Human Body Composition and Fluids
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Questions and Answers

What is the primary function of the cell membrane?

  • Provides a barrier between the inside and outside of the cell (correct)
  • Stores genetic material
  • Produces energy
  • Transports proteins

What are the two main types of cell processes?

  • Mitochondria and ribosomes
  • Dendrites and Axons (correct)
  • Lysosomes and Golgi apparatus
  • Nucleus and cytoplasm

What are the two types of transport mechanisms across the cell membrane?

Passive and Active

The cell membrane is composed mostly of lipids.

<p>True (A)</p> Signup and view all the answers

Passive transport moves substances from a high concentration area to a low concentration area.

<p>True (A)</p> Signup and view all the answers

Active transport requires energy to move substances against their concentration gradient.

<p>True (A)</p> Signup and view all the answers

What is the name of the process by which the cell takes in substances from its surroundings?

<p>Endocytosis (D)</p> Signup and view all the answers

What is the name of the process by which the cell releases substances from its interior?

<p>Exocytosis (A)</p> Signup and view all the answers

What type of junction allows for direct communication between cells?

<p>Gap junctions</p> Signup and view all the answers

Tight junctions prevent the passage of substances between cells.

<p>True (A)</p> Signup and view all the answers

What type of transport mechanism does osmosis rely on?

<p>Passive transport</p> Signup and view all the answers

What is the name of the process by which fluid is forced through a semipermeable membrane due to a pressure gradient?

<p>Filtration</p> Signup and view all the answers

What is the structural unit of the nervous system?

<p>Neuron (nerve cell)</p> Signup and view all the answers

What are the two main components of a neuron?

<p>Cell body (soma) and cell processes (dendrites and axon)</p> Signup and view all the answers

What is the function of myelin sheath in a neuron?

<p>Provides electrical insulation</p> Signup and view all the answers

What is the function of dendrites in a neuron?

<p>Receive nerve impulses</p> Signup and view all the answers

What is the function of the axon in a neuron?

<p>Transmit nerve impulses</p> Signup and view all the answers

What is a stimulus?

<p>Any change in the environment that causes a living tissue to react</p> Signup and view all the answers

The cell body is the largest part of a neuron.

<p>True (A)</p> Signup and view all the answers

What is the name of the gap between two neurons where communication occurs?

<p>Synapse</p> Signup and view all the answers

Flashcards

Total Body Water (TBW)

60% of an adult's body weight is composed of water.

Intracellular Fluid (ICF)

Fluid inside body cells; roughly 40% of total body water.

Extracellular Fluid (ECF)

Body fluid outside body cells; roughly 20% of total body water.

ECF composition - Main Cation

Sodium (Na+) and Potassium (K+)

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ECF composition - Main Anion

Bicarbonate (HCO3-) and Phosphate (HPO4-)

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ICF composition - Main Cation

Potassium (K+) and Magnesium (Mg+2).

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Passive Transport

Movement of substances across a cell membrane without using energy.

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Active Transport

Movement of substances across a cell membrane using energy.

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Dehydration

Negative water balance, output exceeds input.

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Cell Membrane Composition

Proteins (55%), Lipids (40% - Phospholipids & Cholesterol) and Carbohydrates(5%).

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Study Notes

Human Body Composition

  • Human body is composed of 60% water and 40% solids
  • Solids are comprised of:
    • 18% protein
    • 15% fat
    • 1% minerals (organic)

Intracellular Fluid (ICF) and Extracellular Fluid (ECF)

  • ICF (intracellular fluid) accounts for 40% of total body water.
  • ECF (extracellular fluid) accounts for 20%.
  • ICF is within cells.
  • ECF is outside of cells, including:
    • Intravascular fluid (plasma)
    • Interstitial fluid

Calculating Total Body Water (TBW)

  • TBW = 0.60 x body weight (kg)
  • Example for a 70 kg person:
    • TBW = 0.60 * 70 = 42L
    • ICF (28 Liters)
    • ECF (14 Liters)

ECF and ICF Composition

  • ECF:
    • Main cations: Na+, K+
    • Main anions: HCO3⁻, HPO₄²⁻, protein
  • ICF:
    • Main cations: K+, Mg2+
    • Main anions: proteins, phosphate (HPO₄²⁻)

pH and Osmolarity

  • pH of both ICF and ECF is approximately 7.4.
  • Osmolarity of both is also similar.

Fluid Intake and Output

  • Input: 2300 ml/day (drinking, food)
  • Output: 2300 ml/day (urine, sweat, feces, breathing)

Water Balance Disorders

  • Dehydration: Loss of water exceeds intake
    • Causes: excessive sweating, vomiting, diarrhea
    • Symptoms: dry mouth, sunken eyes, fatigue

Treatment of Dehydration

  • Giving the patient 0.9% NaCl (normal saline) or glucose (5%) solution.

Cell Membrane Composition

  • 55% protein
  • 40% lipids
  • 5% carbohydrates

Cell Membrane Lipids

  • Phospholipids: arranged in a bilayer
  • Cholesterol: between the phospholipids

Cell Membrane Proteins

  • Integral proteins: span the membrane
  • Peripheral proteins: located on the surface

Ion Channels

  • Integral membrane proteins
  • Allow specific ions to pass across the membrane
  • Controlled by gates (can open or close)
  • Can be chemically or electrically gated

Carbohydrates

  • Attached to proteins (glycoproteins) or lipids (glycolipids)
  • Carry negative charges
  • Important for cell-cell recognition and adhesion

Cellular Junctions

  • Tight, gap, and anchoring junctions
  • Cell-to-cell connections
  • Enable communication between cells and/or prevent substance passing between cells

Transport Mechanisms Across the Cell Membrane

  • Passive transfer (no energy required): diffusion, osmosis, facilitated diffusion
  • Active transport (needs energy): primary active and secondary active

Passive Transport

  • Simple diffusion (e.g., gases)
  • Facilitated diffusion (e.g., glucose, ions through channels)
  • Osmosis (water movement across a semipermeable membrane)

Active Transport

  • Primary active transport (directly uses ATP): Na+/K+-ATPase pump
  • Secondary active transport (uses a concentration gradient generated by primary active transport): Cotransport (symport) and countertransport (antiport)

Vesicular Transport

  • Endocytosis (e.g., phagocytosis, pinocytosis)
  • Exocytosis (e.g., releasing hormones, neurotransmitters)

Filtration

  • Process of forcing a fluid through a semipermeable membrane by applying pressure.
  • Important in the kidneys for urine formation.

Nerve Cells (Neurons)

  • Components: cell body (soma), dendrites, axon.
  • Function: transmit nerve impulses.

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Description

Explore the intricate details of human body composition, including the distribution of water, solids, and the roles of intracellular and extracellular fluids. This quiz covers calculations of total body water, fluid composition, and important physiological concepts such as pH and osmolarity. Test your understanding of these essential biological concepts!

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