Biology Review: Germ Layers, Tissues, Homeostasis, Nervous System, Sensory System, and Musculoskeletal System

Question-and-answer flashcards covering germ layers, tissues, homeostasis, nervous system, sensory system, and musculoskeletal topics from Pages 1-5 of the notes.

What are the three germ layers?

Ectoderm, Mesoderm, Endoderm

What tissues arise from the ectoderm?

Skin, hair, nails, nervous system, sensory organs

What tissues arise from the mesoderm?

Muscles, bones, blood, connective tissue, kidneys, heart, reproductive system

What tissues arise from the endoderm?

Lining of digestive tract, respiratory tract, liver, pancreas

What are the four primary tissue types?

Epithelial, Connective, Muscle, Nervous

Which germ layer produces epithelial tissue?

All three germ layers (depends on location)

Which germ layer produces connective and muscle tissue?

Mesoderm

Which germ layer produces nervous tissue?

Ectoderm

What is the primary function of epithelial tissue?

Covers, protects, secretes, absorbs

What is the primary function of connective tissue?

Supports, binds, transports, stores

What is the primary function of muscle tissue?

Movement (skeletal, cardiac, smooth)

What is the primary function of nervous tissue?

Communication and coordination

What is the correct level of organization from smallest to largest?

Cell → Tissue → Organ → Organ system → Organism

What is homeostasis?

Maintaining stable internal conditions despite external changes

What are the components of a negative feedback loop?

Stimulus → Sensor → Integrating center → Effector → Response

What is an antagonistic effector?

Effectors with opposite actions that balance each other (e.g., sweating vs. shivering)

What is the mammalian temperature sensor?

Thermoreceptors in the hypothalamus and skin

Give an example of a negative feedback loop.

Blood sugar regulation, body temperature regulation

Give an example of a positive feedback loop.

Childbirth contractions (oxytocin), blood clotting

What are the main phases of an action potential?

Depolarization (Na⁺ enters), Repolarization (K⁺ exits), Hyperpolarization (overshoot), Return to resting potential

How does ion movement correspond to an action potential graph?

Resting: Na⁺/K⁺ pump (-70 mV); Depolarization: Na⁺ influx; Repolarization: K⁺ efflux; Hyperpolarization: extra K⁺ efflux; Recovery: Na⁺/K⁺ pump restores balance

What happens at a chemical synapse?

AP reaches axon terminal → Ca²⁺ influx → neurotransmitter release → NTs cross synaptic cleft → bind postsynaptic receptors → new signal

Define neuromuscular junction.

Synapse between a motor neuron and a muscle fiber

Define synapse.

Junction where neurons communicate with other cells

What is a neurotransmitter?

Chemical messenger released at synapses

What is the synaptic cleft?

Gap between presynaptic and postsynaptic cells

What is a reflex?

Rapid, automatic response to a stimulus

What is depolarization?

Na⁺ ions enter the cell, making it less negative

What is hyperpolarization?

Membrane potential becomes more negative than resting due to K⁺ efflux

What is the sodium-potassium pump’s role?

Uses ATP to pump 3 Na⁺ out and 2 K⁺ in, maintains resting potential

What is threshold potential?

Minimum depolarization to trigger AP (~ -55 mV)

What is resting potential?

≈ -70 mV, maintained by Na⁺/K⁺ pump

What is an oligodendrocyte?

CNS glial cell that makes myelin

What is myelin?

Fatty insulation around axons that speeds conduction

What are the components of the Central Nervous System (CNS)?

Brain and spinal cord

What are the components of the Peripheral nervous system (PNS)?

Nerves and ganglia outside the CNS

How do PNS sensory and motor systems work?

Sensory (afferent) → to CNS; Motor (efferent) → from CNS

Parasympathetic vs. Sympathetic?

Parasympathetic = rest & digest; Sympathetic = fight or flight

What are the major regions of the vertebrate brain?

Forebrain, midbrain, hindbrain, cerebellum, brainstem

What is the sequence of steps in sensory processing?

Stimulus → Receptor → Transduction → Transmission → Processing in CNS → Perception

What are the main types of sensory receptors?

Mechanoreceptors (touch/pressure), Thermoreceptors (temperature), Nociceptors (pain), Photoreceptors (light), Chemoreceptors (smell, taste)

What are the categories of taste sensation?

Sweet, sour, salty, bitter, umami

What are the components of the vertebrate ear?

Outer ear (pinna, canal), middle ear (ossicles), inner ear (cochlea, hair cells)

How does the vertebrate ear interpret sound?

Vibrations → cochlea → hair cells transduce → signal via auditory nerve

What are the components of the vertebrate eye?

Cornea, lens, retina (rods & cones), optic nerve

How does the vertebrate eye interpret light?

Photoreceptors transduce light → signals sent via optic nerve → brain interprets

What is the lateral line (fish/amphibians)?

A sensory system that detects water movements and vibrations

What are the 4 steps of the contraction cycle?

Crossbridge formation → Power stroke → Crossbridge detachment → ATP hydrolysis (myosin re-cocks)

What role do troponin, tropomyosin, and calcium play in contraction?

Ca²⁺ binds troponin → tropomyosin shifts → actin sites exposed → myosin binds → contraction

What are the main components of a sarcomere?

Z line, A band, H band, I band, Thin filaments (actin), Thick filaments (myosin)

What is the sliding filament model?

Actin slides past myosin, shortening sarcomere (filaments don’t change length)

What are the main types of joints?

Ball-and-socket, hinge, pivot, saddle, gliding, condyloid

What happens at the neuromuscular junction (NMJ)?

AP → Ca²⁺ influx → ACh release → binds receptors → muscle depolarization → contraction

Define myofilament, twitch, summation, tetanus.

Myofilament = actin/myosin; Twitch = single contraction-relaxation; Summation = repeated stimuli ↑ tension; Tetanus = sustained contraction