Exam 3 Flashcards
The nervous system uses electrochemical signals called what?
impulses
How are nerve impulses transmitted?
via cells called neurons
What other cells do neurons support?
glia cells
What are the 3 major regions of a neuron?
- dendrites -> receive signals from other cells
- soma -> houses organelles
- axon -> transmits signals AWAY from soma
Dendrites receive what type of potential?
graded potentials from sensory receptors/neurons
Axons transmit what type of potential?
action potentials that travel from axon hillock to terminals
Which potential can be either excitatory or inhibitory and may not cause a neuron to fire?
can be either
What type of potential is always excitatory and can cause a neuron to fire?
action potential
What is an afferent neuron?
- rely on sensory receptor activities
- dendrites lie in PNS
- transmits signals to synapses in CNS
What is an interneuron?
- limited to CNS
- integrate & interpret signals
What are efferent neurons?
- send out motor neurons
- dendrites lie in CNS
- synapses lie in PNS
- act on motor (muscles) or chemical effectors (glands)
What are the functions of the astrocytes & satellite cells in neurons?
- transport nutrients & metabolic wastes
- maintain conc. of chemicals in nervous tissue
- trigger formation of blood brain barrier
What are the cells of the CNS?
- ependymal
- astrocytes
- microglia
- oligodendrocytes
What are the cells of the PNS?
satellite & schwann cells
What is the function of oligodendrocytes?
- insulate axons
- form processes that surround segments of axons in myelin
What is the function of Schwann cells?
each cell wraps around an axon creating a singular myelin sheath
What is the function of microglia?
- derived from macrophages early in development
- engulf & destroy damaged tissue, cells, & foreign invaders
What is the function of ependymal cells?
- line ventricles & central canal of the CNS
- works with blood vessels & filter blood plasma to produce CSF
What is a membrane potential?
difference in electrical charge across the cell membrane
What type of protein drives potential?
transport proteins
What does the NA+/K+ pump drive in & what does it drive out?
3 Na+ in & 2 K+ out
What are the 2 types of gradients created by the Na+/K+ pump?
conc. & electrical gradients
How can we get from -50mV to -70mV?
- negative cystolic proteins
- Na+ & K+ leakage channels in the membrane (more effective)
What is the value of resting potential?
-70mV
What stimuli CAN trigger a graded potential?
- change in voltage
- presence of an environmental chemical
- presence of a neurotransmitter
- mechanical pressure
What rushes in when a graded potential occurs?
Na+
What isthe term to describe a membrane potential being less negative?
depolarization
What is a decremental signal?
when a signal weakens as it moves farther away
When is a threshold reached?
when potential rises to -55mV
What happens when a threshold is reached?
- triggers a series of voltage gated Na+ channels in area near axon hillock
- cell becomes 600x more permeable to Na+ & K+
- action potential is formed
What is an overshoot?
a balanced membrane potential that continues until 30mV potential is reached
What is repolarization?
when the membrane potential is negative
What is hyperpolarization?
when the charge passes -70mV
What are the 7 steps of an action potential formation?
- stimulus causes a graded potential
- when threshold is reached (-55mV), Na+ channels open
- Na+ floods into cell & depolarizes it
- at overshoot (+30mV) Na+ channels are blocked & K+ open
- K+ floods out of the cell & repolarizes/hyperpolarizes it
- action potential travels down the axon
- Ca2+ channels open & enters the cell & neurotransmitter is released
What causes an action potential to travel down an axon?
Na+ rushing in causing neighboring channels to open
What is an absolute refractory/downtime period?
when Na+ is prevented from passing through while the region repolarizes
What is a relative refractory/downtime period?
when it takes more Na+ influx to reach threshold
What speeds up propagation?
myelination
What are Nodes of Ranvier?
areas b/w myelin
What occurs at the axon terminal?
Ca+ floods in
What can the influx of Ca+ in the axon terminal cause?
