BIO310 Midterm Lecture Notes PDF

BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 LECTURE 1 1. Integrative Physiology: Understanding how different biological levels (cells to organ systems) interact highlights the complexity of life processes. This integrative approach is essential for a h...

BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 LECTURE 1 1. Integrative Physiology: Understanding how different biological levels (cells to organ systems) interact highlights the complexity of life processes. This integrative approach is essential for a holistic grasp of physiology. 2. Role of Homeostasis: Homeostasis is not static; it is a dynamic process crucial for survival, illustrating the body’s ability to adapt to changes while maintaining stability. This concept is foundational for understanding physiological responses. 3. Feedback Mechanisms: The distinction between negative and positive feedback systems is critical for understanding how the body regulates its functions, from temperature to hormone levels, ensuring physiological balance. 4. Biological Rhythms: Recognizing the impact of circadian rhythms on physiological processes illustrates the intricate relationship between environment and biology, emphasizing the need for adaptability in homeostasis. LECTURE 2 Page 1: Readings Chapters to Review: ○ Chapter 3 (Pages 45-52) ○ All of Chapter 4 (for both lectures 2 and 3) Page 2: Functions of Plasma Membranes Key Functions: ○ Regulate substance passage into/out of cells and organelles. ○ Detect chemical messengers at the cell surface. ○ Link adjacent cells via membrane junctions. ○ Anchor cells to the extracellular matrix. Page 3: Structure of Membrane Phospholipid Molecules Phospholipid Characteristics: ○ Composed of two hydrocarbon chains from fatty acids. ○ Amphipathic nature affects membrane fluidity. 1 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 ○ Saturated vs. Unsaturated: Saturated: Straight chain structure. Unsaturated: Typically bent structure. Page 4: Cell Membrane Structure Membrane Composition: ○ Major lipids: Phospholipids organized in a bilayer. ○ Nonpolar fatty acid chains are in the center; polar regions face outward. ○ Cholesterol presence affects fluidity: Reduces ordered packing of fatty acids. Maintains intermediate membrane fluidity. Fluid-Mosaic Model: Describes the dynamic nature of the plasma membrane. Page 5: Arrangement of Membrane Proteins Types of Membrane Proteins: ○ Integral Proteins: Amphipathic and closely associated with lipids. Form channels for ions/water or transmit chemical signals. ○ Peripheral Proteins: Not amphipathic; located on the membrane surface. Bound to polar regions of integral proteins. Page 6: Membrane Junctions Types of Junctions: ○ Desmosomes ○ Tight Junctions ○ Gap Junctions Integrins: Transmembrane proteins linking extracellular matrix to adjacent cell proteins. Page 7: Desmosomes Structure: ○ Plasma membranes separated by ~20 nm. ○ Dense plaques serve as anchoring points for cadherins. Function: Hold cells together in areas subject to stretching (e.g., skin). Page 8: Tight Junctions Formation: ○ Extracellular surfaces of adjacent membranes fuse, eliminating space. Function: ○ Create barriers limiting material movement between cells (e.g., gut epithelium). 2 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Page 9: Tight Junctions (Continued) Mechanism: ○ Seal cells beneath the apical surface. ○ Control passage of molecules and ions, requiring them to enter cells for transport. ○ Prevent movement of integral membrane proteins between cell surfaces. Page 10: Gap Junctions Structure: ○ Direct passage of molecules between adjacent cells. ○ Formed by connexin proteins creating a pore (connexon). Function: Allow communication between cells via small molecules. Page 11: Simple Epithelium Cell Types: ○ Absorptive-digestive cells and mucin-secreting cells. ○ Endocrine cells release secretions into blood; paracrine cells affect nearby cells. Page 12: Transcellular and Paracellular Paths Movement Across Epithelium: ○ Two major routes for water and solutes. Page 13: Cellular Processes Regulating Physiology Key Concepts: ○ Biological processes are underpinned by physical and chemical processes. ○ Transport across membranes is crucial for homeostasis and physiological functions. Page 14: Simple Diffusion Overview: Review of diffusion principles. Page 15: Net Diffusion of Glucose Concept: Diffusion equilibrium between compartments. Page 16: One-Way Fluxes in Simple Diffusion Mechanism: High to low concentration movement across a barrier. Page 17: Limitations of Diffusion 3 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Key Points: ○ Diffusion time increases with distance. ○ Membranes slow diffusion significantly. ○ Hydrophobic lipid bilayer is a major barrier. Page 18: Ion Diffusion