Physiology Quiz on Hormones and Reflexes

Chapter 1

• Physiology is the study of the normal functioning of an organism and its parts.
• Levels of organization range from atoms, molecules, cells, tissues, organs, organ systems to organisms.

Chapter 1 - Homeostasis

• Homeostasis is maintaining a stable internal environment despite external changes.

• Disease occurs when homeostasis is disrupted for long periods.

• Homeostasis is a dynamic steady state, not static equilibrium.

• Negative feedback: A process to reverse a change and return to a set point (e.g., regulating body temperature).

• Positive feedback: A process to amplify or increase a change, moving further away from a set point (e.g., childbirth).

• Feedforward control: Processes anticipating changes and activating mechanisms in advance (e.g., salivating before eating).

Chapter 5

• Osmotic equilibrium: Equal solute concentration on both sides of the cell membrane.
• Chemical disequilibrium: Uneven distribution of solutes across the cell membrane (e.g., higher Na+ outside, K+ inside).
• Electrical disequilibrium: Ion distribution creates an electrical potential across the cell membrane.

Chapter 5 - Membrane Transport

• Simple diffusion: Movement of substances down their concentration gradient without energy or proteins.
• Protein-mediated transport: Movement of substances with the help of carrier proteins, can be active (requires energy) or passive (doesn't require energy).
• Vesicular transport: Movement in vesicles (active transport).

Chapter 6

• Local communication: Occurs over short distances (e.g., gap junctions, contact-dependent signals, diffusing chemicals).
• Long-distance communication: Occurs over longer distances (e.g., blood transport, endocrine system, nervous system).

Chapter 6 - Hormone Signaling

• Lipophilic ligand binding: Ligand diffuses across the membrane, binds to intracellular receptor, changes receptor conformation, binds to DNA, changes gene expression. Slower response.
• Lipophobic ligand binding: Ligand binds to surface receptor, activates intracellular signaling pathways, activates second messengers, changes in ion channel and enzyme activity. Faster response.

Chapter 6 - Receptor Types

• Receptor channels: Open or close in response to ligand binding, changes ion flow (e.g., nicotinic acetylcholine receptors).
• G protein-coupled receptors (GPCRs): Activate intracellular G proteins, causing second messengers to be produced (e.g., adrenergic receptors).
• Receptor-enzyme complexes: Contain enzyme activity or are linked to enzymes (e.g., receptor tyrosine kinases like the insulin receptor).
• Integrin receptors: Bind to extracellular matrix proteins and change the cytoskeleton (e.g., integrins in cell adhesion).

Chapter 6 - Reflex Control Pathway

• Stimulus detected--> sensor --> input signal to integrating center --> output signal --> target --> response to restore homeostasis.

Chapter 7 - Endocrine System

• Four characteristics of a hormone: Secreted into blood, travels to distant targets, very low concentrations, affect growth/development, homeostasis, or metabolism.
• Peptide hormones: Made in advance, stored in vesicles, released by exocytosis, rapid response, act on cell surface.
• Steroid hormones: Synthesized on demand, not stored, diffuse across membrane, slow response, act on intracellular receptors.

Chapter 7 - Pituitary Hormones

• Pituitary hormones: List of 6 anterior pituitary hormones, hormones that control its release and their primary targets.

Chapter 7 - Feedback Mechanisms

• Long-loop negative feedback: Hormones from the target endocrine gland inhibit the anterior pituitary and hypothalamus.

Chapter 7 - Endocrine Pathologies

• Hypersecretion: Excess hormone production.
• Hyposecretion: Deficiency of hormone production.
• Target response abnormalities: Cells failing to respond.

Chapter 8 - Nervous System Organization

• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Sensory (afferent) and motor (efferent) branches.

Chapter 8 - Glial Cells

• Astrocytes: Maintain blood-brain barrier; provide structural support and regulate ions, neurotransmitters.
• Oligodendrocytes: Myelinate CNS axons; increasing signal transmission speed.
• Microglia: Act as immune cells; removing debris and pathogens.
• Ependymal Cells: One source of neural stem cells.
• Schwann Cells: Myelinate PNS axons; assist in repair.
• Satellite Cells: Surround neuronal cell bodies in ganglia; provide support and nutrient exchange.

Chapter 8 - Electrical Signals

• Graded potentials: Variable strength, localized, no minimum level required to initiate, can sum.
• Action potentials: All or none, threshold, propagate down axon, cannot sum.

Chapter 8 - Refractory Periods

• Absolute refractory period: No new action potential possible during this period.
• Relative refractory period: New action potential possible with a stronger stimulus.

