Joints
Which functional classification describes a freely movable joint?
Diarthrosis
Which bone cell is primarily responsible for breaking down, or resorbing, bone?
Osteoclast
What is the approximate resting membrane potential of a neuron?
-70 mV
What is the space between the presynaptic and postsynaptic cells called?
Synaptic cleft
What does the synovial membrane do?
Synovial membrane - produces synovial fluid
What type of cartilage covers the opposing bone surfaces in a typical synovial joint?
Hyaline cartilage (articular cartilage)
What is the functional unit of compact bone?
Osteon (Haversian system)
Where is Na+ more concentrated: the intracellular fluid (ICF) or extracellular fluid (ECF)?
Extracellular fluid (ECF)
Which ion enters the presynaptic axon terminal and triggers neurotransmitter release?
Ca2+ (calcium)
What is the site where neuronal decisions/integration occurs?
The axon hillok
Which structure directly produces synovial fluid?
Synovial membrane
What is the difference between compact bone and spongy bone?
Compact bone contains osteons, while spongy bone is organized into trabeculae.
Which statement correctly describes a graded potential?
A. It is always the same magnitude.
B. It occurs only after threshold is reached.
C. Its magnitude depends on stimulus strength, and it weakens with distance.
D. It travels down the entire axon without decreasing.
C. Its magnitude depends on stimulus strength, and it weakens with distance.
Which sequence correctly describes chemical synaptic transmission?
A. Neurotransmitter release -> action potential -> Ca2+ entry -> receptor binding
B. Action potential -> Ca2+ entry -> neurotransmitter release -> receptor binding
C. Ca2+ entry -> receptor binding -> action potential -> neurotransmitter release
D. Action potential -> neurotransmitter binding -> Ca2+ entry -> exocytosis
B. Action potential -> Ca2+ entry -> neurotransmitter release -> receptor binding
Which TWO structures primarily reduce the loss or effects of mechanical/electrical energy in their respective systems?
Myelin and articular cartilage
A structure within a synovial joint divides the synovial cavity in two, improves joint stability, and reduces wear and tear. Name the structure.
Meniscus / menisci (articular disc)
An osteoblast becomes completely surrounded by the bone matrix it has helped produce. What does that cell become, and where will it be located?
It becomes an osteocyte located within a lacuna.
For K+ at resting membrane potential, the chemical and electrical gradients oppose each other. State the direction each gradient pushes K+. (Chemical goes where? Electrical goes where?)
Chemical gradient: out of the cell. Electrical gradient: into the cell.
What is the major functional difference between an EPSP and an IPSP?
An EPSP brings the postsynaptic neuron closer to threshold, increasing the likelihood of an action potential. An IPSP moves it away from threshold, decreasing the likelihood of an action potential.
A neuron is at -70 mV. A stimulus creates a graded depolarization, but the membrane never reaches threshold. Will an action potential occur? Explain.
No. Action potentials are all-or-none and occur only if the graded potential brings the membrane to threshold.
A structure normally allows synovial fluid to be forced out of cartilage during compression and seep back in when pressure is relieved. What is this process called?
Weeping lubrication
A bone experiences a new pattern of mechanical stress over time. Which bone cell detects the mechanical stress, and how can spongy bone structurally adapt to that change?
Osteocytes detect mechanical stress and communicate remodeling needs. Trabeculae can realign according to the new stress pattern.
Why does an action potential normally propagate in only one direction along an axon, and why does myelination increase its speed?
The refractory period prevents the recently activated membrane from immediately firing again, promoting one-way propagation. Myelin insulates the axon and allows voltage-gated Na+ channels to cluster at Nodes of Ranvier, producing faster saltatory propagation.
Neuron A rapidly releases neurotransmitter onto a postsynaptic neuron several times. Neurons B and C instead release neurotransmitter onto that same postsynaptic neuron at approximately the same time. What type of summation is occurring in each situation?
Neuron A: temporal summation. Neurons B and C: spatial summation.
A drug prevents voltage-gated Ca2+ channels in an axon terminal from opening. The action potential still propagates normally down the axon and reaches the terminal. Predict what happens next and explain why the postsynaptic neuron is affected.
Ca2+ cannot enter the axon terminal, so synaptic vesicles are not properly triggered to release neurotransmitter by exocytosis. Neurotransmitter therefore does not bind postsynaptic receptors, and the normal postsynaptic graded potential does not occur.