Nervous System, Brain, Endocrine System Flashcards
0
Q
Axon terminal
A
- End of axon
- converts electrochemical signals into message & sends it to next neuron
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Axon
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Transmits electrochemical signals to neurons
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Q
Dendrites
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Receive messages from neurons & send them to cell body
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Cell body
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Main portion of cell, contains nucleus and organelles
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Nucleus
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Contains genetic material, control center
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Schwann’s cells
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Fatty cells composed of myelin sheath
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Myelin
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- Fatty layer around axons
- insulates electrical impulses -> increases rate of transmission
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Node of ranvier
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Gaps in myelin which allow for quicker transmission of impulse bc it can leap from node to node
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Sensory/afferent neuron
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- takes signal from sense organ (eyes, skin, etc) to cns - long dendrites, short axons
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Motor/efferent neuron
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- carry message from cns to effector organ (muscle, organ, or gland) - short dendrites and long axon
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Interneuron/association neuron
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- only found within cns - conducts impulses btwn parts of cns - short dendrites and short axons
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Sensory input includes
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- vision - sound - smell - pain - temperature - pressure
12
Q
Sympathetic
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-“fight or flight” - dilates pupil - inhibits salivary flow, gastric & pancreatic secretion, & bladder contraction - accelerates heart - dilates bronchi - stimulates conversion of glycogen to glucose - uses norepinephrine - ganglia near cord - spinal nerves
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Q
Parasympathetic
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-“rest and digest” - constricts pupils - stimulates salivary flow, gastric secretion, pancreatic secretion, & release of bile - inhibits heart - constricts bronchi - contracts bladder - uses acetylcholine - ganglia near organ - spinal & vagus nerves
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Q
Resting potential
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- neuron isn’t conducting an impulse - voltage: -65mV
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Difference in charge between inside and outside of neuron
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- caused by difference in number of ions between outside & inside - sodium-potassium pump maintains this difference by transporting Na out of axon and K into axon
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Depolarization
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- sodium gates open - Na flows down concentration gradient, drawn to the negative charge inside axon - voltage changes to 40mV
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Repolarization
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- potassium gates open - K ions flow out of the axon along concentration gradient, repelled by the positive charge inside - voltage changes back to -65mV
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Refractory/Recovery period
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- no conduction of action potential is happening - sodium-potassium pump prevents impulse from travelling backwards by pumping Na to outside and K to inside
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All or none response
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- action potential cannot happen a little bit - either stimulus is strong enough to overcome threshold and send an impulse, or it’s too weak to overcome threshold and the message is stopped
20
Q
Speed of transmission: myelinated vs unmyelinated
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- unmyelinated impulse: 0.5m/s - myelinated impulse: 200m/s
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Reflex arc
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- nerve pathway involved in a reflex action - contains sensory nerve and motor nerve with a synapse in between
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Integration
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- triggering of neuron depends on input of attached neurons -> each neuron has different influence depending on strength of connection
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Summation
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- both excitatory and inhibitory synapses act on one dendrite - whichever impulse is stronger wins - impulse is either cancelled or carried on
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Effects of drugs on nervous system
- enhance release of nt's (ex. caffeine)
- block release of nt's
- mimic actions of nt's (ex. morphine mimics endorphins)
- blocks nt receptors (ex. alcohol)
- interferes with breakdown of nt's
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Central Nervous System Contains
Brain & spinal cord
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Peripheral Nervous System Contains
- somatic system & autonomic system
- sensory neurons & motor neurons
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Somatic controls
- Voluntary muscles/skeletal muscles
- skin
- tendons
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Autonomic controls
- Involuntary muscles/cardiac & smooth muscles
- glands
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2 Parts of the autonomic system
- sympathetic
- parasympathetic
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Transmission of an impulse through a reflex arc
1. receptor generates impulse
2. sensory neuron carries impulse
3. interneurons relay impulse to motor neurons
4. muscle contracts
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How does the brain become aware of an autonomic reflex action?
- because of reflex arc
- it sends message through interneurons, which provide connection to the brain
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Why do nerves have a white appearance?
Because they're myelinated
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Cerebrum
- sulci (shallow grooves) divides hemispheres into lobes
- receives sensory info
- higher thought processes (learning, memory, language, speech) which make it more developed in humans than any other vertebrae
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Thalamus
- part of diancephalon
- relay station for sensory neurons carrying info to cerebrum
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hypothalamus
- part of diancephalon
- "master gland"...controls homeostasis & other glands
- center for hunger, thirst, body temp, etc.
- has neurosecretory cells
- responds to changes by initiating nerve impulses or controlling pituitary gland
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cerebellum
- muscle coordination
- posture & balance
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medulla oblongata
- part of brainstem
- controls heart rate, respiration, blood pressure
- controls reflex center (sneezes, cough, swallow, etc.)