Chapter 8 - Synaptic Communication

• Ionotropic receptors: Ligand-gated channels, fast synaptic transmission (e.g., AMPA receptors).
• Metabotropic receptors: G-protein coupled receptors, slow, long-lasting effects.
• Neurotransmitters: Chemical messengers (e.g., glutamate, GABA, dopamine).
• Neuromodulators: Influence neurotransmitter release or receptor sensitivity.

Chapter 8 - Long-Term Potentiation (LTP)

• Initial signal: Glutamate binds to AMPA and NMDA receptors.
• AMPA activation: Sodium influx, depolarization.
• NMDA activation: Calcium influx, enhances glutamate release.

Chapter 9 - Cerebrospinal Fluid (CSF)

• Formation: Choroid plexus in ventricles; selective filtration of plasma.
• Distribution: Lateral ventricles → third ventricle, cerebral aqueduct, fourth ventricle, subarachnoid space, reabsorbed into venous circulation (dural sinuses)
• Functions: Buoyancy (reduces brain weight by floating), protection, homeostasis, transport.

Chapter 9 - Blood-Brain Barrier (BBB)

• Structure: Endothelial cells joined by tight junctions, astrocytic end-feet, basement membrane.
• Functions: Selective permeability; protects the brain; maintains homeostasis.

Chapter 10 - Sensory Receptors

• Transduction: Converts physical stimulus to electrical signal.
• Threshold: Minimum stimulus strength to produce a response.
• Receptive field: Specific area where stimulus activates a sensory neuron.
• Receptor potential: Graded potential in sensory receptors in response to stimuli.

Chapter 10 - Sensory Coding

• Modality: Type of sensory neuron activated.
• Location: Receptive fields activated.
• Intensity: Number of receptors activated, frequency of action potentials.
• Duration: How long action potentials are generated, receptor adaptation.

Chapter 10 - Receptor Adaptation

• Tonic receptors: Slowly adapting; respond for duration of stimulus (e.g., pain).
• Phasic receptors: Rapidly adapting; respond only at onset and offset of stimulus (e.g., pressure).

Chapter 10 - Pain and Itch

• Nociceptors: Specialized sensory neurons; stimulated by harmful stimuli (mechanical, thermal, or chemical); relays signals to spinal cord.
• Pain: Transmitted via fast (sharp/localized) and slow (dull/aching) fibers. Neurotransmitters like substance P and glutamate relay pain.
• Itch: Mediated by skin nociceptors, often triggered by histamine.

Chapter 11 - Autonomic Nervous System

• Adrenal medulla: Inner part of adrenal glands; releases hormones (epinephrine/norepinephrine). Location is atop kidneys
• Epinephrine/norepinephrine: Released directly into bloodstream; systemic effect (epinephrine), localized effect (norepinephrine)

Chapter 11 - Neuromuscular Junction

• Components: Presynaptic terminal, synaptic cleft, postsynaptic membrane (motor end plate).
• Function: Action potential in motor neuron releases acetylcholine (ACh) -> binds to nicotinic ACh receptors on muscle -> initiates muscle contraction.

Chapter 11 - Somatic, Sympathetic, Para-Sympathetic Divisions

• Compare anatomy, neurotransmitters, receptors, functions of each nervous system division
• Somatic: Single neuron, CNS to skeletal muscle, voluntary, ACh
• Sympathetic: Two neurons, use ACh and NE, preganglionic ACh, postganglionic NE, involuntary (fight or flight)
• Parasympathetic: Two neurons, pre and postganglionic use ACh, involuntary (rest and digest)

Chapter 12 - Excitation-Contraction Coupling

• Action potential in muscle fiber
• Calcium release from sarcoplasmic reticulum
• Calcium binding to troponin, allowing myosin-binding to actin
• Myosin power stroke, cross-bridging
• Calcium removal, relaxation

Chapter 12 - Muscle Length-Tension

• Optimal length: Ideal overlap of actin and myosin, maximum tension.
• Overstretched: Reduced overlap.
• Overly shortened: Interference among filaments.

Chapter 13 - Neural Reflex Pathways

• Classification by: efferent division, CNS integration area, reflexes, number of neurons.
• Stretches reflex: Monosynaptic stretch, sensory neuron → spinal cord → motor neuron → contraction of stretched muscle. Includes reciprocal inhibition.
• Flexion (withdrawal) reflex: Reflex that withdraws limb from harmful stimulus. Associated with crossed extensor reflex.

Test your knowledge on the actions of insulin, the characteristics of different receptors, and the roles of various hormones in the body. This quiz also covers the mechanics of neural reflexes and the sequence of events following ligand binding. Assess how well you understand these essential physiological concepts.