HUMAN ANATOMY AND PHYSIOLOGY I

Lecture: M 6-9:30 Randall Visitor CenterLab: W 6-9:30 Swatek Anatomy Center, Centennial ComplexRequired Text: Marieb 9th edition

Dr. Trevor Lohman DPT(949) 246-5357tlohman@llu.edu

THE CELLCH. 3: THE FUNCTIONAL UNIT OF LIFE

THE CELLULAR BASIS OF LIFE The Smallest Living Unit

Cell Theory:

Generalized or Composite Cell• Plasma Membrane• Cytoplasm• Nucleus

Fig 3.2

THE PLASMA MEMBRANE: STRUCTUREThe Fluid Mosaic Model

Membrane Lipids• Phospholipids• Glycolipids• Cholesterol• Lipid Rafts• Fig 3.3

PLASMA MEMBRANE: STRUCTUREMembrane Proteins:• Integral Proteins

• Peripheral Proteins

• The Glycocalyx

• Fig 3.3-3.4

CELL JUNCTIONS

Tight Junctions:

Desmosomes:

Gap Junctions:

THE PLASMA MEMBRANE: MEMBRANE TRANSPORTPassive Processes• Osmosis

• Aquaporins• Osmolarity• Hydrostatic vs. osmotic pressure• Tonicity (Iso, Hyper, Hypo)• Fig 3.9

• Diffusion• Simple diffusion• Facilitated diffusion• Carrier-Mediated facilitated diffusion• Channel-Mediated facilitated diffusion• Fig 3.6, 3.7, 3.8

THE PLASMA MEMBRANE: MEMBRANE TRANSPORTActive Transport• Primary Active Transport (3.10)

• Sodium-potassium pump• Secondary Active Transport (3.11)

• Symport system vs. antiport system• Vesicular Transport (3.12- 3.13)

• Endocytosis, Transcytosis, Vesicular Trafficking Fig 3.12• Phagocytosis• Pinocytosis• Receptor Mediated endocytosis• Exocytosis

THE PLASMA MEMBRANE: GENERATION OF A RESTING MEMBRANE POTENTIALMembrane Potential and Resting Membrane Potential

Selective Diffusion Establishes Membrane Potential• Fig 3.15

• Step 1• Step 2• Step 3

Active Transport Maintains Electrochemical Gradients

THE PLASMA MEMBRANE: CELL-ENVIRONMENT INTERACTIONSRoles of Cell Adhesion Molecules• Molecular Velcro• The “arms”• Send SOS signals• The Mechanical Sensors• The Transmitters of

intracellular signals

THE PLASMA MEMBRANE: CELL-ENVIRONMENT INTERACTIONSRoles of Plasma Membrane Receptors• Contact Signaling• Chemical Signaling

• Ligands• Catalytic receptor proteins• Chemically gated channel-link

receptors• G-linked receptors

• Second messengers• Cyclic AMP• Ionic calcium• Fig 3.16

THE CYTOPLASM

The Cytosol

Organelles

Inclusions

CYTOPLASMIC ORGANELLES

Mitochondria

Ribosomes

CYTOPLASMIC ORGANELLESEndoplasmic Reticulum

• Smooth endoplasmic reticulum

• Rough Endoplasmic reticulum

CYTOPLASMIC ORGANELLESGolgi Apparatus• Trans face• Cis face

CYTOPLASMIC ORGANELLES

Peroxisomes• Neutralize free radicals

Lysosomes

CYTOPLASMIC ORGANELLESCytoskeleton• Microfilaments

• Intermediate filaments

• Microtubules

CYTOPLASMIC ORGANELLES

• Centrosome

• Centrioles

• Fig 3.25

THE NUCLEUSThe Nucleus• Multinucleate• Anucleate

3 distinguishable regions• The Nuclear Envelope

• Nuclear Pores• Nucleoli• Chromatin

• 30% DNA• 60% globular histone proteins• 10% RNA chains• Nucleosomes• Chromosomes

CELL CYCLE: INTERPHASE/M-PHASEInterphase (Metabolic/Growth Phase)• Subphases

• G1 (gap 1 subphase)/(G0 phase)

• S Phase• G2 (gap 2 subphase)

• DNA Replication• Enzymatic Unwinding

• Replication bubble forms• RNA Primer Formation• DNA Polymerase

CELL DIVISIONCell Division• M (mitotic) phase

• Mitosis• Prophase• Metaphase• Anaphase• Telophase

• Cytokinesis

MITOSISProphase• Early Prophase

• Chromatin condenses, forms chromosomes

• Centrosome separation, Mitotic spindle forms

• Late Prophase• Nuclear envelope dissolves• Spindle microtubules attach to

kinetochores at each centromere• Polar microtubules slide past

each other forcing the poles apart

Fig 3.33

MITOSISMetaphase• Centromeres are at

opposite poles of the cell• Chromosomes align

along the equator of the spindle or metaphase plate

• Enzymatic separation of chromatids begins

ANAPHASE• Shortest Mitotic Phase• Begins with simultaneous

chromatid separation• Motor proteins within the

kinetochores pull chromosomes toward the poles

• Polar microtubules continue to expand, pushing the poles further apart

TELOPHASE• Begins when

chromosomal movement stops

• Resembles prophase in reverse

• Chromosomes unravel and revert to chromatin

• New nuclear envelopes form and nucleoli reform

• Mitotic spindle disappears • Mitosis ends, and cell is

now binucleate

CYTOKINESIS• Actin ring forms and

constricts until cell is pinched in two

• Begins during late Anaphase

• Continues beyond Telophase

PROTEIN SYNTHESISDeoxyribose Nucleic Acid• DNA is the master

blueprint• Composed of 4 nucleotide

bases A, T, C, G• Triplets code for

individual amino acids• Exons and introns• DNA is useless without

RNA

PROTEIN SYNTHESISRNA• Messenger RNA (mRNA)

• The “transcript” from which protein synthesis is performed

• Ribosomal RNA (rRNA)• Building block of

ribosomes• Transfer RNA (tRNA)

• Transport cytoplasmic amino acids to ribosomes

PROTEIN SYNTHESISTranscription• Initiation

• RNA Polymerase• Promoter• Helix pulled apart

• Elongation• Helix unwound and

rewound and as mRNA formed

• Termination• Termination signal• mRNA separation

PROTEIN SYNTHESISTranslation• Nucleic acid language translated to amino

acid language• Codons (64 possible)

Translation Events• Initiation

• Ribosomal subunit binds to initiating tRNA which scans for start codon

• Elongation• Codon recognition• Peptide bond formation• Translocation

• Termination• Stop codon reached• Polypeptide chain released

PROTEIN SYNTHESISFig 3.4Fig 3.39

CH 3: THE CELLStudy Guide