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Questions and Answers
Physiology solely focuses on the anatomical structure of the human body.
False
Epithelial tissues are primarily responsible for protecting organs and facilitating absorption.
True
The Na+-K+-ATPase doesn't play a role in maintaining the integrity of the cell membrane.
False
Osmosis is influenced by pressure differences between the inside and outside of a cell.
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Facilitated diffusion occurs against the concentration gradient without energy input.
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Homeostasis involves maintaining stable internal conditions through feedback mechanisms.
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Carrier proteins can only operate in one direction across cell membranes.
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Water movement occurs exclusively through specialized channels in the cell membrane.
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Primary active transport uses energy derived directly from the breakdown of ATP.
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Secondary active transport relies solely on ATP hydrolysis for energy.
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The Na+/K+ pump moves two sodium ions into the cell and three potassium ions out.
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Active transport of Ca++ is critical to maintaining high intracellular calcium levels in muscle cells.
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Molecule or ion binding to the recognition site of a carrier protein is essential in secondary active transport.
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The energy required for secondary active transport is frequently obtained from the 'downhill' movement of Na+ ions.
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The H+/K+ pump operates independently of other transport mechanisms in the stomach.
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Hydrolysis of ATP is not necessary for the function of carrier proteins in primary active transport.
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Glucose transport via Na+/Glucose co-transport occurs in the epithelial cells of the intestine.
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Active transport mechanisms contribute to the establishment of electrical gradients across cell membranes.
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Co-transporters move moieties in the same direction as Na+ transport.
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The resting membrane potential of a typical neuron is approximately +70 mV.
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Active transport requires energy and involves a special membrane protein.
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Counter-transporters move moieties in the same direction as Na+ transport.
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Total body water content in a healthy adult increases with age.
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The urinary system is responsible for taking in food and eliminating unabsorbed food.
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Changes in resting potential do not influence the basic signaling properties of neurons.
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A healthy female adult's body is composed of 60-65% fluid due to having more fatty tissues.
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Water has a lower specific heat than most other liquids, making it easier to boil or freeze.
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Connective tissue is responsible for transmitting nerve impulses.
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The skeletal system includes only bones and does not contain any related organs.
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In the stomach, epithelial tissue lines the interior, and smooth muscle is present in its wall.
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Capillary action is not an important property of water in physiological processes.
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A healthy adult male weighing 100 kg has an estimated body water content of 70 kg.
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Redox reactions involving water are utilized to enhance immune function by killing pathogens.
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The cell membrane is much thicker than 10 mm.
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Nerve and muscle cells have the ability to reproduce throughout their lifecycle.
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The cell membrane is responsible for creating a barrier between intracellular fluid and extracellular fluid.
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Ribosomes are responsible for eliminating CO2 and waste products from the cell.
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Cholesterol makes up 55% of the composition of the cell membrane.
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The intracellular environment is slightly alkaline with a pH of 7.4.
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Phagocytes are specialized cells that transport oxygen throughout the body.
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Cell membranes regulate cell-cell interactions.
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In terms of concentration, potassium ions are much higher inside the cell than outside.
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All cell functions include obtaining nutrients, performing chemical reactions, and synthesizing cellular components.
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The counter-transporters move moieties in the same direction as Na+ transport.
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The resting membrane potential of a typical neuron is approximately -70 mV.
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Facilitated diffusion requires energy to transport molecules across the membrane.
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Active transport mechanisms are characterized by requiring specialized membrane proteins and energy.
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The energy for secondary active transport is derived solely from ATP hydrolysis.
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Feed-forward control does not involve any anticipatory responses to changes.
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The human body consists of approximately 50-100 trillion cells.
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Positive feedback mechanisms are typically long-lasting and require continuous adjustments.
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Negative feedback systems are utilized for conditions that require infrequent adjustments.
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Differentiation results in cells that are identical in size and function.
