QP Test 2 Flashcards
Name four things involved in excitation-contraction coupling in skeletal muscle
Generation of end plate potential, formation of cross-linkages between actin and myosin, depolarization
What is a feature common to skeletal, cardiac, and smooth muscle?
Increase in cytoplasmic free calcium concentration
How is skeletal muscle innervated?
Motor neurons exclusively
What is the result of a ryanodine receptor knockout?
no Ca release into cytosol from sarcoplasmic reticulum
Name four things that increase intracellular calcium in smooth muscle.
- activation of voltage gated calcium channels
- activation of gap junctions
- activation of IP3 receptor channel
- activation of ligand gated calcium channel
What is the purpose of gap junctions between smooth muscle cells?
electrical communication between neighboring cells
What happens in latch state (smooth muscle)?
(incomplete) dephosphorylation of myosin light chain
What is a pancreatic hormone with a strong hypoglycemic effect?
Insulin
What does a shift in the hormone response curve to the left of the control indicate?
An up-regulation and the receptors are more sensitive to hormone action.
Give an example of a hormone that acts mainly through a membrane receptor.
Growth hormone
Circadian rhythms fluctuate _________.
Daily
Give an example of a hormone released from the pituitary.
Adrenocorticotropic hormone (ACTH)
What pituitary peptide stimulates the thyroid gland?
Thyroid stimulating hormone (TSH)
What is the condition called when the hypothalmus hypersecretes a particular hormone.
Tertiary hypersecretion
In the negative feedback of complex neuroendocrine systems, what happens if negative feedback from the primary gland hormone decreases?
The secondary glad increases secretion of its tropic hormone
What is the pacemaker of the heart?
The sinoatrial node
In an EKG, what causes the P wave?
Atrial depolarization
Where is conduction of cardiac impulse the slowest?
AV nodal fibers
The plateau of cardiac action potential is maintained by what?
Both calcium and potassium channels
What is the most important factor in influencing the amount of blood pumped by the ventricles of the heart?
preload (venous return)
What is another name for the bicuspid valve?
The mitral valve
Beta Blockers are commonly used as what?
Anti-hypertensive drugs
According to starlings law, what happens if the interstitial osmotic pressure decreases?
Less filtration
What is the most important factor in determining vascular resistance?
Vascular diameter
If the diameter changes by a factor of 2, how will the flow change?
Flow will change by a factor of 16
During hemorrhage, activation of baroreceptor reflex causes what?
Increase in heart rate (look up baroreceptor reflex)
What is flow autoregulation?
Maintaining blood flow nearly constant in the face of pressure change
Gases inspired in the tidal volume are thoroughly and rapidly mixed in the alveolar space by ________.
simple diffusion
What disease causes the lungs to become more compliant?
Emphysema
“For a fixed amount of gas kept at a fixed temperature, pressure and volume are proportional” is what law?
Boyle’s law
Lungs are wrapped by two layers of pleura membranes. What is the relationship between the pressure in the space between the membranes and the alveolar pressure?
The space in between the membranes is always more negative than the alveolar pressure.
How is CO2 carried in the blood?
As bicarbonate in plasma
Which way would the oxyhemoglobin dissociation curve move with an increase in PCO?
It would move to the left (learn all of these)
Both peripheral and central chemoreceptors will contribute to increased ventilation as the result of _________.
Increased arterial partial pressure of carbon dioxide.
What is the function of ryanodine receptors?
The release Ca into the cytosol from sarcoplasmic reticulum in skeletal muscle cells
What happens in myosin/actin’s location during activation of skeletal muscle contraction?
Actin filaments slide past myosin filaments shortening the Z discs.
Tetanic skeletal muscle tension is resulted from the sustained elevation of which molecule’s concentration in myocytes?
Calcium
What does the pre-stimulation length of the muscle represent in terms of myosin-actin interaction?
Number of myosin cross-bridges interacting with actin.
What are the differences between Type I (slow, red) human skeletal muscle fibers and Type II (fast, white) muscle fibers?
The type I have more mitochondrias, smaller fiber diameter, more myoglobins, harder to get tired, lower glycolytic enzyme activity than the type II.
What is the primary function of gap junctions between smooth muscle cells?
Allows them to communicate electronically.
What happens if the level of myosin light chain phosphorylation increases in smooth muscle?
