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Nervous system (3)
Bio 3 Lecture 10
| Question | Answer |
|---|---|
| What is action potential? What's another term for it? | Long distance electrical signals produced by excitable membranes. Also called a nerve impulse. |
| What does a nerve impulse involves? | A brief reversal of membrane potential |
| What is graded potentials? How is it produced? What happens when you add graded potentials together? | It's the result from the summation of subthreshhold potentials. It's produced by the opening of different chemically gated channels. A polarity change occurs when graded potentials are added together. |
| What causes changes in membrane potential? | They're due to changes in membrane permeability |
| What are gated channels and what are the types? | Gated channels are like doors that open or close in response to a stimuli. There's chemically gated (or ligand-gated) which responses to a chemical signal and there's voltage-gated channels that respond to a chages in membrane potential. |
| Which gate leads to graded potential and action potential? | Ligand-gated channels lead to graded potential and voltage-gated channels produce action potentials. |
| Explain the process of change in membrane voltage. | Hormones and neurotransmitters act as ligands, inducing opening of ligand-gated channels, and causing changes in plasma membrane permeability that lead to changes in membrane voltage. |
| How are permeability changes measurable? | Permeability changes are measurable as depolarizations or hyperpolarizations of the membrane potential. |
| Depolarization makes the membrane potential what? | A depolarization make the membrane potential less negative (so more positive). Ex: -70mV to -65 mV |
| Hyperpolarization makes the membrane potential what? | A hyperpolarization makes the membrane potential more negative. Ex: -70 mV to -75 mV |
| [Graded potential] A small stimuli causes a ... depolarization. A larger stimuli causes ... depolarization. | A small stimuli causes a small depolarization of the cell membrane. A larger stimuli causes more depolarization. |
| [Graded potential] A stimuli of long duration causes a ... depolarization. | a longer lasting depolarization |
| If the stimulus depolarizes above the thredshold, what could it trigger? | May trigger an action potential in a postsynaptic neuron |
| What causes a stimuli to result in a hyperpolarization? | Depends on the specific ion channels activated in the cell membrane |
| On a graph, identify a depolarization and a hyperpolarization | slide 6 bro |
| Can depolarizing and hyperpolarizing potentials add together? | Yes, they can add together to amplify or reduce their effects (like a wave that adds and created a bigger wave or cancel eachother!) |
| When does action potential occur? | When depolarization reaches the threshold potential ( the threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential, usually about -55mV) |
| What causes action potentials? | It's caused by gated ion channels that open or close |
| What channels are involved in action potentials? | Na+ and K+ (so 2 different ion channels) |
| What are the steps of the action potential? | 1) Resting state 2)Depolarization 3)Repolarization 4)Hyperpolarization |
| [Action potentials] Explain the first step of the action potential. | It starts with the resting state where all gated Na+ and K+ channels are closed. The Na-K pump is opened. |
| [Action potentials] Explain the second step of the action potential. | 2nd is depolarization where the Na+ channels open rapidly and there's an influx of Na+.Potassium channels remain closed, which changes the polarity of the membrane. |
| [Action potentials] Explain the third step of the action potential. | 3rd come repolarization where Na+ channels closes and the K+ channels open. There's an efflux of K+ that repolarizes the membrane. This reverses the polarity back to an inside negative state |
| [Action potentials] Explain the fourth step of the action potential. | Last there's the 4th with hyperpolarization. Some K+ channels remain open longer than necessary to restore the resting potential. Na+ channels reset and Na-K pump continues working |
| Summarize the action potential steps | 1) Depolarization= due to influx of Na+ 2) Repolarization= K+ gates open, Na+ gates close 3) Hyperpolarization (aka undershoot) 4) Reestablishment of resting potential |
