Physiology 101: Homeostasis and Body Fluids

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42 Questions

What is the primary effect of a positive feedback system?

Strengthening or enforcing the stimulus

What percentage of body weight is approximately equal to the total body water?

60%

Which of the following is an example of transcellular fluid?

Cerebrospinal fluid

What is the primary mechanism of movement of fluid between intravascular, interstitial fluid, and intracellular fluid compartments?

Osmosis, filtration, and reabsorption

What is the result of an increase in interstitial fluid?

Edema

What is the approximate percentage of extracellular fluid that is intravascular fluid?

20%

What is the direction of fluid movement during osmosis?

Down the gradient

What is the unit of measurement for osmolarity?

mOsm/L

What is the term for the pressure across a semipermeable membrane required to stop osmosis?

Osmotic pressure

What happens to a cell when it is placed in a hypertonic solution?

Water moves out of the cell

What is the term for the concentration of impermeant solutes that cannot cross semipermeable membranes?

Tonicity

What is oncotic pressure also known as?

Colloidal pressure

What is the primary function of the endothelium in the movement of fluid between ISF and IVF?

To prevent abnormal fluid leaking through blood vessels walls

What is the approximate hydrostatic pressure in the arterial end of capillaries?

35mmHg

What is the term for the buildup of ISF in tissues?

Edema

What is the purpose of the nucleus in a cell?

To regulate cellular activities and store genetic code

What is the term for the fluid component of cytoplasm?

Cytosol

What is the function of the Golgi apparatus in a cell?

To store and modify proteins and lipids

What is the term for the equilibrium within the body's internal environment against the changes in the external environment?

Homeostasis

What is the purpose of the cytoskeleton in a cell?

To provide structural support and shape to the cell

What is the term for the study of changes in physiology that result from a disease or injury?

Pathophysiology

What is the term for the pattern of changes associated with the development of a disease?

Pathogenesis

What is the term for the cells that make up the main organ structure?

Parenchymal cells

What is the function of the lysosomes in a cell?

To break down and recycle cellular waste

What is the term for the exact causes that lead to a disease?

Etiology

What is the term for the external environment that surrounds the body?

External environment

What is the term for the phospholipid bilayer that makes up the cell membrane?

Phospholipid bilayer

What is the term for the internal environment that surrounds the cells?

Internal environment

What is the term for the cycle of events by which the body status is continually monitored, evaluated, and changed?

Feedback system

What is the term for the sensors that receive stimuli, transduce energy into signals, and send signals to a control center?

Receptors

What is the most common form of feedback system?

Negative feedback system

What is the term for the study of the normal functions of cells, their regulation, and communication?

Physiology

What is the function of rough endoplasmic reticulum (rER)?

Protein synthesis, processing, and transporting

What is the function of smooth endoplasmic reticulum (sER)?

Lipid synthesis and transport to Golgi

What is the function of the Golgi apparatus?

Lipids and proteins sorting, packaging, and transport

What is the function of mitochondria?

ATP production

What is the function of lysosomes?

Degrade engulfed components

What is the function of peroxisomes?

Fat digestion and detoxification

What is the function of the cytoskeleton?

Maintain cell shape and structure

What is the function of tight junctions?

Create a seal/barrier to limit permeability

What is the function of gap junctions?

Form channels that permit fast communication

What is the function of desmosomes?

Increase tissue integrity

Study Notes

Positive Feedback System

  • Response strengthens or reinforces the stimulus
  • Tends to disturb the system outside of the homeostatic range
  • Can be harmful (e.g., blood loss) or beneficial (e.g., normal childbirth, clotting cascade)

Body Fluid Compartments

  • Total body water (TBW) ≈ 42 liters (≈ 60% of body weight)
  • Intracellular fluid (ICF) = fluid inside cells ≈ 28 liters
  • Extracellular fluid (ECF) = fluid outside cells ≈ 14 liters
    • Intravascular fluid (IVF) = plasma & lymph ≈ 3 liters (≈ 20% of ECF)
    • Extravascular fluid (EVF)
      • Interstitial fluid (ISF) = fluid surrounding tissue cells ≈ 10 liters (~80% of ECF)
      • Transcellular fluid: fluid formed within cavities by transport activity of cells ≈ 1 liter (e.g., cerebrospinal, aqueous humor, synovial, intrapleural & gastrointestinal fluids)

Movement of Fluid between Compartments

  • Occurs through osmosis, filtration, and reabsorption
  • Osmosis: fluid movement across a semipermeable membrane
    • Fluid moves from higher to lower osmolarity
    • Osmotic pressure: pressure required to stop osmosis
    • Tonicity: concentration of impermeant solutes that cannot cross semipermeable membranes

Human Cells

  • Levels of structural organization: chemical, organelle, cellular, tissue, organ, system
  • Cell structures:
    • Cell (plasma) membrane: phospholipid bilayer with selectively permeable properties
    • Nucleus: largest organelle, regulates cellular activities, contains nucleoli
    • Cytoplasm: fluid contains proteins, stores nutrients, site of chemical reactions
    • Organelles:
      • Endoplasmic reticulum (ER): network of sheets & tubules, involved in protein synthesis, processing, and transport
      • Golgi apparatus: involved in protein sorting, packaging, and transport
      • Mitochondria: involved in ATP production
      • Lysosomes: contain digestive enzymes, involved in cellular digestion
      • Peroxisomes: contain digestive enzymes, involved in fat digestion and detoxification

Intercellular Junctions and Communication

  • Intercellular junctions: tight junctions, desmosomes, gap junctions, adherens junctions
  • Intercellular communication: through direct contact, releasing chemical messengers, and signal transduction

Test your understanding of basic physiological terms and concepts, including internal environment, homeostasis, feedback systems, and body fluid compartments. Learn about osmosis, osmolality, and tonicity, and identify the differences between parenchymal and non-parenchymal cells.

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