Lab Practicum Exam 1 Flashcards
be able to label connective tissue, smooth muscle, epithelial cell layer, and lumen
good luck!
skeletal muscle histology
tubular, striated shapes with the nucleus on the edge
epithelial tissue histology
individual cells
connective tissue histology
see the fibers of the tissue, nuclei are less organized
smooth muscle histology
tightly packed, striated, directionality of the cells
What type of epithelium would you expect most glands to have?
cuboidal or columnar epithelium
epithelial tissue one cell layer thick is called ________
simple epithelium
what type of epithelium has nuclei that appear to be stacked but the tissue is only a single layer of cells?
pseudostatified columnar epithelium
what type of apical surface specialization increases surface area for absorption?
microvilli
provide support and insulation to neurons in the CNS by forming myelin around the axon
oligodendrocyte
produce cerebrospinal fluid that circulates through the ventricular system, around the spinal cord, and around the entire brain
ependymal cell
generate electrical signals in the form of action potentials which serve to transmit from one cell to another
neuron
provide support and insulation to neurons in the PNS by forming myelin around the axon
Schwann cell
wrap foot-like appendage around blood vessels in the brain which forms the blood brain barrier
astrocyte
provide maintenance and immune protection to neural tissue in the CNS by eliminating infectious agents
microglia
gray matter
dense neuron bodies giving it a darker color
white matter
lipid based due to myelin sheaths giving it a lighter color
what is the name given to the electrical signal generated by neurons?
action potential
T or F : the peripheral nervous system can be divided into 2 divisions called the afferent and efferent nervous systems
True
T or F : the autonomic nervous system is responsible for regulating and controlling voluntary actions such as skeletal muscle movements
False
What is the name of the fluid that flows through the ventricular system and central canal of the brain and spinal cord?
cerebrospinal fluid
A peripheral nerve connection consists of bundled of nerve fibers called ______________
fascicles
what is eosin?
a negatively charged, acidic dye (stains acidophilic structures) that stains a histology slide red or pink (ex-cytoplasm)
what is hematoxylin?
a basic dye (stains acidic to basophilic structures) a purplish blue (ex-nucleus)
4 types of tissues
- epithelial
- connective
- muscle
- nervous
3 main types of muscle
- smooth
- skeletal
- cardiac
cell names: simple
one layer
cell names: stratified
multiple layers
cell names: squamous
squished
cell names: cuboidal
cubes
cell names: columnar
column shape
function: simple squamous epithelium
allows material to pass through and secretes lubricating substance
location: simple squamous epithelium
- air sacs of lungs
- lines heart
- blood and lymphatic vessels
function: simple cuboidal epithelium
secretes and absorbs
location: simple cuboidal epithelium
ducts and secretory potrtion of glands and kidneys
function: simple columnar epithelium
absorbs, and secretes mucus and enzymes
location: simple columnar epithelium
bronchi, uterine tubes, uterus, digestive tract and bladder
function: pseudostratified columnar epithelium
secretes mucus
location: pseudostratified columnar epithelium
trachea and upper respiratory tract
function: stratified squamous epithelium
protects against abrasion
location: stratified squamous epithelium
lines the esophagus, mouth, and vagina
function: stratified cuboidal epithelium
protective tissue
location: stratified cuboidal epithelium
sweat glands, salivary and mammary glands
function: stratified columnar epithelium
secretes and protects
location: stratified columnar epithelium
male urethra and the ducts of some glands
function: transitional epithelium
allows urinary organs to expand and stretch
location: transitional epithelium
lines the bladder, uretha, and uterus
a continuation of lumens epithelium made up of columnar or pseduocolumnar epithelium due to there secretion abilities
glands
specialized tissue that regulates and controls bodily functions through conduction of electrical signals that travel along neurons to the brain or to target tissues throughout the body
nervous tissue
2 major divisions of the nervous system
- central nervous system
- peripheral nervous system
about the CNS
- brain and spinal cord
- receives and integrates signals from the sensory system
- receives information from the afferent division
afferent division
division of the nervous system that receives sensory input and relays it to the brain
gray matter
tissue rich in neuron cell bodies
white matter
tissue rich in myelinated neuron axons
about the PNS
- all nervous tissue outside of the brain and spinal cord
- afferent and efferent division
efferent divison
splits into somatic and autonomic nervous system
