Introduction to Human Physiology PDF 2024

INTRODUCTION TO PHYSIOLOGY BY M.D MOHAMMED **DEPARTMENT OF HUMAN PHYSIOLOGY,** **FACULTY OF ALLIED HEALTH SCIENCES,** **EDUSOKO UNIVERSITY, BIDA , NIGER STATE** COURSE TITLE : HUMAN PHYSIOLOGY I COURSE CODE: PIO 201 **2024** 1. **STRUCTURES AND FUNCTIONS OF THE HUMAN BODY** **Physiology**...

INTRODUCTION TO PHYSIOLOGY BY M.D MOHAMMED **DEPARTMENT OF HUMAN PHYSIOLOGY,** **FACULTY OF ALLIED HEALTH SCIENCES,** **EDUSOKO UNIVERSITY, BIDA , NIGER STATE** COURSE TITLE : HUMAN PHYSIOLOGY I COURSE CODE: PIO 201 **2024** 1. **STRUCTURES AND FUNCTIONS OF THE HUMAN BODY** **Physiology**: the word physiology is derived from a Greek word which means study of nature. Jean fernel (1497- 1558), french physician, introduced the term physiology, who is the father of ancient physiology and Claude Bernard is refer to as the father of modern physiology due to his significant contributions to the field, particularly the introduction of the concept of milieu interieur (homeostasis). Physiology is the scientific study of functions and mechanisms in a living system. As a subdiscipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells and biomolecules carry out chemical and physical functions in a living system. According to the classes of organisms, the field can be divided into medical physiology, animal physiology, plant physiology, cell physiology. **Anatomy**: the word anatomy is derived from a Greek word "*Anatome*" meaning to cut up. The father of modern anatomy is Andreaus Vaselius. It is the study of structures that make up the body and how those structures relate with each other. Hence, Anatomy and physiology are studied together to give students a full appreciation and understanding of human body. **Homeostasis** When structure and function are coordinated the body achieves a relative stability of its internal environment called *homeostasis* staying the same. Although the external environmental changes constantly, the internal environment of a healthy body remains the same with in normal limits. Under normal conditions, homeostasis is maintained by adaptive mechanisms ranging from control center in the brain to chemical substances called hormones that are secreted by various organs directly into the blood streams. Some of the functions controlled by homeostasis mechanisms are blood pressure, body temperature, breathing and heart rate. **Level of structural organization of the body** The human body has different structural levels of organization, starting with atoms molecules and compounds and increasing in size and complexity to cells, tissues, organs and the systems that make up the complete organism. - Biochemical (atoms, molecules) - Cellular - Tissue - Organ - Organ system - Organism mm3lf0101\_a **Atoms molecules and compounds**: - At its simplest level, the body is composed of atoms. The most common elements in living organism are carbon, hydrogen, oxygen, nitrogen phosphorus and sulfur. Atoms → Molecule → Compounds. **Cell:** The smallest independent units of life. All life depends on the many chemical activities of cells. Some of the basic functions of cell are: growth, metabolism, irritability and reproduction. **Tissue:** tissue is made up of many similar cells that perform a specific function. The various tissues of the body are divided in to four groups. These are epithelial, connective, nervous and muscle tissue. *Epithelial tissue: -* Found in the outer layer of skin, lining of organs, blood and lymph vessels and body cavities. *Connective tissue: -* Connects and supports most part of the body. They constitute most part of skin, bone and tendons. *Muscle tissue: -* Produces movement through its ability to contract. This constitutes skeletal, smooth and cardiac muscles. *Nerve tissue: -* Found in the brain, spinal cord and nerves. It responds to various types of stimuli and transmits nerve impulses. **Organ:** - Is an integrated collection of two or more kinds of tissue that works together to perform specific function. For example: Stomach is made of all type of tissues **System:** Is a group of organs that work together to perform major function. For example: Respiratory system contains several organs. See in table 1.1 the summering of all system in human body. Table 1.1: showing the system in human body **System** **Major Organs** **Primary Functions** ------------------- ------------------------------------------------------------------------ ------------------------------------------------------ Integumentary Skin, hair, nails Protection, thermoregulation Nervous Brain, spinal cord, nerves Regulation of other body systems Endocrine Hormone secreting glands, such as the pituitary, thyroid, and adrenals Secretion of regulatory molecules called hormones Skeletal Bones, cartilages Movement and support Muscular Skeletal Muscles Movements of the skeleton Circulatory Heart, blood vessels, lymphatic vessels Movement of blood and lymph Immune Bone marrow, lymphoid organs Defense of the body against invading pathogens Respiratory Lungs, airways Gas exchange Urinary Kidneys, ureters ,urethra Regulation of blood volume and composition Digestive Mouth, stomach, intestine, liver, gallbladder, pancreas Breakdown of food into molecules that enter the body Reproductive Gonads, external genitalia, associated glands and ducts Continuation of the human **2.0 CELL STRUCTURE AND FUNCTIONS** Cell is the basic living structural and functional unit of the body. Cytology: - It is a branch of science concerned with a study of cells To know more about cell, we can divide the cell in to four principal parts: - *Plasma (cell) membrane*: it is the outer lining, limiting membrane separating the cell internal parts from extra cellular materials & external environment. *Cytoplasm:* cytoplasm is the substance that surrounds organelles and is located between the nucleus and plasma membrane *Organelles:*these are permanent structures that are embedded in the cytoplasm. *Inclusions*: they are the secretions and storage products of cells. Extra cellular materials are also referred to as the matrix, which are substances external to the cell surface.  **Figure: 2.1 structure of a cell** **Plasma Membrane** Plasma membrane is a thin outer membrane, which maintains the integrity of the cell. It keeps the cell and its contents separate and distinct from the surrounding. It is a double layered measuring about 4.5 nm and made of phospholipids, cholesterol, glyco-lipid, & carbohydrate (oligosaccharides). The bi-layer is self-sealing. If a needle is injected and pulled out, it automatically seals. **Figure 2.2: showin**g **the bilipid and protein layers of cell membrane** Functions: - 1\. Separate the cytoplasm inside a cell from extra cellular fluid. 2\. Separate cell from one another 3\. Provide an abundant surface on which chemical reaction can occur. 4\. Regulate the passage of materials in to and out of cells. It also let some things in and keeps others out. The quality selective permeability **Movement across-cell membrane** Movements a cross membrane takes place in two ways. These are passive and active movements. Passive movement uses energy whereas active movement consumes energy in the form of ATP. **Passive movement:** includes a\. *Simple diffusion*, the random movements of molecules from area of high concentration to the area of low concentration. Example air in alveoli of lung b\. *Facilitated diffusion,* larger molecules, which are not soluble in lipid need protein channel to pass through the plasma membrane. No direct energy needed. Example: - Amino acid passes through the cell membrane. c\. *Osmosis,*a special type of diffusion referring to the passage of water through a selectively permeable membrane from an area of high water concentration to lower water concentration. d\. *Filtration,*small molecules pass through selectively permeable membrane in response to force of pressure. Example: - filtration in the kidney in the process of urine formation. **Active movements across membranes** Substances move through a selectively permeable membrane from areas of low concentration on side of a membrane to an area of higher concentration on the other side. This is against concentration gradient. Therefore, it requires energy. a\) *Active Transport*: till equilibrium substances could more by passive movement. But if equilibrium reached and still more molecules are needed, they must be pumped through the membrane against concentration gradient. This process requires the use of ATP. One example of such processes is Sodium -- potassium pump and calcium pump. In this process all follows similar process. These are molecules bind to carrier protein, molecule- carrier complex pass through the membrane, assisted by an enzyme & ATP and carrier protein returns to its original shape & repeat the process. b\) *Endocytosis,* pocketing in by plasma membrane. It includes: Pinocytosis -- cell drinking Receptor -- mediated Endocytosis- Endocytosis with the help of receptor. Phagocytosis- cell eating. c\) *Exocytosis, o*pposite to Endocytosis, to remove out undigested particles. **Cytoplasm** Cytoplasm is a matrix or ground substance in which various cellular components are found. It is thick semitransparent, elastic fluid containing suspended particles and a series of minute tubules and filaments that form cytoskeleton. Water constitutes 75-90% of the cytoplasm. It also contains solid components, proteins, carbohydrates, lipids and inorganic substances. The inorganic components exist as solutions because they are soluble in water. The majority of organic substances however are found as colloids. Colloids are particles that remain suspended in the surrounding medium. **Organelles** Organelles are specialized portion of the cell with a characteristic shape that assume specific role in growth, maintenance, repair and control. a\) *Nucleus,* Oval in shape and is the largest structure in the cell. Contain the hereditary factor in the cell. Hence it controls cell activity & structure. Most cell contain single nucleus but some like matured Red Blood cell do not contain. However Muscle cell contain several nucleuses. The nucleus separated from other cell structure by double membrane called *nuclear membrane.* Pores over the nuclear membrane allow the nucleus to communicate with the cytoplasm. In the nucleus a jelly like fluid that fills the nucleus is *karylymph (neucleoplasm)*, which contain the genetic material called *chromosome*. Nucleus also contain dark, somewhat spherical, non-membrane bound mass called *nucleolus*. It contains DNA, RNA and protein, which assist in the construction of ribosome. b\) *Ribosome,* tiny granules, composed of Ribosomal RNA (rRNA). They are site of protein synthesis c\) *Endoplasmic reticulum* is a double membrane channel. It is continuous with the nuclear membrane. It involved in intracellular exchange of material with the cytoplasm. Various products are transported from one portion of the cell to another via the endoplasmic reticulum. So it is considered as intracellular transportation. It is also storage for synthesized molecules. Together with the Golgi complex it serves as synthesis & packaging center. Endoplasmic reticulum (ER) is divided in to two. These are, granular E.R. Containing granule and involving in synthesis of protein and agranular E.R. that synthesize lipid & involves in detoxification. d\) *Golgi Complex*, near to the nucleus. It consist 4-8 membranous sacs. It process, sort, pack & deliver protein to various parts of the cell. e\) *Mitochondria, a s*mall, spherical, rod shaped or filamentous structure. It generates energy. Each mitochondria possess two membrane, one is smooth (upper) membrane and the other is arranged with series of folds called cristae. The central cavity of a mitochondrion enclosed by the inner membrane is the matrix. f\) *Lysosomes* appear as membrane enclosed spheres. They are formed from Golgi complexes & have single membrane. They contain powerful digestive (hydrolytic enzyme capable of breaking down many kinds of molecules. The lysosomal enzyme believed to be synthesized in the granular endoplasmic reticulum and Golgi complex. g\) *The cyto-skeleton*, the cytoplasm has a complex internal structure consisting of a series of exceedingly small microfilaments, microtubule & intermediate filaments together referred to as the cyto-skeleton. h\) *Centrosome,* a dense area of cytoplasm generally spherical and located near the nucleus it contain centrioles. It also contains DNA that controls their replication. Centrosomes are made of microtubules, which seam drinking straws. They are Involved in the movement of chromosome during cell division.