resting membrane potential
potential difference between the inside of the cell and the outside of the cell across the membrane; depends on the resting permability of the membrane to ions and
what are the most important ions in neurons?
Na and K
How are the concentrations of Na and K established
by transport protein such as Na K pump; so that na inside the cell is low and K is high
What is the typical concentration intracellular? extracellular?
K 150mM and Na 5mM; K 5mM and Na 150mM
what can be used to measure the membrane potetntial?
amplifier
what is the thickest part of a neuron and how wide is it?
cell body ; 5-100um and axon is only about 0.5 um wide
What effect did increasing the extracellular potassium have on the resting membrane potential?
the resting membrane potential became less negative
What effect did decreasing the extracellular sodium have on the resting membrane potential?
only a small change occurred, because the resting neuron is not permeable to sodium
The channels that provide for the movement of potassium in the resting neuron are
leakage
Establishing the resting membrane potential requires energy through the use of the
sodium potassium pump
nerve
bundle of axons
what is it called when the axon extends from the cell body?
axon hillock
on a myelinated axon what is the first region called?
initial segment
Where is an AP usually initiated?
at the junction of the axon hillock and the initial segment; called trigger zone
The minimum voltage that is required to generate an action potential is called the
threshold voltage
Increasing the voltage resulted in which of the following?
no change to the AP
An axon that is more negative than the resting membrane potential is said to be
hyperpolarized
If an increase in extracellular potassium hyperpolarizes a neuron, which of the following would be correct?
it would change the membrane potential to a less negative value
how is a AP generated?
when the voltage-gated sodium channels open in sufficient numbers
when do voltage gated sodium channels open
when membrane depolarizes
An action potential requires _______.
voltage-gated sodium channels to open and sodium to flow with its electrochemical gradient
To reach threshold, the amount of sodium _______.
entering the cell must overcome the potassium exiting
Which of the following blocks voltage-gated sodium channels?
tetrodotoxin and lidocaine
Which of the following is used to block pain?
lidocaine
why do you think TTX is not used during dental procedures?
it irreversibly blocks voltage-gated sodium channels in axonal membranes
How can conduction velocity be calculated?
by knowing the distance the AP travels and the amount of time it takes; meters/second
myelination in CNS? in PNS?
oligodendrocytes; schwann cells
what is A fiber? B fiber? c fiber?
large diameter heavily myelinated axon; medium-diameter lightly myelinated axon; thin unmyelinated fiber
why is the striated muscle called skeletal muscle
it attaches to none and skin and is responsible for mobility of the body and limbs
is skeletal muscles voluntary or involuntary?
voluntary
why is skeletal muscle striated?
the striations are caused by filaments of two proteins Actin(thin and light) and Myosin(thick and dark band)
endomysium?
every individual muscle fiber is wrapped in it
fassicle?
a bunch of muscle fibers wrapped together
perimysium?
wraps around fascicles
muscle?
a bunch of fascicles wrapped together
epimysium
wraps around a muscle
What is the origin of a muscle? insertion?
stationary, immovable or less movable attachment(more proximal); movable attachment(more distal or lateral)
tendons?
pull on joints; attach muscle to bone
ligaments?
muscle to muscle
aponerosis?
attach muscle to bones- sheet like
What happens at the neuromuscular junction?
ACh is released and rapidly diffuses across the junction and combines to receptors on the sarcolemma; channels that allow both sodium and potassium ions to pass open briefly; because more sodium diffuses into the muscle fibers than K diffuses out, depolarization of the sarcolemma and subsequent contraction of the muscle fibers occur
what does ACh do?
causes the depolarization of the sarcolemma which makes the muscle contract
What effect did increasing the extra cellular potassium have on the resting membrane potentail
depolarization
what effect did decreasing the extracellular sodium have on the resting membrane potential?
doesn’t change alot
what do we call the minimum voltage that us required to generate an AP?
threshold -50MV
what was the threshold voltage?
30MV
after reaching the threshold voltage, what was the effect of further increasing the voltage?
no change bc AP are yes or no answers-AP was already seen
Why is the AP recorded by R2 delayed relative to R1?