The rate of the actin-myosin cross-bridge cycle increases. The maximum contraction force increases.
What is the “latch state” in smooth muscle?
The cross bridge cycle is slowed down due to the myosin light chain dephosphorylation but not completely stopped.
What are the similarities between smooth muscle and skeletal muscle contraction?
Both involve voltage dependent calcium channels, ATP consumption, myosin-actin interaction and Ca release from the SR
What four factors modulate smooth muscle contraction?
- autonomic nerves
- circulating hormones
- local signals from other cells
- electrical signals from other smooth muscle cells
Why does the force of smooth muscle in blood vessels continually increase after (longer than) the optimal length?
Because passive stress from other tissues continually increases
What are the 5 sequential events during smooth muscle cell contraction?
- rising intracellular Ca
- binding of Ca to calmodulin
- Activation of MLCK by Ca/calmodulin complex
- phosphorylation of myosin light chain
- activation of myosin ATPase
What 4 factors regulate intracellular calcium of skeletal muscle?
L-type Ca channel, calcium pump, ryanodine receptor, Na/Cl exchanger
What are the differences among skeletal, cardiac, and smooth muscle in terms of nucleus?
Skeletal muscle has many nuclei, smooth muscle is mononuclear, cardiac muscle is a mixture of the two
What are the differences among skeletal, cardiac, and smooth muscle in terms of performing autonomic phase contraction?
Only smooth muscle performs autonomic phase contraction
What are the differences among skeletal, cardiac, and smooth muscle in terms of fatigue?
Only white (fast twitch) muscle fibers get fatigued
Is skeletal muscle innervated by sympathetic nervous system?
No. Diaphram and facial muscles are exceptions though
What type of contraction is happens when myosin heads bind to the same F-actin monomer during cross-bridge cycling?
Isometric contraction
Why can airway allergies be treated with epinephrine?
Epinephrine activates Beta2 adrenergic receptors, which then activate the cAMP signaling pathway which causes smooth muscle cell relaxation
Can nerve stimulation induce smooth muscle relaxtion?
Yes, smooth muscle innervation regulates both contraction and relaxation.
In a single stimulated isotonic contraction, what 4 things change in the shortness-time relationship while load is increasing?
- latency of contraction increases
- total shortening duration decreases
- speed of contraction decreases
- maximal shortening distance decreases
Where is adrenocorticotropic hormone (ACTH) secteted from?
pituitary gland
Where is progesterone secreted from?
The ovaries
Which hormones regulate calcium absorption?
Vitamin D increases calcium absorption, parathyroid hormone (PTH) increases Vitamin D synthesis
Where is insulin secreted from?
Pacreatic Beta Cells
What class of receptors does testosterone belong to?
Nuclear receptors
Compare the endocrine and exocrine systems.
Both are essential communicating systems. The nervous system uses neurons to target specific cells and the endocrine system send hormones through the body affecting cells nonspecifically. Endocrine system’s action is much slower and longer compared to the nervous system.
What is the hormone secreted from the adipose tissue that controls food intake?
Leptin
What is the pituitary peptide that stimulates the thyroid gland?
Thyroid stimulating hormone
What is the largest class of hormones?
The proteins (peptide) hormones
How are steroid hormones made?
The enzymatic conversion from cholesterol
What type of chronotropic control observed within the endocrine system that occurs with a pulse every 24 hours?
Circadian rhythm
Name 2 types of hormones that come from amino acids
- Thyroid hormones are basically a double tyrosine with three or four iodine atoms.
- catecholamines including epinephrine, norepinephrine, dopamine
What is the receptor for catecholamine?
Adrenergic receptor that is a 7-trans-membrane spanning protein
What does a shift of the hormone dose response cure to the right from the control indicate?
An ED50 dose of hormone that is greater than before the shift occurred. The response of receptor (binding, activity, etc.) is reduced for the same concentration of hormonal stimulation.
What is the relationship between metabolic clearance of a hormone and its half-life?
The shorter the half life, the higher the metabolic clearance number
Give 4 examples of the way that the nervous system integrates its control with the classical endocrine system?
- hypothalamus secretion of releasing hormones
- hypothalamus secretion of posterior pituitary hormones
- adrenal medulla secretion of catecholamines
- autonomic nervous system control of endocrine secretion
In a complex control system with three hormones, where is the tertiary endocrine gland?
At the hypothalamus