Poll Questions Flashcards
(41 cards)
Which best describes a “myofibril”?
It is a cylindrical cellular organelle
composed of myofilaments
What is the role of calcium in muscle contractions?
to bind with troponin, changing its shape so
the actin filament is exposed.
You have designed a drug that is supposed to bind to the myosin binding sites on actin. You inject it into a relaxed muscle, but find that none of the drug is bound. Why?
The myosin binding sites on actin are covered by
tropomyosin.
How is the length of a skeletal muscle cell related to the
force it can generate?
Skeletal muscle cells generate the most force when the
contraction occurs at an intermediate length
What would be the result if the administration of a
drug sequesters (inactivates) all the ATP in a
cell?
All cross-bridges will remain tightly bound to
actin
The major physiological difference between single-unit
smooth muscle and multi-unit smooth muscle is
Action potentials can spread from cell to cell in single-
unit, but not in a multi-unit muscle.
Which group of chemicals does
NOT contain hormones?
Carbohydrates
The specific action of hormones is due to:
hormone-specific receptors in target cells
When a certain gland extract gland is applied to
some cells, these cells respond by starting cell
division. However, when a c-AMP inhibitor is first
applied to the cell and then the gland extract is
applied, the cells do not divide.
Therefore, the gland extract most likely contains
a peptide hormone
The anterior pituitary gland releases all of
the following hormones
follicle-stimulating hormone (FSH).
thyroid stimulating hormone (TSH).
prolactin.
growth hormone (GH)
What controls the release of corticoids
from the adrenal cortex?
Higher brain centers
CRH from the hypothalamus
ACTH from the anterior pituitary
Which of these pituitary hormones is not
released in response to a releasing hormone
from the hypothalamus?
ADH
Insulin
Which of these is true of the adrenal medulla?
It functions as part of the sympathetic nervous
system
The mode of action of insulin is by
adding GLUT-4 transporters to muscle and fat
cells
stimulating phosphorylation of intracellular
glucose in liver cells.
Blood samples from an individual who has fasted
(not eaten) for 24 hours would have:
high levels of glucagon and low levels of insulin.
he hormone ____ is a modified amino
acid, whereas ____ is a steroidal hormone.
epinephrine, testosterone
George’s symptoms
1. Frequent urination: polyuria.
2. Increased thirst: polydipsia.
3. Increased appetite: polyphagia.
Are George’s symptoms consistent with
type 1 DM, type 2 DM, both, or neither?type 1 DM, type 2 DM, both, or neither?
Both
Where is the Atrial repolarization?
Hidden in QRS complex.
In vertebrate heart, many pacemaker cells
(myogenic cells) in SA node, each with their
own spontaneous AP firing rate.
If they all start firing at the same time, which
pacemaker cell determines the basic heart
beat frequency?
Cell with fastest AP frequency
In vertebrate heart, many pacemaker cells
(myogenic cells) in SA node, each with their own
spontaneous AP firing rate.
What happens to the heart beat frequency if
this pacemaker cell dies? Which cell
determines basic heart rate frequency?
Cell with next fastest AP frequency
If the stroke volume is 80 ml and the
heart rate is 70 beats per minute, the
cardiac output is
5600 ml/min
CO = HR X SV
Through which vessel is the velocity
of blood flow the slowest?
capillaries
Which of the following statements concerning the
capillaries is FALSE?
Increasing capillary hydrostatic pressure decreases
the likelihood that filtration will occur.
The affinity of hemoglobin for oxygen is
____ if PO2 is low and is ____ if PO2 is high.
low, high