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Shivering in cold water is an example of a feed-forward control mechanism.
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Insulin secretion decreases blood glucose levels following a meal due to positive feedback.
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Phagocytes are specialized cells primarily involved in the transport of oxygen in the body.
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Osmosis refers to the movement of solutes through a selectively permeable membrane from lower concentration to higher concentration.
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Isotonic solutions have equal osmotic pressure in extracellular fluid and intracellular fluid.
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Infusing an isoosmotic solution of urea into the blood is preferable to using isotonic NaCl for restoring blood volume.
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In a hypotonic solution, water moves into the cell causing it to swell.
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Osmotic pressure only influences the movement of water, while solutes remain static.
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Hypertonic solutions will cause cells to retain water and expand.
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The osmotic pressure inside human cells is equivalent to a 0.9% solution of sodium chloride.
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The term 'isotonic' implies that turgor pressure is maintained in plant cells.
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Cells in a hypertonic solution will show a net gain in water.
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Osmosis can occur through structures such as capillary walls in the human body.
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The thickness of the cell membrane is approximately 10 mm.
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Phospholipids comprise 55% of the cell membrane composition.
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The intracellular fluid is slightly alkaline with a pH of 7.4.
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Cholesterol contributes 13% to the overall composition of the cell membrane.
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The function of the cell membrane includes acting as an interface between the cytoplasm and the external environment.
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Cell membranes only control the movement of substances in one direction.
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The main role of ribosomes is to synthesize cellular components like proteins.
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Red blood cells function by eliminating CO2 and waste products from the body.
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Muscle and nerve cells retain their ability to reproduce throughout their lifecycle.
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The cell membrane regulates the interactions between cells.
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Phospholipids are entirely hydrophilic molecules and do not have hydrophobic regions.
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Only certain small and neutral molecules can pass through the lipid bilayer of a cell membrane without assistance.
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Facilitated diffusion requires ATP to move substances across the cell membrane.
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Active transport processes involve the movement of substances from an area of low concentration to an area of high concentration, requiring energy.
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Both simple diffusion and osmosis are examples of active transport mechanisms.
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Hydrophilic heads of phospholipids form the interior of the lipid bilayer.
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In osmotic processes, water moves through the membrane exclusively via specialized channels.
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The net movement of molecules during diffusion continues until equilibrium is reached.
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Active transport can only occur in one direction across the cell membrane.
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The concentration gradient is irrelevant for passive transport processes.
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Study Notes
Introduction to Physiology
- Physiology is the study of the function of the human body.
- Understanding the relationship between physiology's structure and function requires knowledge of anatomy, which studies the structure of the human body.
Levels of Organization
- The human body is organized in a hierarchical manner, starting from the simplest level - cells - to the most complex - the organism.
- The levels of organization are:
- Cells: the basic unit of life.
- Tissues: groups of similar cells working together to perform a specific function. The four primary tissue types found in humans are epithelial, connective, muscle, and nervous.
- Organs: structures made up of two or more tissue types that work together to perform a specific function.
- Organ systems: groups of organs that work together to perform a common function.
- Organism: a complete living individual made up of all the organ systems.
Epithelium
- Epithelial tissue lines the surfaces of the body, both internal and external.
- Its functions include:
- Protection from the environment
- Absorption
- Secretion
- Filtration
- Excretion
Body Fluids
- The human body is composed of approximately 60% water, varying based on age and gender.
- Body water content decreases with age; newborns have a higher percentage of body water (up to 80%).
- Females have a lower percentage of body water than males because they have more fatty tissues.
- Water is an essential component of body fluids due to its properties:
- High specific heat: it takes a lot of energy to raise its temperature or freeze it.
- Capillary action: allows for the transport of fluids in narrow spaces (tears, breastfeeding).
- Excellent solvent: dissolves many essential solutes like Na+, K+, and Cl-, allowing them to pass through cell channels.