AP needs to propagate down axon
why would an increase in extracellular potassium depolarize a neuron?
bc of leaky channels
-difference between outside and inside is less
why does tetrotoxin inhibit the genreration of AP?
blocks sodium channels; irreversibel
why does lidocaine inhibit the generation of an AP?
blocks sodium channel but is only temporary
Why would breaking your neck cause you to stop breathing?
because there you have your phrenic nerve which regulates and controls diaphragm
Do you really have a funny bone? what is it youre actually hitting?
no; ulna nerve
what is the largest nerve in the body?
sciatic nerve; goes from your spinal cord to your toes
What what happen if your sciatic nerve was cut?
lose control and sensation of leg
referred pain?
pain in one place but feel it somewhere else
reflexes?
rapid, predictable, involuntary responses to stimuli
autonomic reflexes?
mediated through autonomic system and we are not usually aware of them; activate smooth muscle, cardiac muscle and they activate glands of the body and regulate body functions such as digestion, elimination, blood pressure, salivation, and sweating
somatic reflexes?
stimulation of skeletal muscle by somatic division of the nervous system; rapid withdrawal of hand from hot stove
What are the five basic components of the reflex arc?
receptor – site of stimulus action
sensory neuron – transmits impulses to CNS
integration center –
motor neuron – conduct efferent impulses from integration center to effector
effector – responds to the efferent impulse
in a patellar reflex what muscle is being contracted/
quadriceps
knee jerk reflex: what nerve is carrying the afferent and efferent impulses?
femoral nerve
What 3 factors influence the rapidity and effectiveness of the patellar reflex test?
1. mental distraction
2. effect of simultaneous muscle activity in another body area
3. fatigue
ankle jerk reflex: what was the result?
planter flexion at the foot
during walking what is the action of the gastrocnemius at the ankle?
in contracts and pulls on the heel
planter reflex?
stimulating the cutaneous receptors in the sole of the foot; causes toes to flex and move closer together; superficial cord reflex
Superficial cord reflexes: what 2 stimuli initiate the superficial cord reflexes?
pain and temperature changes
Why is the Babinski’s sign seen in infants? and what would there response show?
because myelination of the nervous system is incomplete.
Toes flare and the great toe moves in an upward direction
pupillary reflexes?
retina of the eye is the receptor, the optic nerves contain the afferent fibers, (occipital lobe is integration center) the oculomotor is responsible for conducting efferent impulses to the eye, and smooth muscle of the iris is the effector
Shine a flashlight into the subjects left eye. The pullilary response was?
pupil constricted
When a consensual (ipsilateral and contralateral together) response occurs, what does this indicate about the pathways involved?
pathways are connected for eyes, some fibers to same side and others to opposite side; therefore the reflex observed from one side of the body will affect both eyes. (parasympathetics are more integrated allowing more to happen with less stimulation)
What is the function of these pupillary responses?
to protect the retina from light damage by controlling the amount of light entering the eye. In parasympathetic mode the less information coming in allows for the rest and repose mode to take place.
referred pain
is a sensory experience in which pain is perceived as arising in one area of the body when in fact another, often quite remote area is receiving the painful stimulus
What is the probable explanation for referred pain?
referred pain may occur because the nerves innervating both viscera (organs) and somatic structures travel along the same pathways
where are cutaneous receptors located?
skin
How are the true and false vocal cords different?
true vocal cords vibrate when air is expelled for speech and false don’t vibrate
What is the significance of the shape of the rings in the trachea?
the incomplete parts of the rings allows the esophagus to expand anteriorly when a large food bolus is swallowed; the solid portions of the rings reinforce the trachea walls to maintain its open passageway regardless of the pressure changes that occur during breathing
What is the Adams apple?
thyroid cartilage found on the larynx
What is the function of the epiglottis? Uvula?
elastic cartilage that closes larynx so food doesn’t go through it; prevents food from going up the wrong way through the nose
What happens at the respiratory membrane? at the tissues?
gas exchange; gas exchange
Why do cells need oxygen?
for cellular respiration….creates energy CO2 and H2O
what is the function of the pleural membrane?
