Anatomy Lecture 2.docx

Anatomy Lecture 2

Extracellular matrix. 

  • All eukaryotic cells are sorrounded by a protective layer that the cells themselves secretes, it is known as the Extracellular matrix. 

  • Most of it possess collagen. 

  • Reticular fiber, type of collagen. Number 3 type. 

  • They all posses glycosaminoglycan  

 

Collagen 

  • Collagen is the most abundant glycoprotein in the animal kingdom. 

  • Glycoprotein: is a compound composed of sugars and proteins. 

  • Whatever comes first is smaller, and last bigger, so 

  • It is a glycoprotein, small sugar, large protein. 

  • Collagen is insoluble, hydrophobic 

  • Secreted by many types of cells, especially the fibroblasts, epithilio cells. 

  • Fibrovlasts are the cells in charge of creating your connective tissue, they also create elastin. 

  • Skin is a type of epithilio cell. 

  • Collagen serves for structural support and protecion. 

  • Collagen is made out of collagen fibrils, each of the fibrils are composed by three chains, two a1, and one a2. 

  • The alpha 2 is different. 

  • Many fibrils get together to form a fiber. 

 

Elastin 

  • Elastin is a highly hydrophobic protein 

  • Elastin is a protein 

  • Elastin form Elastin fiber 

  • Is designed to stretch 

  • Cobbled with fibrylin form elastic fibers. 

  • Two forms of fytbrilin, they connect elastin proteins toether to form elastic fibers. 

  • They are abundant in the parts fo your body that need to stretch. 

  • Ability to form issus with a recoil capability. 

  • They will lose their elasticity (why people get facelifts) 

 

Glycosaminoglycon and proteoglycon 

  • GAGs, compose of polysaccharides, repeating dysacharides.  

  • Proteoglycans: small protein, large sugar. Posses a negative charge. 

  • They atract cations. Like Sodium.  

  • Where sodium goes water will follow. 

  • All the water fills up the extracellular matrix 

  • Water: great barrier of protection. Provides a defusion gradient, for exchange of waste materials. 

  • Hyaluronic acid is a type of GAGs. 

  • Moisturizer creams moisturize by the GAGs attracts sodium, so it attracts water. 

 

Adhesive glycoproteins 

  • Also found in the extracellular matrix 

  • Group of compounds 

  • Gives the cells and tissues the ability to adhere to the extracellular matrix 

  • Designed to bind to surface proteins, known at integrin collagen fibers. 

  • Various types depending on the tissue: 

  • Fibronectin: type of adhesive glycoprotein found in the ground substance of connective tissues. As well as the lower layer. 

    • It helps keep your skin connected to another tissue. 

  • Laminin: type of adhesive glycoprotein found in the ground substance of coinnective tissues. 

  • Integrin: connects to both, together they work to connect the tissue. 

  • Condronectin: found in cartilage 

  • Osteonectin: found in bones 

 

  • Laminin, fybronectin and intregrin work together to prevent the skin to fall off. 

  • Connective tissue 

 

 

------------------ALL OF THIS FOUND IN THE EXTRACELLULAR MATRIX--------------------------------------------------

 

Plasma membrane 

  • Cell membrane, plasmolema 

  • Made out of phospholipids 

 

Semi-permeable 

  • The plasma membrane is semi permeable. 

  • They allow certain things to go trough, and they repulse others 

  • Hydrophobic molecules pass through freely 

  • Hydrophilic molecules do not pass through freely 

  • Steroids are hydrophobic. 

  • Anything charged will repulse 

 

Phospholipids 

  • Epathetic molecule: "two personalities" hydrophobic and hydrophilic 

  • How does a phospholipid interact with water: 

    • The hydrophobic tails will try to hide from the water 

    • The exact opposite with the hidrophilic 

    • Hydrophobic tail hides inside the membrane 

    • Bi layer forms on its own.  

 

Floud mosaic model 

  • Membrane composed by phospholipid bi layer. 

  • Embedded by proteins, glycoproteins, cholesterol, irregular patterns 

  • Plasma membrane are fluid, and have a consistency of olive oil. 

  • Being fluid means that they are constantly moving, nonetheless is anchored by the cytoskelethon 

 

Glycolipids: 

  • Similar to composition as the phospholipids 

  • Phosphate group is replaced by a long chain sugar group. 

  • Hydrophilic end is composed of the sugars that is sticking out of the membrane 

  • Glycolipid commonly used as surface receptors by the cells. 

 

Cholesterol 

  • Used to strengthen 

  • Posseses hidroxic group 

  • Aligns with the dipolar portion of the phospholibids 

  • Also, with the hydrophobic end. 

