Endocrine System Quiz

Chapter 1

• Physiology is the study of the normal functioning of a living organism and its parts
• Levels of organization, from smallest to largest: atoms, molecules, cells, tissues, organs, organ systems, organism
• Homeostasis is the maintenance of a relatively stable internal environment; disease occurs when homeostasis is disrupted for prolonged periods
• Negative feedback reverses a change to return the system to its set point (e.g., regulating body temperature)
• Positive feedback amplifies a change, moving the system further from its set point (e.g., childbirth)
• Feedforward control anticipates changes and activates mechanisms in advance to prevent deviations (e.g., salivating before eating)

Chapter 5

• Osmotic equilibrium means equal solute concentration on both sides of a cell membrane, preventing net water movement
• Chemical disequilibrium refers to unequal distribution of solutes across a cell membrane (e.g., higher sodium outside, potassium inside)
• Electrical disequilibrium describes charge differences across the cell membrane, maintained by ion channels and pumps like Na+/K+ ATPase

Transport across membranes

• Simple diffusion moves molecules down their concentration gradient, without energy or proteins
• Carriers (e.g., proteins) are involved in mediated transport, which can be active or passive (e.g., facilitated diffusion, active transport)
• Vesicular transport (endocytosis, exocytosis, phagocytosis) involves vesicles for movement across membranes

Overview of Channels, Vesicular, and Carrier Transporters

• Channels: Allow specific ions to cross the membrane passively via an electrochemical gradient (e.g., voltage-gated Na+ channels)
• Vesicular transport actively uses vesicles to move substances into or out of the cell (e.g., exocytosis)
• Carriers require energy and can move substances against their gradient (e.g., Na+/K+ ATPase pump)

Membrane Potential

• Membrane potential is the difference in electrical charge across a cell membrane (resting membrane potential: typically around -70 mV)
• Ion permeability changes affect membrane potential (e.g., more permeable sodium causes depolarization)

Chapter 6

• Local Communication: Gap junctions, contact-dependent signals, and diffusing chemicals
• Long-Distance Communication: Endocrine system (hormones travel through blood), and nervous system (electrical signals and neurochemicals for rapid delivery to specific targets)

General Sequence of Events for Lipophilic and Lipophobic Ligand Binding

• Lipophilic: Diffuse through membrane→bind receptor inside cell →activated complex binds to DNA →transcription/translation of new proteins (slower response)
• Lipophobic: Binds to receptor on cell surface →transduction →second messengers trigger changes in ion channels/enzyme activity/gene expression/rapid response

Four Major Types of Cell Surface Receptors

• Receptor channels: Open or close in response to ligand binding, altering ion flow
• G protein-coupled receptors: Activate intracellular G proteins, leading to second messenger production
• Receptor-enzyme complexes: Contain enzyme activity or are linked to enzymes
• Integrin receptors: Bind to extracellular matrix proteins

Seven Steps of Reflex Control Pathway

• Stimulus detected
• Sensor detects stimulus
• Input signal travels to integrating center through afferent pathways
• Integrating center processes input, determines response
• Output signal travels to target through efferent pathways
• Target (effector) carries out response
• Response homeostasis is restored

Neural Reflexes versus Endocrine Reflexes

• Neural reflexes are fast, highly specific, and employ electrical and chemical signals
• Endocrine reflexes are slow, broad, and utilize hormones in the bloodstream

Peptide and Steroid Hormones

• Peptide hormones are synthesized in advance and stored, released via exocytosis
• Steroid hormones are synthesized on demand and released immediately

Hormone Receptors and Cellular Mechanisms

• Peptide hormones have receptors on the cell surface and use second messengers
• Steroid hormones have intracellular receptors, affecting gene expression

Three Main Groups of Amine Hormones

• Catecholamines (derived from tyrosine, e.g., epinephrine, norepinephrine) act like peptide hormones
• Thyroid hormones (derived from two tyrosine, e.g., thyroxine and triiodothyronine): act like steroid hormones
• Melatonin (derived from tryptophan): regulates circadian rhythms