- triggers depolarization in post-synaptic cells
- triggers exocytosis of neurotransmitters
What type of gap lies b/w cells?
synaptic cleft
What occurs if a neurotransmitter is inhibitory?
causes K+ or Cl- to rush into the cell
Endorphins are most likely what?
inhibitory neurotransmitter
What are the 2 ways a neurotransmitter can be removed?
- degraded by Ach-terase
- taken up by neuron that released it (ex:serotonin)
What are the 2 divisions of the nervous system?
- CNS -> brain & spinal cord
- PNS -> sensory & motors; all other nerves
How does the PNS communicate with the CNS?
sends sensory info in & receives motor info out
What type of neuron enters via the dorsal root ganglion?
afferent = sensory response
What type of neuron exits ventrally via ventral root ganglion?
efferent neuron = motor response
What matter does the CNS have?
- white matter -> composed of myelinated neurons
- grey matter -> cell bodies & interneurons
What matter transmits signals to/from the brain?
white
What is the only nervous system that has NO interneurons and everything is myelinated?
PNS
What are the 3 layers of protection of the CNS?
- bone -> skull & vertebrae
- meninges -> membrane b/w bone & brain
- cerebrospinal fluid -> provides support & nutrients
What is the order of the layers of the meninges from top to bottom?
dura -> arachnoid -> pia
What does dura matter connect to?
bone
What is dura matter?
- forms a layer of tough fibrous connective tissue
- houses venous sinuses for blood return from CNS
What is arachnoid matter?
- avascular layer
- surrounds subarachnoid space that houses CSF
What does pia matter attach to?
brain
What is pia matter?
- lines inside & outside of CNS
- contains blood vessels that branch from arteries
- forms plexuses in brain ventricles
- lies on top of brain & spinal cord
Where does CSF lie?
in subarachnoid space b/w arachnoid & pia
What are the 3 functions of CSF?
- transfers nutrients, O2, & waste for the CNS
- cushions brain & protects it
- supports brain so it doesn’t rest on bone
Where does CSF travel?
- travels through aqueducts b/w ventricles
- connects central canal of spinal cord
- passes into suarachnoid
- forced into blood of dural sinuses
What type of glial cell forms CSF?
ependymal cells
What is the blood- brain barrier?
- barrier b/w vessels traveling around the brain & brain
- prevents materials from passing
Capillaries are connected by what type of junction in the blood-brain barrier?
tight
What cells surround the capillaries in the brain?
- pericytes
- astrocytes
- microglia
What is the purpose of the 3 cells surrounding the capillaries in the brain?
to prevent pathogens & non-lipid soluble molecules from crossing into the neural tissue
What are the 4 components of the brain?
- cerebrum -> sensory & motor; memory & reasoning
- diencephalon -> processes & delivers sensory info
- cerebellum -> movement & balance
- brainstem -> connects spinal cord to brain
What connects the 2 hemispheres of the cerebrum?
ant. & post. commisures -> bundles of axons
What is the name of the thick band of axons traveling through the cerebrum hemispheres?
corpus callosum
What part of the brain sets humans apart from other animals?
an outer cortex in the cerebrum
What does the cerebrum outer cortex form?
forms folds (sulci) & hills (gyri) that increase surface area/volume
What cell types does the cerebrum outer cortex form layers with?
- stellate cells -> processes incoming sensory info
- pyrimidal cells -> send motor signals out
What are the 4 lobes of the cerebral cortex?
- frontal lobe -> skeletal muscles, decison making, speech, planning
- parietal lobe -> touch, sensory integration, speech recognition
- temporal lobe-> hearing, taste, smell
- occipital lobe -> vison
What structures lie deep to the cerebral cortex?
nuclei
What do the nuclei do beneath the cerebral cortex?
- regulate unconcsious processes (aggression, fear, memory)
- combine with regions of diencephalon to form limbic system
What region in the cerebral cortex controls movement?
substantia nigra
What region of the brain forms a relay station?
diencephalon
What are the thalamus & hypothalamus?
