Midterm 1 Flashcards
fossa
concavity
foramen
short passage (doorway)
fissure
deep groove
fenestration
small openings/ windows
true anatomical position
body erect
head facing forward
arms hanging down and lateral to trunk w palms facing forward
legs slightly apart w feet/toes facing forward
feet flat on the ground
body cavities
dorsal, ventral
what does the dorsal cavity contain?
CNS- brain and spinal cord
what does the ventral cavity contain?
thoracic
abdominal
pelvic
what does the serous membrane line?
body cavities and organs (viscera)
parietal layer
outer layer of serous membrane lining interior wall of body cavity
visceral layer
inner layer of serous membrane lining external surface of organs
serous cavity
thin layer containing a very small amount of fluid that acts as a surfactant to reduce friction between the two layers when they slide against each other
scanning electron microscopy (SEM)
offers 3D views that allow for study of surface features
transmission electron miscroscope
2D views through thin-cut sections
optimal for visualizing internal structures of cell or within an organelle
The maximum resolution of a light microscope is 0.2-0.5 um. Which of the following would you be able to visualize?
mitochondrion
nucleus
ribosome
lysosome
microfilaments/ intermediate filaments/ microtubules
nucleus, mitochondrion, lysosome
nonmembranous organelles
ribosome, centrosome/centriole, cilia/flagella, cytoskeleton, nucleolus
membranous organelles w 2 lipid bilayer membranes
nucleus, mitochondria
membranous organelles w 1 lipid bilayer membrane
lysosome, peroxisome, endoplasmic reticulum, golgi body, plasma membrane
Nuclear envelope
contains nuclear pores that allow molecules to pass btwn nucleus and cytoplasm
function of nucleus
stores and transmits genetic information [DNA], sends genetic info to cytoplasm where ribosomes read mRNA to code for AA to make protein
nucleolus
spherical, densely stained filamentous structure within nucleus
nucleolus function
Site of ribosomal RNA (rRNA) synthesis
Assembles RNA and protein components of ribosomal subunits, which then move to the cytoplasm through nuclear pores
ribosomes
packages of rRNA and protein
free ribosomes
synthesize proteins for local use within cell from mature mRNA
membrane-bound ribosomes
attached to the rough endoplasmic reticulum and synthesize protein needed for export or for use within the cell membrane (i.e., integral, peripheral proteins)
where can ribosomes be found?
cytosol, attached to rough ER, mitochondria
rough endoplasmic reticulum
continuous w nuclear envelope w attached ribosomes that synthesize, processes and packages proteins for export from cell or to cell membrane
smooth endoplasmic reticulum
synthesize phospholipids [plasma membrane], steroids [plasma membrane, cholesterol], and fats
functions in detoxifying harmful substances like alcohol
golgi apparatus/body form and location
Series of cup-shaped, closely apposed, flattened, membranous sacs with associated vesicles typically situated near the nucleus/rough ER
golgi body function
Concentrates, modifies, and sorts proteins arriving from the rough ER prior to their distribution via vesicles that will remain in the cell (lysosome) or to the outside of the cell via exocytosis
lysosomes
-“membranous vesicles”, “stomach of the cell”
-formed in golgi complex and filled w digestive enzymes
-pumps in H+ ions until internal pH reaches 5.0
lysosome function
Digest foreign substances (i.e., bacteria) or digest/recycle components of the cell’s organelles (autophagy) or in cases of cell destruction (autolysis)
peroxisomes
Vesicles smaller than lysosomes and contain enzymes (catalases) that oxidize toxic organic material (alcohol, aldehydes, hydrogen peroxide = H2O2)
crista
inner membrane of mitochondria
who does mitochondrial DNA come from and why?
mother; sperm mitochondria broken off during fertilization and, therefore, fail to enter the egg cell
mitochondria function
ATP generators and can self-replicate if significant ATP is required by the cell to properly perform its functions
how much cell volume does cytosol take up?
