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Anatomy Unit 11
| Question | Answer |
|---|---|
| Functions of the nervous system | - body's information gatherer, storage center, control system - collect info about body state with senses - transfer info to brain to analyze - send impulses to initiate motor response |
| organs of nervous system division | - central nervous system - peripheral nervous system |
| Central nervous system | - brain - spinal cord - main component - processes information |
| Peripheral nervous system | nerves of the body - cranial nerves - spinal nerves - receives information from environment (senses) - responds to environment (motor movements) |
| Peripheral nervous system | somatic nervous system and autonomic nervous system |
| Somatic nervous system | - connect CNS to nervous system - controls conscious actions (voluntary) - made of spinal nerves (13 pairs) (connect to body parts - everything but spinal column and brain - sensory neurons and motor neurons |
| Types of spinal nerves | sensory neurons - get messages from senses, up spinal column, to brain motor neurons - get messages from brain down spinal column to muscles |
| Autonomic nervous system | - nerves connect the central nervous system to organs like; heart, stomach, intestine, gland - controls subconscious actions, involuntary |
| Autonomic nervous system division | sympathetic and parasympathetic |
| Sympathetic nervous system | - fight or flight - respond to stress - prepares body for energy expending, stressful situations - increase everything (heart rate, and breathing) |
| Parasympathetic nervous system | - rest and digest - brings body down from stressful situations - active during ordinary, restful situations - keeps everything at normal levels |
| Neuron | - nerve cell - unique type of cell found in brain and body |
| Nerve impulse | - electrical messages that travel down a neuron - how messages are transmitted to and from brain |
| Neuron anatomy: cell body | - soma - spherical part of cell - main control center - contains nucleus |
| Neuron anatomy: dendrites | branches coming off the cell body |
| Neuron anatomy: axon | long, hair-like extension |
| Neuron anatomy: axon terminal | end of axon |
| Neuron anatomy: synaptic vesicles | - in axon terminal - small bubbles that contain neurotransmitters |
| How are neurons connected | dendrites to axons |
| synapse | point of contact with another neuron or muscle |
| how many neurons are in the human brain | 100 billion |
| how many neurons are in the spinal cord | 1 billion |
| are all neurons equal size | no, peripheral nervous system neurons are bigger |
| Unipolar | one branch (dendrite and axon combined) |
| bipolar | two branches (dendrite, axon, separate) |
| multipolar | many branches, many dendrites, only one axon - most neurons in brain |
| all neurons have only one | axon, the difference is the number of dendrites |
| afferent neurons (sensory) | - lie in PNS (outside of spinal cord and brain) - unipolar - dendrites are sensory receptors |
| Interneurons | - lie with CNS (brain and spinal cord) - multipolar - connect one neuron to another neuron - most neurons of body |
| motor efferent neurons | - lie in PNS (brain and spinal cord) - connect to muscles or glands - multipolar |
| What is an action potential | - Action potential = when charges flip - resting membrane potential = -70mv - positive on inside, negative on outside - this only happens temporarily as it flips back to go back to normal |
| Nerve impulse | Multiple action potentials! - travels down an axon in the form of multiple action potential! - moves only in one direction - like dominos or lighting a fuse |
| How does an action potential happen physiologically | Depolarization Repolarization Hyperpolarization |
| Depolarization - Action Potential | - sodium channels open up and sodium rushes into neuron cell - neuron cell now becomes positive, charges flip |
| Repolarization | - Potassium channels open up and potassium rushes out of neuron cell - the neuron cell now becomes negative, charges flip again |
| Hyperpolarization | - sodium potassium pump works with ATP - goes against concentration gradient to bring the cell back to normal - 3 sodium get pulled out of cell - 2 potassium get pulled back into cell |
| Cell membrane | - outermost boundary cell - made of phospholipids - fluid mosaic: phospholipids move constantly - Bilayer, heads like water, tails don't like water - Selectively permeable: actively functions in order to control what enters and leaves the cell |
| Cytoplasm | Fluid on inside of a cell |
| Extracellular fluid | - fluid on outside of cell - fluid runs throughout body - keep constant to stay at homeostasis |
| Diffusion | - atoms, molecules, and Ions move across cell membrane - can only move across if permeable - moves with concentration gradient |
| Concentration gradient | from an area of high pressure to an area of low pressure |
| Sections of Axon in neuron each have | 2 carriers and 1 pump |
| Resting Neuron | - No nerve impulse going through it - High Na+ on outside of cell, low Na+ on inside of cell - High K+ on inside of cell, low K+ on outside of cell |
| Anions | Negatively charges ions, distributed throughout inside of cell |
| Resting membrane potential | - neurons have electricity running through them at all times - resting neuron reading is - 70mv = resting membrane potential - every resting neuron has this charge |
| Difference in charge across the membrane | - Negative because there is a difference in amount of Na+ outside neuron as opposed to amount of K+ inside neuron - More Na+ outside, more positive outside - anions inside |
| What is the difference between neuron to outside neuron | - Difference from inside of a neuron (cytoplasm) to outside neuron (extracellular fluid) = -70mv |