- thalamus -> routes all signals to cerebrum
- hypothalamus -> main homestatic setpoint
What are examples of homeostatic processes that the hypothalamus controls?
- HR & BP
- body temp.
- hunger
- water balance
- regulates endocrine system
What is the cerebellum?
- maintains muscle tone
- sends out corrective signals to maintain balance
- muscle memory
- coordinates activites of skeletal muscles
What are the 3 parts of the brainstem?
- midbrain -> connects cerebrum to spinal cord
- pons -> connects cerebrum & cerebellum
- medualla oblongata -> HR, breathing, visual/auditory
What si the medulla oblongata largely directed to?
reticular formation
How does the white matter carry signals to/from the brain?
- ascending tracts (goes up)-> sensory
- descending tracts (goes down)-> motor
- dorsal columns -> ONLY sensory axons
- lateral & ventral columns -> BOTH motor & sensory
How does the grey matter communicate with the PNS?
- dorsal horn -> receives sensory from spinal nerves
- ventral horn -> carries motor info out
What type of neruons does the dorsal horn have?
interneuerons & sensory neurons
What type of neruons does the ventral horn have?
dendrites & soma of motor neurons
What are the 2 major divisions of the PNS?
- afferent -> carries sensory impulses to CNS
- efferent -> motor senses
What are the 2 divisions of the afferent division in the PNS?
somatic sensory & visceral sensory
What are the general & special divisions in the afferent PNS?
- general -> touch, pain, pressure, vibration, temp.
- special -> hearing, vision, equil., taste, smell
What are the 2 divisions of the efferent division in the PNS?
- somatic nervous -> motor inn. of skeletal muscles
- autonomic -> motor inn. of smooth & cardiac muscles, & glands
What are the characteristics of parasympathetic nerves?
- constrict pupils
- slow HR
- constrict airways
- contract bladder
- inhibit release of glucose
What are the characteristics of sympathetic nerves?
- dilate pupils
- fast HR
- relax airways
- relax bladder
- release of glucose to make ATP
What are the 2 types of nerves in the PNS?
- cranial -> connect directly to brain
- spinal -> pass through spinal cord
What are the 4 plexuses that form from spinal nerves?
- cervical -> inn. neck & head
- brachial -> inn. arms
- lumbar -> inn. pelvis & ant. leg
- sacral -> inn. rest of leg
What are neurons called when organized into groups?
fascicles surrounded by perineurium
What surrounds a neuron?
layer of connective endoneurium
What is an entire nerve wrapped in?
epineurium
What are the 2 branches of the spinal nerve?
- dorsal -> sensory/afferent neurons
- ventral -> motor/ efferent neurons
What type of ganglia is acosciated with parasympathetic signals?
terminal
What type of ganglia is associated with thoracic & upper lumbar regions?
sympathetic
Where does the temrinal ganglia receive input from?
cranial nerves & lumbosacral plexus
What happens when ion channels open in dendrites?
increased stimulus activity
What density affects perception?
neuron density
What is acuity?
affects our ability to localize the signal
Do stimuli near the center or the edge of the receptor field generate greater responses?
stimuli near the center
What are phasic receptors?
- exhibit on/off response
- adapt rapidly & only respond when stimulus is applied/removed
What are tonic receptors?
respond for the duration of a stimulus (ex: stretch in muscles)
What is the ascending pathway?
- 1st order neurons receive receptor stimuli
- 1st neuron synapse with 2nd neuron in spinal cord/ medulla oblongota
- 2nd neuron travel to thalamus to synapse with 3rd order neuron
- 3rd order neuron travels into cerebral cortex
What receptors are associated with general senses?
- thermo
- mechano
- nociceptor
What receptors are associated with special senses?
- chemo
- mechano
- photo
What are thermoreceptors?
