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Intracellular fluid (ICF) contains a high level of K+ and less Na+.
True
Extracellular fluid (ECF) constitutes approximately 2/3 of the total body water.
False
Total body water for a male with a body weight of 70 kg is 42 L.
True
Plasma accounts for 75% of extracellular fluid.
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Homeostasis refers to the maintenance of a relatively constant internal environment.
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The interstitial fluid is primarily conditioned by the extracellular fluid.
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The intracellular fluid makes up 40% of total body weight.
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Intracellular fluid (ICF) is found outside of the cells.
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Homeostasis means that the internal environment is absolutely unchanging.
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The golden goal of every organ is to maintain homeostasis.
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PH is one of the factors that is homeostatically regulated.
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Homeostasis is a completely static process.
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Receptors, control centers, and effectors are parts of homeostatic control mechanisms.
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Successful compensation in homeostasis results in pathophysiology.
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Negative feedback loops are essential for regulating homeostasis.
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All cells contribute to maintaining a stable internal environment.
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Blood volume and pressure are factors regulated by homeostasis.
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The control center tells what a particular value should be, known as the set point.
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Cells can obtain nutrients and oxygen from their surrounding environment.
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The cell membrane has a thickness of 7.5-10 mm.
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Nerve and muscle cells have the ability to reproduce throughout their life.
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The primary function of the cell membrane is to control the movements of substances in and out of the cell.
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Cell membranes create and maintain concentration differences of ions between the intracellular and extracellular environments.
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The concentration of potassium (K+) is higher outside the cell than inside.
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The cell membrane is mechanically strong and difficult to break.
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Phospholipids make up 55% of the cell membrane composition.
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The intracellular fluid (ICF) is slightly alkaline with a pH of 7.4.
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Cholesterol constitutes 13% of the cell membrane composition.
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Osmosis is the movement of water from regions of lower concentration to higher concentration.
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The osmotic pressure inside human cells is equivalent to a 0.9% sodium chloride solution.
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In a hypotonic solution, the osmotic pressure in the extracellular fluid is greater than that in the intracellular fluid.
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When a cell is placed in a hypertonic solution, it gains water from the surrounding fluid.
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An isotonic solution has the same osmotic pressure as the intracellular fluid.
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Osmosis can occur through capillary walls.
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Infusing an isoosmotic solution of urea is better than infusing isotonic NaCl for restoring blood volume.
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Cells will swell when placed in a hypertonic solution.
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Osmosis is a fundamental process at both cellular and tissue levels.
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The concentration of water increases during the process of osmosis.
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Co-transporters move one moiety in the same direction as Na+.
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Facilitated diffusion requires energy to occur.
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The resting potential of a cell is approximately +70 mV.
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Active transport is capable of uphill transport.
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Counter-transporters move one moiety in the opposite direction of Na+.
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Intracellular fluid (ICF) constitutes one-third of the total body water.
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Plasma is part of the extracellular fluid (ECF).
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Interstitial fluid (ISF) constitutes 50% of the extracellular fluid (ECF).
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The intracellular fluid is characterized by a high concentration of sodium (Na+).
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Homeostasis is the maintenance of a relatively constant internal environment.
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The total body water of a male weighing 70 kg is approximately 56 kg.
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Osmosis involves the movement of water from regions of higher concentration to lower concentration.
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Extracellular fluids exist outside the body cells.
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Physiology is the study of the function of the human body.
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The primary function of epithelial tissue is to provide structural support to organs.
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Osmosis is the movement of water from regions of higher concentration to lower concentration.
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Active transport requires energy to move substances across cell membranes against their concentration gradient.
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Homeostasis indicates that the internal environment of the body is dynamic and constantly changing.
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Facilitated diffusion does not require energy to occur.
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Cholesterol makes up a significant portion of the cell membrane composition.
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The cell membrane is permeable to water-soluble substances.
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Secondary active transport uses ATP directly as its energy source.
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Phospholipids have water-soluble heads and water-insoluble tails.
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Hypotonic solutions cause cells to lose water and shrink.
