OPTM1011 Human Anatomy & Physiology Lecture 1 PDF

OPTM 1011 HUMAN ANATOMY & PHYSIOLOGY Lecture 1 Introductory Topics Nikita S. D. Sahadeo, Ph.D. Learning Objectives Define the terms “anatomy” and “physiology” Define the anatomical terms relating to position, directions and geometric planes of the body Classify six levels of struct...

OPTM 1011 HUMAN ANATOMY & PHYSIOLOGY Lecture 1 Introductory Topics Nikita S. D. Sahadeo, Ph.D. Learning Objectives Define the terms “anatomy” and “physiology” Define the anatomical terms relating to position, directions and geometric planes of the body Classify six levels of structural organization in the human body Define the four types of tissues existing in the human body and their respective sub- types Discuss Identify the eleven major systems that exist in the human body Describe the role of homeostasis in the body Anatomy vs. Physiology Anatomy is the study of the structure of body parts and their relationships to one another Two main approaches – Regional – Systemic Physiology is the study of normal function within living creatures. Anatomical Organization Cells – smallest unit of life Tissues – group of similar cells performing a common function, example muscle tissue consists of muscle cells Organs – group of different kinds of tissues working together to perform a particular activity Organ Systems – two or more organs working together to accomplish a particular task Regional vs. Systemic Anatomy Regional One region of the body at a time Study of the structures such as bones, joints, muscles, blood vessels, nerves and organs and their relationship to each other Systemic One organ system at a time – Organ system is a group of related organs Subdivisions of Anatomy Gross anatomy (Macroscopic anatomy) – Study of structures that can be seen with the eye (muscles, bones, organs) Microscopic anatomy: Study of structures that cannot be seen with the eye – Histological techniques used – sectioning, staining and examining under a microscope – Cytology (study of cells), histology (study of tissues) Anatomical Positions Anatomical Planes & Sections Plane – an imaginary flat surface that passes through the body Median plane: Divides the body into equal left and right halves Sagittal plane: vertical plane passing through the body parallel to the median plane Coronal (frontal) plane: Divides the body or an organ into front and back portions Transverse (horizontal) plane: Divides the body or an organ into upper and lower portions Oblique plane: Combination of other planes The (Four) Primary Tissue Types Epithelial tissue refers to groups of cells that cover the exterior surfaces of the body, line internal cavities and passageways, and form certain glands Connective tissue binds the cells and organs of the body together Muscle tissue contracts forcefully when excited, providing movement Nervous tissue is excitable, allowing for the generation and propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body  Embryonic Origin of Tissues The cells composing a tissue share a common embryonic origin The first embryonic cells generated are omnipotent Each germ layer is identified by its relative position: – ectoderm (ecto- = “outer”) – mesoderm (meso- = “middle”) – endoderm (endo- = “inner”) Epithelial tissue originates in all three layers, whereas nervous tissue derives primarily from the ectoderm and muscle tissue derives from the mesoderm Tissue Membranes A thin layer of cells that (i) covers the outside of the body (e.g. skin), (ii) lines an internal body cavity (e.g. peritoneal cavity), (iii) lines a vessel (e.g. blood vessel), or (iv) lines a movable joint cavity (e.g. synovial joint) Connective tissue membranes – include synovial membranes Epithelial membranes – include mucous membranes, serous membranes, and the cutaneous membrane Epithelial Membranes An epithelial membrane is composed of an epithelial layer attached to a layer of connective tissue A mucous membrane lines a body cavity or hollow passageway that is open to the external environment – The underlying connective tissue, called the lamina propria, helps support the epithelial layer A serous membrane lines the cavities of the body that do not open to the external environment – Serous fluid secreted by the cells of the epithelium lubricates the membrane and reduces abrasion and friction between organs A cutaneous membrane is a multi-layered membrane composed of epithelial and connective tissues – The skin is an example of a cutaneous membrane Epithelial Cell Junctions Tight junctions restrict the movement of fluids between adjacent cells due to the presence of integral proteins that fuse together to form a firm seal – Tight junctions are observed in the epithelium of the urinary bladder, preventing the escape of fluids comprising the urine Anchoring junctions provide a strong yet flexible connection between epithelial cells – There are three types of anchoring junctions: desmosomes, hemidesmosomes, and adherens – These junctions influence the shape and folding of the epithelial tissue Gap junctions form an intercellular passageway between the membranes of adjacent cells to facilitate the movement