Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Nervous System
| Question | Answer |
|---|---|
| What are neurones? | Nerve cells. They transmit information. |
| What are the two kinds of signals used in nervous communication? | Electrical and chemical signals |
| What is a nervous impulse/signal? | An electrochemical change that travels along the length of a neurone. |
| What are neurotransmitters? | Chemical signals used to transmit nervous impulses between neurones. |
| What are the two components of the central nervous system(CNS)? | Brain and spinal cord |
| What is the function of the central nervous system(CNS)? | The control of all organ systems (circulatory, digestive, urinary etc) to ensure proper functioning. |
| What is the peripheral nervous system (PNS)? | The nerves which conduct impulses between the CNS and all body tissues, organs and systems. |
| What are the three types of neurones? | 1) Motor 2) Sensory 3) Interneurone (relay) |
| State the function of sensory neurones. | They transmit information from sensory receptors to the central nervous system. |
| Name a few external stimuli which can be detected by sensory receptors. | Heat, cold, smell, taste, sound, touch |
| Name a few internal stimuli which can be detected by sensory receptors. | Blood pressure, carbon dioxide, blood glucose levels, heart rate etc. |
| What is the role of the dendron? | Brings information TO the cell body. |
| What is the role of the axon? | Takes information AWAY from the cell body. |
| State the function of motor neurones. | They transmit information from the CNS to muscles or glands. |
| What is a motor output? | The response to a nerve impulse by a muscle or gland (eg. muscle contraction or gland secretion) |
| State the function of interneurones. | They link sensory neurones with motor neurones. They convey signals to and from the CNS. |
| Describe THREE functions of neurones in the human nervous system. | 1) Receiving sensory input from receptors via sensory neurones. 2) Integration (analysis and interpretation) of all received input from neurones. 3) Generation of a response via motor neurones. |
| List FOUR steps used in nervous system information processing. | 1) Identify the stimulus 2) Determine the intensity of the stimulus 3) Integrate information from the neurones 4) Determine the appropriate response |
| What are the two types of cells which make up nervous tissue? | Neurones and neuroglia(cells which nourish and support the neurones). |
| What is the role of dendrites? | They receive signals from other neurones and conduct them towards the cell body via the single dendron. |
| What is the role of the axon? | Conducts nerve impulses away from the cell body and transmits them to other cells. |
| Describe the myelin sheath and its role. | It is a layer of mostly lipids that acts as electrical insulation of the axon. |
| What is the relationship between lipids and electrical conduction? | Lipids are poor conductors of electrical current because they are non-polar. |
| Name the two types of neuroglia which make up myelin sheaths. | Schwann cells (myelinate neurones in the PNS) and oligodendrocytes (myelinate neurones in the CNS) |
| What is the name for unmyelinated (uninsulated) gaps along the axon? | Nodes of Ranvier |
| What is the function of nodes of Ranvier? | They speed up conduction (see saltatory conduction) |
| Where are neurotransmitters made? | In the cell body(soma) of neurones. |
| Where are neurotransmitters stored? | Secretory vesicles at the tip (synaptic knob)of the axon. |
| What is a synapse? | A gap/junction between the branched ends of two neurones. |
| What is a synaptic cleft? | A narrow gap (10-20 nm) separating the synaptic knob of a transmitting neurone from a receiving neurone or effector cell. |
| What is a membrane potential of a neurone? | Voltage difference across the plasma membrane. |
| Define resting potential. | The membrane potential of a neurone that is not conducting any nerve impulses (not sending any signals). |
| What is the value of the resting potential? | -70 mV The inside (axoplasm) is negative with respect to the outside(extracellular space) |
| What is meant by the membrane being polarized? | There is a difference in the distribution of positive and negative ions on the outside and inside of the neurone. |
| Name the two ions which are mainly responsible for the formation of a resting potential. | Na+ and K+ |
| Another name for the plasma membrane of the neurone. | Neurilemma |
| Name the protein carrier which uses ATP to transport Na+ and K+ against their concentration gradients. | Sodium-potassium pump |
| Describe the relative distribution of Na+ and K+ in the neurone at rest. | K+ concentration greater INSIDE. Na+ concentration greater OUTSIDE. |
