Human Physiology Chapter 2

• Chemical level: a molecule in the membranes that encloses a cell
• Cellular level: epithelial cell, cell=basic unit of life
• Tissue level: layers of tissue in the stomach wall
• Organ level: the stomach
• System level: the digestive system
• Organism level: the whole body

• Smallest living subdivision of the human body
• Diverse in structure and function
• Divided into organelles

• Structures and compartments in the cell
• Isolation of chemical reactions
• Each organelle performs a specific function

• Obtain nutrients and oxygen from surrounding environment
• Perform chemical reactions that provide energy
• Eliminate carbon dioxide and other wastes
• Synthesize needed cellular components
• Control exchange of materials between cell and its surrounidng environment
• Sensing and responding to changes in surrounding environment
• Reproduction

• Plasma membrane
• Cytoplasm
• Nucleus

• Outer boundary of cell
• Separates intracellular environment from the extracellular environment
• Regulates movement of materials in and out of cell

• Composed of Lipids, Proteins and Carbohydrates
• -Arranged in bylayer of phospholipids with proteins suspended and attached
• -"Fluid mosaic model"

• Microvilli
• Cillia
• Flagella

• Found on the apical surface of some cells
• Fingerlike projections
• Greatly increase surface area
• Facilate movement of materials between intracellular and extracellular fluids

• Hair-like structures projecting into the extracellular fluid
• Contain microtubules
• Generate flow in extracellular fluid

• Long whip-like structures found on mature sperm
• Contain microtubule
• Allows sperm to swim

Portion of cell interior not occupied by the nucleus

• Organelles (little organs") - Distinct, highly organized, membrane-enclosed structures
• Cytoskeleton - Framework of cell
• Gel-like material inside cells outside organelles

• Enzymatic regulation of intermediate metabolism
• Place where proteins are made
• Storage of fat, glycogen and secretory vesicles

• Network of protein fibers throughout cytosol
• Ex: Microtubules, Microfilaments

• Structural support and shape of cell
• Movement of materials inside the cell
• External movement - Cilia and flagella

• Nucleus
• Endoplasmic reticulum
• Golgi complex
• Lysosome
• Perxisome
• Mitochondrion

• Sac-like organelles which contain enzymes
• Break down large molecules
• -cell's "digestive system"
• Destroy: Bacteria, Old organelles, Food Molecules

• Lysosomal Storage Diseases
• -Accumulation of macromolecules (proteins, polysaccharides, lipids) in the lysosomes
• -Genetic failure to manufacture an enzyme needed for their breakdown
• -Tay-Sach's Disease

• Membranous sacs
• -Detoxify H2O2
• -Breakdown of fatty acids
• -Bud off from ER
• -Choleserol synthesis

• Structure - double membrane
• Possess own DNA
• Power generators of the cell - synthesize cellular fuel (ATP) using energy released from the breakdown of food

• Large protein-RNA complexes
• Found free floating in cytosol or attached to endoplasmic reticulum
• Synthesize proteins

• Coated with ribosomes
• Synthesizes proteins for :
• -Cell membranes
• -Interior (lumen) of membrane-bound organelles
• -Export out of the cell

• No ribosomes
• Functions
• -Lipid synthesis
• -Ca²⁺ storage
• Metabolize various molecules

• Cell's "control center"
• Largest organelle
• Surrounded by double lipid bilayer (nuclear envelope) linked to the cytosol by nuclear pores
• Contain DNA in the form of chromosome

• DNA and associated proteins
• One single DNA double-helix + associated proteins forms a chromosome

Stacks of flattened sacs

• Processes ER products into final form
• Sort and direct finished products to final destinations (intracelluar or extracellular)

• Small membrane-enclosed chambers used to transport materials within the cell
• -Delivery within and outside cells

• 1. The rough ER synthesizes proteins
• 2. The smooth ER packages the products into transport vesicles, which bud off and move to the Golgi complex.
• 3. The transport vesicles fuse with the Golgi complex, open up, and emty their contents into the closest Golgi sac.
• 4. The golgi complex, modifies the proteins into final form; sorts and directs the finshed products
• 5. Secretory vesicles bud off the Golgi complex and remain in the cytosol, storing the products until signaled to empty.
• 6. On stimulation, secretory vesicles fuse with the plasma membrane, open, and empty.
• 7. Lysosomes also bud from the Golgi.

• Sequences of DNA containing information needed to make proteins with the proper amino acid sequence
• Genes can encode for more than one protein
• Different types of cells express different sets of genes

The total of all the genes in the human body (~25,000)

All the different proteins produced in the human body (~100,000)

• Double Helix
• Nucleotide : Base, Phosphate, Sugar

• complimentary base pairing of DNA
• DNA read in groups of three nucleotides
• Codon=mRNA

The sequence of triplets

• RNA sequence read by ribosomes
• -Ribosome binds to mRNA
• -Reads codons
• -Binds tRNA with complementary sequences (anticodons) carrying specific amino acids
• -Catalyzes reaction that transfer the aminio acid from tRNA to a growing polypeptide chain
• -Ribosome shifts, then reads the next codon and repeats the process

• DNA must be copied prior to cell division
• Strands of a double helix are separated
• Each strand used as a template to synthesize a new copy of the complementary strand

• Formation of two identical daughter cells
• 4 Stages
• Strands of a double helix are separated
• Each strand used as a template to synthesize a new copy of the complementary strand

• 1. Prophase - condensation of DNA
• 2. Metaphase - chromosomes line up
• 3. Anaphase - chromosomes are pull apart
• 4. Telophase - plasma membranes and nucleus reform

• Necrosis
• Apoptosis

• Pathological cell death
• -Death of cells damages adjacent cells

• Homeostatic cell death
• -Process where specific cells die off in a controlled fashion that does not damage adjacent cells.

• Energetic sum of all chemical reactions occuring in a living organism
• -break down of some substances=catabolism
• -build up of other substances=anabolism

Matter and energy cannot be created or destroyed, but can be converted from one form to another

• Adenosine Triphosphate
• Energy carrier molecule
• -ATP--> ADP + P, (energetically very favorable)
• -Energy released is used to drive unfavorable reactions
• ATP must be continually resynthesized by the cell from ADP and inorganic phosphate (P_i)

• long series of enzyme-catalyzed reactions
• allow high degree of control + regulation

By the end product inhibition enzymes

• 1. Aerobic Respiration: oxygen utilizing
• 2. Anaerobic Respiration: no oxygen used

It would explode if all the energy were release at once.

• Uses oxygen in breakdown of materials and release of energy
• Energy is released in small increments via long metabolic pathways
• -Allows cells to efficiently release and use energy contained in food molecules

• Glycolysis - Glucose --> pyruvic acid
• Krebs Cycle - formation of electron carriers and CO₂
• Oxidative Phosphorylation - electron carriers used to generate ATP

• Occurs in the cytoplasm
• Breakdown of one glucose molecule into two pyruvate molecules
• Anaerobic

2

• Process of producing ATP without consuming oxygen
• Used regularly by skeletal muscle fibers and red blood cells
• Lactic Acid Frementation
• -Pyruvic acid reacts with NADH to produce lactic acid and NAD⁺
• -Regenerates NAD⁺ needed for glycolysis