Biology 110
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Page 2: Respiration & Circulation Part 1
Path of Oxygen to Mitochondria
Step 1: Oxygen enters the lungs from the air.
Step 2: Oxygen crosses the epithelium of the alveoli and blood capillaries.
Step 3: Oxygen travels through the bloodstream to various tissues.
Step 4: Oxygen exits the blood, crosses the capillary epithelium, enters the cell, and reaches the mitochondria, serving as the final electron acceptor in the Electron Transport Chain (ETC).
Oxygen Transport Mechanisms:
Bulk Flow:
Movement of matter from one location to another, e.g., air currents when inhaling and blood flow from heart.
Diffusion:
Random molecular motion from high to low concentration.
Rate of diffusion is influenced by:
Steepness of concentration gradient.
Distance for diffusion.
Shorter distances and steeper gradients lead to faster diffusion.
Neither mechanism is active transport.
Muscle contractions enhance oxygen flow without using ATP.
Page 3: Oxygen Transport Mechanism
Summary of Oxygen Transport to Mitochondria:
Oxygen enters lungs, crosses epithelial barriers, travels through the bloodstream, and reaches mitochondria.
Diffusion vs. Bulk Flow:
Diffusion is effective over short distances,
Bulk flow operates over longer distances.
Breathing Organs:
Example: Lungs and Gills with main properties comprising of:
Ventilation system for rapid air/water transport to gas exchange membranes.
Thin gas exchange membrane with a large surface area between air/water and blood.
High perfusion rate mediated by the circulatory system.
Types of Ventilation:
Tidal Ventilation: Air moves in and out the same passageway (humans).
Unidirectional Ventilation: Water flows one-way across gas exchange membranes (gills and avian lungs).
Page 4: Gas Exchange Membranes
Gas exchange membranes are designed for maximum surface area via folding.
Types of Membranes:
Lungs: Epithelial invagination into the body filled with air.
Gills: Epithelial evagination surrounded by water.
Perfusion:
Blood must adequately pick up oxygen in the lungs/ gills and deliver it to tissues that are heavily vascularized.
Page 5: Unidirectional Flow in Gills
Process of Water Flow:
Water enters through the fish's mouth.
Flows over gills and gas exchange membranes.
Oxygen diffuses into the capillaries, where blood flow countercurrent to water flow optimizes gas exchange.
Water exits through the operculum flap.
Flow Types:
Cocurrent Flow: Fluids move in the same direction; less efficient oxygen absorption.
Countercurrent Flow: Fluids move in opposite directions, maintaining a concentration gradient for effective oxygen uptake. Constant net movement of oxygen from water to blood.
Page 6: Birds and Air Flow
The concentration of oxygen remains higher in water than in the blood, ensuring continual oxygen diffusion.
Birds' Unidirectional Air Flow:
Inhalation: Fresh air enters posterior air sacs, moving to parabronchi for gas exchange.
Exhalation: Stale air leaves, driving fresh air further and enabling efficient gas exchange.
Gas exchange occurs in parabronchi only due to structure.
Page 7: Human Respiratory System
Anatomy:
Trachea branches into two primary bronchi, leading to secondary bronchi, bronchioles, and alveolar sacs.
Highly branched airways increase surface area, enhancing diffusion efficiency.
Blood vessels surround alveolar sacs to facilitate gas exchange.
Page 8: Mammalian Lung Mechanics
Lungs are suspended in the thoracic cavity and work with the diaphragm muscle.
Mechanism of Breathing:
Inhalation: Diaphragm contracts, expanding thoracic cavity, and sucking air in.
Exhalation: Relaxation leads to elastic recoil of lungs, expelling air.
Respiration Metrics:
Tidal Volume: Air volume per breath.
Respiratory Minute Volume: Total air inhaled/exhaled per minute.
Exercise increases tidal volume and breath rate, thus respiratory minute volume.
Page 9: Breathing Control Mechanism
Control Center:
Medulla oblongata responds to pH changes; CO2 is a metabolic waste.
Increased cellular activity raises CO2 levels, impacting blood pH, detected by medulla receptors.
The cascade signal from medulla increases respiration, helping to regulate blood CO2 and pH levels.
Page 10: Circulatory System Overview
Key Components:
Heart: Muscular pump.
Fluid: Blood or similar substance.
Vessels: Transport oxygen, nutrients, hormones, waste.
Circulatory system enables bulk flow of essential substances throughout the body.
Page 11: Closed Circulatory System
Blood Flow Dynamics:
Arteries carry blood away from the heart to smaller vessels (arterioles) then to capillaries.
Blood returns through capillaries to venules and then to veins.
Veins contain valves preventing backflow, aiding low pressure return to the heart which has elastic tissues.
Page 12: Arterioles and Capillaries
Arterioles' Role:
Maintain proper blood flow through capillaries by regulating contraction and relaxation.
Capillaries: Smallest vessels ideal for diffusion due to single cell layer.
Page 13: Components of Blood
Blood Composition:
About 50% water; contains red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.
Red Blood Cells:
Lack nuclei and organelles; must be flexible to traverse capillaries.
Contain hemoglobin, enabling oxygen transport efficiently to body tissues.
Page 14: Heart Anatomy
Heart Structure:
Comprises four chambers: right atrium, right ventricle, left atrium, left ventricle.
Blood flow: right atrium → right ventricle → lungs → left atrium → left ventricle → body.
Atrioventricular valves prevent backflow during contraction.
