U2-Functional Organization of the Human Body PDF

U2-FUNTIONAL ORGANIZATION OF THE HUMAN BODY 1. Levels of functional organization of living beings. 2. Biomolecules 3. The Cell 4. Cellular differentiation. Tissues and organs 1. LEVELS OF FUNCTIONAL ORGANIZATION OF LIVING BEINGS The organization goes form the most basic elem...

U2-FUNTIONAL ORGANIZATION OF THE HUMAN BODY 1. Levels of functional organization of living beings. 2. Biomolecules 3. The Cell 4. Cellular differentiation. Tissues and organs 1. LEVELS OF FUNCTIONAL ORGANIZATION OF LIVING BEINGS The organization goes form the most basic elements à to the most complex levels. Cell combine to form à tissues combine to form à organs organize into à systems combine to form à organism Systems vs apparatus: -Systems: all the organs come from different embryological tissues. -Apparatus: all the organs come from the same embryological tissues. 2. CHEMICAL COMPONENTS OF LIFE Atoms: the smallest particles with unique chemical identity. Molecules: composition of atoms, that make up organelles and other cellular components. Macromolecules: such as proteins, carbohydrates, fats, DNA or ATP. Water is the most abundant component (60%) MACROMOLECULES CARBOHYDRATE Nutritive function àthey provide energy. They are also components of glycoproteins and nucleic acids, as well as the plasma membrane. The monosaccharides are their monomer. They can exist by themselves (glucose, fructose, galactose) or combined (glucose + fructose = sucrose). LIPIDS They are nonpolar molecules à therefore, insoluble in water. Making them perfecto to form barriers (membranes) in the form of: - phospholipids - cholesterol Triglycerides: energy storage Chemical signals: - steroid hormones - prostaglandins Thermal and electrical insulation. 1  PROTEINS After water, the most abundant compound (10-20% of cell mass) Polymers of amino acids Types: -Structural: Filamentous polymers such as cellular microtubules or collagen (in the extracellular space) -Functional: globular form - enzymes or globins. Amino acids can combine into proteins in the ribosomes into RNA. Hemoglobin has quaternary structure. ENZYMES Catalysts for chemical reactions Responsible for metabolism and other chemical reactions of the organism The enzyme in its active site binds a subtract (enzyme-substrate complex). Where the enzyme hydrolases the subtract into products. Then the enzyme be used again to catalyze. NUCLEIC ACIDS Components of the genetic material, DNA and RNA (which nucleic acids). They are composed by the union of a nitrogenous base (A, G, T, C, U), a phosphate group, and a sugar (Ribose or Deoxyribose). DNA is the molecule that holds genetic information. Nucleotide polymer: nitrogenous bases (A, G, T, C), Deoxyribose and phosphate. Genes encode different proteins and ultimately are what controls the cell, and therefore, the functionality of the organism. RNA contains ribose in its structure and is the intermediary between DNA and proteins. Polymers of different compounds, they control the hole organism. DNA cannot leave the nucleus while the RNA can à key for transcription. Simple moleculesà polymers à plasma membrane à prokaryotic cell, eukaryotic cells à multicellular organism (their cells specialize and cooperate) 3. THE CELL Cells are the basic functional units of the body. They come in a variety of shapes and sizes. This diversity reflects their diverse functions. 2  Cells do share some common features: – Plasma membrane and associated proteins – Cytoplasm and organelles – Nucleus (not all cells have one) They do not have nucleus when they finish, but they have when is growing. While developing they have a nucleus but once the cell is formed and they do not need the nucleus they get rid of it. (Hemoglobin: they do not live much). MEMBRANES Composed by: lipids (phospholipids, cholesterol) and proteins Types: – Plasma membrane – Nuclear membrane – ER membrane – Mitochondrion membrane – Lysosome membrane – Golgi apparatus membrane Fluid mosaic lipid bilayer studded with proteins. It protects the cell, mediates the entry and exit of substances, transports and identifies organelles. Border of the cell, it isolates the outside of the cell and the inside of it. Its structure is different but has similar composition. CYTOPLASM Includes organelles, a fluid called cytosol, and an organized system of microtubules and microfilaments called the cytoskeleton. CYTOSKELETON Network of three types of protein filaments (microfilaments, intermediate filaments and microtubules). It maintains shape and is responsible for cellular movements. ENDOPLASMATIC RETICULUM Membranous network of flattened sacs Rough ER is also called granular ER. – Has ribosomes – Functions in protein synthesis (synthesizes glycoproteins and phospholipids) Smooth ER is also called agranular ER. – Has many functions, depending on the cell, synthesis of lipids and steroids (synthesizes fatty acids and steroids, detoxifies drugs, removes phosphate from glucose-6-phosphate and stores and releases Ca+ in muscle cells) 3 GOLGI COMPLEX Consists of stacks of flattened sacs (cisternae) – One side receives proteins from the ER (cis) – Proteins are packaged in vesicles and fuse with the plasma membrane for exocytosis (trans). – In the other side vesicle fuse with the plasma membrane for exocytosis (trans). Membrane btw different compounds synthesized in the cell. LYSOSOMES Organelles filled with digestive enzymes – Fuse with food vacuoles (endosomes and vesicles) after an immune cell engulfs a bacterium or dead cell, to finally release the products into the