somatic nervous system
voluntary muscle movement (skeletal muscle)
autonomic nervous system
involuntary functions - split into sympathetic and parasympathetic
sympathetic nervous system
controls “fight or flight”
parasympathetic nervous system
controls “rest and digest”
cortex
outermost layer
medulla
innermost layer
neuron
the functional unit of the nervous system that generates electrical signals called action potentials
myelin sheath
a lipid rich sheath that wraps around the axon created by oligodendrocytes (CNS) and Schwann cells (PNS)
glial cells
other specialized non-neuron cells that make up the nervous system
astrocyte
CNS - wrap around blood vessels
oligodendrocyte
CNS - form myelin sheaths around multiple axons
microglia
CNS - provide maintenance and immune protection
ependymal cells
CNS - neuroepithelial cells that provide cerebrospinal fluid
Schwann cells
PNS - wraps myelin sheath around and individual axon
three primary layers of a blood vessel
tunica intima, tunica media and tunica externa
tunica intima
innermost layer
tunica media
middle layer
tunica externa
outermost layer
general appearance: artery
thick walls with a small lumen, appear rounded
general appearance: veins
thin walls with a large lumen, appear flattened
artery vs vein: tunica intima
an artery’s is more wavy while a veins is smooth
thickest layer in the artery
tunica media
thickest layer in the vein
tunica externa
arteries
move oxygenated blood away from the heart
veins
move deoxygenated blood to the heart
What is the purpose of valves in veins?
promote unidirectional flow of blood toward the heart and prevent back flow toward the capillaries caused by low blood pressure
what happens when a valve in a vein fails?
varicose veins
capillaries
where nutrient, gas and fluid exchange in the tissues occurs
What is the main function of the vena cava?
safely transporting blood to the heart
Which component in the medium artery wall allows the artery to control the diameter of the lumen via vasoconstriction and vasodilation?
smooth muscle cells
Why does our body develop anastomoses in various places?
Anastomoses exist to ensure adequate blood supply to particular regions of the body. By joining arterioles together, the body creates some redundancy in the pathways of blood circulation. This means that if one pathway is injured or otherwise blocked, there is another pathway that still allows blood to reach the important site.
venules
The main function of venules is to collect blood from capillary beds, starting the return of blood to the heart
most permeable capillary
discontinuous (sinusoidal) capillary
least permeable capillary
continuous capillary
continuous capillary location
muscle and nervous tissue
fenstrated capillary location
kidneys and intestine
sinusoidal capillary location
liver and speen
What makes up the cerebellar cortex?
gray matter
What is the name of the fatty sheath that surrounds neuronal axons within the white matter of the brain? From what cells does this fatty sheath originate from?
myelin sheath, Schwann cells and oligodendrocytes
The cell bodies of somatic motor neurons lie in which horn of the spinal cord?
Anterior (ventral) horns
What fluid runs through the central canal of the nervous system?
Cerebrospinal fluid
What is the function of myelin and why is it important?
Myelin insulates the axon and reduces the amount of charge lost across the membrane, which greatly increases the conduction speed of an action potential.
How do the relative locations of gray and white matter differ in the spinal cord, compared to the brain?
The cortex of the brain is gray matter and the cortex of the spinal cord is white matter. The medulla in the brain is white matter while the medulla of the spinal cord is gray matter.
Which is the main function of stratified squamous epithelium?
protection
Which is the main function(s) of simple cuboidal epithelium?
secretion and absorption
Which is the main function of pseudostratified columnar epithelium?
secretion and protection
Which glands are simple coiled tubular glands?
Sweat glands in the skin
What is the difference between an endocrine and an exocrine gland?
Exocrine glands secrete substances into ducts within the skin. Endocrine glands secrete directly into the bloodstream.
What are the major functional differences between cilia and microvilli?
Microvili increase surface area and cilia protect.
Why would it be problematic if the esophagus was lined with simple squamous epithelium?
Simple squamous would not protect the esophagus and it would allow materials to easily pass through.
membrane potential
voltage differences that exist across membranes established by movement of ions
where is Na more concentrated (in or out of the cell)?
outside the cell (extracellular fluid)
where is K more concentrated (in or out of the cell)?
inside the cell (cytoplasm)
what is more permeable, K or Na? by how much?