  • Helps mantain cellular membrane stability 

  • Interacting with neighbouring phospholibids via hydrogen bonds. 

  • Close interaction of cholesterol with phospholipids to help stabilize the membrane. 

 

Peripheral and integral protein 

  • Inside the plasma membrane there are two major group of proteins. 

 

  • Peripheral protein: embedded on one or the other side of the phospholipid, bounded through covalent or hydrogen bonding. 

  • Also anchored in the membrane via cytoskelethon 

  • Function mostly envolve with the structural integrity of the plasma membrane and helps stabilize it. 

 

  • Integral protein: multipass protein, embedded within the phospholipid bi layer and stretchces the width of the membrane. 

  • Anchored through covalent bonding or no covalent interactions. 

  • Integral protein refered as epithetic molecules. 

  • Most of these proteins are glycoproteins 

  • Hydrophoic regions embedded inside the membrane 

  • Hydrophilic on the ends 

  • Integral proteins have numerous functions. 

 

Channel protein (top) and carrier protein (bottom) 

  • Defusion: Substances will flow from ares of high concentration to areas of low concentration based upon their defusion gradient. 

  • Active transport: Substances will flow from ares of low concentration to areas of high concentration based against their defusion gradient. 

ABO blood type

  • Body’s immune system is composed by a group of cells called glucocydes

  • Many of these are capable of recognizing the glycoproteins.

  • Go through the body recognizing what belongs to you and what not

  • If a skin cell locates in the liver, it is eliminated by the glucocydes

  • Self-recognition protein

  • Each one of us have a different set of sugar

  • Cell to cell recognition, different combination of sugar allows to recognize.

  • They are all recognized by your glucocyde

  • Generally, different cells do not cause an immune response

Receptor proteins

  • Composed of glycoproteins

  • “Cellular switch”

  • G Protein complex

  • If you want your cells to start or stop producing something

Enzyme proteins

  • Integral proteins found on the membrane

  • Enzyme located in the membrane

  • Involved on the secondary messenger

  • Once the receptor protein is activated, a chain of reactions is generated.

  • Called cascade reactions.

  • If anything goes wrong during this process you may suffer a disease

Passive transport (No energy involved; no ATP required)

Diffusion

  • Moving molecules from areas of higher concentration to lower concentrations

  • Diffusion gradient

  • For example: a sugar cube dissolving in water.

Osmosis

  • Water crosses from areas of higher concentration to areas of lower concentration trough a semi permeable membrane.

Tonicity

  • Isotonic: Water enters and leaves the cell at the same rate, maintaining balance

  • Hypotonic: More water enters the cell then leaves, causing the cells to swell and potentially burst

  • Hypertonic: More water leaves the cell than enters, causing the cell to shrink.


Aquaporin (channel)

  • In order to maintain the cells tonicity, and an isotonic environment, there are channels.

  • Channels that allow water to enter or exit the cell based on their concentration gradient 

  • Called water channels, towards the middle of there is a sort of hallway called the aquaporin.

Facilitated diffusion

  • Carrier proteins also known as transporters

  • Could be either passive or active transport

  • Facilitate diffusor (carrier proteins of passive transport)

Ion channels

  • Transporting sodium anions, calcium anions, potassium anions, chloride anions.

  • There are “free willing” channels

  • Nonspecific mono valent positive anion channel

  • Nonspecific bi valent canion channel

Passive transport – potassium ion channel

  • How do they identify what molecule is trying to enter the cell

  • Identify the water molecules surrounding

  • The opening of the pore

  • The negativity of the pore

  • Carboxyl oxygen

Open channel or leaky channels

  • These channels are always open.

Ligand gated channel

  • Channels with a door, depending on the “switch”

  • Gates that require a single molecule.

  • Extra cellular ligand triggers to open or close

  • Binds to a specific receptor, which causes the gate to open or close

Voltage gated channel

  • Integral proteins channels, that allows ions to enter the cell

  • If there is an electrical charge the gate will open or close

Mechanically gated channel

  • Requires a physical force to open or close the gate

  • Pressure sensing channels

Temperature gated ion channels

  • Open and closes based upon a preset temperature

  • Temperature sensitive nerves

  • pH gated ion channels

  • Based upon preset pH levels

Active transport (carrier protein)

  • When molecules move against their concentration gradient

  • Creating a state of disequilibrium

  • It will make one side greater (even greater than before)

  • It requires ATP

  • Active transporters. Membrane transport proteins

Mechanisms and types of active transport carrier proteins

  • Three types

  • Uniport: capable of transporting one substance ion or molecule in one direction in or out of the cell

  • Symport: is capable of transporting two or more substances in or out of the cell

  • Antiport: is capable of transporting two or more substances in and out of the cell

  • Last two are referred to cotransporters

Sodium potassium pump

  • Best antiport example

  • Useful to restore the membrane

  • Nerves: generate electrical current to transmit information

  • Muscle: to cause muscle contraction

  • Takes three sodium out and then two potassium in

  • Shape determines function

Membrane assisted transport (endocytosis)

  • Another form of active transport system that requires ATP

  • Allow big things to get in or out of the cell

  • Endocytosis: process by which the cell takes in substances via vesicle formation to form intracellular vesicle

  • Phospholipid bi membrane is fluid.