- change in temp triggers Ca2+ channels to open
- group of specialized nerve endings
- found in skin & internally
What chemicals lower the resting potential of a receptor?
- capsaicin
- ethanol
- menthol
What are pain receptors?
- highly conc. in the skin
- damage to tissue causes Ca2+ channels to open
What releases endorphins?
medulla oblongota
Taste buds house what type of cells?
epithelial
Taste buds sends signals to what nerves?
facial, vagus, & glossopharyngeal
What are the 5 receptors in taste buds?
- bitter (alkaloids)
- sour (H+)
- salty (cations)
- umami (L-glutamate)
- sweet (simple sugars)
How does smell work?
- odorants are inhaled & dissolved in mucus
- bind to cilia on dendrites of olfactory cells
- receptor cells depolarize & sends signal through olfactory bulb to the brain
What are the 3 places smell go once in the brain?
- piriform cortex in temporal lobe
- secondary olfactroy in frontal lobe
- amygdala in diencephalon/cortex
How are soundwaves funneled from the environment?
by the pinna (outer ear) -> ext. acoustic meatus -> ear canal -> tympanic membrane (eardrum)
The tympanic membrane vibrates to what 3 bones of the middle ear?
- malleus
- incus
- stapes
What is the movement of sound in the middle ear?
- malleus attaches to eardrum which vibrates
- incus vibrates
- stapes vibrates which attaches to oval window
What separates the middle & inner ear?
oval window
What 2 muscles in the middle ear modify the vibrations?
- tensor tympani -> controls malleus; dampens loud sounds
- stapedius -> controls stapes
How is sound amplified in the ear?
pinna -> funnel that focuses sound to tympanum
What is the full path of sound travelling through the ear?
- outer ear: pinna -> auditory canal -> tympanic membrane
- middle ear: malleus -> incus -> stapes
- inner ear: oval window -> cochlea -> temporal lobe
How do vibrations travel through the cochlea?
- vibrations enter cochlea & travel along vestibular duct
- transfers energy to cochlear duct
- causes basilar membrane to vibrate
What happens in the organ or corti?
- the hair cells get bent & sends a signal to the brain
- the more frequent the vibration = the louder the sound = more action potentials
What hair cell in the inner ear is associated with equilibrium?
vestibule
What is static equilibrium?
up & down or forward & backward movement
What are the 2 structures involved with static equilibrium?
saccule (vertical movment) & utricle (forward/backward movement)
What is dynamic equilibrium?
angular motion using semicircular canals (ex: feeling dizzy being drunk)
The endocrine system is under control of what other system?
nervous system
What are the characteristics of the endocrine system?
- involves hormones
- hormones transported by blood
- slow
- short or long lived responses
- involuntary
- affect more than one organ
Endocrine glands are what type of cells?
epithelial
What are the characteristics of epithelial glands?
- produce/secrete hormones
- released into blood
- stimulated by neurons/hormones
Hormones are derived from what 2 things?
lipids or amino acids
Steroid hormones have what type of solubility?
lipid
Protein hormones have what type of solubility?
water
How does signal transduction occur in protein hormones?
- bind to a receptor on the surface of the cell
- receptor changes shape & activates something inside
Which hormone is faster, stronger, & shorter acting than the other?
protein hormones > steroid hormones
What are the 7 types of endocrine glands?
- brain -> pituitary & pineal
- throat -> parathyroid & thyroid
- abdomen -> adrenal & pancreas
- gonads -> ovaries & testes
What is the neurohypophysis in the pituitary gland?
- organ that forms from the diencephalon
- grows from infundibulum & swells
- comosed of neurosecretory cells
What is the adenohypophysis in the pituitary gland?
- organ that forms from the pharynx
- wraps around infundibulum
- composed of glandular epithelium
What is the antidiuretic hormone?
- akavasopressin
- affects blood volume
- constricts blood vessels to increase BP
- increases water absorption
What is the oxytocin hormone?