K is 25 times more permeable
what is the resting membrane potential?
-70 mV
action potential
large changes in the distribution of changes across a membrane that occurs rapidly, but only lasts a short amount of time
why does an action potential occur?
when specialized voltage gated membrane sodium channels are activated leading to a rapid influx of sodium ions
define depolarization
a large increase of Na+ in the cell making it more positive
refractory period
occurs from the beginning of an action potential to the restoration of resting membrane potential when it cannot produce another action potential
absolute refractory period
impossible to initiate a second action potential
relative refractory period
only a very strong stimulus can initiate a second action potential
what does it mean that action potentials are all or none?
the action potential will either reach threshold and occur or they will not, there is no relation between stimulus strength and response amplitude in a single axon
orthodromic
a preferred natural direction of conduction (away from the soma)
antidromic
the direction of conduction is towards the soma
What is the relationship between stimulus strength and response amplitude in a single axon?
The action potential amplitude should be similar across all recordings. This is known as the all-or-none response.
latency period
a longer duration of time between stimulus and start of the action potential
Why do you suppose the latency differed between the median and lateral fibers?
A longer latent period suggests that the lateral giant nerve fibers conduct more slowly than the median fiber.
The conduction velocity (CV) along the nerve can be most accurately calculated using which equation?
CV = (D2 - D1)/(T2 - T1) or distance over time
Do you think that the nerve fiber would be able to generate impulses continuously at this rate? Why or why not?
No. Eventually the ion gradients would dissipate as the Na+ pump would be unable to keep up with the inflow of Na+ and outflow of K+. But this problem would not be detected for some time.
Briefly describe the cellular events responsible for the refractory period (Hint: Discuss the mechanism of repolarization).
An action potential occurs when positive ions (Na+) are permitted to enter the axon through special ion channels in the membrane. These channels open briefly when the membrane potential reaches its threshold. The channels then must “reset”, and during this time they are closed and inactive. Although the reset time is very fast, it is detectable as the refractory period. A second stimulus that occurs during this time will not cause an action potential.
are there gap junctions in skeletal muscle?
no, each fiber behaves independently
myofibrils
a single muscle fiber that consists of actin and myosin
motor unit
a single motor neuron and all the muscle fibers it innervates
twitch
the mechanical response of a single muscle fiber to a single action potential (all or none)
strength of muscle contraction is increased in 2 ways:
- recruitment (increase the number of motor units)
- summation (stimulating existing motor units more frequently)
what is the neurotransmitter used in motor nerves?
acetylcholine
how does acetylcholine initiate contraction in skeletal muscle?
- ACh is released
- ACh goes into junctional cleft and binds to receptors
- receptors open channels depolarizing the muscle and Ca2+ is released from the sarcoplasmic reticulum
- Ca2+ binds to troponin and initiates actin and myosin to contract
- Ca2+ moves back into the ER and ACh is hydrolyzed and the contraction stops
latent period
delay between the stimulus and contraction
summation of skeletal muscle
a second stimulus arriving before the muscle has relaxed again causes a second twitch on top of the first so that the peak is greater developed
tetanus
contractions fuse and create a smooth powerful contraction (seen in the summation of skeletal muscle contraction)
causes for muscle fatigue in skeletal muscle
- neural fatigue (limitations of a nerves ability to generate a sustained signal)
- metabolic fatigue (reduced ability of the muscle fiber to contract)
isometric muscle contraction
increasing tension with in a muscle without shortening the muscle
isotonic muscle contraction
the muscle changes length as it contracts while the load or resistance remains the same
threshold stimulus
the weakest stimulus that produces the greatest contraction of which a muscle is capable
maximal stimulus
the stimulus that produces the greatest contraction of which a muscle is capable
refractory period
the time following the stimulation of a muscle when the muscle will not normally contract
As you increase the voltage applied to the skeletal muscle, describe how it responds to the increased stimulus.
As we increased the voltage applied to the muscle, the force of the muscle increased. The muscle responds to the force and once it reaches a certain point it stops increasing in response.
What happened to the number of fibers contracting as you increased the voltage in skeletal muscle?
More and more motor units were recruited as the stimulus amplitude (voltage) increased.
In light of the “all or none” law of muscle contraction, how can you explain the graded response?