Page 15: Blood Circulation Overview
Pulmonary Circulation: Blood picks up oxygen in the lungs, returns to heart.
Systemic Circulation: Oxygenated blood is distributed to tissues, returning deoxygenated blood to the heart.
Page 16: Comparison: Fish vs. Mammals
Fish: Two-chambered heart with gill circulation.
Mammals: Four-chambered heart supporting pulmonary and systemic circulation.
Page 17: Nervous System Overview
Components:
Central Nervous System (CNS): Brain and spinal cord.
Peripheral Nervous System (PNS): All other nervous system elements.
Neurons: Specialized cells transmitting signals between CNS and PNS.
Page 18: Neurons Function
Neuron Structure:
Cell Body: Contains nucleus and organelles.
Dendrites: Receive incoming signals.
Axon: Long extension for signal transmission.
Axon Terminals: Connect to other neurons for signal transmission.
Page 19: Types of Neurons
Motor Neurons: Carry signals to muscle cells.
Sensory Neurons: Transmit signals from sense organs to CNS.
Relay Neurons: Connect sensory and motor neurons; can transmit in both directions.
Page 20: Neuron Signaling Mechanism
Action Potentials: Neurons can generate and conduct electrical currents.
Resting potential: Membrane is more negatively charged inside.
Depolarization leads to action potentials.
Page 21: Neuron Voltage Dynamics
Voltage: Exists when charge distribution is unequal across the membrane.
Ions create currents by moving across the membrane through channel proteins.
Page 22: Establishing Resting Potential
Mechanism: Sodium-Potassium Pump moves ions to create potential difference across membranes.
Resting Potential: Neuron maintains negative charge inside relative to outside.
Page 23: Action Potential Process
Stages:
Depolarization
Repolarization
Hyperpolarization
Refractory period before next action potential starts.
Page 24: Action Potential Initiation
Action potentials start after membrane depolarizes due to sodium influx, leading to rapid signaling.
Page 25: Repolarization & Hyperpolarization
Post depolarization, potassium channels open, leading to exit of K+, restoring the negative membrane potential.
Page 26: Refractory Period
The phase after an action potential during which the neuron cannot fire again, due to inactivated voltage-gated ion channels.
Myelination: Increases signal transmission speed along the axon by insulating regions of the axon.
Page 27: Signal Propagation
Action potentials propagate faster along myelinated axons using nodes of Ranvier, where voltage-gated channels are present.
Page 28: Signal Transmission to Next Cell
The action potential reaches the axon terminal, triggering calcium influx and neurotransmitter release into the synaptic cleft.
Page 29: Synaptic Transmission Mechanism
Acetylcholine release into the synapse triggers muscle cell depolarization, leading to action potential initiation in the muscle cell.
Page 30: Signal Integration
Neurons process both excitatory and inhibitory signals simultaneously, which can dictate action potential firing.
Page 31: Learning Objectives Review
Key elements include anatomy, signaling properties, and mechanisms of neurons and their role in the nervous system.
Page 32: Muscle Types
Skeletal Muscle: Voluntary, striated, multi-nucleated.
Smooth Muscle: Involuntary, non-striated, single nucleus.
Cardiac Muscle: Striated, involuntary, interlinked for synchronized contraction.
Page 33: Skeletal Muscle Contraction
Involves actin and myosin interactions, forming the sarcomeres, the basic contractile unit.
Page 34: Muscle Fiber Structure
Contractile activity involves sliding of actin and myosin past each other, altering the band pattern and shortening the muscle fiber.
Page 35: Muscle Cell Components
Sarcoplasmic reticulum and T-tubules coordinate muscle contractions by releasing calcium ions in response to action potentials.
Page 36: Role of Calcium and ATP
Calcium binds to troponin, allowing myosin actin interaction, driven by ATP hydrolysis crucial for the contraction cycle.
Page 37: ATP Supply and Muscle Function
Muscle cells utilize several ATP production methods, including immediate reserves and glycolytic/oxidative systems for energy during contraction.
Page 38: Slow vs. Fast Muscle Fiber Types
Slow oxidative cells endure long-term activities; fast glycolytic cells provide short bursts of power.
Page 39: Learning Objectives in Muscle Biology
Covers muscle types, structure, contraction mechanics, ATP production, and specific contracts in skeletal and cardiac muscle physiology.
Page 40: Developmental Biology Overview
Cell Division: Rapid mitotic divisions post-fertilization lead to totipotent cells which then specialize.
Page 41: Early Developmental Stages
Stages of Cell Division: Morula, Blastula, Gastrula, with specific germ layers (ectoderm, mesoderm, endoderm) forming distinct tissue systems.
Page 42: Differential Gene Expression and Cell Fate
Morphogen gradients guide cells to their fates, affecting their eventual function within the organism's structure.
Page 43: Coordinate Processes in Development
Cells communicate through signaling pathways to influence fate and structure during organismal development.
Page 44: Role of Specific Genes in Pattern Formation
Different genes regulate early body plan patterns, such as bicoid and hunchback in segmentation.
Page 45: Molecular Mechanisms of Axis Formation
Maternal deposits of specific RNA regulate protein expressions critical for anterior-posterior axis establishment.
Page 46: Conserved Developmental Genes
Hox genes dictate segment-specific body plans and are highly conserved across species, essential for proper limb development and embryo segmentation.
Page 47: Hox Gene Role in Limb Development
Shh gradients relay positional information in limb patterning, activating downstream regulatory genes, crucial for limb structure.