| How does the Na+/K+ pump maintain the resting potential? | 3 Na+ ions actively pumped out for every 2K+ ions pumped in. |
| What does the Na+ protein channel do? | Allows Na+ to 'leak' down its concentration gradient when closed. Allow diffusion of Na+ ions in when open. |
| What does the K+ protein channel do? | Allow K+ to 'leak' down its concentration gradient when closed. Allows diffusion of K+ ions when open. |
| What is a stimulus? | A detectable change (chemical, thermal, electrical or mechanical) in the internal or external environment, which changes the membrane potential. |
| What is an action potential(nerve impulse)? | The change in the voltage in the neurone membrane(neurilemma). |
| What is a threshold value? | The minimum change in membrane voltage (polarity) across the neurone membrane that is required to generate an action potential. |
| What is the numerical value of the threshold potential in humans? | -55mV |
| What must happen before an action potential can be triggered? | Stimulus must be sufficIent to cause neurilemma to reach threshold potential. |
| What does 'all or nothing' response mean? | If a stimulus causes the neurilemma to reach threshold potential, an action potential is triggered and cannot be stopped. If it does not reach threshold potential, the neurone will NOT be triggered. |
| Why is the depolarization of the neurone membrane a positive feedback loop? | The influx of Na+ ions causes further depolarization and more Na+ to enter. |
| What happens when a neurone is stimulated? | Sodium channels open and Na+ enter into the neurone. This causes depolarization. |
| What happens when membrane potential reaches threshold value? | An action potential is triggered. |
| What is repolarization? | The process of restoring membrane resting potential. This occurs after the action potential reaches a peak of +40mV. Potassium ion channels open and K+ flow out of the neurone. |
| What is hyperpolarization? | A dip(overshoot) below resting potential which occurs as the membrane potential decreases. |
| Which ion channel is shut during repolarization? | Sodium channel |
| Which protein works to restore the membrane resting potential by active transport? | Sodium-potassium pump |
| Which ion channels are closed when the membrane is at resting potential? | Both Na and K channels are closed but leakage still occurs down their gradients. The sodium-potassium pump works to maintain the membrane potential. |
| What is the refractory period? | Period of time after an action potential has occurred during which a second action potential cannot be triggered even if the stimulus surpasses threshold value. |
| T or F. All neurones generate the same type of action potential. | T |
| T or F. All action potentials are of similar duration and magnitude. | T |
| T or F. The strength(intensity) of the stimulus is signalled by the frequency of the action potentials in a neurone. | T |
| T or F. A stronger stimulus will cause more neurones to trigger nerve impulses and a weaker stimulus will cause fewer neurones to trigger nerve impulses. | T |
| State three factors which influence the speed of transmission along the axon. | Diameter of axon, presence of Myelin sheath, temperature |
| How does the diameter of the axon influence speed of transmission? | Wider diameter offers less resistance to flow of tiny currents and allow faster depolarization. |
| What is saltatory conduction? | The mechanism by which an action potential jumps from one node of Ranvier to the next in a myelinated neurone. |
| Multiple sclerosis is a chronic disease characterized by loss of myelin. What is demyelination? | The loss of myelin sheath from a neurone. |
| What is a consequence of demyelination? | The transmission of nerve impulses is slowed, stopped or jumps across into other demyelinated neurones. |
| What needs to happen to an action potential when it arrives at the synaptic terminal? | It must be converted to a chemical signal. |
| Name the voltage gated channels which open in the synaptic terminal membrane. | Ca2+ calcium channels open |
| What is the result of the calcium channels opening? | High Ca2+ concentration causes the synaptic vesicles to fuse with the presynaptic membrane. |
| Name the chemical released into the synaptic cleft which diffuses across. | Acetylcholine |
| What does acetylcholine do ? | It binds to its specific receptor and opens the gated channel in the post synaptic membrane for Na+ and K+ ions to diffuse. When it is released from its receptors, the channels close. Acetylcholine is degraded by acetyl cholinesterase. |
| Name the two categories of neurotransmitters | Excitatory and inhibitory |