| Neuroglia | makes up nerve tissue with neurons |
| Neuroglia functions | maintain homeostasis - provide support and protection for neurons - form myelin (IMPORTANT) for fast nerve impulses |
| Types of neuroglia in CNS | Astrocytes Oligodendrocytes Ependyma |
| Types of Neuroglia in PNS | Schwann cells |
| Neuroglia of the CNS: astrocytes | Structural support, communication between neurons |
| Neuroglia of the CNS: oligodendrocytes | wrap around axons (CNS) |
| Neuroglia of CNS: microglia | Immune protection (fight off infection) |
| Neuroglia in CNS: Ependyma | form porous layer between brain and spinal cord and cerebrospinal fluid |
| Neuroglia of the PNS: Schwann | - wrap around axons (with myelin) (PNS) - make it so the speed of the nerve impulse goes FAST |
| Oligodendrocytes and Schwann cells similarity | do the same thing in different places (CNS vs PNS) Both make axons look white - Breaks between individual cells = nodes on ranvier - made up of myelin sheets |
| Neurons vs Neuroglia | Neurons: You are born with the number of neurons that you will have throughout your life. No Cell division. Lose them for good if you lose them Neuroglial cells: do divide and make more. Go through cell division. |
| Regeneration of Neurons | - PNS neurons can regenerate - Injury to cell body kills the neuron, no mitosis - damaged peripheral axon may regenerate |
| Action potential | - Always stays about the same size - does not diminish as it goes down the axon |
| Absolute refractory period | time after action potential in which it's impossible to initiate another action potential (about 1 millisecond) |
| Multiple action potentials | - rate of action potential generation = magnitude of stimulus - firing frequencies increases with increasing stimulus - as magnitude increases, firing of action potentials increases |
| Saltatory conduction | - speed on action potential increased because action potential jumps from node to node - cuts down on number of action potentials to get to end of axon, making it much faster - most neurons of the body |
| Neurotransmitters definition | Chemical that an axon terminal releases to cause the transfer of a nerve impulse to another neuron or a muscle fiber |
| Neurotransmitters | - at least 30 different types in the body - some neurons release only one type - others can release 2-3 |
| Types of neurotransmitters | Excitatory + Inhibitory |
| Excitatory neurotransmitters | type of neurotransmitter that WILL continue the nerve impulse to the next neuron or muscle |
| Inhibitory neurotransmitter | type of neurotransmitter that will NOT continue the nerve impulse to the next neuron or muscle |
| synapses definition | - the region of contact where a neuron transfers information (nerve impulse) to another neuron - neurons transfers information to and from the brain - dendrites recieve information, axon sends information - neurons connect from axon to dendrite |
| Anatomy of a synapse | - presynaptic synaptic neuron - postsynaptic synaptic neuron - synaptic cleft - synaptic vesicles - neurotransmitters - protein channels - calcium protein channels |
| Anatomy - presynaptic synaptic neuron | - first neuron - axon terminal - transfers nerve impulse to next neuron |
| Anatomy - postsynaptic synaptic neuron | - second neuron - dendrite - receives nerve impulse from presynaptic neuron |
| Anatomy - synaptic cleft | - space between pre + postsynaptic neuron - filled with matrix, helps neurons adhere to each other |
| Anatomy - synaptic vesicles | - in the terminal axon, small membrane - enclosed spheres - stores neurotransmitters |
| Anatomy - neurotransmitters | - chemical used to communicate with postsynaptic neuron (excitatory and inhibitory) |
| Anatomy - protein channels | - on postsynaptic membrane - allow ions to enter |
| Anatomy - calcium proteins channels | - on sides of axon terminal |
| Ions and locations | - Calcium (Ca2+) - Extracellular fluid - Sodium (Na+) - extracellular fluid (in synaptic cleft) - potassium (K+) - cytoplasm - Chloride (Cl-) - NEGATIVE - extracellular fluid (in synaptic cleft) |
| Synaptic transmission | Process by which the nerve impulse in the presynaptic neuron signal the postsynaptic cells so the nerve impulse can continue |
| Nerve impulse is a electrochemical message | electrical - axon chemical - synapse |
| Physiology Synapse Part 1 - Action Potential and Calcium Rushing in | Action potential travels down axon + axon terminal. - calcium protein channels open, Ca2+ rushes in from extracellular fluid, TRIGGERS synaptic to fuse to presynaptic membrane.- |
| Physiology Synapse Part 2 - Synaptic Vesicles Open | - Synaptic vesicles open up and spill out neurotransmitter into synaptic cleft - neurotransmitters bind to protein channels or postsynaptic neuron, stimulate protein channels to open and allow ions in |
| Excitatory Neurotransmitter Physiology | - Na+ goes into cell, causes depolarization in post-synaptic membrane - causes the neuron to be positive, action potential continues, nerve impulse continues |
| Inhibitory Neurotransmitter Physiology | - Causes chloride (Cl-) to rush in, which causes hyperpolarization (away from threshold, opposite). - This change in membrane potential causes the membrane to be "inhibited". - No action potential triggered |
| Reuptake of Neurotransmitter | After neurotransmitter has done its job - 3 options - Diffuses into extracellular fluid. - An enzyme comes in and decomposes it. - Transported back into the synaptic vesicles of the axon terminal. Called reuptake |
| Electrical to Chemical to Electrical | In other words, the nerve impulse goes from an electrical signal down the axon, to a chemical signal in the synapse, back to an electrical signal down the next neuron. |
Created by:
Shannonnev0822