- Redox reactions: helps to destroy harmful microorganisms.
Basic Cell Functions
- Cells have essential functions to maintain life:
- Obtaining nutrients and oxygen from the environment.
- Performing chemical reactions to provide energy.
- Eliminating waste products.
- Synthesizing cellular components.
- Controlling the movement of materials in and out of the cell.
- Sensing and responding to changes in the environment.
- Reproduction, except for nerve and muscle cells, which lose their ability to reproduce during early development.
Cell Membrane
- The cell membrane is a thin and fragile structure that surrounds cells.
- Its functions include:
- Maintaining cell structural integrity.
- Controlling the movement of substances in and out of the cell (selective permeability).
- Regulating cell-cell interactions.
- Acting as an interface between the cytoplasm and the extracellular environment.
- The cell membrane creates a barrier between the intracellular fluid (ICF) and the extracellular fluid (ECF).
- It maintains concentration differences between the ICF and ECF, keeping a higher concentration of K+ inside the cell than outside, and a higher concentration of Na+, Cl-, and Ca++ outside the cell than inside.
- The pH on the inside of the cell is neutral (7), while it is slightly alkaline on the outside (7.4).
Composition of the Cell Membrane
- The cell membrane is composed primarily of phospholipids (25%), cholesterol (13%), and proteins (55%).
Membrane Transport
- Different mechanisms allow for the movement of substances across the cell membrane, driven by concentration gradients or active processes:
- Simple Diffusion: Movement of a solute from an area of higher concentration to an area of lower concentration. Requires no energy and is not carrier-mediated.
- Facilitated Diffusion: Movement of a solute from an area of higher concentration to an area of lower concentration with the help of carrier proteins. Carrier-mediated but does not require energy.
-
Active Transport: Movement of a solute from an area of lower concentration to an area of higher concentration, going against the concentration gradient. Carrier-mediated and requires energy.
- Primary Active Transport: Energy is derived directly from the breakdown of ATP.
- Secondary Active Transport: Energy is derived from the concentration gradient of another molecule (usually Na+).
-
Osmosis: Movement of water across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.
- The rate of osmosis depends on the difference in water concentration between the two compartments.
- Hypertonic solution: More solutes outside the cell, leading to water movement out of the cell.
- Hypotonic solution: Fewer solutes outside the cell, leading to water movement into the cell.
Active Transport Mechanisms
-
Primary Active Transport:
- Hydrolysis of ATP is directly required for the carrier protein function.
- Examples:
- Na+/K+ pump: Found in all cells, pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell.
- Ca++ active transport: Found in the cell membrane and inside the cell, maintaining a low level of intracellular Ca++.
- H+ active transport: Found in the gastric gland of the stomach and distal and collecting tubules of the kidney.
- H+/K+ pump: Found in the stomach, responsible for acid secretion.
-
Secondary Active Transport:
- Energy is derived from the concentration gradient of another molecule, usually Na+.
- Examples:
- Co-transporters: Move a molecule in the same direction as Na+ (e.g., glucose).
- Counter-transporters: Move a molecule in the opposite direction of Na+ (e.g., Na+/Ca++ counter-transport).
Membrane Resting Potential
- The membrane resting potential is a constant potential difference across the membrane of a resting cell.
- It is maintained at approximately -70 mV (-.07 volt) in neurons.
- The cell's ability to fire an action potential is due to its ability to maintain this potential difference.
- Changes in the resting potential influence the signaling properties of neurons.
Feedback Control
- Feed-forward control is a type of control mechanism where a response is made in anticipation of a change, before feedback signals occur.
- This type of control is considered adaptive feedback control as it prepares the body for an anticipated change.
-
Examples:
- Shivering before diving into cold water
- Salivation when smelling food before eating
Negative Feedback
- Negative feedback mechanisms work to suppress the initial change by initiating a response that opposes the change.