  • Curve the membrane around the substance

Endocytosis

  • Two types of endocytosis

    • Phagocytosis: Intake of a one large molecule

  • Vesicle formed: phagosome

    • Pinocytosis

  • Pino: to drink

  • Cell is taking in many of smaller substances

  • Receptors activated by a ligan (single molecule)

  • Many receptors that bind to the same thing

Exocytosis

  • Is a process by which the cells send out certain substances

  • Active transport

  • Respiratory track, glycoproteins that produce mucus when mixed with the water on the cell

  • Goblin cells: mucus producing cells

  • Keep respiratory track nice and moist

  • Endocrine glands produce hormones that have to be released via exocytosis

Ionotropic receptors

  • Ligand-gated channels that open to allow ions to pass.

  • Ligand binding causes a conformational change in the protein, facilitating ion movement along the concentration gradient

Metabotropic receptors

  • G-protein coupled receptors involved in signaling pathways

  • They act like switches that can turn on or off. Various cellular activities

  • G-protein have three subunits (alpha, beta gamma)

  • Binding of a ligand causes a series of events leading to the activation or inhibition of downstream proteins.

G-protein complex

  • Metabotropic receptors (G protein complex)

  • An on-off switch

  • Are not part of a channel protein, bit they can sit right next to one and activate

  • Change in shape causes the three subunits to separate

  • The beta and gamma subunit would join together to form a dimer

  • This dime will activate the alpha subunit. It is an enzyme. GTP aze

  • Any word that ends with aze is an enzyme

  • Now you have an activated GTP alpha subunit

  • To shot it out, you remove the ligand

  • The GTP is hydrolyzed

  • Converting into GDP

  • Alpha subunit is there to break down GTP

  • Separating the alpha sub unit from those things

  • When the subunits return back to their original shape, then the switch is off.

  • In the activated state, a ligand binds to the receptor, causing the G-protein to switch GDP for GTP, activating the alpha subunit

  • The alpha subunit then influences target proteins, such as ion channels or enzymes

  • Deactivation occurs by hydrolyzing GTP back to GDP and removing the ligand, thus resetting the protein complex

G-protein regulation of synthesis of intracellular mediators

  • Glucagon is a hormone

  • Exact opposite function than insulin

  • Is released with the sugar blood level is low

  • Alpha sub unit GTP complex

  • Adenylate cyclase change its shape. Intra cellular messenger

  • GTP forms into cAMP

  • cAMP (cyclic AMP) acts as a secondary messenger within cells.

  • cAMP go and binds with protein kinase

  • Break down glycogen

  • Convert it into glucose

G PROTEIN ONE OF THE MAJOR QUESTIONS

Domains

  • Cell to cell orientation and connection

  • Apical domain is the top of the cell

  • Secrete into lumen

  • Tube within a tube design

  • Apical domain is the top of the cell

  • Basal domain is the bottom of the call

    • Where most of the channel proteins exist as well as the receptors proteins like the G-protein

    • Very busy domain

  • Lateral domain

    • Sides of the cell

    • Usually connected with other cells

  • Tight junctions – Occluding junctions (typically exist toward the apical side of the cell)

    • Responsible for forming an impermeable barrier

    • Prevent excessive movements between the cells

    • Adhesion junctions (toward the mid lateral sides of the cell)

    • Responsible for maintaining the physical contact between adjacent cells

    • Found in various cell types

    • On the ones with mechanical stress

    • Forms an impermeable barrier

    • Reduce cellular movements between tissues

  • Desmosome (spot weld junction) (Typically found toward the basal side of the cell)

    • Provide strong adhesion between cells

    • Design to withstand stresses such as bending twisting and compression

    • Commonly found in stress prone tissues such as the epidermis and the heart muscles

      • Button desmosome, found in the apical side of the cell

      • Built desmosome, towards the middle

      • Hemi desmosome, basal domain of the tissue

Gap junctions (found on the lateral domain)

  • Also known as communication junctions

  • Intercellular channel proteins that happen to be located on the lateral side of the cell

  • They are also gated

  • An extension cord, connecting one cell to the next

Cytoskeleton

  • Is composed of a network of interconnecting filaments and tubules

  • Responsible for maintaining cellular shape

  • Involved in the growth and division of the cell

  • Three types of filaments

  • Actin filaments:

    • Long, thin fibers that form bundles.

