Introduction to Human Physiology PDF

Introduction to Human Physiology: Cell components and organelles Assistant Lecturer Ahmed Makki  ‫قال الشاعر ‪:‬‬ ‫لنا صنعةٌ من غري نارٍ تُضيءُنا‬ ‫ويُطْ َفأُ نو ُر النّارِ حني تُضاءُ‬...

Introduction to Human Physiology: Cell components and organelles Assistant Lecturer Ahmed Makki  ‫قال الشاعر ‪:‬‬ ‫لنا صنعةٌ من غري نارٍ تُضيءُنا‬ ‫ويُطْ َفأُ نو ُر النّارِ حني تُضاءُ‬ ‫نشيدٌ له بني السّماء مكانٌ‬ ‫يُحيطُ به السكونُ واهلدوءُ‬ ‫ماذا يعني لك هذا البيت من الشعر ؟؟؟‬  ‫االهداف السلوكية‬ ‫بعد نهاية المحاضرة سيكون الطالب قادرا على ان ‪-:‬‬ ‫‪ -1‬يعرف المبادئ األساسية لعلم الفسيولوجيا البشرية وأهمية دراستها‪.‬‬ ‫‪ -2‬يعدد المكونات األساسية للخلية‪.‬‬ ‫‪ -3‬يذكر أسماء العضيات الموجودة في الخلية ووظائفها‬ ‫‪ -4‬يحلل العالقة بين الخاليا المختلفة في األنسجة وكيفية تفاعل العضيات الخلوية لتحقيق وظائف معينة‪.‬‬ ‫‪ -5‬يقيم تأثير تلف أو فقدان إحدى العضيات الخلوية على وظائف الخلية بشكل عام‪.‬‬ Levels of organization The body consists of many components, starting with the smallest of them – the atom – and towards the largest, the body is organized in this way: 1- The atom – e.g. hydrogen, carbon 2- The molecule – e.g. water, glucose 3- The macromolecule (large molecule) – e.g. protein, DNA 4-The organelle (found in the cell) – e.g. nucleus, mitochondrion 5-The tissues – e.g. bone, muscle 6- The organs – e.g. heart, kidney 7- The organ system – e.g. skeletal, cardiovascular 8- The organism – e.g. animal, a plant, a bacterium, or a fungus Characteristics of life :- All living organisms have certain characteristics in common. Although these characteristics may differ from organism to organism, they are important for the maintenance of life. These characteristics are: 1 Reproduction – both at the micro - and the macro - level, reproduction is essential because the new cells are important to maintain the efficiency and growth of the organism 2 Growth – essential for the growth and development of an organism 3 Movement – both changes in position and motion are parts of the movement. This characteristic is essential to allow the organism to seek out nutrition and partners for reproduction, as well as to escape predators 4 Respiration – respiration is important for obtaining oxygen and releasing carbon dioxide (or obtaining carbon dioxide and releasing oxygen if a green plant). 5 Responsiveness – this allows the organism to respond to changes, for example in the environment or to other stimuli. 6 Digestion – this is the breakdown of food substances so that the organism can produce the energy necessary for life. 7 Absorption – the movement of substances (including digested food) through membranes and into body fluids, including blood and lymph, which then carry the substances to the parts of the organism requiring them. 8 Circulation – the movement of substances through the body in the body fluids. 9 Assimilation – the changing of absorbed substances into different substances, which can then be utilized by the tissues of the body. 10 Excretion – the removal of waste substances from the body. These waste substances are either removed because they are of no use to the body or because they are harmful to the body. ▪ Introduction to the cell biology What is a Cell? Cells: are the microscopic fundamental units of all living things. ▪ Every living thing has cells: bacteria, protozoans, fungi, plants, and animals are the main groups (Kingdoms) of living things. ▪ Some organisms are made up of just one cell (e.g. bacteria and protozoans). ▪ But animals, including human beings, are multicellular. ▪ An adult human body is composed of about 100 trillion cells! Each cell has basic requirements to sustain it. and the body's organ systems are largely built around providing the many trillions of cells with those basic needs (such as oxygen, food, and waste removal) ▪ About 200 different specialized cells carry out many functions that help each system contribute to the homeostasis of the entire body. At the same time, all cells share key structures and functions that support their intense activity. A cell has three main parts: 1.plasma membrane 2.cytoplasm 3. nucleus ▪ Human Cell, Structure, and Functions: ▪ The cell is the basic human function, meaning it is a self-contained and fully operational living entity. ▪ Humans are multicellular organisms with various types of cells working together to sustain life. ▪ Other non-cellular components in the body include water, macronutrients (carbohydrates, proteins, lipids), micronutrients (vitamins, minerals), and electrolytes. ▪ A collection of cells that function together to perform the same activity is known as tissue. Masses of tissue work collectively to form an organ that performs specific functions in the body. Despite this structural organization, all activity boils down to the cell – a complex unit that makes life possible. ▪Parts of the Human Cell The cell contains various structural components to allow it to maintain a life which is known as organelles. All the organelles are suspended within a gelatinous matrix, the cytoplasm, which is contained within the cell membrane. ▪ The main organelles are as follows : oNucleus oCell membrane oEndoplasmic reticulum: rough and smooth oGolgi apparatus oLysosomes oPeroxisomes oMitochondria ocytoskeleton Human cell oNucleus The nucleus: is the master control of the cell. It contains genes, and collections of DNA, which determine every aspect of human anatomy and physiology. Within the nucleus is an area known as the nucleolus. It is not enclosed by a membrane but is just an accumulation of RNA and proteins within the nucleus. The nucleolus is the site where the ribosomal RNA is transcribed from DNA and assembled. o Cell Membrane The cell membrane is the outer coating of the cell and contains the cytoplasm, substances within it, and the organelle. It is a double-layered membrane composed of proteins and lipids. The lipid molecules on the outer and inner part (lipid bilayer) allow it to selectively transport substances in and out of the cell. o Endoplasmic Reticulum The endoplasmic reticulum (ER) is a membranous structure that contains a network of tubules