-
Examples:
- Blood glucose regulation: After eating, blood glucose increases, the pancreas secretes insulin, which then reduces blood glucose levels
- Body temperature regulation
- Blood pressure regulation
Positive Feedback
- Positive feedback loops amplify the initial change by initiating a response that further increases the change.
- These loops are short-lived and do not require continuous adjustments.
-
Examples:
- Blood clotting: Once clotting begins, it triggers further clotting until the bleeding stops
- Urination: Sensory impulses trigger more impulses, leading to further muscle contraction and urine release
- LH surge before ovulation
- Sodium inflow in the generation of nerve signals
- Contraction of the uterus during childbirth (parturition)
Cell Membrane
- The cell membrane surrounds each cell and is essential for the cell's survival
- It is thin and mechanically weak, making it vulnerable to breakage
-
Functions:
- Maintaining the structural integrity of the cell
- Controlling movement of substances in and out of the cell (selective permeability)
- Regulating cell-cell interactions
- Acting as an interface between the cytoplasm and the external environment
Composition of the Cell Membrane
-
Major Components:
- Proteins (55%)
- Phospholipids (25%)
- Cholesterol (13%)
- Other lipids (4%)
- Carbohydrates (3%)
-
Phospholipid bilayer:
- Hydrophilic (water-soluble) heads form the surface of the membrane
- Hydrophobic (water-insoluble) tails form the interior of the membrane
- This structure allows lipid-soluble substances to pass through while preventing water-soluble substances from easily crossing
Cell Membrane Permeability
- The cell membrane is selectively permeable, meaning it allows certain substances to pass through while blocking others
- Lipid-soluble materials can cross the membrane easily
- Water-soluble (lipid-insoluble) materials require channels or transporters to cross the membrane
Concentration Differences Across the Cell Membrane
- The cell membrane maintains distinct concentration gradients between the intracellular fluid (ICF) and the extracellular fluid (ECF)
- ICF: High concentration of potassium (K+), higher protein content, pH = 7
- ECF: High concentration of sodium (Na+), chloride (Cl-), calcium (Ca++), slightly alkaline pH = 7.4
Movements Across the Cell Membrane
-
Passive Processes:
- Simple Diffusion: Movement of substances down the concentration gradient (high to low) without requiring energy, no involvement of membrane proteins
- Facilitated Diffusion: Movement of substances down the concentration gradient with the help of membrane proteins, no energy required
- Osmosis: Movement of water through a semi-permeable membrane from areas of high water concentration to areas of low water concentration (or from low solute concentration to areas of high solute concentration)
-
Active Processes:
- Active Transport: Movement of substances against the concentration gradient, requiring energy (ATP), involves membrane proteins
- Primary Active Transport: Directly uses ATP to move substances
- Secondary Active Transport: Uses the energy from the movement of one substance down its concentration gradient to move another substance against its gradient
Osmotic Pressure and Solutions
- Osmotic Pressure (OP): The pressure required to prevent the inward osmosis of water across a selectively permeable membrane
- Isotonic Solution: A solution with the same osmotic pressure as the ICF, meaning no net movement of water in or out of the cell
- Hypotonic Solution: A solution with lower osmotic pressure than the ICF, resulting in water moving into the cell
- Hypertonic Solution: A solution with higher osmotic pressure than the ICF, resulting in water moving out of the cell
Membrane Resting Potential
- The difference in electrical charge across the cell membrane when the cell is at rest (not actively transmitting a signal)
- Typically around -70 mV (millivolts)
- Caused by differences in ion concentrations across the membrane, primarily due to potassium (K+) and sodium (Na+)
- This resting potential is crucial for the cell's ability to fire an action potential, the electrical signal that neurons use to communicate.
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Description
This quiz covers the basics of physiology, including the relationship between anatomy and physiology, as well as the hierarchical levels of organization in the human body. Participants will explore cells, tissues, organs, organ systems, and understand the significance of epithelial tissue.
