarization (K+ channels open) causes inhibition - depolarization (k+ channels closed) causes excitation |
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what organs are with dual innervation( both para and symp work together) |
heart rate= PS decreses, S increases digestive functions = PS inreases, S decreases pulip diamiter = PS decreases, S increases |
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what are organs without dual innervation? |
the following are only innervated by SYMPATHETIC: -adrenal medulla - arrector pili muscles in skin - sweat glands in skin - most blood vessels
regulation by increasing and decreasing sympathetic nerve activity important for body temp regulation |
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what is the law of specific nerve energies? |
- information from given sensory nerve can only be experienced as ONE STIMULUS TYPE EX: punch to the eye is perceived as flash of light because that's the only info the eye can send to brain because doesn't have pressure receptors, only light |
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What is meant by receptor potential or generator potential and how does it differ from action potential? |
- similar to AP because stimulus causes increase in ion permeability of membrane leading to production of a depolarization: receptor or generator potentials - differs from AP because is graded...increasing intensity of stimulus increases magnitude of the generator potential until threshold is met and AP occurs |
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how do tonic and phasic receptors respond? |
1. tonic receptors- respond at constand rate as long as stimulus is applied; doesnt go away quickly; EX= pain 2. phasic receptors- respond with burst of activity but quickly reduce firing rate to constant stimulation (=adaptation) ; EX= smell, touch eventually goes away because adapted to it |
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how is the generator potential in tonic receptors? |
- generator potential is proportional to the intensity of the stimulus - increased intensity results in increased frequency of AP after threshold is reached - the stronger the stimulus, the larger generator will become. However, for APs, magnitude does not change but the frequency of how much is fired changes! |
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what are the cutaneous receptors and their functions? |
1. free ending nerves- light touch, hot, cold, pain 2. merkel's disk- sustained touch, pressure 3. ruffini corpuscles- sustained pressure 4. meissner's corpuscles- tecture, slow vibrations 5. pacinian corpuscles- deep pressure, fast vibrations
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what are the five tastes? |
sour, salty, sweet, umami, and bitter |
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where are the receptors for taste buds located? |
papillae
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what does the inner ear consists of? what is it important for? |
- consists of a bony labyrinth surrounding a membranous labryinth - between the two is a fluid called perilymph and within this is called the endolymph - endophymph has high K+ concentration - contains vestibular apparatus - important for equilibrium and balance - also containe cochlea! |
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What are the names of various structures that constitute vestibular apparatus ? |
- this apparatus provides sense of equilibrium - is located in the inner ear - consists of the uricle and saccule - helps with linear acceleration
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what are the functions of the uricle and saccule? |
- they provide a sense of linear acceleration - URICLE = horizontal orientation - SACCULE= verticle orientation |
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what is within each of the uricle and saccule? what is its function? |
MACULA - consists of hair cells and supporting cells - is like a little rock and moves when we move - when hair cells move to left, AP are stimulated - when hair cells move to right, APs are inhibited
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What is the mechanism by which sensory hair cells are activated? |
- when sterocilia bend toward kinocilum, k+ channels open and vice versa -sensory cells have high concentration of K+ outside of cells so when k+ channels open, it rushes in and causes DEPOLARIZATION |
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Where are hair cells located for linear (horizontal and vertical) and angular motion? |
- hair cells for linear motion is located the macula, which is located within the uricle and saccule - for 3D movement, hair cells are embedded in CUPULA of crista amullaris...when endolymph moves, cupula moves...is in semicircular canals!