    • Composed of twisted chains of globular actin monomers

    • They structural support to the cell

  • Intermediate filaments

    • Rope-like polypeptides that support the nuclear envelope and plasma membrane

    • Facilitate cell-cell junctions such as desmosomes

    • In the skin, these filaments are known as keratin, providing strength and waterproofing structures like hair, nail and skin

  • Microtubules

    • Small, hollow cylinders made of tubulin proteins

    • They originate from a microtubule organizing center known as the centrosome, composed of two centrioles at a 90-degree angle.

    • They maintain cellular structure, and serve s tracks for organelle movement

    • They are critical for the function and movement of cilia and flagella

  • Centrosome: “microtubule organizing center” where the formation of microtubules take place

Centrosome

  • Made out of two centrioles

  • Centriols are made out of nine plus zero microtubule triplets

  • Centrioles is the place where microtubules are assembled or disassembled

  • Basal body: it directs the organization of microtubules in the cilia and flagella

  • 9+0

Flagella and Cilia

  • They are hair-like projections that facilitate cell movement by propelling the cell forward.

  • Both structures are composed of a 9+2 arrangement of microtubule doublets

  • Nine pairs of microtubules arranged in a circle with two additional microtubules at the center

Differences in Structure and Function

  • Flagella:

    • Longer projections that move cells via a whipping motion

    • An example of flagellum is the long tail of a sperm cell

  • Cilia:

    • Shorter projections that move in an oar-like fashion

    • Common in the respiratory tract, where they help move mucus and trapped debris toward the throat for expulsion or swallowing

Basal Body

  • The base of both cilia and flagella is the basal body

  • It is made up of a 9+0 arrangement of microtubules triplets.

  • It shares the same structural design as the centriole, but the structures built above it (cilia and flagella) differ in function and arrangement.

Microvilli

  • Non mobile structures

  • Generally located towards the apical side of the epithelium cell

  • Increase surface area for absorption

  • Mainly composed of actins

Microvillus

  • Constructed of a core bundle of inter linking proteins

  • Majority of there are actin filaments surrounded by cellular membrane

  • Actin is a crucial component in the construction of microvillus

  • It is a non-mobile structural protein, part of the cytoskeleton structure, forming the core of the microvillus

Types of tissues

  • Tissues are defined as a group of cells that has specialized structures and functional roles

  • There are 4 main tissues

    • Epithelial tissue

      • Lines the internal body organs or surround your body like the skin

    • Connective tissue, the tissue that fills up empty space

      • Store energy

      • Connect bones and muscles together

    • Muscle tissue

    • Nervous tissue

Epithelial tissue

  • Covers all body surfaces including the skin, and are responsible of lining body cavities and hollow organs

  • They form a significant part of tissues present in glands

  • Their functions are: protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception

  • Involved in forming encapsulated sensory nerves, which will be explored further in the course

  • They are anchored to a basal membrane, a thin, non-living connective tissue membrane

Basement membrane

  • Cell-free layer that supports and anchors epithelial cells

  • Main components

    • Collagen-4: primary collagen type in the basement membrane, forming a scaffolding structure that support other components

    • Adhesive glycoproteins:

      • Laminin: Major structural component that binds to integrins in epithelial

      • Fibronectin: Also binds to integrins and stabilizes epithelial tissues similarly to laminin.

    • Integrin:

      • Integral protein in the cell membrane that interacts with laminin and fibronectin

      • Affect cellular behaviors like shape, migration, proliferation, and differentiation

    • Entactin:

      • A glycoprotein that connects collagens and laminins

      • Maintaining the structural integrity of the basement membrane

    • Proteoglycans

      • Composed of a core protein attached to glycosaminoglycans

      • They possess a high negative charge which repulses harmful radicals and attracts cations like sodium, drawing water to the basement

  • Role of water: The attraction of cations leading to water influx provides structural supports and facilitates the diffusion of gases, nutrients and waste between epithelial cells and the surrounding movement

Simple and stratified epithelium – design

  • Composed of tightly packed cells forming a barrier, typically resting on a basement membrane

  • It gains nutrients via diffusion from the underlying blood-vessel-rich connective tissue

  • It receives ample oxygen and nutrients, enabling them to heal quickly when injured

