Human Physiology Test 2

In the case of a hemorrhage the blood volume decreases, which leads to a decrease in stroke volume. What happens to cardiac output?

Decreased cardiac output

What type of molecule binds to a surface receptor?

Water soluble

What type of molecule binds to a receptor on the inside of the cell?

Lipid soluble

In chemical messenger pathways, what is the molecule that initially binds to the receptor, usually outside of the cell?

First messenger

What are substances that enter or are generated in the cytoplasm as a result of receptor activation by the first messenger?

Second messenger

Which subunit of a of a G-coupled receptor (GPR) leaves the other subunits as it gains an affinity of for GTP?

Alpha subunit

In a cAMP associated GPR pathway, the alpha subunit eventually activates a special protein embedded in the membrane that will catalyze the conversion of ATP into cAMP. What is this protein?

Adenylyl cyclase

When comparing lipid soluble and water soluble messengers, which will have a slower, but more sustained response?

Lipid soluble messengers

What is a second messenger?

generated in cytoplasm as a result of receptor activation by the first messenger, is brought into the cell as a response to the first messenger, and helps relay the signal transduction message to lead to a cell’s response (ALL OF THE ABOVE)

Caffeine works by inhibiting cAMP phosphodiesterase. What effect will this have on cells?

Increased activation due to increased cAMP concentration

In cross bridge cycling for a muscle cell, ____ions are first released from the _____.

Calcium, smooth ER

Calcium ions bind to the _____, which cause them to pull up on ______ on the thin filament, also known as ______.

Troponin, Tropomyosin, Actin

The pulling up on actin opens up binding sites for the thick filaments, otherwise known as _____.

Myosin

This allows an _____ thick filament to bind to the thin filament.

Energized

From here, the thick filament _____, initiating the sliding filament mechanism while also releasing ______.

Flexes, ADP

______ binds to the thick filament, allowing the two filaments to _____.

ATP, Detach

_______ of ATP by the thick filament reenergizes the cross bridge so that the process can start again.

Hydrolysis

What is the definition of a “motor unit”?

A single motor neuron plus all the muscle fibers it innervates

Anti-histamines work by binding to the same receptor that histamine would normally bind to. This means that anti-histamines and histamines have the same ____ for that protein.

specificity

What are ways in which binding of a chemical messenger with a cell’s receptor can bring about a cellular?

opening/closing of ion channels, activation of a second messenger, promoting/inhibiting the transcription of genes, activating/inhibiting intracellular enzymes (ALL OF THE ABOVE)

Heroin is an opioid agonist. What would you expect to see for the number of opioid receptors in an individual that is addicted to heroin?

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

Amplification during a second-messenger cascade is beneficial because amplification ____.

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

What is a myelin sheath?

an area of the axon covered in layers of membrane that is impermeable to ion movement

What is FALSE about neurons?

a neuron receives info on its axons and delivers it to other neurons through its dendrites (opposite way around)

What is TRUE about typical, resting neurons?

The permeability of the plasma membrane to potassium ions is much greater that 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 _____ in the axon terminal.

Ca2+

These Ca2+ channels are triggered when the membrane potential inside the cell becomes more _______.

Positive

As the Ca2+ ions rush in, they attach to _____ proteins.

SNARE

SNARE proteins allow vesicles that carry _____ to combine with the plasma membrane of the neuron, thereby releasing neurotransmitter into the synaptic cleft.

neurotransmitter

The neurotransmitters bind to ____ gated ion channels, which mostly allow ____ ions to move into the cell. This initiates a wave of electrical current across the muscle fiber.

Ligand, Na+

The action potential reaches a _____.

Transverse tubule (T-tubule)

DHP receptors sense the action potential and pull on ______ receptors that are on the surface of the _____.

Ryanodine, Sarcoplasmic reticulum

Ryanodine receptors are channels that allow ____ ions to flow out of the organelle into the cytosol.

Ca2+

What is TRUE about the Na+/K+ ATPase pump in neurons?

It maintains a concentration gradient for K+ such that diffusion forces favor movement of K+ out of the cell

What is FALSE regarding action potentials generated in a neuronal membrane?

