membranes and transport
A red blood cell is placed in 0.9% NaCl and keeps its normal shape because water has no reason to rush in or out.
What is an isotonic environment?
The stimulus was strong, but not strong enough to reach threshold, so the neuron stayed silent.
What is the all-or-nothing rule?
A synapse passes current directly through low-resistance protein channels with almost no delay.
resistance protein channels with almost no delay.What is an electrical synapse?
These CNS cells form myelin sheaths around neurons.
What are oligodendrocytes?
This brain structure is involved in thermoregulation and is described as an endocrine center.
What is the hypothalamus?
A cell is surrounded by a solution with more particles than the inside of the cell, so water leaves and the cell shrinks.
What is a hyperosmotic environment?
A signal seems to “jump” from one node of Ranvier to the next instead of traveling continuously down the axon.
What is saltatory conduction?
Calcium enters the presynaptic terminal and activates machinery that lets vesicles release neurotransmitter.
What is exocytosis?
These “first responders” of the CNS act like immune defense cells.
What are microglia?
A patient has muscle rigidity, rhythmic hand tremors, shuffled gait, and loss of dopamine.
What is Parkinson’s disease?
A molecule moves from high to low concentration without ATP until equilibrium is reached.
What is simple diffusion?
Sodium channels open, Na⁺ rushes into the cell, and the membrane potential becomes more positive.
What is depolarization?
A patient has muscle weakness that worsens with activity, drooping eyelids, and antibodies attacking ACh receptors.
What is myasthenia gravis?
A person can still produce fluent speech, but it makes no sense because comprehension is damaged.
What is Wernicke’s area damage?
This treatment crosses the blood-brain barrier and becomes dopamine, but is not considered a permanent long-term solution.
What is L-Dopa?
Glucose gets transported using the energy stored in the sodium gradient instead of directly using ATP.
What is secondary active transport?
Potassium leaves the cell, bringing the membrane potential back toward resting conditions.
What is repolarization?
This medication helps myasthenia gravis by blocking acetylcholinesterase, leaving more ACh available.
What is neostigmine?
A person understands language but struggles to speak and write properly after a stroke.
What is Broca’s area damage?
Alzheimer’s is associated with tau buildup inside neurons, forming these structures.
inside neurons, forming these structures.What are neurofibrillary tangles?
This pump spends ATP to move 3 Na⁺ out of the cell and 2 K⁺ into the cell, helping maintain resting membrane potential.
What is the Na⁺/K⁺ ATPase pump?
A squid solves the speed problem with a giant axon, while humans solve it using this insulating structure.
What is myelin?
A toxin blocks nicotinic ACh receptors at the NMJ, producing severe paralysis and respiratory failure.
What is alpha-bungarotoxin?
Oxygen-starved neurons release too much glutamate after a stroke, creating this damaging overexcitation effect.
What is excitotoxicity/hypertoxicity?
A flat EEG reading indicates this condition, classified as clinical death.
What is brain death/electrocerebral silence?