  • Epithelial cells are connected by structures like thigh junctions and desmosomes, creating a watertight and effective barrier

  • The basement membrane helps in attracting water through ionic interactions, supporting the epithelial tissue

  • Epithelial cells can function as secretory cells, producing and secreting various compounds

  • They can also absorb substances in the digestive system

Types of epithelial tissue

  • I GIVE YOU A LOCATION YOU TELL ME WHAT EPITHILIO TISSUE IS THEIR EXAM QUESTION

  • Simple epithelium:

    • Single cell layer, all cells have equal access to nutrients, gases, and waste removal, promoting tissue health and rapid healing

  • Stratified epithelium:

    • Consists of multiple layers of cells, where only the bottom layer, in contact with the basement membrane has direct access to nutrients and oxygen

    • Only the lower layers remain alive due to the proximity to the nutrient sources; upper layer consists of dead cells

  • Simple Squamous Epithelium:

    • These cells are oval, flattened, and form a thin single-layer cell sheet resting on the base of a membrane

    • Funcion is to facilitate diffusion, such as during gas exchange processes

    • Commonly found in the alveoli of lungs and the lining of the vascular system, particularly blood vessels.

    • Efficient exchange of gases and nutrients across all membranes

  • Simple Cuboidal Epithelium

    • Cube-shaped cells that from a layer

    • Involved in secretion and absorption between tissues

    • Increased thickness compared to other epithelial types, limited diffusion capacity

    • Neons of kidneys and the thyroid gland. Also, some areas of the digestive tract

  • Simple Columnar Epithelium

    • Rectangular-shaped cells

    • Digestive, particularly un the lining of the stomach and intestines.

    • Main functions: forming a protective layer against digestive juices, secreting digestive juices, and absorbing nutrients

    • In the digestive system, these cells have apical projections known as microvilli.

    • It serves to increase the surface area of the cells, which enhances cell’s ability to absorb substances.

  • Pseudostratified epithelium

    • They vary in shape

    • Typically found in the respiratory tract and is equipped with cilia, which are mobile projections

    • Specifically locates in the trachea and larger bronchi

    • It is a simple epithelium

Goblet cells

  • Type of cell that exist in abundance in both of these epithelium tissues

  • Gastrointestinal tract they secrete mucus. Protect stomach lining, and from the digestive enzyme. To trap garbage. Mucus that goes to your throat is considered flem

  • Moisturize the air you breathe.

  • Stratified squamous epithelium

    • Composed of many layers of cells. Constantly undergoing mitosis

    • Keratonised and no kertonised.

    • Keraton: type of intermediate filament.

    • When they divide, they push other cells upward.

      • Keratonised: epidermis, upper layer of skin

        • Thin skin: 30 layers

        • Thick skin 60+ layers of cells

      • Non keratonised (skin)

        • Vagina, anal canal, mouth and throat

        • Always moisturized and soft

  • Stratified cuboidal epithelium

    • consists on 2-3 layers of cuboidal cells

    • Memory gland, swear gland, salivary gland, inside your pancreas

  • Stratified columnar epithelium

    • Rectangular shaped cells

    • Found in the male urethra, vas deferens, and certain ducts

  • Transitional epithelium

    • Designed to stretch

    • Composed of two layers of cuboidal cells

    • When is not stretched it appears to have many layers of cells

    • When it stretches you see the two layers of cell

    • Serve as a barrier and prevent urine leakage, protecting surrounding organs

    • Found in the lining of the urinary bladder and tethers

Typed of glandular epithelium

  • Endocrine glands: Secrete hormones and other products directly into the bloodstream to regulate bodily functions

  • Exocrine glands:

    • Secrete products into ducts that lead to internal or external surfaces.

    • They include goblet cells and are further classified based on structure of their ducts and the nature of secretion

    • Simple glands: Have a singular duct

    • Compound glands: Feature a branched duct system

    • Merocrine glands: Utilize exocytosis to release protein-rich fluids

      • Serous Cells: Produce enzyme-rich watery solutions (e.g salivary glands)

      • Mucous cells: Produce mucus by secreting mucin

    • Apocrine glands: Secrete by shedding part of the cell, found in mammary and ceruminous (ear wax) glands.

    • Holocrine glands: Secretion involves the rupture and disintegration of entire cells, exemplified by sebaceous glands in the skin.

    • Alpha amylase: produced in serous cells, initiate carbohydrate digestion.

    • Mucus produced by mucous cells aid in lubricating food for easier swallowing

    • Exocrine secretions serve various roles such as digestion, lubrication, and protection (e.g., oily secretions that waterproof skin through sebaceous glands)