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UNIT 1 THE ORGANIZATION OF THE HUMAN BODY ---------------------------------- 1. Levels of organization. 2. The chemical composition of living things. 3. Cells: the basic unit of living things. 4. Prokaryotic cells. 5...

UNIT 1 THE ORGANIZATION OF THE HUMAN BODY ---------------------------------- 1. Levels of organization. 2. The chemical composition of living things. 3. Cells: the basic unit of living things. 4. Prokaryotic cells. 5. Eukaryotic cells. 6. Cell organelles and structures. 7. Human tissues. 8. Organs and organ systems. UNIT 1 1 UNIT 1 2 CELLS are elemental units of independent life. They are different from each other, They have specialized features and group together to form more complex structures in multicellular organisms. TISSUES are groups of cells of the same type and origin, which are specialized in performing one particular function. An ORGAN consists on two or more tissues that perform a particular function. SYSTEMS are group of different organs that work together in one or more functions. An ORGANISM is formed of the ensemble of systems that function in a coordinated way. UNIT 1 3 2. THE CHEMICAL COMPOSITION OF LIVING THINGS INORGANIC BIOMOLECULES – Water Water is the most abundant substance in living things. In fact, water is the 65% in human body; but we have one difference: 64% in women and 66% in men. There are different amounts of water in organs depending on its function: Blood >> Brains >> Bones Water is a thermal regulator, and it is responsible for the balance of body temperature. Metabolism is made in water because it is the universal dissolvent. INORGANIC BIOMOLECULES – Mineral Salts Mineral Salts can be found in living things in the form of dissolved ions, such as sodium ion (Na+) and potassium ion (K+); or precipitated crystals, such as phosphate and calcium carbonate, in bones. ORGANIC BIOMOLECULES – Carbohydrates There are different types: MONOSACCHARIDES are composed of one molecule, for example, Glucose. DISACCHARIDES are composed of 2 monosaccharides, such as Sucrose or Maltose. POLYSACCHARIDES are composed of many monosaccharides joined in a chain, such as Cellulose or Starch. ORGANIC BIOMOLECULES – Lipids These molecules have a wide variety of chemical structure: fats, phospholipids, colesterol… ORGANIC BIOMOLECULES – Proteins These large molecules are composed of smaller molecules called amino acids. Some human proteins are Haemoglobin, Collagen, Antibodies… UNIT 1 4 ORGANIC BIOMOLECULES – Nucleic Acids These molecules are composed of nucleotides. There are two types: DNA (deoxyribonucleic acid) that has all the information of one individual, and RNA (ribonucleic acid). 3. CELLS: THE BASIC UNIT OF LIVING THINGS. All living things, for the simplest to the more complex, are made up of cells. CELL is the simplest living unit that carries out the life functions of Nutrition, Interaction and Reproduction; and the Cell Theory explains all of these. The Modern CELL THEORY contains 4 statements, in addition to the original Cell Theory: 4. The cell is the structural unit, because all living things are formed of 1 or more cells. 5. The cell is the functional unit, because cells carry out life functions. 6. The cell is the genetic unit, because it contains the genetic material with all its information. 7. The cell is the basic unit, because all cells come from a pre-existing cell («omnis cellula ex cellula»). Living things can made of one or many cells: UNICELLULAR ORGANISMS: microscopic living things made up of one cell, such as organisms found in Monera Kingdom (bacteria), Protista Kingdom (protozoa and unicelular algae) and some species of Fungi Kingdom. MULTICELLULAR ORGANISMS: macroscopic living things made up of many cells. Their organization is complex. Examples can be found in Protista Kingdom (algae) and in Fungi, Plant and Animal Kingdoms. UNIT 1 5 LIFE FUNCTIONS IN CELLS Cells performs 3 life functions: Nutrition, Interaction and Reproduction. - CELLULAR NUTRITION consists of all the processes in which cells obtain the matter and energy to perform their functions. To do this, cells take nutrients from the outside and the nutrients undergo chemical processes called cellular metabolism. There are 2 types of metabolism: Catabolism and Anabolism. Catabolism is the destructive phase of metabolism, in which the cell obtains energy for its functions. Anabolism is the constructive phase of metabolism, in which the cell obtains complex molecules for its growth and structural repairs. - CELL INTERACTION enables cells to get information from their environment, and communicate with other cells. - CELLULAR REPRODUCTION is the process in which a parent cell divides into two or more new cells. In unicellular organism, cell division reproduces a whole organism. In multicellular organism, cell division results in an increase in the number of cells, not only for the growth of the organism but also to repair damaged or lost parts. 