Intro Structure and Function + Neuro (Part 1) Flashcards
Mechanistic vs. Teleological
How vs. Why
Composition
Cells, tissue, organs, organ system
Four types of tissue
- Nervous
- Muscle
- Epithelial
- Connective
Homeostasis
Maintaining steady state around set point
Fluid composition
2/3 ICF + 1/3 ECF
ECF = ISF + PLASMA
Nervous tissue
Communication though electricity and chemical
Muscle tissue
Contraction
Epithelial tissue
Protect, transport, barrier, transduce
Connective tissue
Structure, transport, protect
Negative feedback
i.e. thermostat
Opposite reaction to return to set point
Positive feedback
ex. oxytocin during labor
Explosive reaction
Feedforward regulation
ex. hunger, exercise
Anticipatory, body preparation
Membrane potential
Voltage across membrane from separation of charge
K+ ion
Major contributor to resting membrane potential
High concentration inside cell
Moves through leak channels, ion channels and Na/K pump
Equilibrium potential
Flow into cell = flow out of cell
Resting membrane potential
Balance of equilibrium potential of all ions
Excitable cells
Trigger by change in membrane potential
Steps of action potential
- Membrane depolarized to threshold
- Na channels open and Na flows in
- Depolarization cascade
- Na inactivation gate; K channels opens
- K flows into cell
- Repolarization
- Overshoot - hyperpolarization
- K channels close, membrane repolarizes
Action potential
Regenerated along axon, sped up by myelination, all or none
Graded potentials
EPSPs or IPSPs
Amplitude can change, decay along axon
Summed temporally or spatially
If they reach threshold, can be act pot
Release of neurotransmitters
- Act pot reaches axon terminal
- Ca channels open
- Ca enters and binds to vessicles
- Vessicles released and neurotransmitter released
Removal of neurotransmitter
- Diffusion away
- Reuptake
- Broken down into components
CNS and PNS connection
Separated by foramen magnum
Afferent
Sensory signal to CNS
Efferent
CNS to effectors
Cell bodies
CNS - nucleus
PNS - ganglion
Axons
CNS = tracts
PNS = nerves
Cerebrum
Cerebral cortex
Basal nuclei
Limbic system
Cerebral cortex
4 lobes - Frontal, temporal, parietal, occipital
2 halves - connected by corpus callous
6 layers - pyramidal or nonpyramidal neurons
Columns specialized
Basal nuclei
Voluntary movement, especially initiation
Limbic system
Learning, memory and emotion
Diencephalon
Thalamus
Hypothalmus
Pituitary
Pineal gland
Thalamus
Sensory relay
Hypothalamus
Homeostasis
Pituitary
Release hormones
Pineal gland
Biological clock
Cerebellum
Regulating voluntary movement
Brainstem
Medulla, pons, midbrain
Control centers i.e. respiratory, cardiovascular
Cranial nerves
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
Spinal canal
Made of stacked foramen
Cervical, thoracic, lumbar, sacral
CTLS
Dorsal and ventral horns
Sensory enters dorsal, motor exits ventral
Choroid plexus
Secretes CSF
CSF
derived from plasma, flows through subarachnoid space and ventricles
bathes brain and spinal cord
provides cushion and removes waste
Blood Brain Barrier
Astrocytes wrap around blood vessels creating tight junctions
Flow in and out limited, preserving brain ECF
Lipid soluble, sugar, H2O, O2, CO2
signal transduction
energy to neural signal
primary afferent neurons
send sensory info to CNS
things to encode in signal
- Modality
- Intensity
- Adaptation
- Location
Increase action potential frequency by…
Receptor amplitude
Amount of neurotransmitters
Modality
“Adequate stimulus” for different types of receptors
Types of receptors
- Mechanoreceptors
- Thermoreceptors
- Nociceptors
- Chemoreceptors
Labelled line
Different modalities have different paths to cortex
Areas of brain involved in sensation
Primary cortical sensory areas
Cortical associaation areas
Intensity
Increase action potential frequency
Recruitment other cells
Adaptation
Decreased action potential frequency
Slow adapting
Continuous stimulus
Rapid adapting
Changes in stimuli
Location
On the body vs. outside the body
Acuity
Receptive field
Increase size of receptive field, decrease acuity
Receptor density
Increased receptor density, increased acuity
Convergence
Increased convergence, decreased acuity
Outer ear
- Pinna or auricle
- Ear canal
- Outer surface of tympanic membrane
Middle ear
- Tympanic membrane
- Ossicles - malleus, incus, stapes
- Muscles
- Eustachian tube
Inner ear
- Cochlea
- Oval window
- Round window
- Scala vestibuli
- Scala tympani
- Scala media
- Basilar membrane
Sound transduction
- Modality
- Intensity (loudness)
- Frequency (pitch)
- Duration
- Spatial location
Frequency
Place code or tonotopic organization
Damage of hair cells in certain spot of basilar membrane causes hearing loss at specific frequency
Labelled line of traveling wave, specific part of membrane
Basilar membrane organization
Base: thinner, more stiff, high frequency
Apex: wider, less stiff, lo frequency
Hair cells
Mechanically gated
With movement, K enters & depolarizes, Ca released, glutamate released
Steps of audition
- Sounds hits tympanic membrane
- Middle ear bones move
- Stapes transmits vibrations to cochlear fluid
- Change in pressure of cochlear
- Movement of membranes causes movement of hair bundles
- K enters and depolarizes
- Current generates receptor potential
- Calcium released
- Glutamate release triggered
- EPSP induced
Organ of corti
Filled with hair cells
Localization of sound
Auricle, comparison of sound between 2 ears, hearing centers in brain
Cochlear prothesis
Microphone for sound input, stimulating electrons to activate labelled line