- promotes uterine contraction in childbirth
- triggers ejaculation
- promotes lactation
- associated with pair bonding (love & affection)
What is the hypophyseal portal system?
capillaries in the infundibulum where regulatory hormones from the hypothalamus can enter
What organ controls adenohypophysis activity?
hypothalamus
What are tropic hormones?
hormones that have a cascading effect on other endocrine glands
What are the tropic hormones of the adenohypophysis in the anterior pituitary?
- FSH & LH -> gonads
- growth hormone -> liver, organs & tissues
- TSH -> thyroid
- ACTH -> adrenal cortex
What is the non-tropic hormone?
prolactin : triggers milk production and breast development
Whata re growth hormones?
- increase protein synthesis
- promotes lipolysis & gluconeogenesis
- reduces uptake of glucose by liver
- acts on liver to produce IGF-1
The pineal gland have what type of cells?
photoreactive cells
What are follicular cells?
- produce T3/T4
- regulated by thyroid hormone
What does T3 in the thyroid affect?
- HR
- temp.
- metabolism -> increases activity of proteins & abundance of free fatty acids
What is hyperthyroidism?
- overproduction of T3/T4
- weight loss & high metabolism
- common cause: Grave’s disease
What is calcitonin?
- produced by thyroid
- acts on kidneys, bones, & digestive tract
- prevents Ca2+ resorption
- downregulates osteoclasts & activates osteoblasts
What is the parathyroid hormone?
- upregulates osteoclasts
- promosyes Ca2+ resorption
- triggers Vit D activation
What are the 2 parts of the pancreas?
- exocrine -> controls digestion in intestine with enzymes produced by acinar cells
- endocrine -> forms islets of langerhans
What are the 4 cell types of the islets?
- alpha -> produce glucagon
- beta -> produce insulin
- gamma -> produce pancreatic polypeptide
- delta -> produce somatostatin
What is type 1 diabetes?
autoimmune system destroys beta cells in pancreas and no can longer produce insulin
What is type 2 diabetes?
pancreas can make insulin, but body is insensitive to insulin; decreases insulin receptors
What are the 2 regions of the adrenal glands?
outer cortex & inner medulla
What are the functions of the inner medulla?
- has sympathetic neurons
- produce epinephrine & norepinephrine
- long lived sympathetic activity
- increase HR, blood glucose, dilate blood vessels
What are glucocorticoids?
- made by adrenal gland
- regulated by ACTH
- promotes glucose synthesis
- suppresses immune system & blocks inflammation
What are mineralcorticoids?
- made by adrenal gland
- affect sodium
- regulated by ACTH
- release stimulated by renin & angiotensin
What are androgens?
- made by adrenal gland
- testosterone & estrogen
What provides mucous for the eye?
conjunctiva
What makes the outer layer of the eye?
- cornea -> transparent window of the eye
- sclera -> white part of eye & reflects light
- optic nerve -> pierce sclera in the back
What makes the middle layer of the eye?
- choroid coat -> contains pigments & blood vessels
- ciliary body -> adjusts lens of the eye
- iris -> smooth muscle that adjusts the amount of light into the eye with pupil; eye color
What does accomodation mean with the eye?
when the ciliary body sharpens the image a received by photoreceptors
What makes the inner layer of the eye?
retina -> photoreceptor cells of eye; continuous with optic nerve; “blindspot”
What are rod shaped photoreceptors?
- long & thin
- respond to any light
- DO NOT transmit color info (scotopic vision - black & white vision)
What are cone shaped photoreceptors?
- short
- give color vision (photopic)
What are the 3 different types of cones?
- blue (cyanolabe) -> max 420 nm
- green (chlorolabe) -> max 530 nm
- red (erythrolabe) -> max 560nm
Rods in the eye contain what type of pigment?
rhodopsin
Where are the cones in the eye found?
fovea centralis
What is the pathway of light?
- light passes through the cornea
- passes through pupil
- hits lens
- lens focus light onto retina