cytosol. MITOCHONDRIA mitochondria – organelles specialized for synthesizing ATP “Powerhouses” of the cell – energy is extracted from organic molecules and transferred to ATP Centrosome: A pair of centrioles plus pericentriolar material (tubulin) which are used for growth of the mitotic spindle during cell division and microtubule formation. Ribosome: Two subunits containing ribosomal RNA in charge of synthesizing proteins. Mitochondria: Organelles specialized in cellular respiration reactions that produce ATP (“Powerhouses” of the cell because energy is extracted from organic molecules and transferred to ATP). Peroxisome: Vesicle that contains oxidases and catalases, responsible for the oxidation of amino acids and fatty acids, detoxifying harmful substances and producing hydrogen peroxide. Proteasome: Tiny structure that contains proteases and is responsible for degrading damaged proteins by cutting them into small peptides. 5.CELLULAR DIFFERENTIATION Differentiation: structural and functional changes of the cells to form different tissues and organs as they develop into an embryo. Cells with similar functions are grouped together forming tissues (NERVOUS, EPITHELIAL, MUSCLE, CONNECTIVE). An organ is composed of two or more tissues that serve different functions in the organ. STEM CELLS Zygotes are totipotent, which means their cells can become any type of cell. These are true stem cells. – Adult stem cells are still limited to a narrow range of possibilities but can become several related cells and thus are called multipotent. Bone marrow cells can become any type of blood cell. 4  THE PRIMARY TISSUES Our organs are composed of four major categories of tissues: – Muscle tissue – Nervous tissue – Epithelial tissue – Connective tissue Each tissue has particular structures and functions that dictate the physiology of the organ. MUSCLE TISSUE Specialized for contraction The three types are: – Skeletal muscle – Cardiac muscle – Smooth muscle SKELETAL MUSCLE TISSUE Voluntary muscle (muscle you can consciously control) Associated with bones that are pulled to produce movements. – The tongue, esophagus, sphincters, and diaphragm are also skeletal muscle. Has cells organized in striations. The difference from the other depends on the structure (which is based on the bonds). CARDIAC MUSCLE TISSUE Found only in the heart. Striated, but very different in structure and action from skeletal muscle. – Intercalated discs allow a quicker transmission of the impulse through the passage of sodium ions between cells. It is of involuntary contraction. SMOOTH MUSCLE TISSUE Found in the walls of digestive, urinary, and reproductive organs, blood vessels, and bronchioles of the lungs. Not striated and with involuntary movement à controlled by autonomous nervous system. NERVOUS TISSUE Found in the brain, spinal cord, and nerves. Composed of neurons and glial cells, which support (physical and chemical) the neurons. Neurons conduct impulses and have three parts: – Dendrites: receive signal from other neurons – Axon: sends signal to dendrites of other neurons – Cell body or soma: metabolic center 5 EPITHELIAL TISSUE Forms the membranes that line /cover body surfaces as well as glands. Cells are touching each other (like a pavement) à not leaving space in btw. Epithelial membranes are classified by the number of layers: -Simple epithelium has one layer and is specialized for transport of substances. -Stratified epithelium is composed of multiple layers and provides protection. They can be further classified based on the shape (simple squamous, cuboidal, columnar, etc). GLANDS Derived from epithelial tissues. Secretions are transported by ducts (exocrine glands). – Examples include lacrimal, sweat, and sebaceous glands; digestive enzyme glands; and the prostate. They are specialized epithelial tissue that can synthetize secretions, store them in small spaces and release them: -Exocrine glands à through a duct -Endocrine glands à to the interstitial space into the blood stream where it can go anywhere. Like in hormones. CONNECTIVE TISSUE Characterized by a matrix made up of protein fibers and extracellular material (very abundant) à there is a lot of space btw the cells. There are four (or five) major categories: – Connective tissue proper – Cartilage – Bone – Blood – Adipose CONNECTIVE TISSUE PROPER Composed of protein fibers and a gel-like ground substance Subtypes: – Loose: collagen fibers scattered loosely with room for blood vessels and nerves – Dense regular: Densely packed collagen fibers with little room for ground substance Presents many collagen fibers à will determine the subtype. The blue cells generate collagen à help build the connective tissue. BONE Cells called osteoblasts trap mineral salts (will calcify and form the bone), forming concentric layers of calcified material around a canal filled with blood vessels and nerves. 6 BLOOD fluid connective tissue plasma – blood’s liquid substance formed elements – cells and cell fragments – erythrocytes: red blood cells à transport O2 and CO2 – leukocytes: white blood cells à defense against infection and other diseases – platelets: cell fragments involved in clotting and other mechanisms ORGANS An organ is composed of two or more tissues that serve different functions in the organ. The skin is the largest organ in the body. – The skin has all four primary tissues. Epithelial tissue à epidermis Connective tissue à dermis Muscular tissue à allows hair to move. Nerve tissue à to have sensitive skin (to feel/touch). SYSTEMS Organs that perform related functions are grouped into systems. 7