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Active transport moves substances from regions of higher concentration to regions of lower concentration.
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Phospholipids compose a large percentage of the cell membrane and are crucial for its structure.
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Passive processes require energy to move substances across the cell membrane.
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Osmosis specifically describes the movement of water.
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Homeostasis remains absolutely unchanging despite external changes.
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Primary active transport directly uses the energy from ATP hydrolysis.
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Receptors, control centers, and effectors are essential components of homeostatic control mechanisms.
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Secondary active transport relies on the energy stored from ionic concentration differences created by primary active transport.
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Active transport moves substances down a concentration gradient.
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Negative feedback loops are crucial for maintaining homeostasis.
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The Na+/K+ pump transports two sodium ions into the cell and three potassium ions out of the cell.
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Facilitated diffusion can only occur if a carrier is present.
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Homeostasis is a completely static process.
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Na+/Glucose co-transport requires both Na+ and glucose molecules to be present for transport.
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Lipid-soluble substances can readily pass through the lipid bilayer membrane.
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The concentration of potassium (K+) is higher inside the cell than outside.
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Water-soluble materials can cross the phospholipid bilayer easily without assistance.
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Successful compensation in homeostasis results in illness.
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Simple diffusion does not require ATP.
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Each cell has no role in maintaining a stable internal environment.
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The primary role of the phospholipid bilayer is to allow all substances to pass through freely.
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Body temperature is one of the factors that homeostasis regulates.
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The control center sets the conditions under which homeostasis operates.
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Pathophysiology is the result of unsuccessful compensation in homeostasis.
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Study Notes
Body Fluids
- Extracellular fluid (ECF) makes up 1/3 of total body fluid and includes plasma (inside blood cells) and interstitial fluid (around cells).
- Intracellular fluid (ICF) makes up 2/3 of total body fluid and is found within all body cells.
- ICF has higher K+ levels and less Na+ compared to ECF. It also contains protein carrying a negative charge.
- Total body water = 60% of body weight.
- For a 70kg male, ICF is approximately 28L and ECF is approximately 14L.
- Plasma makes up 1/4 of ECF (3.5L), while interstitial fluid makes up 3/4 of ECF (10.5L).
Balancing the Internal and External Environment
- Cells constantly exchange nutrients and waste products with their surroundings.
- The internal environment (extracellular fluids) is directly influenced by the organ systems it passes through, creating a feedback loop: ICF - ISF - plasma - organs - external environment.
Homeostasis
- Refers to the maintenance of a relatively constant and stable internal environment (extracellular fluids).
- It involves maintaining a dynamic steady state where internal conditions are kept within a narrow range, despite changes in the external environment.
- Each organ contributes to the maintenance of homeostasis.
- Homeostasis is crucial for the survival and function of all cells.
Factors Homeostatically Regulated
- Concentration of nutrients (glucose, O2, CO2, and waste products)
- Concentration of water, salt, and other electrolytes
- pH
- Blood volume and pressure
- Body temperature
Homeostasis and Controls
- Successful compensation leads to re-establishment of homeostasis.
- Failure to compensate results in pathophysiology, potentially leading to illness or death.
Homeostatic Control Mechanisms
- Involve a receptor, a control center, and an effector.
- The receptor detects changes in the internal environment.
- The control center determines the set point for the variable being regulated.
- The effector produces a response that changes the internal conditions.
Regulation of Internal Constancy
- Homeostasis is not a static state, but rather a dynamic equilibrium around a set point.
- Negative feedback loops are crucial for maintaining homeostasis.
- Sensors monitor internal conditions and detect changes.
- Integrating centers receive and integrate information from the sensors.
- Effectors respond to changes and return conditions to normal levels.
Basic Cell Functions
- Obtaining nutrients and oxygen from the environment.
- Performing chemical reactions to provide energy (metabolism).
- Eliminating waste products (CO2 etc.).
- Synthesizing cellular components (e.g., proteins).
- Controlling material movement in and out of cells.
- Sensing and responding to environmental changes.
- Reproduction (except for nerve and muscle cells which lose this ability during development).
