BIOL 103 Module 2 Flashcards
What are the two major classes of hormones based on solubility?
Hydrophilic (water-soluble) and Hydrophobic (lipid-soluble)
Where are receptors for hydrophilic vs hydrophobic hormones found?
Hydrophilic = on the membrane; Hydrophobic = intracellular (cytoplasm or nucleus)
What is a tropic hormone?
A hormone that stimulates the release of another hormone
What is the HP axis?
Hypothalamus → Pituitary → Target endocrine gland (e.g., adrenal)
What is the main difference between short- and long-term stress responses?
Short = epinephrine (fast, nervous); Long = cortisol (slow, endocrine)
What is a sarcomere?
The basic contractile unit of striated muscle (Z-disc to Z-disc)
What protein blocks myosin from binding actin in resting muscle?
Tropomyosin
What triggers tropomyosin to move and allow contraction?
Calcium binding to troponin
What is the role of myosin ATPase?
Breaks down ATP to power the “power stroke” (bending of myosin head)
What’s the difference between striated and smooth muscle?
Striated = organized sarcomeres; Smooth = random filament orientation
What is the resting membrane potential of a neuron?
Around –70 mV
What ions are high outside vs. inside the neuron?
Na⁺ high outside, K⁺ high inside
What is depolarization?
Membrane potential becomes less negative (closer to 0)
What is the role of voltage-gated Na⁺ channels in the action potential?
They open at threshold, causing rapid depolarization
How does tetrodotoxin (from pufferfish) affect neurons?
Blocks voltage-gated Na⁺ channels → prevents AP
What is saltatory conduction?
Action potentials jump between nodes in myelinated axons
What are the two types of sensory receptors?
Neuronal (direct) and Non-neuronal (release signal to neuron)
What do TRP channels do?
Detect temperature and some chemicals (like mint or capsaicin)
What are statocysts used for?
Balance/orientation using gravity-sensitive particles
What sensory system is used by fish to detect water movement?
Lateral line system (hair cells)
What are magnetoreceptors used for?
Detecting Earth’s magnetic field (e.g., migration)
What is the role of the spinal cord in reflex arcs?
Direct connection between sensory and motor neurons (fast response)
What are the three main divisions of the brain?
Forebrain (sensory), Midbrain (integration), Hindbrain (motor control)
What’s the difference between the CNS and PNS?
CNS = brain & spinal cord; PNS = nerves connecting to rest of body
