human physiology exam 2

In the case of a hemorrhage the blood volume decreases, which leads to a decrease in stroke volume. What will happen to cardiac output? (prior to any homeostatic mechanisms)

Decreased Cardiac Output

In order to start signal transduction in a G-protein coupled receptor, a ______________ soluble molecule will bind to the receptor on the surface of the outer membrane. This molecule is known as the ______________ in this system. When bound, this leads to a ______________ change in the receptor, which will thereby activate the ______________ subunit of the G-protein. This makes that subunit increase its affinity for ______________. Once that molecule binds it causes that subunit to dissociate from the rest of the G-protein. It can then activate an enzyme embedded within the membrane, known as ______________, which will generate a molecule of cAMP. The generated molecule is known as a(n) ______________. This molecule can then go to activate a variety of pathways inside the cell.

Water, first messenger, Conformational (Shape), Alpha, GTP, Adenylyl cyclase, and second messenger.

In skeletal muscle cells, calcium initiates contraction by binding to?

troponin

Binding of ______________ to myosin permits cross-bridge ______________ between actin and myosin in skeletal muscle fibers.

ATP; detachment

What is the definition of a "motor unit"?

A single motor neuron plus all the muscle fibers it innervates.

Some glucose transport proteins can also bind fructose, another 6-carbon monosaccharide, but not lysine, an amino acid, because transport proteins exhibit ______________ for their ligands.

specificity

Which of the following are ways in which binding of a chemical messenger with a cell's receptor can being about a cellular response?

Opening/Closing

Activation

Promoting

Activating/Inhibiting

ALL OF THE ABOVE

Dr. Sazama loves caffeine. He loves it so much that he drinks a lot of it every morning. If you were to look at the cells that normally have receptors for caffeine, what would you notice about a number of those receptors?

A decrease in number due to down-regulation

Naloxone (Narcan) is a high affinity antagonist to the opioid receptor, the same receptor to which heroin is an agonist. If both heroin and naloxone were in the bloodstream, what would the user experience?

A decrease in the effects of heroin

Which of the following is true regarding G-protein coupled receptors?

G-proteins work by using the alpha subunit to activate an effector protein, such as adenylyl cyclase, an ion channel, or another enzyme in the membrane.

Amplification during a second-messenger cascade is beneficial because amplification

allows small amounts of hormones to produce large responses in target cells.

You are studying a cross-sectional tissues slice of a nerve using a transmission electron microscope. You find an area where there appears to be a small amount of cytoplasm surrounded by about 100 layers of stacked cell membranes, which would make it very non polar. You conclude that you have found

a myelinated axon

Which is FALSE about neurons?

A neuron receives information on its axons and delivers it to other neurons through its dendrites.

Which is TRUE about typical, resting neurons?

The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions causing the RMP to be closer to the equilibrium potential for potassium.

An action potential does not re-stimulate the adjacent membrane that was previously depolarized because

that area of the membrane is in the absolute refractory period.

What is the best description of a tetanic contraction in a skeletal muscle cell?

Multiple action potentials in the motor neuron cause a sustained contraction.

An action potential travels down the axon where it reaches ______________ gated ______________ channels in the axon terminal. These ions travel through the membrane where they attach to ______________ proteins. These proteins allow vesicles that carry neurotransmitter to combine with the plasma membrane of the neuron, thereby releasing neurotransmitter into the ______________. The neurotransmitters than bind to ______________ gated ion channels, which allow ______________ ions to pass through. This then initiates a way of electrical current across the muscle fiber. The action potential reaches a ______________, where it is able to travel deep into the muscle fiber. ______________ receptors sense the action potential and pull on the ryanodine receptors that are on the surface of the ______________. The ryanodine receptors are channels that allow ______________ ions to flow out of the organelle into the cytosol. From t

Voltage, Ca2+, SNARE, Synaptic Cleft, Ligand, Na+, Transverse Tubule (T-Tubule), DHP, Sarcoplasmic reticulum, Ca2+, Troponin, Tropomyosin, Actin, Myosin

Which is TRUE about the Na/K pump in neurons?

It generates a small electrical potential such that the inside is made negative with respect to the outside.

Which of the following statements regarding action potentials generated in a neuronal membrane is FALSE?

Action potentials travel in both directions along the axon.

Binds to calmodulin; used in muscle contraction

Ca2+

Activated by a G protein and adenylyl cyclase

cAMP

High concentration within the sarcoplasmic reticulum

Ca2+

High extracellular concentration; involved in a typical action potential

Na+

High intracellular cytosol concentration; involved in repolarization

K+

Synthesized from guanosine triphosphate in a reaction catalyzed by guanylyl cyclase

cGMP

Neuronal axons typically have abundant

Voltage-gated channels for Na+ that open in response to depolarization in a positive feedback loop.

A motor neuron needs to innervate muscle gibers at a very fast rate. What characteristic(s) will give the neuron the ability to conduct a signal the fastest?

