Lecture 3: Cells and Tissues Bio 219 Dr. Adam Ross
Cell Physiology
Cell Physiology Brief review of organelles Should be mostly review Cell surrounded by plasma membrane Lipid bilayer Also surrounds organelles Polar heads face aqueous environments Non-polar tails face inwards away from polar aqueous environment
Nucleus Site where DNA is stored Transcription happens here DNA to mrna Gene expression can be regulated by a number of factors Contains nucleolus
Rough Endoplasmic Reticulum Associated with the ribosome Non membrane bound organelle (ribosome) Makes proteins from mrna Also folds proteins
Smooth E.R. Synthesizes lipids, phospholipids, and steroids Carbohydrate metabolism Detoxification of drugs Gluconeogenesis
Mitochondria Produces ATP H+ ion gradient drives ATP-synthase Created by electron transport chain
Cell Membrane Lipid bilayer also contains other non-phospholipid elements Cholesterol Glycoproteins Receptor proteins Surface proteins Glycolipids
Plasma Membrane Carbohydrate Plasma membrane Embedded protein Extracellular fluid Cholesterol Glycoprotein Glycolipid Outer surface of plasma membrane Plasma membrane Phospholipid bilayer Inner surface of plasma membrane Cytoplasm Surface protein Filaments of cytoskeleton
Three basic ways to transport things Pores Non gated channels. Always open Channels Gated pores, allow transport when open Carriers Opens upon presentation of thing to be transported Generally unidirectional
Pores, channels and carriers Pores- always open Aquaporin channels in kidney Look like a straight, open tube Channels Alternatively open and closed Allow specific things to pass Ion channels regulate cell membrane potential Carriers Two gates that are never open at same time Never provides continuous path
Membrane proteins have diverse functions Ionotropic receptor (type of gated channel) Nicotinic acetylcholine receptor (nachr) Voltage gated channel Opens in response to changes in electrical potential Metabotropic receptor β-adrenergic Transport proteins Na-K ATPase Structural Proteins Integrin
Ionotropic receptors Binding of ligand to receptor opens ion channel Allows ions to enter or leave cell, changing the electrical potential or activity of a cell or downstream messenger nachr In skeletal muscle; allows for communication between nerves and muscles Binding of acetylcholine to nachr, opens a cation channel which starts the process of muscle contraction There are also voltage gated ion channels Open in response to changes in cell electrical potential
nachr
Metabotropic receptors Binding of ligand causes metabolic cascade of G-proteins This cascade used second messengers to change activity of some cellular parameter In the heart muscarinic acetylcholine receptors are used to slow heart rate Use of heterotrimeric G-protein
Metabotropic vs ionotropic
Transport proteins Transport can be active or passive Example: Glucose transporters (GLUT)
Cotransporters Can also be called exchangers Exchange one molecule or ion for another Generally driven by the inward Na+ gradient Many examples Na/Glucose K/Cl
Connective proteins Surface proteins that aid in cell to cell adhesion Integrin is one example Interacts with extracellular matrix to help provide cell stability Tight junctions Make gaps between cells impenetrable Made up of a number of proteins Gap junctions Allow for electrical communication between cells Via direct cell to cell exchange of ions and/ or small molecules Found in most cells in solid tissue
Integrin
Tight junctions
Gap junctions
Membrane has a diverse array of functions Protect cell from pathogens Maintain proper salt-water balance And corresponding membrane potential Respond to signaling ligands via surface receptors Endo and Exocytosis Anchor cell in place Communication with neighboring cells
4 basic tissue types Epithelial Connective Neuronal Muscular
Epithelial tissue Continuous sheets of cells Squamous, columnar, cuboidal Boundary covering internal environment (ECF) from external environment Covering/ lining epithelia Protection/ absorption Skin GI tract Secretory epithelia Exocrine and endocrine glands
Types of epithelial tissue Squamous Flattened sheet of cells Columnar Tall column shaped cells Cubodial Cube shaped cells Simple Single layer of epithelial cells Compound/ Stratified Multiple layers of cells
Squamous epithelia Simple Single layer Often a mediator of filtration and diffusion Stratified Multiple layers Only one layer of cells is attached to the basement membrane Good for areas with lots of abrasion
Squamous epithelia Simple: Glomerulus on top, Bowman s capsule on bottom Stratified: Human epidermis
Columnar epithelia Simple Single layer of column shaped cells Most organs of human digestive tract Stratified Secretion and protection Urethra, vas deferens, uterus, eye, anus Pseudostratified Appears to be stratified Actually only one layer of cells Linings of upper respiratory tract (ciliated) Male vas deferens (non-ciliated) Ciliated Columnar cells have cilia attached to the apical membrane Used to trap debris
Columnar epithelia Simple (stomach)
Cubodial epithelia Simple Single layer of cube shaped cells Kidney tubules, glandular ducts Stratified Sweat, mammary, and salivary glands Often times only top layer is cuboidal, other layers are other cell types
Cubodial epithelia Pig kidney Parotid gland (stratified)
Functions of epithelial Exchange Simple squamous; alveoli Transport Simple columnar; small intestine & simple cuboidal; renal tubule Ciliated Pseudostratified; trachea & simple ciliated columnar; uterine tube Protective Stratified squamous; skin Secretory Glandular; endocrine and exocrine glands
Connective tissue Major support tissues of the body Most abundant and diverse tissue type Storage site for fat Composed of cells and extracellular matrix Considered to be two parts of one thing Cells are tissue specific ECM is mostly protein fibers used for anchoring and support
Types of connective tissue Many different types of connective tissue: 1. Areolar 2. Adipose 3. Dense (Tendons and Ligaments) 4. Cartilage 5. Bone 6. Blood
Loose connective tissue (Fibroblasts)
Loose adipose tissue Adipose (fat) tissue Found under skin, around kidneys and heart Functions in energy storage and insulation; cushioning for organs
Dense connective tissue Dense connective tissue Found in tendons and ligaments Forms strong bands that attach bone to muscle or bone to bone
Cartilage Cells = chondrocytes
Bone
Bone- functions Functions: 1. Protects and supports internal structures 2. Facilitates movement along with muscles 3. Stores lipids, calcium, and phosphorus 4. Produces blood cells
Bone Bone Found in the skeleton Functions in support, protection (by enclosing organs), and movement
Blood Blood Found within blood vessels Transports nutrients, gases, hormones, wastes; fights infections
Blood Blood consists of liquid (plasma) and formed elements including: Red Blood Cells (RBC) - transports oxygen to body cells. White Blood Cells (WBC) - fight infection Platelets cell fragments necessary for clotting of the blood.
Connective tissues
Neuronal tissue Designed to transmit information from one part of the body to another Uses electrochemical signals Action potentials Neurotransmitters Synapses Also includes support cells for the cells sending the messages (neurons) Microglia, astrocytes, schwann cells, etc
Nervous tissue Axon Dendrite Cell body Neuron Neuroglia
Muscular tissue Cardiac, skeletal, and smooth muscle in the body Produces force to move body, pump blood, or help move digested food. Relies on the interaction of actin and myosin to produce force Different muscle tissues have different properties Will cover in depth during muscle lecture
Skeletal muscle Voluntary Striated Activated by acetylcholine release at synapse Majority of body s energy and blood are used here
Skeletal muscle
Cardiac muscle Only in the heart (duh.) Involuntary Striated No direct neural control
Smooth muscle Involuntary Non striated Involved in digestive process