Specialized Cell Functions
- Each cell type has specialized functions (e.g., white blood cells phagocytize foreign materials while red blood cells transport oxygen).
Cell Membrane
- Thin and mechanically weak membrane surrounding each cell.
- Functions include: maintaining cell structure, controlling substance movement in and out (selective permeability), regulating cell-cell interactions, and acting as an interface between the cytoplasm and the external environment.
The Importance of the Cell Membrane
- Creates a barrier between the ICF and ECF.
- Cell death occurs if the membrane breaks.
- Maintains concentration differences between intracellular and extracellular solutions:
- Higher K+ concentration inside than outside.
- Higher Na+ concentration outside than inside.
- Higher Cl- concentration outside than inside.
- Higher Ca++ concentration outside than inside.
- Higher protein concentration inside than outside.
- The extracellular fluid is slightly alkaline (pH=7.4), while the intracellular fluid is neutral (pH=7).
Composition of the Cell Membrane
- Proteins: 55%
- Phospholipids: 25%
- Cholesterol: 13%
Osmosis
- Movement of water across a selectively permeable membrane from areas of higher concentration to areas of lower concentration.
- Important at the cellular level, affecting cell shrinkage or swelling.
- Also occurs in tissues like the gastrointestinal tract, renal system, and capillary walls.
Cell Membrane Physiology
- Osmotic pressure (OP) is determined by the concentration of solutes inside the cell.
- Human cells have an osmotic pressure equivalent to that of a 0.9% solution of sodium chloride (normal saline).
- Solutions can be classified based on their osmotic pressure relative to the intracellular fluid:
- Hypotonic: OP outside is less than OP inside, causing water to enter the cell.
- Hypertonic: OP outside is greater than OP inside, causing the cell to lose water.
- Isotonic: OP outside is equal to OP inside, resulting in hydrostatic equilibrium.
Secondary Active Transport
- Requires energy indirectly from the movement of another molecule, typically Na+.
- Co-transporters move molecules in the same direction (e.g., glucose transport).
- Counter-transporters move molecules in opposite directions (e.g., Na+/Ca++ exchange).
Movements Into and Out of the Cell
- Simple diffusion: Passive movement across the membrane, does not require energy, not highly selective.
- Facilitated diffusion: Requires membrane proteins, still passive and does not require energy, highly selective.
- Active transport: Requires membrane proteins and energy, can move molecules against their concentration gradient.
Membrane Resting Potential
- A constant potential difference across the resting cell membrane.
- Allows cells to fire action potentials.
- The resting potential is typically around -70mV.
Membrane Potential
- The difference in electrical potential between the inside and outside of the cell membrane.
- Established and maintained by the distribution of ions across the membrane.
- Key contributors to membrane potential:
- Sodium-Potassium pump: Actively transports Na+ out and K+ in, contributing to the Na+ gradient.
- Potassium leak channels: Allow K+ to move down its concentration gradient, contributing to the membrane potential.
- Negative charges inside the cell: Due to large, negatively charged proteins and other molecules.
Body Fluids
- Extracellular fluid (ECF): The fluid environment surrounding cells, including plasma (inside blood cells) and interstitial fluid (around cells)
- Intracellular fluid (ICF): The fluid inside body cells, with a higher concentration of potassium (K+) and lower sodium (Na+) compared to ECF
- Total body water: 60% of body weight
- ICF: 2/3 of total body water
- ECF: 1/3 of total body water
- Plasma is 1/4 of ECF
- Interstitial fluid is 3/4 of ECF
Balancing the Internal and External Environments
- Cells exchange nutrients and waste with their surroundings
- ICF is conditioned by interstitial fluid, which is conditioned by plasma
- Plasma is conditioned by the organs it passes through and the external environment
- Internal environment refers to the fluid surrounding cells (extracellular fluids)
Homeostasis
- Homeostasis is the maintenance of a relatively constant internal environment.
- It is essential for survival and function of all cells.
- Each cell contributes to maintaining a stable internal environment.