Small Diameter

Myelin sheaths absent

Both a and c

The receptor itself functions as an enzyme

Receptor tyrosine kinase

Cytoplasmic kinase that interacts with a receptor

Janus Kinase

Receptor that has a 3-subunit protein associated with it

G-protein coupled receptor

Channel that opens in response to an action potential

Voltage-Gated ion channel

Channel that opens in response to a chemical messenger

Ligand-Gated ion channel

Cell body is in the central nervous system

Two of the above

Sends messages towards the integrating center

Afferent neuron

Sends messages away from the integrating center

Efferent neuron

Cell body is in the peripheral nervous system

Afferent neuron

Most abundant type

Interneuron

Carries the message directly to the effector cell (i.e. muscle, gland, etc.)

Efferent neuron

Can conduct an action potential

All three neuron types

Lies entirely within the central nervous system

Interneuron

How is the strength of a stimulus encoded by neurons?

By the frequency of action potentials

At rest, the ______________ maintains the ion concentrations on both sides of the neuronal membrane. To generate an action potential, ______________ ion channels are opened, leading to a(n) ______________ of those ions through the neuron membrane. These types of channels are ______________ gated ion channels. Once these channels are opened, the membrane ______________. When a(n) ______________ charge is reached inside the cell, the "ball and chain" portion of a(n) ______________ ion channel inactivates that ion channel. At this point, the slower ______________ ion channels finally open, leading to a(n) ______________ of those ions across the cell membrane. The cell membrane ______________. Once this state of charge on the membrane is reached, the ion channels close.

Sodium/Potassium Pump, Na+, Influx, Voltage, Depolarizes, Positive, Na+, K+, Efflux, Repolarizes

Visual signs travel on myelinated axons. While most pain signals travel on unmyelinated axons. Theoretically, if you get a paper cut, will you see the cut happen or feel the pain first?

You will experience the visual sensation before the pain sensation.

In the first few seconds of skeletal muscle contraction, what is the main mechanism by which ATP is replenished after the initial stores are depleted?

Energy and phosphate are transferred from creatine phosphate to ADP.

An action potential is able to travel quickly through a cardiac muscle cell due to the presence of

Gap junctions within the intercalated discs

What occurs during isovolumetric ventricular contraction?

Ventricular pressure meets its maximum value for the cardiac cycle

Which is a TRUE statement about smooth muscle?

Smooth muscle does not use troponin-tropomyosin to regulate cross-bridge activity.

Rigor mortis (stiffness of the dead body) is caused by

lack of ATP.

Uses troponin for regulation of tropomyosin

Two of the above

Has actin and myosin

All three muscle types

Has gap junctions between cells

Cardiac Muscle Cells

Striated

Two of the above

Cannot undergo tetanic contraction due to L-type calcium channels

Cardiac Muscle cells

Undergoes cross-bridge cycling

All three muscle types

Blood control into the capillaries is controlled by the ______________, whereby ______________ will increase flow, and ______________ will decrease flow. At the arterial end of the capillaries, ______________ pressures index the capillary is higher, and this will favor ______________ out of the capillaries. At the venous end, ______________ pressure is higher from the interstitial fluid, and this will favor ______________ into the capillaries. This pressure is typically constant because of the presence of ______________ in relatively stable concentration throughout the body. These biomolecules cannot pass through the ______________ of the capillaries due to their size. As blood travels through the capillaries, it will ______________ due to the cross sectional area of the capillaries.

Arteriole/Arterioles, Vasodilation, Vasoconstriction, Hydrostatic, Filtration, Osmotic, Absorption, Protein(s), Intercellular Cleft(s), slow down

Any situation where a decrease in blood flow to an organ or tissue leads to damage is called

shock

Which of the following changes would most increase the resistance to blood flow in a blood vessel?

Halving the diameter of the vessel, making it smaller

Hank had heart surgery to repair the pacemaker of his heart. Into which structure did the surgeon need access?

Sinoatrial (SA) node

The plateau of the action potential in cardiac ventricular cells results from the opening of voltage-gated long-lasting ______________ channels in the plasma membrane of the cell.

Ca2+

The plateau mentioned in the previous question regarding the action potential in cardiac muscle cells leads to the prevention of what activity by the heart?

Tetanic contraction

Following hemorrhage, reflexes are triggered that attempt to compensate for the blood loss. As a result the blood loss and the reflex mechanism, which of the following will be TRUE, compared to pre-hemorrhage values?

Cardiac output will be decreased and total peripheral resistance will be increased.

The nodal cells within the heart (i.e. SA, AV nodes) have a few characteristics. Which characteristic(s) corresponds to the nodal cells? (choose the most correct answer)

F-Type sodium channels

Depolarization caused by movement of Ca ions

Slowly depolarizes on its own after repolarization

A, B, D are correct

In the clotting system, activated platelets will release chemicals that bring in more platelets, which in turn will release more chemicals to draw in more platelets. This is an example of

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