Factors Influencing Ion Movement: ○ Concentration gradients. LECTURE 3 Transport Mechanisms: Passive Transport: Movement of molecules across membranes without energy, including diffusion and facilitated diffusion through channels and carriers. Active Transport: Requires energy (ATP) to move solutes against their concentration gradient, utilizing pumps like Na+/K+-ATPase. Types of Transport Proteins: Channels: Allow specific ions (e.g., Na+, Ca2+) to pass through the membrane, can be voltage-gated or ligand-gated. Carriers: Facilitate the movement of larger or polar molecules (e.g., glucose, amino acids) through conformational changes. Ion Transport: Electrochemical Gradients: Essential for maintaining cellular function, influencing the movement of ions like Na+, K+, and Cl−. Secondary Active Transport: Utilizes the energy from primary active transport to move other solutes, often through symport or antiport mechanisms. Water Movement: Aquaporins: Specialized channels that enhance water permeability, crucial for osmosis and maintaining cell volume. Osmolarity and Tonicity: The effects of isotonic, hypotonic, and hypertonic solutions on cell volume and function. Cellular Homeostasis: Regulatory Systems: Maintain balance of solutes and water, ensuring proper physiological function. Endocytosis and Exocytosis: Mechanisms for bulk transport of materials into and out of cells, involving vesicles. Membrane Permeability: Lipid Bilayer: Selectively permeable to small, nonpolar molecules while restricting larger or charged particles. 4 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Conformational Changes: Integral proteins undergo changes to facilitate the transport of solutes across membranes. Physiological Importance: Cell Function: Proper transport mechanisms are vital for nutrient uptake, waste removal, and overall cellular health. Transport Systems in Epithelial Cells: Specialized for absorption and secretion, playing a key role in organ function (e.g., intestine, kidney). This summary encapsulates the key concepts related to transport across cell membranes, highlighting the mechanisms, types of proteins involved, and their physiological significance. LECTURE 4 Description:This section covers the fundamental structure and function of the nervous system, including the central nervous system (CNS) and peripheral nervous system (PNS). It also introduces the concept of the resting membrane potential and the forces that influence the movement of ions across the cell membrane. Key Points: The nervous system is composed of two main divisions: the CNS (brain and spinal cord) and the PNS (nerves connecting the CNS to the body). The functional unit of the nervous system is the neuron. Axonal transport occurs along microtubules using the motor proteins dynein and kinesin. Neurons can be both pre- and postsynaptic, allowing for the transmission of information through chemical and electrical signals. Glial cells in the CNS (astrocytes, microglia, ependymal cells, oligodendrocytes) play important supportive and regulatory roles. Schwann cells in the PNS form myelin sheaths around axons, which speeds up signal conduction. Injury and Regeneration of the Nervous System Description:This section discusses the effects of injury on the nervous system and the potential for regeneration and functional recovery, particularly in the peripheral nervous system versus the central nervous system. Key Points: Axons in the PNS can regenerate and restore function after injury, provided the cell body is not damaged. 5 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Spinal cord injuries in the CNS typically result in the loss of myelin sheaths around axons, impairing signal transmission. Severed axons in the CNS have limited ability to regenerate, and significant functional recovery is rare. The Resting Membrane Potential Description:This section explores the concept of the resting membrane potential, the forces that influence it, and how changes in the membrane potential can act as electrical signals. Key Points: The resting membrane potential is maintained by the unequal distribution of ions (primarily Na+, K+, and Cl-) across the cell membrane. The Na+/K+-ATPase pump establishes the concentration gradients for Na+ and K+, while the relative permeability of the membrane to these ions determines the resting potential. The resting membrane potential is typically around -70 mV, close to the equilibrium potential for K+. Changes in the membrane potential can be classified as depolarization, repolarization, or hyperpolarization. Graded potentials are localized changes in membrane potential that vary in magnitude depending on the strength of the stimulus. Graded Potentials and Stimulus Strength Description:This section focuses on the relationship between the strength of a stimulus and