| What does an excitatory neurotransmitter do? | It causes a change in membrane potential that brings the axon close to triggering an action potential (depolarising effect). |
| What does an inhibitory neurotransmitter do? | It does the opposite of the excitatory neurotransmitter and reduces the membrane potential (hyperpolarizing effect). |
| Botulism is severe food poisoning from Clostridium botulinum. What does the toxin from the bacterium do the neurone? | It inhibits the presynaptic release of acetylcholine. This can be fatal because the muscles required for breathing do not contract when acetylcholine release is blocked. |
| How does botox work? | The same toxin from Clostridium botulinum is used to temporarily paralyze facial muscles thus reducing the appearance of wrinkles around the eyes and mouth. |
| How does Viagra work? | The drug inhibits the enzyme which inactivates nitric oxide(a neurotransmitter in males which causes smooth muscle in erectile tissue to relax and thus engorge with blood producing an erection) |
| What is an excitatory postsynaptic potential(EPSP)? | The effect of excitatory neurotransmitters which depolarize the postsynaptic membrane. |
| What is an inhibitory postsynaptic potential (IPSP)? | The effect of inhibitory neurotransmitters which hyperpolarize the postsynaptic membrane. |
| Describe what is meant by integration in a neurone. | Each neurone sums the excitatory post synaptic potentials and the inhibitory postsynaptic potentials and then decides whether an action potential is to be triggered or not. |
| What is the axon hillock? | The area of the neurone that leads into the axon. All EPSPs and IPSPs received from axon terminals of other neurones combine there. If the combination of signals is sufficient to overcome the threshold potential, an action potential is generated. |
| T or F. The magnitude of postsynaptic potentials is influenced by the amount of neurotransmitter that was released into the synapse by the presynaptic neurone. | T |
| What is spatial summation? | The summing up of all EPSPs and IPSPs received by the neurone from different places along it's cell body |
| What is temporal summation? | The summing up of all EPSPs and IPSPs received at the same place in a rapid sequence from one single synapse. |
| T or F. Drugs interfere with neurotransmitter release and uptake in the brain. | T |
| What is the effect of nicotine on the nervous system? | It causes neurones to release dopamine (a neurotransmitter which affects behaviour)and in excess leads to dependence on the drug. |
| What is the effect of cocaine on the nervous system? | It causes dopamine to be released. Furthermore, it prevents the removal of dopamine from the synaptic cleft so the neurotransmitter continues to stimulate the postsynaptic membrane causing a euphoric feeling. |
| What is the effect of nerve agents such as sarin gas on the nervous system? | They inhibit the enzyme acetylcholinesterase and prevent the breakdown of the neurotransmitter acetylcholine. This results in overstimulation of the CNS and PNS and the neuromuscular junction. |
| What is a neuromuscular junction? | A synapse found between a motor neurone and a skeletal muscle fibre. An overstimulation can lead to constriction of the pupils, drooling, constriction in the chest, difficulty breathing and respiratory failure. |
| What is the effect of caffeine on the nervous system? | It stimulates the neurones and as a result the adrenal glands to secrete adrenaline. This causes the heart to race, muscle tension and blood vessel constriction. It blocks the action of adenosine(a sleep inducing chemical) and stimulates dopamine. |
| List 6 roles of synapses. | Transmission of impulses Integration of impulses Summation Dispersal of impulses Filtering out impulses Memory |
| What are cholinergic synapses? | Synapses which uses the neurotransmitter acetylcholine. |
| What are adrenergic synapses? | Synapse which use nor-adrenaline. |
| One of the most common inhibitory neurotransmitters is GABA. What does it stand for? | gamma amino butyric acid |
| Distinguish between the location of action potentials in myelinated vs unmyelinated neurones. | Myelinated neurones - action potential occur only at the nodes of Ranvier via saltatory conduction. Speed is MUCH faster. Unmyelinated neurones - action potentials occur along the whole length. Speed is slower. |
| T or F. Impulses flow in one direction between neurones as evidenced by synapses. | T |
| What is an electrical synapse? | An electrical synapse is a gap which has channel proteins connecting the two neurons, so the electrical signal can travel straight over the synapse. These can be found in the brain of humans. |
Created by:
CAPE Biology Unit 2
Popular Biology sets