ALL ARE LOCATED IN INNER EAR! |
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what is nystagmus? |
- when person's body spinning, eye movements are towards opposite direction of the spin to maintain fixation point - when body comes to a stop, capula is bent by fluid inertia and eye movements still affected - jerky eye movement = nystagmus |
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what is vertigo? |
- can occur when nystagmus causes a loss of equilibrium - symptoms included dizziness, pallor, sweating, nausea, vomitting, |
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how is hearing done in the OUTER EAR? And what does outer ear consist of? |
- sound waves are funned by the pinna(auricle) into the EXTERNAL AUDITORY MEATUS, which channels sound waves to the TYMPANIC MEMBRANE - outer ear = ausicle and external auditory meatus |
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what does the middle ear consists of and what is its function? |
- middle ear is between tympanic membrane and the cochlea; it holds the auditory ossicles - the malleus (hammer) is attached to the tympanic membrane and carries vibrations to the INCUS( anvil)... the STAPES (stirrup) receives vibrations from incus, transmits to oval window
- vibrations are carried along these three parts and vibrate to make sounds because in contact with tympanic membrane |
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what is the cochlea divided into and what part of the ear is it apart of? |
- makes up part of the INNER EAR - is divided into 1. scala vestibuli 2. cochlear duct 3. scala tympani |
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what types of hearing impairment are there and describe. |
1. conduction deafness- sounds waves not conducted from outer to inner ear; maybe due to buildup of earwax, too much fluid in middle ear, and damage to eardrum; can be helped by hearing aids 2. sensorineural- nerve impulses not conducted from cochlea to auditory cortex - may be due to damaged hair cells, may only impair hearing of particular sound frequencies and not others - helped by cochlear implants |
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what is the basic process of how we can see? |
1. light passes through cornea and into anterior chamber of eye 2. passes through pupil, which can change shape to let more or less light in...iris responsible for changing shape 3. then it passes through the lens, which can change shape to focus the image 4. finally, light hits retina where photoreceptors are located |
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where are photoreceptors located? |
retina |
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what is the optic disc and optic nerve? |
axons in retina gather at optic disc and exit eye in optic nerve - optic disk = BLIND SPOT - have no photoreceptors here |
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what increases/decreases pupil shape? |
iris
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is constriction of the pupil sympathetic or parasympathetic stimulation? |
- via parasympathetic - occurs when in bright light, so trying to not let that much light in cause too strong |
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is dialation of pupil sympathetic or parasympathetic stimulation? |
- via sympathetic - occurs when in dim light and pupil becomes bigger so more light can come in
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what is the importance/characteristics/function of retina? |
- is an extention of the brain - photoreceptors are located here - has 3 layers: rods and cones (deepeds layer), bipolar cells (middle) and ganglionic cells (furthest away) - light passes through rods and cones then bipolar cells then ganglionic cells, which combine to form optic nerve and leaves eye at the blind spot
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how do RODS work? |
- VISION IS SHADES OF GREY - is sensitive to light so better for peripheral and night vision - photopigment is OPSIN, but when compines with retinen becomes RHODOPSIN - LIGHT CHANGES CHEMICAL CHANGE IN RHODOPSIN in dark: 11-cis-retinene in light: all trans- retinene |
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how do CONES work? |
- photoigment = photopsin - has 3 types of wavelengths= blue, green, and red... these three colors make different colors - USED FOR COLOR VISION - high acuity - less sensitive to light, so in order to work better, have to be in room with lots of light...wont work well in dimly lit room
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how does phototransduction occur in dark conditions? |
- is ACTIVATED IN DARK CONDITIONS!! DARK CONDITIONS: - Na , Ca channels OPEN....DEPOLARIZATION OCCURS and there is a release of NT - NT= glutamate, which is used to INHIBIT bipolar cells
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how does phototransduction occur in LIGHT conditions? |
- Na/Ca channels = CLOSED - closed b/c of conversion of cGMP to GMP, which causes Na/Ca channels to close and release of NT inhibited - no release of NT causes no inhibition to occur and thus, nerve impulse from bipolar to ganglionic cell is stimulated
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what is the fovea centralis? |
is where visual acuity is best - therefore we can see fine details due to this |
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what it the bone that moves that is attached at the muscle? |
insertion
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what is the muscle attached to a bone that does not move at the muscle? |
ORIGIN |
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when a muscle contracts, does it shorten or become longer>? |
SHORTENS |
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what are fllexor muscles? |
they decrease the angle between two bones at a joint EX: bending your knee |
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what are extensor muscles? |
they INCREASE ANGLE between two bones at a joint EX: extending your leg |
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what is the structure of skeletal muscles? |
- are surrounded by a fibrous EPIMYSIUM - connective tissue sheath around column of muscle cells called PERIMYSIUM, which subdivides he muscle into bundles called FASSICLES - each fassicle is divided into muscle fibers surrounded by ENDOMYSIUM |
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what is sarcolemme? |
- are plasma membranes in muscle fibers - are specialized for muscle function and forms transverse tubules, which spread electrical signals
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what are I bands? |
they are the light bands in muscle fibers
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what are A bands? |
they are the dark bands of muscle fibers |
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what are myofibrils? |