One muscle fiber will react the same each time a stimulus is given. However, if the stimulus is increased then more motor units will be recruited to produce more force.
What effect does stretching the muscle have on contraction strength? Is this effect linear?
At the cellular level, actin and myosin are arranged so they slide past each other. These protein molecules must overlap in order to interact with each other. As the muscle stretches, it contracts more forcibly up to some maximum. Past this point, the actin and myosin layers begin to be pulled apart. As less and less of these proteins overlap, the muscle produces less and less force. The effect is not linear, as the contraction force increases at first then decreases.
Describe how the isolated muscle behaved as the interpulse interval was decreased progressively.
As the stimulus interval between the two pulses is reduced, the two contractions gradually merge into each other. As the two contractions merge (summate), there is a resulting increase in the force of contraction.
how many nuclei are in a smooth muscle cell?
one
where is smooth muscle found?
in the digestive tract, arteries, bladder, uterus, etc
is smooth muscle striated?
NO
is smooth muscle voluntary or involuntary?
involuntary
does smooth muscle have fast or slow contractions?
slow contractions that can be sustained for long periods of time
what makes smooth muscle different from skeletal muscle?
- slowness
- ability to propagate wave of contraction (gap junction)
- rhythmical contraction
- not prone to muscle fatigue
- involuntary
what does it mean to be an involuntary muscle?
have the ability to self-excite and exhibit a basic, coordinated rhythm even in the absence of neural stimulation
what type of neural regulation does smooth muscle receive?
autonomic stimulation from the sympathetic and parasympathetic nervous system
what neurotransmitter does the sympathetic nervous system produce?
norepinephrine
what neurotransmitter does the parasympathetic nervous system produce?
acetylcholine
how does norepinephrine affect smooth muscle contractile rate and force?
decreases rate and force
how does acetylcholine affect smooth muscle contractile rate and force?
increased rate and force
how does smooth muscle contract?
- Ca2+ channels are leaky
- slow Ca2+ intake (depolarization) until threshold
- high Ca2+ activates calmodulin which activates myosin and actin to contract
What is the biological importance of rhythmic contractions of the earthworm gut? Are these contractions similar to those in the guts of vertebrates?
The rhythmic contractions of the gut are involuntary movements of the muscle to keep material moving through the gastrointestinal tract. Yes because vertebrae also need to move material through their gut.
What effects did you observe when the temperature of the solution bathing the earthworm smooth muscle was changed?
increased activity with warm solutions and decreased activity with cold solutions
What effects did you observe when the high Ca2+ and Ca2+-free Ringer’s solution was bathing the earthworm smooth muscle?
stronger contractions would be expected to occur when the muscle is bathed in a high Ca2+ solution, and weaker contractions will be seen when the muscle is bathed a Ca2+-free solution.
Describe the contractile response (rate and force) of the earthworm gut to high Ca2+ Ringer’s solution.
High calcium increased contractile force and rate.
Describe the contractile response (rate) of the earthworm gut to high K+ Ringer’s solution.
You should observe increased contraction rate. The K+ concentration in the solution has profound effects on the smooth muscle cell’s resting potential. Increasing the extracellular K+ concentration makes the membrane potential more positive (that is, less negative), bringing it closer to threshold. Because the smooth muscle cells in the earthworm gut undergo a spontaneous depolarization, bringing the membrane potential closer to threshold increases the contraction rate.
neurotransmitter that increases permeability of Ca2+
acetylcholine
neurotransmitter that decreases permeability of Ca2+
epinephrine
What effects did you observe about smooth muscle when earthworm was in the the different neurotransmitter solution (epinephrine and acetylcholine)?
Epinephrine decreased contractile rate and force. Acetylcholine increased contractile rate and force.
serosa
Outside covering of a connective tissue. Present on
organs that are within a body cavity (e.g. the abdominal cavity)
muscularis
Layers of smooth muscle which normally consist of an
inner circular layer and an outer longitudinal layer.
mucosa
Includes an epithelial lining, the underlying connective
tissue and underlying glands if present.
lumen
Hollow center of organ.
simple vs compound glands
simple glands do not brand while compound galnds branch
alveolar vs tubular glands
alveolar are more circular at the end while tubular looks more elongated (like tubes)
