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