are densely packed subunits that run along the length of the muscle fiber] - are composed of THICK and THIN myofilaments |
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what is the sarcomere? |
- is the area from one Z line to the next Z line - is the smallest functional unit and capable of contraction
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what is titin? |
protein that anchors in the thick filaments and allows elastic recoil |
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sliding filament theory |
when a muscle contracts, the sarcomeres shorten - A bands DO NOT shorten - I bands DO shorten, but thin filaments DO NOT - thin filaments SLIDE toward H zone, causing overlap - as contracting, overall size of sarcomere shortens |
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what type of protein does thick myofilaments contain? |
- contain myosin - each protein has two globular heads with actin binding ATP binding sites
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what type of protein does thin myofilaments contain? |
- composed of actin - have proteins called TRYPOMYOSIN and TROPONIN that prevent myosin binding at rest |
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what is the mechanism of the sliding filament theory? |
1. muscles shorten due to thin filaments sliding (pulled) towards center of A bands - shortens distance between Z lines 2. H band becomes smaller and may disappear 3. I bands shortens 4. A bands DO NOT CHANGE - thin filaments slide over thick filaments |
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how does tropomyosin function? |
- physically blocks cross bridges - Troponin I inhibits binding of myosin - troponin T binds to tropomyosin - Troponin C binds to calcium |
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what are the roles of calcium? |
- muscle cells are stimulated by the directed release of Ca2+ inside the muscle fiber - some attaches to troponin C, causing conformational change in troponin and tropomyosin - myosin is allowed access to form cross bridges |
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what does the sarcoplasmic reticulum store? |
stores CALCIUM when musle is AT REST |
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where is most calcium stored? |
terminal cisternae |
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in the sarcoplasmic reticulum, when a muscle fiber is stimulated what happens to calcium? |
calcium diffuses our of calcium release channels - at end of contraction, calcium is actively pumped back into sarcoplasmic reticulum |
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what is the neuromuscular junction? |
is the site where a motor neuron stimulates a muscle fiber |
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what is the motor end plate? |
is the area of the muscle fiber sarcolema where a motor neuron stimulates it - is where membrane depolarization occurs |
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what are transcerse tubules and its functions? |
- are narrow membranous tunnels formed from the sarcolemma - open to extracellular environment - able to conduct APs - closely situated next to terminal cisternae |
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what happens for muscle relaxation? |
1. action potentials cease 2. Ca2+-ATPase pumps move Ca2+ back into sarcoplasmic reticulum 3. no more calcium is acailable to bind to troponin C, so no more cross bridges are formed |
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what happens if you run our of ATP for muscle contraction? |
PROBLEMS: 1. ATP needed to pump calcium back to sarcoplasmic reticulum 2. ATP needed to bind to myosin so that myosin head released from actin
- if run out of ATP, cant have inorganic phosphate - also prevents a contraction because gets "locked" and needs ATP to start |
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what are motor units? |
- a single motor neuron and all the muscle fibers it innervates - all muscle fibers in a motor unit contract at once - like neural divergence - its contraction strength comes from motor unit - motor unit= number of muscle fibers controlled by a single somatic motor neuron |
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what are two primary methods for grading of muscle contraction? |
1. varying number of muscle fibers contracting within a muscle- recruitement - each muscle is innervated with several motor neurons - each motor neuron branches out to several motor units
2. Manipulating tension developed by each contracting muscle fiber - variation of muscle repsonse to AP - frequency of stimulation - one stimulation = TWITCH - two stimulation = SUMMATION - high frequency stimulation causes fusing of twitches and results in TETANUS |
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how can we lift things for an indefinite period of time? |
ASYNCHRONOUS ACTIVATION of motor units - some motor units start to twitch when others start to relax - this produces continuous contraction of the whole muscle - recruitment makes contractions stronger |
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what is muscle strength determined by? |
- number of fibers recruited to contract - frequency of stimulation - thickness of each muscle fiber (thickness= stronger) - initial length of fiber at rest
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what are two types of muscle fibers? and their functions? |
1. extrafusal fibers- responsible for contraction 2. intrafusal fibers- proprioceptor mechanism - allows monitoring of muscle contraction - MONITORS EXTRAFUSAL FIBERS |
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what are golgi tendon organs? |
monitors tension on tendons from muscle groups - produces inhibitory motor responses |
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what is the muscle spindle apparatus? |
- monitors length - muscles that require more control have more spindles - stretching a muscle causes spindles to stretch |
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what are types of lower motor neurons? |
1. alpha- innervate extrafusal( contracting) muscle fibers - responsible for muscle contraction - fast conduction 2. Gamma- innervate intrafusal (stretch) muscle fibers (spindle fibers) - does not cause contraction - increases sensitivity to stretch - allows muscle tone to be maintained when no contraction is occuring
EXTRAFUSAL FIBER = GAMMA NEURONS INTRAFUSAL FIBERS = ALPHA NEURONS - active stretch
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what is the monosynaptic stretch reflex? (knee jerk reflex) |
1. stretch on a muscle stretches spindle fibers 2. activates sensory neurons 3. sensory neuron activates alpha motor neuron 4. motor neuron stimulates extrafusal muscle fiber to contract 5. stretch on spindle is reduced |