4. PROKARYOTIC CELLS. Prokaryotic cells have a simple structure and are generally much smaller than the eukaryotic cells. Prokaryotic cells have three main characteristics: - No nucleus - Genetic material is dispersed in the cytoplasm. - Ribosomes are the only organelles. - The cell membrane is covered by a cell wall. Bacteria are prokaryotes and consists in a single and simple cell, and they belong to the Monera kingdom. UNIT 1 6  PLASMA MEMBRANE: It surrounds the cytoplasm and regulates the exchange of substances with outside. CELL WALL: It is a thick and rigid layer around the cell membrane. It protects the bacteria and gives it its shape. BACTERIAL CAPSULE: It is a thick outer covering on some bacterial cells, that promotes adhesion to other cells (cells that they infect) and protects the cell. CYTOPLASM: It is the liquid substance that fills the internal space. NUCLEOID: It is the bacterial chromosome, a circular DNA molecule that contains genetic material with the genetic information. RIBOSOMES: They are organelles that carry out protein synthesis. INCLUSION: It is an aggregate of stable substances, usually proteins. APPENDICES: They are structures like flagella and cilia, that are involved in movement. Flagella are longer and a few per cell. Cilia are shorter and more numerous. Fimbriae are short and numerous appendices that enable bacteria to adhere to a surface. Pili are responsible for the exchange of DNA fragments with another cell. 5. EUKARYOTIC CELLS. Eukaryotic cells are more complex and larger than prokaryotic cells. Their size can range from 10-100 µm1 to several centimetres, and we can find them in animals and plants. All eukaryotic cells have three structures: CELL MEMBRANE: This membrane surrounds the cell and enables the exchange of substances with the outside environment. The membrane has two layers of phospholipids with cholesterol and proteins; the structured is called “fluid mosaic” because these elements move and change position. CYTOPLASM: It is the substance that fills the space between the membrane and the nucleus. The cytoplasm contains: - Hyaloplasm: The fluid component of the cytoplasm. - Organelles: Cellular structures that carry out different functions. - Cytoskeleton: Protein fibres involved in movement, internal organization and cell division. 1 1 µm = 1 micrometre = 1 x 10-6 metre UNIT 1 7  NUCLEUS: This spherical structure contains the chromatin or the genetic material that controls cellular function. It is surrounded by a double membrane called the nuclear envelope. This envelope has tiny holes called nuclear pores, that regulate the exchange of substances between the nucleus and the rest of the cell. 6. CELL ORGANELLES AND STRUCTURES. UNIT 1 8  CYTOSKELETON: A network made up of different types of protein filaments that maintains the shape of the cell and facilitates the movement of cell, organelles and internal vesicles. MITOCHONDRIA: It is an oval-shaped organelle with two membranes: the outer one is smooth while the inner one folds forming the mitochondria cristaes. It produces the most of the energy of a cell through Cellular Respiration. RIBOSOMES: They are non-membranous organelles made up of RNA and proteins. They are free in the cytoplasm or attached to the Rough Endoplasmic Reticulum. They are responsible for protein synthesis. ENDOPLASMIC RETICULUM (ER): It is a network of interconnected membranous sacs and channels. There are two types: - ROUGH ER: This type is connected to the nuclear envelope. Many ribosomes are attached to it; and due to that, this type of ER is involved in the process and transport of proteins to the Golgy Apparatus. - SMOOTH ER: This type has not attached ribosomes. This type is responsible for lipid synthesis. GOLGY APPARATUS: This organelle has flats, membranous sacs arranged in layers. It stores, processes and packages proteins from Rough ER. Then, it produces secretory vesicles to transport proteins out of the cell. UNIT 1 9  VESICLES: They are small and rounded organelles that store and transport substances. LYSOSOMES: They are rounded vesicles produced by Golgi Apparatus that contain enzymes involved in Cellular Digestion. CENTROSOME: This organelle consists in two centrioles or cilindrical structures composed of protein fibres. During cell division, the centrosome controls the movement of chromosomes. 