CELLS AND BODY FLUIDS

What are cells?

Basic structural and functional units of life

What are the 3 main components of a cell?

Cell membrane, cytoplasm, nucleus

What is the function of the cell membrane?

Separates cell from environment and regulates substance movement

What does selectively permeable mean?

Allows some substances to pass while restricting others

What are the two fluid compartments separated by the membrane?

Intracellular fluid (ICF) and extracellular fluid (ECF)

What is the phospholipid bilayer?

Double layer with hydrophilic heads and hydrophobic tails

What is the role of membrane proteins?

Transport, enzymes, receptors, and cell communication

What is the function of cholesterol in the membrane?

Stabilizes and maintains flexibility

What is cytoplasm?

Gel-like substance containing organelles

What is cytosol?

Fluid portion of cytoplasm

What are organelles?

Structures that perform specific cell functions

What is the function of mitochondria?

Produce ATP (energy)

What is the function of ribosomes?

Protein synthesis

What does rough ER do?

Makes proteins and phospholipids

What does smooth ER do?

Lipid synthesis and detoxification

What does the Golgi apparatus do?

Modifies and packages proteins/lipids

What do lysosomes do?

Digest waste and foreign material

What do peroxisomes do?

Break down toxic substances

What is the cytoskeleton?

Structure that supports the cell

What is the function of the nucleus?

Controls cell activities and contains DNA

What is DNA?

Genetic material that codes for proteins

What are genes?

DNA segments that code for proteins

What is RNA?

Molecule that helps produce proteins

What percentage of body mass is body fluid?

About 55–60%

What are the two main fluid compartments?

Intracellular (ICF) and extracellular (ECF)

What are the two types of ECF?

Plasma and interstitial fluid

What is osmolarity?

Total concentration of solutes in a fluid

Which electrolyte is highest in ICF?

Potassium

Which electrolyte is highest in ECF?

Sodium

What is passive transport?

Movement without energy, down concentration gradient

What is diffusion?

Movement from high to low concentration

What is simple diffusion?

Direct movement through membrane

What is facilitated diffusion?

Movement via protein channels or carriers

What is osmosis?

Movement of water across a membrane

In osmosis, water moves where?

From low solute concentration to high solute concentration

What happens if osmolarity is unequal?

Fluid shift occurs

What is an isotonic solution?

No fluid shift; cells stay same size

What is a hypotonic solution?

Water enters cells; cells swell

What is a hypertonic solution?

Water leaves cells; cells shrink

What is filtration?

Movement of water/solutes due to pressure

Filtration moves from where to where?

High pressure to low pressure

What is active transport?

Movement using ATP against gradient

What is the Na+/K+ pump?

Pumps sodium out and potassium into cells

What is exocytosis?

Vesicles release substances outside the cell

What is endocytosis?

Cell takes substances in via vesicles

How much water is lost daily?

About 2500 mL

What triggers thirst?

Increased osmolarity or low blood volume

What hormone controls water retention?

ADH

What hormone regulates sodium retention?

Aldosterone

What hormone regulates calcium levels?

Parathyroid hormone (PTH)

What is hypovolemic shock?

Severe loss of blood volume causing organ failure