Factors Homeostatically Regulated
- Concentration of nutrients (glucose, oxygen, carbon dioxide, and waste products)
- Concentration of water, salt, and other electrolytes
- pH (acidity/alkalinity)
- Blood volume and pressure
- Body temperature
Homeostasis & Controls
- Successful compensation leads to reestablishment of homeostasis
- Failure to compensate leads to pathophysiology, illness, and death
Homeostatic Control Mechanisms
- These mechanisms monitor and correct internal environmental variations within limits
- They consist of:
- Receptor: Provides information about stimuli
- Control Center: Determines the set point for a particular value
- Effector: Elicits responses to change internal environment conditions
Regulation of Internal Constancy
- Homeostasis is not a static state, it is dynamic with changes around set points
- Relies on negative feedback loops
- Sensor: Monitors internal conditions and detects changes
- Integrating Center: Receives and integrates information
- Effector: Responds to changes and returns the condition to normal levels
Cell Membrane
- The phospholipid bilayer is the major component of the plasma membrane
- Phospholipids are amphipathic, meaning they have both water-soluble and water-insoluble parts
- Phospholipid heads are water-soluble (hydrophilic) and form the surfaces of the membrane
- Phospholipid tails are water-insoluble (hydrophobic) and form the interior of the membrane
- Membrane permeability is influenced by the lipid-soluble nature of substances
Movements Into and Out of the Cell
- Passive processes: Net movement down a concentration gradient (high to low concentration)
- Does not require energy (ATP)
- Examples: Simple diffusion, facilitated diffusion, osmosis
- Active processes: Net movement against a concentration gradient
- Requires energy (ATP)
- Examples: Primary active transport, Secondary active transport
1- Simple Diffusion
- Movement of molecules from an area of high concentration to an area of low concentration
- Does not require a carrier protein
2- Facilitated Diffusion
- Movement of molecules across membranes with the aid of carrier proteins
- Carrier proteins facilitate the movement of molecules down a concentration gradient
- Does not require energy (ATP)
3- Osmosis
- Movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration
- Water moves down its concentration gradient
- Does not require a carrier protein
4- Active Transport
- Carrier molecules transport substances across membranes from regions of lower concentration to regions of higher concentration
- Requires energy (ATP)
- Carrier proteins facilitate the movement of molecules against their concentration gradient
- Examples:
- Primary active transport: Uses energy directly from ATP hydrolysis
- Secondary active transport: Uses energy stored in ionic concentration differences created by primary active transport
4.1 Primary Active Transport
- Energy is derived directly from ATP breakdown
- The carrier protein is phosphorylated (ATP breakdown)
- This causes a conformational change that releases the transported molecule to the other side of the membrane
- Example: Na+/K+ pump (Found in all cells) It pumps three sodium (Na+) ions out of the cell and two potassium (K+) ions into the cell
4.2 Secondary Active Transport
- Energy is derived indirectly from stored energy by the concentration gradient
- The movement of one molecule is coupled with the movement of another molecule down its concentration gradient
- Example: Na+/Glucose co-transport Na+ moves down its concentration gradient (energy source), providing the energy for Glucose to move against its concentration gradient
Factors Affecting Body Fluids
- Osmolarity: The concentration of solutes in a solution
- Permeability: The ability of a membrane to allow substances to pass through it
- Pressure: The force exerted by a fluid on a membrane
- Temperature: Higher temperature increases the rate of diffusion
Membrane Potential
- The difference in electrical charge between the inside and outside of a cell membrane
- Created by the uneven distribution of ions across the membrane
- Essential for nerve impulse transmission, muscle contraction, and other cellular processes
Studying Physiology
- Understanding the relationship between structure and function requires knowledge of anatomy and physiology
- Homeostasis is maintained by dynamic changes around a set point, not a static state
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Description
This quiz explores the concepts of body fluids, including intracellular and extracellular fluids, their compositions, and their roles in maintaining homeostasis. It covers the distribution and importance of these fluids in the body, as well as the feedback loops that regulate the internal environment. Test your knowledge on these fundamental physiological principles.