the resulting graded potential, as well as how the graded potential decreases in size with distance from the site of initial depolarization. Key Points: Graded potentials can be either depolarizing or hyperpolarizing, depending on the ion channels that open. The magnitude of a graded potential is proportional to the strength of the stimulus (e.g., the amount of neurotransmitter released). Graded potentials decrease in size with distance from the site of initial depolarization due to the leakage of charge (predominantly K+) across the plasma membrane. Table: Distribution of Major Ions Across the Plasma Membrane of a Typical Neuron Ion Extracellular Concentration (mM) Intracellular Concentration (mM) 6 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Na+ 145 15 Cl- 107 10 K+ 5 150 LECTURE 5 Summary This text covers the physiology of the nervous system, highlighting electrical signals, synapses, and action potentials. It describes graded potentials, the role of voltage-gated ion channels, action potential propagation, and the differences between electrical and chemical synapses. It also touches on neurotransmitters and neuromodulators, emphasizing their roles in neuronal communication and integration. Highlights 1. Action Potentials: Large changes in membrane potential that can occur rapidly. 2. Graded Potentials: Decrease in amplitude with distance due to ion leakage. 3. Refractory Periods: Limit action potential frequency and ensure directional propagation. 4. Synapses: Electrical and chemical types facilitate communication between neurons. 5. Neurotransmitters: Chemicals like ACh and catecholamines play vital roles in signaling. 6. Myelination: Increases conduction speed and reduces metabolic cost via saltatory conduction. 7. Neuronal Integration: Excitatory and inhibitory postsynaptic potentials influence neuronal response. Key Insights 7 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 1. Action Potentials and Voltage-Gated Channels: The rapid changes in membrane potential during action potentials are crucial for neural communication. Voltage-gated Na+ channels initiate these potentials, highlighting the complexity of ion channel interactions and their role in excitability. 2. Graded Potentials and Decremental Spread: Graded potentials serve as initial signals but lose strength over distance due to ion leakage and resistance. This characteristic necessitates the need for action potentials to relay strong signals over long distances. 3. Refractory Periods and Signal Clarity: The absolute and relative refractory periods are essential for maintaining the integrity and timing of action potentials, preventing overlap and allowing for clear, distinct signaling in the nervous system. 4. Synaptic Communication Types: Understanding the differences between electrical and chemical synapses is vital; electrical synapses allow for rapid signaling, while chemical synapses provide more complex modulation and integration of signals. 5. Neurotransmitter Diversity: The diverse classes of neurotransmitters, including biogenic amines and neuropeptides, illustrate the complexity of synaptic transmission and its implications for mood, behavior, and physiology. 6. Myelination and Conduction Efficiency: Myelination enhances signal propagation through saltatory conduction, emphasizing the evolutionary advantage of this adaptation in the nervous system for faster and more energy-efficient communication. 7. Neuromodulation and Synaptic Plasticity: Neuromodulators can alter the effectiveness of neurotransmitters, contributing to processes like learning and memory, highlighting the dynamic nature of neuronal signaling and its implications for behavior and cognition. LECTURE 6 covers neurotransmitters and neuromodulators, detailing their classes, functions, and mechanisms of action. Key neurotransmitters like acetylcholine, biogenic amines, amino acids, neuropeptides, gasses, and lipids are discussed, highlighting their roles in rapid communication and modulation of neuronal activity. The distinction between neurotransmitters and neuromodulators is emphasized, along with the influence of receptor types on synaptic strength and transmission. 