Thermoregulation and Homeostasis
What is the human body’s temperature set point?
About 37 degrees Celsius.
What is the dendrite and axon?
Dendrite receives signals; axon sends signals.
CNS parts
CNS = brain + spinal cord
What ion triggers neurotransmitter vesicles' exocytosis?
Ca²⁺ entering the axon terminal.
What happens when body temperature increases?
Sweating, vasodilation, behavioural cooling (ie. moving under shade, drink water).
Name the insulating structure around many axons.
Myelin sheath.
Somatic vs autonomic.
Somatic = voluntary movement; autonomic = involuntary responses.
What is the name of the space between the pre- and postsynaptic neurons?
Synaptic cleft.
Define homeostasis.
Maintaining a stable internal environment despite external changes.
What is the resting membrane potential? What establishes the resting membrane potential?
-70 mV, Na/K pump
Sympathetic nervous system function.
“Fight or flight”: pupils dilate, ↑ heart rate, ↓ digestion.
Which structure do synaptic vesicles fuse with to release neurotransmitters?
The presynaptic membrane.
What is the difference between negative and positive feedback?
Negative reverses a change to bring conditions back to the set point, and a positive feedback amplifies the change further from the set point.
What is saltatory conduction?
AP jumps between nodes of Ranvier along myelinated axons.
Parasympathetic function.
“Rest and digest”: pupils constrict, ↓ HR, ↑ digestion.
Where are neurotransmitters stored before release?
Synaptic vesicles.
Identify stimulus, control center, effector:
Your blood CO₂ rises, which triggers your medulla oblongata to stimulate your diaphragm to contract to increase your breathing rate.
Stimulus: high CO₂; Control center: medulla oblongata; Effector: diaphragm/intercostal muscles.
Why is an action potential all or nothing?
A minimum threshold (–55 mV) must be reached or no AP occurs; once triggered, it always reaches the same magnitude.
Which ions are most concentrated inside the neuron at rest?
K+
What happens if neurotransmitters were not removed from the synaptic cleft?
Continuous stimulation → uncontrolled firing, paralysis, or overstimulation.