Hypothalamic-Anterior Pituitary Pathway

• Hormones in the hypothalamus regulate anterior pituitary hormones (e.g., Prolactin (PRL), Thyroid-Stimulating Hormone (TSH), Adrenocorticotropic Hormone (ACTH), Growth Hormone (GH), Follicle-Stimulating Hormone (FSH), Luitenizing Hormone (LH)) via releasing and inhibiting hormones

Long-Loop Negative Feedback

• Hormones from target endocrine glands inhibit the anterior pituitary and hypothalamus to help regulate hormone release

Endocrine Pathologies

• Hypersecretion: Excess hormone production
• Hyposecretion: Deficient hormone production
• Target response disorders: Target cells fail to respond appropriately

Chapter 8

• Nervous System organization: CNS (brain, spinal cord, coordination/processing), PNS (nerves, sensory division, motor division)
• Glial cells (astrocytes, oligodendrocytes, microglia, ependymal cells) support and nourish neurons
• Graded potentials vary in strength, spread short distances, and are crucial in initiating action potentials
• Action potentials are rapid signals, travel long distances, and rely on voltage gated channels

Action Potential

• Resting phase: membrane potential (-70mV) maintained by ion pumps and leaky channels
• Depolarization: Na+ channels open, allowing Na+ influx
• Repolarization: Na+ channels close, K+ channels open; K+ efflux
• Hyperpolarization: K+ channels close slowly; membrane potential undershoots resting value, before returning to normal

Refractory Periods

• Absolute refractory period: no action potential can be fired
• Relative refractory period: only a larger-than-normal stimulus can trigger an action potential—Some sodium channels have reset, but potassium channels remain open

Synaptic Communication

• Ionotropic receptors: mediate fast synaptic transmission (e.g., AMPA receptors)
• Metabotropic receptors: G-protein-coupled receptors; mediate slow, long-lasting effects
• Neurotransmitters (glutamate, GABA, dopamine): chemical messengers
• Neuromodulators influence neurotransmitter release or receptor sensitivity
• Fast/Slow Synaptic Potentials; excitatory/inhibitory postsynaptic potentials

Long-Term Potentiation (LTP)

• LTP involves AMPA and NMDA receptors
• Initial signal (glutamate) binds receptors → AMPA activation (Na+ influx)→ depolarization → NMDA activation (Ca++ influx) → cellular response

Chapter 9

• Cerebrospinal fluid (CSF) functions: Buoyancy, protection, homeostasis, and transport
• Blood-brain barrier (BBB) structure and function: Endothelial cells, astrocytes, and basement membrane; selective permeability
• Major neuroanatomical regions: Cerebrum (higher-level processing), cerebellum (movement coordination), diencephalon (thalamus and hypothalamus), and brainstem (reflex centers)

Chapter 10

• Sensory receptors convert physical stimuli into electrical signals via transduction
• Threshold: Minimum stimulus strength for a response
• Receptive field: Area where stimulus affects sensory neuron
• Receptor potential: Graded potential produced in response to stimulus; if threshold reached, it will fire an action potential
• Sensory modality, location, intensity and duration of stimuli are processed by the nervous system

Chapter 11

• Adrenal medulla structure: inner region of adrenal glands, containing chromaffin cells (modified sympathetic neurons that secrete epinephrine/norepinephrine into bloodstream)
• Autonomic nervous system: Two-neuron pathway (preganglionic, ganglionic post-ganglionic); acetylcholine is the primary neurotransmitter.
• Somatic nervous system: One-neuron pathway from CNS to skeletal muscles; acetylcholine is the primary neurotransmitter for somatic motor neurons.

Chapter 12

• Muscle contraction: The sliding filament model; involves excitation-contraction coupling (action potential triggers calcium release into cytoplasm
• Cross-bridge formation between actin and myosin (requires ATP)

Chapter 13

• Neural reflexes involve several pathway types (tonic, phasic, etc.).
• Stretch reflexes are monosynaptic reflexes, involving sensory neuron to spinal cord to motor neuron
• Flexion reflects and crossed-extensor reflexes are multi-synaptic reflexes, involving other interneurons and other muscles.

Test your knowledge on the endocrine system, including the roles of various hormones produced by the anterior pituitary, hypothalamus, and their targets. This quiz covers hormone functions, characteristics, and regulatory mechanisms essential for understanding human physiology.