7. HUMAN TISSUES. A tissue is a group of specialized cells that work together to perform a specific function. Tissues can be grouped into four types: epithelial, connective, muscle and nervous. EPITHELIAL TISSUE Epithelial cells are generally polyhedral-shaped. They are closely packed together and arranged in layers. There are two main groups: covering epithelia and glandular epithelia. COVERING EPITHELIA This tissue covers internal and external body surfaces. It protects surfaces and regulates the exchange of substances. The types varies depending on location: UNIT 1 10  - Epidermis. This type consists of many layers of cells and it forms the outer layer of human skin. - Mucous membrane. This tissue protects internal cavities such as the digestive and respiratory tracts. - Endothelia. This tissue consists on a single layer of cells; and it lines the internal surfaces of the body, such as blood vessels and heart. GLANDULAR EPITHELIA This tissue makes up the glands. It produces and secretes substances. There are three types of glands: EXOCRINE GLAND ENDOCRINE GLAND MIXED GLAND They secrete substances into a They secrete hormones directly They have exocrine and body cavity or outside the body into the bloodstream. endocrine functions. CONNECTIVE TISSUE This tissue connects other tissues. It has three components: cells, fibres and an intercellular substances or matrix. There are several types: OSSEOUS or BONE TISSUE This tissue is made up of a strong, solid matrix, the cells responsible for bone formation, osteoblasts, and the other cells in mature bone, osteocytes. UNIT 1 11  ADIPOSE TISSUE It is made up of fat cells or adipocytes and these cells store lipids. It protects some organs. CARTILAGE TISSUE Its cells, chrondocytes, contain elastic fibres and produce a solid, flexible matrix like the cartilage found at joints. CONECTIVE TISSUE PROPER It is found between tissues and organs holding them together: tendons and ligaments are examples. BLOOD TISSUE This special tissue is made up of red blood cells or eritrocytes, white blood cells or leucocytes and platelets or thrombocytes. Its matrix, plasma, is liquid with no fibres. Its function is to transport substances. UNIT 1 12 MUSCLE TISSUE This contractile tissue has elongated cells called myocytes or muscle fibres. There are three types of muscle tissue: SMOOTH MUSCLE TISSUE SKELETAL MUSCLE TISSUE CARDIAC MUSCLE TISSUE Its cells have a single nucleus. Its cells have many nuclei. Its cells are joined in a Contraction is slow and Skeletal muscles are striated, network. They have a single involuntary. This type is and contraction is fast and nucleus, and its contraction found in the walls of internal voluntary. This type is found is fast and involuntary. This organs. in skeletal muscles. tissue is found in heart wall. NERVOUS TISSUE Its cells transmit and receive information throughout the body. There are two types of cells: NEURONS They are star-shaped with many projections. These cells are specialized in transmission of nerve impulses (electrical impulses). They have two types of projections: a lot of dendrites that are branching and receive the nerve impulse from the previous neuron, and just one axon that is covered by a sheath and send the nerve impulse to the following neuron. UNIT 1 13  GLIAL CELLS This type of nervous cells feed and support neurons, because neurons are so essential to spend energy in other functions different from transmission of nerve impulses. Glial cells do not transmit nerve impulses. 8. ORGANS AND ORGAN SYSTEMS. The human body is made up of many organs organized by function into organs systems. An ORGAN is a group of tissues that work together to perform a specific function or action. The heart, skin and muscles are examples. An ORGAN SYSTEM is a group of organs that work together to perform one or more functions. All the systems work together to enable the body to function. Organ systems can be grouped by life function: Nutrition, Interaction and Reproduction. NUTRITION INTERACTION REPRODUCTION Digestive System Nervous System Male Reproductive System Respiratory System Endocrine System Female Reproductive System Circulatory System Muscular System Excretory System Skeletal System -------------------------------------------------------------------------------------------------- UNIT 1 14