8 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Highlights Neurotransmitters: Major players in rapid communication between neurons. Neuromodulators: Modify synaptic responses over longer periods. Acetylcholine (ACh): Key neurotransmitter at neuromuscular junctions. Biogenic Amines: Include dopamine and serotonin, impacting mood and behavior. Amino Acids: Primary neurotransmitters in the CNS, such as GABA. Receptor Types: Ionotropic vs. metabotropic receptors influence synaptic effects. Toxins and Diseases: Affect neurotransmitter release, showcasing clinical relevance. Key Insights Neurotransmitter Classes: Different classes of neurotransmitters (e.g., amino acids, biogenic amines) perform distinct roles, influencing everything from muscle control to emotional regulation. This classification helps in understanding their functions in various physiological processes. Rapid vs. Slow Signaling: Neurotransmitters act quickly (milliseconds), while neuromodulators induce slower changes (minutes to days), emphasizing the importance of temporal dynamics in neural communication. This distinction is crucial in understanding how the brain processes information over time. Acetylcholine’s Role: ACh is vital for muscle activation and cognitive functions, linking peripheral and central nervous systems. Its rapid degradation by acetylcholinesterase highlights the need for precise control in synaptic signaling. Dopamine and Mood: Dopamine’s influence extends beyond motor control to emotional states and reward pathways, illustrating its role in mental health disorders, such as depression and addiction. Understanding this connection can lead to targeted therapies. GABA as an Inhibitory Neurotransmitter: GABA is essential for balancing excitation in the brain, preventing overactivity that could lead to seizures or anxiety disorders. Benzodiazepines enhance GABA’s effects, emphasizing its therapeutic potential. Synaptic Strength Modulation: Factors such as neurotransmitter availability and receptor sensitivity can significantly affect synaptic transmission, underscoring the complexity of neuronal communication and its regulation. This has implications for learning and memory. 9 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Clinical Impact of Toxins: Toxins like botulinum and tetanus illustrate how alterations in neurotransmitter release can lead to severe physiological effects, emphasizing the clinical relevance of understanding neurotransmitter dynamics in treating neurological disorders. LECTURE 7 Summary covers the organization and functionality of the nervous system, particularly focusing on the autonomic nervous system (ANS). It discusses synaptic strength factors, the effects of diseases like tetanus and botulism on neurotransmitter release, and the structural organization of neurons. The ANS is divided into sympathetic and parasympathetic divisions, each with distinct functions, pathways, and neurotransmitters, regulating involuntary actions within the body. Highlights Nervous System Structure: The PNS has 43 pairs of nerves connecting to the CNS. Synaptic Strength Factors: Presynaptic and postsynaptic influences affect neurotransmitter release. Disease Impact: Tetanus and botulism toxins disrupt neurotransmission, leading to muscle dysfunction. Neuron Types: Afferent, efferent, and interneurons play distinct roles in signal transmission. Autonomic Nervous System: Comprises sympathetic (“fight-or-flight”) and parasympathetic (“rest-and-digest”) branches. Neurotransmitter Differences: Various neurotransmitters and receptors govern ANS responses. Autonomic Reflex Arcs: Many autonomic functions occur through simple neural circuits without conscious brain involvement. Key Insights 10 BIO310 MIDTERM LECTURE NOTES - MAIA NITSOTOLIS - ON FRIDAY OCTOBER 4/24 Synaptic Strength: Factors like neurotransmitter availability and receptor activation critically determine synaptic efficacy, influencing overall nervous system communication. This highlights the complexity and delicacy of synaptic interactions essential for proper functioning. Disease Mechanisms: Understanding how specific toxins like tetanus and botulinum disrupt neurotransmission reveals the vulnerability of the nervous system and underscores the importance of neuroprotective strategies in medicine. Neuron Classification: The differentiation between afferent, efferent, and interneurons illustrates the intricate organization of the nervous system, emphasizing the integration and processing roles of interneurons which comprise the majority of neural cells. Autonomic Nervous System Dynamics: The dual nature of the ANS allows for a balanced response to varying physiological demands, ensuring homeostasis through its opposing divisions. This reflects the body’s adaptability to stress and rest. Neurotransmitter Diversity: The distinction between neurotransmitters and their receptors in sympathetic and parasympathetic pathways elucidates how different bodily responses are achieved, impacting therapeutic approaches for various conditions. Structural Organization: The arrangement of neurons in the PNS and CNS reveals how signals are processed and transmitted throughout the body, highlighting the importance of spinal cord pathways in reflex actions. Simple Neural Circuits: Autonomic reflex arcs function independently of conscious control, indicating that many bodily processes operate automatically, which is vital for survival and efficiency. 11