post lectures/quizzes exam 4

why does an action potential travel in one direction down an axon?

because voltage-gated sodium ion channels can’t open immediately

the phrase “saltatory propagation” refers to the:

ability of an action potential to “jump” from one node of Ranvier to the next

the release of neurotransmitter from the axon terminal’s controlled by voltage-gated:

calcium ion channels

the initial depolarization association with the action potential is the consequence of the opening of __ at the axon hillock

voltage-gated sodium ions

threshold potential refers to the membrane potential required to:

open-voltage-gated sodium ion channels & initiate an action potential

during synaptic transmission:

receptors that bind neurotransmitters trigger a change in postsynaptic membrane potential

membrane potential is determined by:

the difference in concentration of ions & charged molecules on the 2 sides of a cell’s membrane

the area within the neuron where stimuli are summed is called the:

axon hillock

an important function of myelin is to:

increase the speed of nerve signal transmission along the axon

the area of the sarcomere where the actin & myosin myofilaments overlaps is called the

A-band

why’s calcium necessary for muscle contraction?

calcium is needed to activate the troponin so that tropomyosin can be moved to expose the myosin-binding sites on the actin filament

which bone cells would be called on to increase the concentration of calcium in the blood?

osteoclasts

the power stroke in muscle contraction describes:

the pivoting of the myosin head, which causes actin & myosin to slide relative to each other

a single motor neuron & population of muscle fibers that it innervates is called a(n)

motor unit

what’s the function of tropomyosin in muscle cells?

tropomyosin covers the myosin-binding sites on the actin filaments, preventing contraction from occuring

which option is a correct pairing of structutre & function?

sarcoplamic reticulum: modified endoplasmic reticulum that stores Ca₂₊

at the level of actin & myosin molecules, what’s producing force when a skeletal muscle contracts?

the binding of myosin to actin

which of these statements is true regarding receptors for peptide or amine hormones?

receptors for peptide or amine hormones are typically located in the plasma membrane of cells

temporal summation is a response to the:

frequency of stimulation of a postsynaptic cell

the dental anesthetic lidocaine blocks voltage-gates Na+ channels. how would exposure to lidocaine affect the nerve function?

the nerve cell wouldn’t be able to depolarize and conduct an action potential

why are some body cells responsive to a particular hormone, whereas others are not?

responsive cells express a receptor specific for the hormone

a new hormone is discovered that appears to play a role in bone development the hormone is hydrophilic & composed of several amino acids. how should this hormone be classified?

peptide hormone

you measure levels of Ca²⁺ in various locations within a motor neuron & a skeletal muscle fiber when the motor neuron isn’t depolarized & the muscle fiber’s at rest. where do you expect to find high levels of Ca²⁺?

within the sarcoplasmic reticulum of the muscle fiber

which scenario would be most likely to result in an action potential within the postsynaptic cell?

dendrites: low-frequency inhibitory postsynaptic potential (IPSP); cell body: high-frequency excitatory postsynaptic potential (EPSP)

which statement about muscle contraction is accurate?

actin & myosin filaments overlap when a muscle is contracted than when it is relaxed

what even results from the hydrolysis of ATP to ADP by the myosin head?

cocking of myosin head

the function unit of a muscle cell is:

the sarcomere

the __ is stimulated by releasing factors from the __ that are transported in the bloodstream

anterior pituitary gland; hypothalamus

which of the following statements regarding negative feedback is FALSE?

negative feedback means that nay deviation from the set point is further amplified to maintain homeostasis

which of the statements is true regarding neurotransmitters, synaptic signaling, & hormones?

most synaptic signaling is rapid, compared with hormones

when a fracture begins to heal, one type of bone cell moves into the fracture site and tears down the damaged bone tissue. which of the following tears down bone?

osteoclasts

tropic hormones:

act on other endocrine organs

often it’s important for health reasons to induce labor (i.e., smooth muscle contractions) in pregnant women. the drugs used for this purpose would most closely resemble:

oxytocin

each hormone’s organ specificity is determined by:

its ability to interact with a specific receptor

which example describes a system that is NOT able to maintain homeostasis?

a person with diabetes will experience large spikes and crashed of blood glucose without proper monitoring

which of these structures serves as a connection between the nervous & endocrine systems?

hypothalamus

diffusion of material between the blood & body tissues occurs at which of the blood vessels?

capillaries

movement of food from the stomach into the esophagus is normally prevented by

the esophageal sphincter

bile produced in the liver is associated with which activity?

breakdown of fat globules into small fat particles in the small intestine

what’s the correct order of events in the control of the heartbeat?
1: activation of the SA node

2: contraction of the atria

3: contraction of the ventricles

4: activation of the AV node

5: transmission of the action potential through a set of modified conducting muscle fibers

1, 2, 4, 5, 3

aside from whatever digestion has happened before the food reaches the small intestine, the bulk flow of digestion takes place in the:

duodenum

the pacemaker of the mammalian heart is:

a group of specialized cardiac muscle cells that initiate the heartbeat

which of the statements about open & closed circulatory systems is correct?

closed circulatory systems can more effectively control the flow of blood to specific body regions than open circulatory systems

which of the statements about veins is true?

the blood pressure within the veins is much lower than the blood pressure within arteries

the pH of gastric of the stomach is about 2 due to the formation of HCl. where is the source of this HCl?

the parietal cells of the stomach

if the partial pressure of oxygen outside of a cell is 100 mmHg & the partial pressure of oxygen inside of a cell is 25 mmHg, which of the statements is correct?

there will be a net diffusion of oxygen from outside the cell to inside

imagine a mutation where the adrenal cortex no longer produced receptors for ACTH released by the anterior pituitary. which answer option is most likely to occur?

the adrenal cortex would not release cortisol

an increase in blood glucose levels will lead to which condition?

increased insulin production

some individuals with lung disease have damage that has resulted in a decrease in the overall amount of surface area in the lungs/ what would you expect to see regarding diffusion of oxygen across the lung surface?

diffusion rates are slower, & less oxygen will be absorbed than in individuals without lung disease

which of the factors affects the rate of diffusion of a substance across a respiratory surface?

concentration gradient

you and you friend have just finished working out. when the workout is over, your friend purchases a drink that contains calcium. after finishing the drink, the concentration of calcitonin circulating in the bloodstream will __ compared to before your friend started the workout.

increase

which statement about nervous & endocrine signaling is accurate?

the nervous system transmits between adjacent cells using neurotransmitters, whereas the endocrine system signals with hormones

which option is an example of positive feedback involving hormones?

the increases intensity of uterine contractions during childbirth