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cerebral cortex
outer part of cerebrum
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Gray matter
- unmyelinated
- CENTER of spine, SURFACE of cerebrum
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White Matter
- myelinated
- CENTER of brain, SURFACE of spine
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Meninges
protective membranes that cover brain & spinal cord
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Cerebrospinal fluid
cushions and protects CNS
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Midbrain
provides link btwn forebrain, branstem, & spinal cord
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diancephalon
control center for thirst, anger, fatigue
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Brainstem
controls reflexes
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How are sympathetic & parasympathetic similar?
1. control involuntary responses
2. have effectors
3. use 2 neurons for each signal
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Steps in transamission of an impulse across a synapse
1. impulse comes to synaptic bulb
2. contractile porteins shorten & draw vesicle towards pre-synaptic membrane
3. vesicles merge w/pre-synaptic membrane
4. vesicle releases neurotransmitters
5. nt's diffuse across synaptic gap
6. nt's enter lock & key receptor sites in post-synaptic membrane
7. integration & summation occurs
8. impulse moves down dendrite of new neuron
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Central endocrine glands & their location
- only located in CNS
- pineal gland
- hypothalamus
- pituitary gland
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peripheral endocrine glands & their location
- located throughout body (NOT in CNS)
- thyroid
- adrenal glands
- parathyroid
- pancreas
- thymus
- gonads
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6 functions of endocrine system
- maintains homeostasis
- deals w/stress
- growth & development
- controls reproduction
- regulates RBC production
- controls circulation, digestion & absorption
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Tropic hormones
control other endocrine glands and cause them to secrete hormones
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adrenal glands
- on top of kidneys
- secretes steroid hormones (epinephrine & norepinephrine)
- work during stressful situations to create fight or flight responses (stimulated by hypothalamus)
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thyroid
- in lower neck
- produces thyrosine & thyroxine
- uses iodine to make hormones (not enough iodine = goiters)
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posterior pituitary
- stores vasopression & oxytocin
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anterior pituitary
- causes giantism or dwarfism if not working
- produces tropic hormones (ex. vasopressin) to control kidneys
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pancreas
- secretes insulin & glucagon to control blood glucose levels (not working = diabetes)
- secretes hormones & digestive juices, so is part of endocrine system & digestive system
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excitatory nt's
- make post-synaptic membrane more permeable to sodium ions
- results in depolarization
- ex. norepinephrine, acetylcholine
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inhibitory nt's
- make post-synaptic membrane less permeable to sodium
- results in hyperpolarization (no action potential)
- ex. GABA, dopamine, seratonin
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endocrine glands produce ______ which travel to \_\_\_\_\_\_\_
hormones (one gland can produce multiple hormones); target cells (one hormone can have many different target cells, and one target cell can be influenced by multiple hormones)
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How do hormones control target cells?
through positive/negative feedback loops, which draw things back to optimal level
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chemical types of hormones
1. peptide/protein (insulin)
2. steroid (estradiol)
3. Amine (melatonin)
4. Eicosanoid (prostoglandine)
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what happens to hormones after they're used?
- most deactivated by enzymes
- some excreted in urine
- others re-absorbed by original gland
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pineal gland
- pea-sized
- secretes melatonin
- keeps body in synch w/ light/dark cycles (circadian rhythms)
- inhibits hormones that stimulate reproductive activity
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3 effects of hormones on the body
- influence metabolism of cells
- growth & development of body parts
- homeostasis
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exocrine glands
- have ducts
- ex. salivary glands
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endocrine glands
- no ducts
- ex. pineal gland
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nervous system vs. endocrine system
- nervous system: has brain, spinal cord, & nerves that transmit sensory input and motor commands
- endocrine system: has glands & tissues that secrete hormones
- both: involved in homeostasis
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antagonistic hormone
- controls the effect of another hormone by off-setting it
- ex. insulin is offset by glucagon
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What 2 categories are hormones generally seperated into, and what's the difference between how they can be received?
- peptides: received by cell membrane
- steroids: can enter cell
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spinal cord
- communication btwn brain & PNS
- protected by CSF & meninges
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pons
- part of brainstem
- bundles of axons bridging cerebellum to CNS
- works w/medulla oblongata to control breathing rate & reflex centers
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frontal lobe
- in cerebrum
- movement of voluntary skeletal muscles
- higher mental processes (concentration, problem-solving, etc.)
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parietal lobe
- in cerebrum
- receive info from skin receptors
- speech & use of words for expression
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temporal lobe
- in cerebrum
- hearing & smelling
- interprets sensory experiences, visual memory of music, sensory patterns
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occipital
- vision & combining vision with other sensory experiences
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limbic system
- stimulates different lobes to lead to expression of emotions
- also involved in memory
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Getting info from short term/working memory to long term memory depends on
- reinforcement
- neurotransmitters in limbic system
- hippocampus
- protein
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Broca's area
matriculate speech
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Wernicke's area
understanding of written & spoken word
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semantic memory
remembering words, numbers, etc.
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episodic memory
remembering people, events, etc.