55%
cytoskeleton
Network of protein filaments throughout the cytosol that are continuously reorganized that provides cell support and gives the cell its characteristic shape
types of filaments
microfilaments
intermediate filaments
microtubules
microfilaments
comprised of actin
locomotion and division
intermediate filaments
made up of multiple proteins
anchor organelles
microtubules
made of tubulin
flagella, cilia, and centrosomes
centrosome
found near nucleus
has 2 perpendicular centriols, 9 clusters of 3 (triplet) microtubules
centrosome function
Play vital role in formation of cilia & flagella basal bodies as well as development of the mitotic spindle during cell replication
cilia and flagella structure
shaft contains pairs of microtubules along with a central pair (9+2 array)
basal body derived from centriole, so microtubule arrangement is same (9+0)
what are the differences between cilia and flagella?
cilia- short, multiple projection from cell membrane, typically have coordinated mvmts
flagella- long, single, wavelike mvmts
cell membrane contents
phospholipids- 75%
cholesterol- 20%
glycolipids- 5%
proteins
cholesterol features and location
stiff steroid rings, within hydrophobic cell membrane around fatty acid tails of phospholipids
integral proteins
extend into or completely across cell membrane
function as channels, receptors, or interact w extracellular matrix
peripheral proteins
lie near intercellular side of membrane
are integral proteins hydrophobic, hydrophilic, or amphipathic
amphipathic
glycoproteins
sugar protein
faces extracellular fluid to form glycocalyx
glycocalyx
found in cell membrane; protects cell from being digested, allows for tear film adherence
molecules permeable in lipid bilayer
nonpolar, uncharged molecules
O2, CO2, steroids, small amount of water which flows through gaps that form in hydrophobic core of membrane
molecules that go through transmembrane proteins
small and medium sized polar and charged particles
total body water mostly ______ fluid
intracellular (67%)
extracellular fluid is mostly ______
interstitial (26% of total body water, 75% of extracellular fluid)
concentration higher intracellular
K+, ATP, proteins (amino acids)
concentration higher extracellular
Na+, Cl-, Ca2+ (muscle contraction, neurotransmitter release), glucose
hypertonic solution leads to
cell shrinkage
hypotonic solution leads to
cell expansion; lysis/hemolysis of expansion is great enough
The greater the difference in concentration, the ____ the rate of diffusion
faster
the higher the temperature, the ____ the rate of diffusion
faster
the larger the size of the diffusing substance, the _____ the rate of diffusion
slower
an increase in surface area, ____ the rate of diffusion
increases
increasing diffusion distance, ____ rate of diffusion
slows
simple diffusion
small, nonpolar molecules
facilitated diffusion
requires membrane protein transporter via ion channels or carrier protein
types of facilitated diffusion channels
non-gated (leak) channels
chemical/ligand-gated
voltage-gated
what passes through non-gated channels?
ions and water
sodium channel function
-mediate fast depolarization of action potential and conduct electrical impulses throughout nerve, muscle, and heart
-slow rate and amplitude of initial, rapid depolarization of an action potential
-reduces cell excitability and conduction velocity
sodium channel blockers
Class I antiarrhythmic medications, anesthetics, TTX/tetrodotoxin
How does TTX/tetrodotoxin block Na+ channels?
irreversibly binds to binding site on Na+ channel, blocking ion influx into cell preventing depolarization
highly neurotoxic, found in pufferfish
K+ channel function
K+ outflow from cell results in hyperpolarization during an action potential
K+ channel blockers
-TEA (tetraethylammonium) previously used to treat heart arrythmias and HTN
-potassium chloride (KCl) used in lethal execution procedure (blocks repolarization that would allow for the initiation of another action potential
Na+/K+ ATPase pump
used in primary active transport - pumps ions against concentration gradient
helps establish and maintain membrane potential of cell
secondary active transport
uses electrochemical gradient across membrane via transporter ion (usually Na+)
types of endocytosis
phagocytosis (cell eating), pinocytosis (cell drinking), receptor-mediated endocytosis (something binds to receptor on membrane)
typical molecules using secondary active transport
polar: amino acids, glucose, some ions
typical molecules using primary active transport
ions: Na+, K+, Ca2+, H+
membrane potential
Represents the separation of electrical charges that exists across plasma membranes
electrical charge (intracellularly and extracellularly)
intracellular- more negative adjacent to membrane
extracellular- more positive adjacent to membrane
cells w excitable cell plasma membranes
muscle fibers and neurons
typical resting membrane potential in neuron
-70 mV
is resting membrane potentials same for other cell types?
