BSCI 201: Anatomy & Physiology Chapter 3 Notes- Part 1
BSCI 201: Anatomy & Physiology Chapter 3 Notes- Part 1 BSCI201
Popular in Human Anatomy and Physiology 1
verified elite notetaker
Popular in Department
This 5 page Class Notes was uploaded by mehrnazighani Notetaker on Monday September 19, 2016. The Class Notes belongs to BSCI201 at University of Maryland - College Park taught by Justicia Opoku-Edusei in Fall 2016. Since its upload, it has received 37 views.
Reviews for BSCI 201: Anatomy & Physiology Chapter 3 Notes- Part 1
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 09/19/16
. 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 . 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 contraction 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 3. Gap junctions Tight junctions: (Fig. 3.5a) o Prevent fluids and most molecules from moving in between cells o Integral proteins on adjacent cells fuse to form an impermeable junction that encircles the whole cell o Useful to prevent leakage such as the digestive track and the urinary bladder Desmosomes: (Fig. 3.5b) o Linker proteins of neighboring cells interlock like the teeth of a zipper o Linker protein is anchored to its cell through thickened areas on inside of plasma membrane called plaques o Keratin filaments connect plaques intracellularly for added anchoring strength o Useful to counteract mechanical stress such as skeletal muscles and the cardiac muscle Gap junctions: (Fig. 3.5c) o Transmembrane proteins form tunnels that allow small molecules to pass from cell to cell o Used to spread ions, sugars, or other molecules o Allow electrical signals to be passed quickly from one cell to the next cell o Used in cardiac and smooth muscle cells . Plasma membranes are selectively permeable: 2 ways which substances can cross membrane: 1. Passive processes (no ATP required) 2. Active processes (ATP required) Passive transport: 2 types: 1. Diffusion: 1. Simple diffusion 2. Osmosis 3. Carrier and channel mediated facilitated diffusion 2. Filtration: usually occurs across capillary walls . Diffusion: going from high concentration to low concentration (Fig. 3.6) Difference is called concentration gradient Rate of diffusion is influenced by size of molecule and temp. Molecules have natural drive to diffuse down concentration gradients that exist between extracellular and intracellular areas Plasma membranes stop diffusion and create concentration gradients by acting as permeable membranes If plasma membrane is damaged, substances diffuse freely into and out of cells, compromising concentration gradients Molecules that passively diffuse through membrane include: 1. Lipid soluble and nonpolar substances 2. Very small molecules 3. Large molecules assisted by carrier molecules Facilitated diffusion: certain hydrophobic molecules are transported down their concentration gradient by: 1. Carrier mediated facilitated diffusion: substances bind to proteins 2. Channel mediated facilitated diffusion: substances move through water filled channels Carrier mediated facilitated diffusion: (Fig. 3.7b) Carriers are transmembrane integral proteins Carriers transport specific polar molecules such as sugars and amino acids that are too large for membrane channels . Ex. Glucose molecules by glucose carriers Binding of molecule causes carrier to change shape, moving molecules in process Binding is limited by the number of carriers present Carriers are saturated when all are bound to molecules and are busy transporting Channel mediated facilitated diffusion: (Fig. 3.7c) Channels with aqueous filled cores are formed by transmembrane proteins Channels transport molecules such as ions or water (osmosis) down their concentration gradient . Specificity based on pore size or charge . Water channels are called aquaporins 2 types: 1. Leakage channels: always open 2. Gated channels: controlled by chemical/ electrical signals Works Cited Lindsey, Jerri K., Katja Hoehn, and Elaine Nicpon Marieb. Human Anatomy & Physiology, 9th Edition Elaine N. Marieb, Katja Hoehn. Boston, MA: Pearson, 2013. Print.