PRODUCE LUBRICATING SEROUS FLUID THAT CAUSES THEM TO ADHERE CLOSELY TO ONE ANOTHER, HOLDING THE LUNGS TO THE THORACIC WALL AND ALLOWING THEM TO MOVE EASILY AGAINST ONE ANOTHER DURING THE MOVEMENTS OF BREATHING
what does the phrenic nerve do?
NERVE THAT ACTIVATES THE DIAPHRAGM DURING INSPIRATION
what is function of cilia? goblet cells?
cilia moves the mucous which traps bacteria; the goblet cells secrete mucous
why are the alveoli good for gas exchange?
they are thin and made of simple squamous
how are type 1 and type 2 cells different?
type 1 is simple squamous and helps with gas exchange while type 2 secrete surfactant which makes sure alveoli don’t stick together and reduces surface tension
how does o2 move from the lungs to the blood? how does it get to the cells?
simple diffusion; simple diffusion
what is a buffer?
balances out of pH
what is an acid?
donates H+ ion and raises pH
What is a base?
accepts H+ ions and lowers pH
acidosis?
below 7.35
alkalosis?
above 7.45
respiratory alkalosis?
too little CO2 in the blood; results from traveling to high altitude where O2 is less or hyperventilation(fever, panic attack, anxiety)
What happens in hyperventilation?
increase in rate and depth of breathing which removes CO2 from the blood faster than it is being produced reducing the amount of H+ in the blood
What compensates for respiratory alkalosis and acidosis? how?
renal system; retaining H+ ions and excreting bicarbonate ions to lower the blood pH levels back to normal range
What is the normal range for the partial pressure of carbon dioxide in the blood?
35-45 mmHg
Why was the breath held after the second hyperventilation?
to retain carbon dioxide
respiratory acidosis?
result of impaired respiration(airway obstuction of lung disease) or hypo-ventilation which leads to the accumulation of too much carbon dioxide in the blood
re-breathing?
breathing in air that was just expelled from the lungs; results in accumulation of CO2 in the blood; breathing in paper bag is an example
Carbon dioxide levels in the blood and blood pH are
inversely proportional to each other
renal compensation?
body’s primary method of compensating for conditions of REsp. acidosis and alkalosis
How do the kidneys regulate the acid base balance?
by altering the amount of H+ and HCO3- excreted int eh urine
The movement of fluid and solutes from the peritubular capillary to the renal tubule is referred to as _
tubular secretion
the nephron unit is responsible for maintaining
acid balance in eh body, fluid balance in body and electrolyte balance in body
The kidneys compensate for respiratory alkalosis by ___
conserving H+ and excreting bicarbonate
At which partial pressure of carbon dioxide did respiratory acidosis occur?
60 mmhg
metabolic acidosis?
low plasma HCO3- and pH; caused by ketoacidosis, salicylate poisoning(ingestion of too much aspirin oil of wintergreen), ingestion of too much alcohol, diarrhea(loss of bicarbonate ), and strenous exercise(cause a build up of lactic acid from anaerobic exercise
metabolic alkalosis?
high plasma bicarbonate and pH; causes include ingestion of alkali, vomiting(result in loss of too much H+), constipation(results in significant re absorption of HCO3-)
How does the respiratory system compensate for metabolic acidosis and alkalosis?
expelling or retaining carbon dioxide int eh blood
Excessive diarrhea results in which of the following?
loss of bicarbonate, metabolicacidosis
Ketoacidosis is usually a result of _______.
uncontrolled diabetes mellitus
Which of the following occurred when the metabolic rate was set to 20 kcal/hr?
metabolic alkalosis and hypoventalation
Which metabolic rate resulted in metabolic acidosis?
80 Kcal/hour
What does amphoteric mean? ex.
behave as base in acidic environment and acid in basic environment; protein draw it out
what role does exhalation of CO2 play in maintaining the pH of the blood?
if there is low pH in the blood then you have low H+ ions meaning you have a more acidic envornment
what areas of the brain control respiration?
medulla oblongata
What is the normal pH of arterial blood?
7.41
what is HCl and NaHCO3?
hydrochloric acid and sodium bicarbonate (base)
x

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