| How can the velocity of conduction can be increased in the nerve impulse transmission? | 1)Increasing the axon diameter 2)Action potential is only produced at the nodes of Ranvier through a saltatory conduction (action potential basically jumps) |
| What are synapses? | Intercellular junctions |
| What are the types of synapses? | 1) Presynaptic cell which transmits nerve impulses 2) Postsynaptic cell which receives the nerve impulse |
| What serves as a depolarization of the next region of the axon? | When one region produces an action potential and undergoes a reversal of polarity, it serves as a depolarization of the next region of the axon. |
| What do chemical synapses have? | They have synaptic cleft between the 2 cells |
| What do presynaptic cells contain? | Synaptic vesicles with neurotransmitters |
| Explain the steps involved in synaptic transmission. | 1) Nerve impulse (action potential) travels down axon to axon terminal 2)Action potential open Ca2+ channels, causing Ca2+ to diffuse into synaptic knob 3)Ca2+ influx triggers the release of neurotransmitters from synaptic vesicles into the synapse |
| Explain the steps involved in synaptic transmission. (suite ) | 4) Neurotransmitters diffuse accross synapse and bind to receptors on the post-synaptic cell |
| Neurotrasnmitters can be classified into 2 types, what are they? | Some are inhibitory and others are excitatory. This means the post-synaptic cell may be stimulated or inhibited depending on the neurotransmitter |
| After a synaptic trasmission, how must the signal be stopped? | By removing neurotransmitters from the synaptic cleft. |
| Explain what are the 3 possible fate of neurotransmitters (see slide 21/22) | 1) Immediately transported back into the presynaptic neuron in a process called reuptake 2)Go through enzyme degradation 3)Diffuse into glial cells |
| Recognize the fate of the neurotrasmitter based on a visual representation | See slide 22 |
| What is Acetycholine process (ACh) (aka what does it do and where is it)? | ACh crosses the synapse between a motor neuron and a muscle fiber. It binds to a receptor in the postsynaptic membrane. It stimulates muscle contraction. |
| In what class of neurotransmitters is ACh? | It's an excitatory neurotransmitter |
| Name inhibitory neurotransmitters | There's glycine and GABA (lawnda-aminobutyric acid). They're both amino acids |
| Epinephrine (adrenaline) and norepinephrine are neurotransmitters, what are they reponsable for? | For the fight or flight response |
| What is dopamine responsible for? | It's used in some areas of the brain that control body movements |
| What is serotonin responsible for? | It's involved in the regulation of sleep |
| What part of the body does cocaine affect? | It affects neurons in the brain's pleasure pathways (aka the limbic system) |
| Explain the process of how cocaine affects these neurons (how does it become addictive) | 1) Binds dopamine transporters and prevents the reuptake of dopamine 2)Dopamine fired pleasure pathways more and more 3)Prolonged exposure triggers the limbic system neurons to reduce receptor numbers 4)The cocaine user is now addicted yay |
| What is the central nervous system subdivided into? | The brain and the spinal cord |
| What is the spinal cord protected by? | Enclosed and protected by the vertebral column and the meninges |
| What are the functions of the spinal cord? | It serves as the body's "info highway", it relays messages between the body and the brain. Also functions in reflexes. |
| What kind of reflexes types with the spinal cord? | 1) 3 reflexes arc, for example the withdrawal reflex 2) 2 neurons reflex arc |
| What does the PNS consist of? | Consist of nerves and ganglia. |
| What are nerves and ganglia? | Nerves are bundles of axons and ganglia aggregates of neuron cell bodies |
| In the somatic nervous system, how many neurons are needed from the CNS | One neuron |
| I love crystal meth ______ | so much |
| In the autonomic nervous system (sympathetic and parasympathetic), how many neurons are needed from the CNS | 2 neurons |
| What neurotransmitter is needed at effector for somatic nervous system? | ACh (Acetylcholine) |
| What neurotransmitter is needed at effector for autonomic nervous system (sym and para)? | Sympathetic has NE (norepinephrine) and parasympathetic has ACh (Acetylcholine) |
| The somatic nervous system takes care of what organs? | Skeletal muscles |
| What effect does the somatic motor system has? | Stimulatory |