no- cardiac muscle: -90mV, epithelial cells: -50mV
graded potentials
Small deviations from resting potential of -70mV
occur in the receptive segment of the neuron (i.e., dendrites and soma)
graded potential signal initiation
chemical (neurotransmitter, hormone) or mechanical stimulus via ligand-gated or mechanical-gated ion channels
T/F: graded potentials signal propagation can travel long distances
limited to short distance (i.e. synapse to neuron cell body)
neuron segments where action potential can occur
Initial segment (axon hillock)
Conductive segment (axon)- propagation
Transmissive segment
membrane threshold
-55mV
receptive segment of neuron
binding of neurotransmitter; produces graded potentials
dendrites and soma
initial segment of neuron
axon hillock
summation of graded potentials
initiation of action potential
conductive segment of neuron
axon
propagation of action potential
transmissive segment of neuron
release of neurotransmitter
depolarization triggered by
a stimulus from multiple graded potentials in the soma changes membrane charge at the axon hillock (initial segment) from -70mV up to the membrane threshold of -55mV
As membrane reaches threshold, voltage-gated ___channels …
Na+; open and Na+ streams into the cell
depolarization membrane potential
+30mV
at full depolarization
voltage-gated Na+ channels are inactivated (remain open but no longer allow for passage of Na+ ions due to “gate” covering channel opening)
voltage-gated K+ channels slowly begin to open
repolarization
outflow of K+ from cell returns membrane potential back to -70mV
hyperpolarization
too much K+ leaves the cell, membrane potential reaches -90mV
returns to -70mV via ion leak channels and Na+/K+ ATPase pump
refractory period
Time during an action potential when a neuron cannot generate another action potential
absolute refractory period
Not even a strong stimulus will generate another action potential when the membrane potential is above the threshold of -55mV.
relative refractory period
A strong-enough stimulus may generate another action potential even if the membrane potential has not yet returned to -70mV
continuous conduction
Step-by-step depolarization of each portion along the entire length of the axolemma of unmyelinated axons
saltatory conduction
Depolarization occurs only at the nodes of Ranvier of myelinated axons where there is a high density of voltage-gated ion channels
is propagation speed of a nerve impulse related to stimulus strength
no
A fibers
largest and provide fastest impulse propagation
are myelinated (somatic sensory + motor fibers)
B fibers
medium-sized; somewhat myelinated
autonomic
C fibers
smallest, slowest impulse propagation
unmyelinated
somatic sensory + autonomic fibers
What type of axons allow for fastest conduction?
myelinated AND large-diameter
what type of axons allow for slowest conduction of an impulse?
unmyelinated AND small-diameter
synapse
locations where an axon of an upstream (presynaptic) neuron ‘connects’ with the dendrite(s) of a downstream (postsynaptic) neuron or effector (i.e., muscle, gland, etc.)
mechanical synapses
Channels are pulled open by physical movement (cochlear hair cells, muscle spindles)
electrical synapses
Currents (ions) pass through gap junctions rapidly between bound presynaptic and postsynaptic neurons (cardiac and smooth muscle, retina)
chemical synapses
Most common type of synapse
presynaptic neuron contains synaptic vesicles (containing neurotransmitter), mitochondria, and the active zone
postsynaptic neuron is separated by the synaptic cleft and contains receptors that bind to a specific neurotransmitter
where are neurotransmitters synthesized
axon terminal
where are neurotransmitters stored?
clathrin- protein-coated membranous vesicles
formed by budding and pinching of cell membrane during endocytosis
ways neurotransmitter can be removed
- reuptake- active transport back into presynaptic axon terminal
- transported to nearby glial cells for degradation
- diffuses down concentration gradient away from receptor site
- enzymatically degraded
excitatory postsynaptic potentials (EPSP)
result in greater influx of Na+ into the cell vs. outflow of K+
membrane potential becoming more positive/less negative than the resting membrane potential (depolarization)
inhibitory postsynaptic potentials (IPSP)
greater outflow of K+ and influx of Cl- vs. Na+ influx
net hyperpolarization of the cell (membrane potential becomes more negative than resting membrane potential)
Spatial summation
Numerous EPSPs, IPSPs (or both) are initiated by different presynaptic neurons around the same time
temporal summation
Numerous EPSPs, IPSPs (or both) are initiated by the same presynaptic neuron around the same time
myasthenia gravis
autoimmune disease where the body produces antibodies against the acetylcholine (Ach) receptor
effects of myasthenia gravis on eye
dipolopia (double vision due to reduced ability for EOMs to move), ptosis
caused by damage to Ach receptor
myasthenia gravis treatment
neostigmine (acetylcholinesterase inhibitor)
allows more time for Ach to bind to still-functioning Ach postsynaptic receptors
Multiple sclerosis (MS)
autoimmune disease that affects neurotransmission by producing antibodies against the myelin sheath of myelinated axons
plaques form in white matter of CNS
effect of MS on eye
optic nerve can be affected bc it’s myelinated
color vision defects, blurred vision, peripheral vision defects
what do botox injections do?
block synaptic release of neurotransmitter from presynaptic axon terminal which ultimately relaxes muscle (i.e., removes wrinkles, relieves eyelid spasms)