Action potentials travel in both directions along the axon (they travel only down the axon)

High extracellular concentration, involved in a typical action potential

Na+

Binds to calsequestrin in the smooth ER, high concentration within the sarcoplasmic reticulum

Ca2+

Activated by a G protein and adenylyl cyclase

cAMP

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 fibers at a very fast rate. What characteristic gives the neuron the ability to conduct a signal the fastes?

Large diameter

Receptor tyrosine kinase

the receptor itself functions as an enzyme

Janus kinase

cytoplasmic kinase that interacts with a receptor

G-protein coupled receptor

receptor that has a 3-subunit protein associated with it

Voltage-gated ion channel

channel that opens in response to an action potential

Ligand-gated ion channel

channel that opens in response to a chemical messenger

How is the strength of a stimulus encoded by neurons?

By the frequency of action potentials

Which of the neuron types has its cell body inside the CNS?

interneuron and efferent neuron (two of the above)

Which of the neuron types sends messages away from the stimulus?

Afferent neuron

Which of the neuron types is most abundant?

Interneuron

Which of the neuron types can conduct an action potential?

Afferent, Interneuron, and Efferent (ALL 3)

Which of the neuron types lies entirely within the CNS?

Interneuron

In response to a hemorrhage, the body will “autotransfuse” and take fluid from elsewhere in the body. From where is the body able to pull extra fluid?

The interstitum/interstitial fluid

In an individual that is dehydrated, their hematocrit will usually go up, such that they have “thick” blood. What effect will this have on flow rate?

A decrease in flow rate

In the excitation of the heart, the signal stops at the AV node for a short delay. What is the consequence of this delay?

It allows the atria to fill up the ventricles fully before contracting

Local anesthetics such as lidocaine and procaine block voltage-gated sodium channels. What is the consequence of this blockage?

A failure to depolarize the membrane

Cardiac nodal cell membrane potentials function as a ______ potential.

Pacemaker

Pacemaker potentials occur when _____ depolarization occurs in the membrane after repolarization.

Gradual

In the nodal cell, this depolarization is caused by ____ sodium channels that open when the membrane is repolarized.

F-type (funny)

As depolarization occurs, the ______ calcium channels open, which help bring the membrane potential to threshold.

T-type (transient)

From there, L-type _______ channels open, causing depolarization of the membrane.

Calcium

______ channels then fully open to allow for repolarization.

Potassium

At rest, the ______ maintains the ion concentrations on both sides of the neuronal membrane.

Sodium/Potassium pump

To generate an action potential, ____-gated _____ ion channels are opened, leading to an influx of those ions through the neuron membrane.

Voltage, Na+

As the voltage-gated Na+ ion channels are opened, the membrane _____.

Depolarizes

When a _____ charge is reached inside the cell, the “ball and chain” portion of a _____ ion channel inactivates that ion channel.

Positive, Na+

At this point, the slower _____ ion channels fully open, leading to an efflux of those ions across the cell membrane.

K+

The cell membrane ______. Once this state of charge on the membrane is reached, the ion channels close.

Repolarizes

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?

No blood enters or leaves the ventricles (volume stays constant)

Which is a TRUE statement about smooth muscle?

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

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

lack of ATP

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

Halving the diameter, making it smaller

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 regarding the action potential in cardiac muscle leads to the prevention of what activity by the heart?

Tetanic contraction

Visual signals travel on myelinated axons. While most pain signals travel on myelinated 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 ATP

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 ______.

Positive feedback

Which of the following is NOT TRUE about endothelial cells of the cardiovascular system?

They are only found in the capillaries

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

shock

Blood control into the capillaries is controlled by the _____.

Arteriole/Arterioles

At the arterial end of the capillaries, _____ pressure inside the capillary is higher, and this will favor _____.

Hydrostatic, Filtration

At the venous end of the capillary, ______ pressure is higher from the interstitial fluid, and this will favor ______.

Osmotic/oncotic, Absorption

This pressure is typically constant because of the presence of ______.

Proteins

These biomolecules cannot pass through the ______ of the capillaries due to their size.

Intercellular clefts

As blood travels through the capillaries, it will ______ due to their cross sectional area of the capillaries.

Slow down