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PHYS 201 - Class Notes - Week 4

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PHYS 201 - Class Notes - Week 4

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background image . Cell theory:  ­ Cell: the structural and functional unit of life 
­ How well the entire organism functions depends on individual and 
combined activities of all of its cells ­ Biochemical functions of cells are directed by shape of cell and specific subcellular structures ­ Continuity of life has cellular basis
­ Cells differ in shape, size, and subcellular components which lead to 
different functions (Fig. 3.1) ­ Erythrocytes (RBCs), epithelial, and fibroblasts connect body parts or  transport gases ­ Macrophages fight disease and skeletal muscle cells and smooth  muscle cells move organs ­ All cells have some common structures and functions . Human cells have 3 basic parts: 1. Plasma membrane: flexible outer boundary
2. Nucleus: contains DNA
3. Cytoplasm: intracellular fluid containing organelles
Extracellular materials: substances found outside cells 1. Extracellular fluids: Interstitial fluid: cells are bathed in this fluid  Blood plasma: fluid of the blood Cerebrospinal fluid: fluid surrounding nervous system organs 2. Cellular secretions such as mucus and saliva
3. Extracellular matrix: substance that acts as a glue to hold cells 
together in tissues . Plasma membrane (cell membrane): (Fig. 3.3) ­ Acts as an active barrier separating intracellular fluid (ICF) from  extracellular fluid (ECF) ­ Controls what enters and what leaves the cell
­ Consists of a flexible lipid bilayer that have membrane proteins which 
results in changing patterns referred to as fluid mosaic pattern ­ Surface sugars form Glycocalyx
­ Membrane structures help to hold cells together through cell 
junctions ­ Lipid bilayer is made of:  75% phospholipids, which consist of 2 parts:
1. Phosphate heads (hydrophilic and polar)
2. Fatty acid tails (hydrophobic and nonpolar)
5% glycolipids
background image . Lipids with sugar groups on outer membrane surface 20% cholesterol
. Increases viscosity and stability of the membrane
­ Membrane proteins: . Allow cell communication with environment 
. Makeup about half the mass of plasma membrane
. Most have specialized membrane functions
. Some float freely and some are connected to intracellular structures 
. 2 types of proteins: (Fig. 3.4)
1. Integral
2. Peripheral
. Integral proteins: o Inserted into membrane 
o Most are transmembrane proteins (span membrane) 
o Have hydrophobic and hydrophilic regions
o Function as transport proteins (channels), enzymes, or 
receptors                  . Peripheral proteins: o Not embedded in the lipid bilayer
o Loosely attached to integral proteins
o Function as enzymes, cell to cell connections, and motor 
proteins for shape change during cell division and muscle 
­ Glycocalyx Consists of sugars sticking out of cell surface  Every cell has different patterns of this sugar coating Some sugars attached to lipids  glycolipids Some sugars attached to proteins  glycoproteins Functions as specific markers for cell to cell recognition  Allow the immune system to recognize itself vs. non-self cells Glycocalyx of some cancer cells change rapidly that the immune 
system can’t recognize the cell as being damaged
Cell junctions ­ Some cells such as sperm and erythrocytes (RBCs) are not bound to  any other cells ­ Most cells are bound to form tissues and organs
­ 3 types of junctions:
1. Tight junctions
2. Desmosomes 

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School: University of Maryland - College Park
Department: Physics
Course: Human Anatomy and Physiology 1
Professor: Justicia Opoku-Edusei
Term: Fall 2016
Tags: cells, tissues, celljunctions, anatomy, Anatomyandphysiology, Anatomy& Physiology, Science, Physiology, cellmembranes, Biology, Diffusion, activetransport, passivetransport, Osmosis, Molecules, and Chemistry
Name: BSCI 201: Anatomy & Physiology Chapter 3 Notes- Part 1
Description: Chapter 3: Cells
Uploaded: 09/19/2016
5 Pages 12 Views 9 Unlocks
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