and vesicles. Its structure is such that substances can move through it. There are two types of endoplasmic reticulum – rough and smooth oThe cytoplasm : consists of all the cellular contents between the plasma membrane and the nucleus. This compartment has two components: cytosol and organelles Cytosol: means the fluid portion of the cytoplasm. Contains: (water, dissolved solutes, and suspended particles). Surrounded by cytosol are several different types of organelles (little organs). Each type of organelle has a characteristic shape and specific functions. Examples include: ( the cytoskeleton, ribosomes, endoplasmic reticulum, Golgi complex, lysosomes , peroxisomes, and mitochondria ) oGolgi Apparatus: The Golgi apparatus is a stacked collection of flat vesicles. It is closely associated with the endoplasmic reticulum in that substances produced in the ER are transported as vesicles and fuses with the Golgi apparatus. In this way, the products from the ER are stored in the Golgi apparatus and converted into different substances that are necessary for the cell’s various functions oLysosomes: Lysosomes are vesicles that break off from the Golgi apparatus. It varies in size and function depending on the type of cell. Lysosomes contain enzymes that help with the digestion of nutrients in the cell and break down any cellular debris or invading microorganisms like bacteria. o Peroxisomes These organelles are very similar to the lysosomes and contain enzymes that act together in the form of hydrogen peroxide to neutralize substances that may be toxic to the cell. Peroxisomes are formed directly from the endoplasmic reticulum rather than from the Golgi apparatus like lysosomes. oMitochondria These are the powerhouses of the cell and break down nutrients to yield energy. Apart from producing its own energy, it also produces a high-energy compound called ATP (adenosine triphosphate) which can be used as a simple energy source elsewhere. Mitochondria are composed of two membranous layers – an outer membrane that surrounds the structure and an inner membrane that provides the physical sites of energy production. The inner membrane has many folds that form shelves where enzymes attach and oxidize nutrients. The mitochondria also contain DNA which allows it to replicate where and when necessary. oCytoskeleton The cytoskeleton serves as a framework for positioning and moving organelles and macromolecules within the cell Components of the cytoskeleton There are three structural elements of the cytoskeleton -Microtubules (the largest structural elements of the cytoskeleton) -Microfilaments (the smallest components of the cytoskeleton) -Intermediate filaments ( larger in diameter than microfilaments but smaller than microtubules) -The functions of the human cell varies based on the type of cell and its location in the human body. All the organelles work together to keep the cell alive and allow it to carry out its specific function. Sometimes these organelles are highly specialized and can vary in (size, shape, and number). The organelles are the most basic functional units but they cannot exist and operate without the cell as a whole. Its functions include intake of nutrients and other substances, processing of these compounds, production of new substances, cell replication, and energy production. -Type of transporting in the cell membrane Endocytosis Endocytosis (endo = internal, cytosis = transport mechanism) is a general term for the various types of active transport that move particles into a cell by enclosing them in a vesicle made out of a plasma membrane. There are variations of endocytosis, but all follow the same basic process. First, the plasma membrane of the cell invaginates (folds inward), forming a pocket around the target particle or particles. The pocket then pinches off with the help of specialized proteins, leaving the particle trapped in a newly created vesicle or vacuole inside the cell. Endocytosis can be further subdivided into the following categories: phagocytosis and, pinocytosis. 1.Phagocytosis Phagocytosis (literally, “cell eating”) is a form of endocytosis in which large particles, such as cells or cellular debris, are transported into the cell. We’ve already seen one example of phagocytosis because this is the type of endocytosis used by the macrophage to engulf a pathogen 2- Pinocytosis Pinocytosis (literally, “cell drinking”) is a form of endocytosis in which a cell takes in small amounts of extracellular fluid. Pinocytosis material is held in small vesicles, much smaller than the large food vacuole produced by phagocytosis. Exocytosis Cells must take in certain molecules, such as nutrients, but they also need to release other molecules, such as signaling proteins and waste products, to the outside environment. Exocytosis (Exo = external, cytosis = transport mechanism) is a form of bulk transport in which materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. ▪ Cilia and Flagella Cilia are tiny hairlike structures that project from the surface of a cell into the extracellular fluid. Motile cilia (those able to move) can beat like rowers in a boat, Such motile cilia are found in only particular locations in the human body, where they project from the apical surface of epithelial cells (the surface facing the lumen, or cavity) that are stationary and line certain hollow organs. For example, ciliated epithelial cells are found in the respiratory system and the female reproductive tract. In the respiratory airways, the cilia transport strands of mucus to the pharynx (throat), where the mucus can be swallowed or expectorated. Cilia, as seen with the electron microscope. ▪ Microvilli In areas of the body that are specialized for rapid diffusion, the surface area of the cell membranes may be increased by numerous folds called microvilli. With the rapid passage of the products of digestion across the epithelial membranes in the intestine, Similar micro-villi are found in the epithelia of the kidney tubules, which must reabsorb various molecules that are filtered out of the blood. Microvilli in the small intestine Thank You