| The automatic nervous system takes care of what organs? for para and sym | Smooth muscles, cardiac muscles and glands |
| What effect does the automatic motor system has? | It's either stimulatory or inhibitory (depends on neurotransmitter and receptors on effector organs) |
| What is the sympathetic division for? What are the symptoms? | The fight or flight response. Symptoms: pupils dilate, salivary glands stop secretion, speed up heartbeat, secretes adrenaline, stops digestion, delays emptying urinary bladder, sweat. |
| What is the parasympathetic division for? What are the symptoms? | Relax state response. Opposite symptoms to the sympathetic N.S |
| What are senses? What are they for? | Vision, hearing, taste, smell and touch. Senses provide information about the environment |
| What are the 3 classes of receptors? | There's mechanoreceptors, chemoreceptors and electromagnetic receptors |
| What are mechanoreceptors? | stimulated by mechanical forces such as pressure |
| What are chemoreceptors? | They detect chemicals or chemical changes |
| What are electromagnetic receptors? | They react to heat and light energy |
| What are the four-steps of sensory information conveyed by the CNS and perception? | 1)stimulation 2)Transduction 3)Transmission 4)Interpretation |
| Describe the process of information perception | First there's the stimulus, then transduction of stimulus into receptor potential in sensory receptor. Then transmission of action potential in sensory neuron. Finally, interpretation of stimulus in central nervous system |
| What is a receptor potential? | It's like a graded potential, so the greater the sensory stimulus, the greater the depolarization of the receptor potential and the higher the frequency of action potentials |
| Where are mechanoreceptors and what are their funtions? for cutaneous receptors :) | They're receptors in the skin. They respond to stimuli at the borders between internal and external environments. They're the receptors for pain, heat cold, touch and pressure |
| What are thermoreceptors? | Thermoreceptors are naked dendritic ending of sensory neurons that are sensitive to changes in temperature. |
| What are cold receptors stimulated by? | By a sudden fall in temperature and are inhibited by warming (it's the reverse for warm receptors) |
| What can you say about the numbers and location of cold receptors? | They're higher in the skin and are more numerous than warm receptor |
| What senses is detected by mechanoreceptors? | The sense of touch |
| What are the 2 types of mechanoreceptors? | Phasic (intermittently activated) and tonic (continuously activated) |
| What receptors are in phasic mechanoreceptors? | Hair follicle receptors, meissner corpuscles and pacinian corpuscles |
| What receptors are in tonic mechanoreceptors? | Ruffini corpuscles and merkel's disks |
| Identify mechanoreceptors in the skin | slide 47 |
| What are the functions of merkel cell, meissner corpuscle, ruffini corpuscle and pacinian corpuscle? | 1)Merkel: Near surface skin, sensitive to touch, pressure 2) Meissner: Concentrated in hairless skin sensitive to fine touch 3)Ruffini: Near surface skin, sensitive to touch, pressure 4)Pacinian: Pressure-sensitive deep below skin in subcutanous tissue |
| What are the parts of the ear? | Outer ear, middle ear and inner ear |
| What is the outer ear? | It's the auditory canal to the tympanic membrane (eardrum) |
| Kermit sniffing cocaine is so inspiring, it is my ___ | motto |
| What is the middle ear? | Middle ear includes the bones! |
| What are the bones in the middle ear? | The Malleus (hammer), the incus (anvil) and the stapes (stirrup) |
| What does the inner ear consist off ? | It consists of the cochlea and the semicircular canals |
| What is the cochlea? | A bony structure filled up with fluid that translates sound into nerve impulses |
| What are semicircular canals? | It detects acceleration, gives a sense of balance |
| What are taste buds? Where are they located? | Collections of chemosensitive cells associated with afferent neurons. Located in the epithelium of the tongue and oral cavity within areas called papillae |
| What does the sense of smell involves? How is info transmitted? | Involves neurons in the upper portion of the nasal passages. The neurons transmit impulses directly to the brain via the olfactory nerve. |
| How many odor can humans smell? | thousand of different smells (10,000) |
Created by:
Malayka
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