of small molecules and ions between cells – These junctions allow electrical and metabolic coupling of adjacent cells Classification of Epithelial Tissue Epithelial cell shapes are classified as being either squamous (flattened and thin), cuboidal (boxy, as wide as it is tall), or columnar (rectangular, taller than it is wide) Cells in the tissue can be arranged in a single layer (simple epithelium), or more than one layer (stratified epithelium) Pseudostratified (pseudo- = “false”) describes an epithelial tissue with a single layer of irregularly shaped cells that give the appearance of more than one layer Transitional epithelium describes a form of specialized stratified epithelium in which the shape of the cells, and the number of layers present, can vary depending on the degree of stretch within a tissue Connective Tissue – Structural Elements Connective tissues typically have in common three characteristic components: – cells – large amounts of amorphous ground substance – protein fibers Cells of connective tissue are widely dispersed within the extracellular matrix Connective Tissue – Cell Types The most abundant cell in connective tissue proper is the fibroblast Chondroblasts and osteoblasts are the primary specialized cell type located in cartilage and bone, respectively Adipocytes are cells that store lipids as droplets that fill most of the cytoplasm The mesenchymal cell is a multipotent adult stem cell – These cells can differentiate into any type of connective tissue cells needed for repair and healing of damaged tissue Connective Tissue – Cell Types The macrophage cell is a large cell derived from a monocyte, a type of blood cell, which enters the connective tissue matrix from the blood vessels The mast cell, found in connective tissue proper – When irritated or damaged, mast cells release histamine, an inflammatory mediator, which causes vasodilation and increased blood flow at a site of injury or infection  Connective Tissue – Fibers & Ground Substance Collagen fiber is made from fibrous protein subunits linked together to form a long, straight fiber. – Flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience. Elastic fiber contains the protein elastin along with lesser amounts of other proteins and glycoproteins. – The main property of elastin is that after being stretched or compressed, it will return to its original shape. Reticular fiber is formed from the same protein subunits as collagen fibers, – Prominent in elastic tissues however, these fibers remain narrow and are arranged in a branching found in skin, the walls of large network. blood vessels, and in a few ligaments which support the – Found throughout the body, but are most abundant in the reticular spine. tissue of soft organs, such as the liver and spleen, where they anchor and provide structural support to the parenchyma (the functional cells, blood vessels, and nerves of the organ). Classification of Connective Tissue Muscle Tissue  Nervous Tissue Nervous tissue is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. Two main classes of cells make up nervous tissue: the neuron and neuroglia. Neurons propagate information via electrochemical impulses, called action potentials, which are biochemically linked to the release of chemical signals.  Nervous Tissue Neuroglia or glial cells have been characterized as having support role for the neurons – Astrocyte cells, named for their distinctive star shape, are abundant in the central nervous system. The astrocytes have many functions, including regulation of ion concentration in the intercellular space, uptake and/or breakdown of some neurotransmitters, and formation of the blood-brain barrier, the membrane that separates the circulatory system from the brain. – Microglia protect the nervous system against infection and are related to macrophages. – Oligodendrocyte cells produce myelin in the central nervous system (brain and spinal cord) – Schwann cells produces myelin in the peripheral nervous system Homeostasis Claude Bernard (1813-1878) wrote, "La fixitédu milieu intérieurestla condition d'unevie libre et indépendante"... "The constancy of the internal environment is the condition for a free and independent life" While never actually utilizing the term ‘homeostasis’ Bernard is widely credited for first defining the concept Defined as the dynamic maintenance of a relatively constant internal environment, to create optimal functioning for the body Maintaining Homeostasis Autoregulation –process whereby biological systems have an internal adaptive mechanism that allows them to automatically adjust to specific environmental change. Regulation controlled by central systems Involves activities of nervous and endocrine systems Requires centers that monitor changes in parameters and then institute processes to counteract change Maintaining Homeostasis The stimulus is provided by the variable that is being regulated – Generally, the stimulus indicates that the value of the variable has moved away from the set point or has left the normal range. The sensor monitors the values of the variable and sends data on it to the control center The control center matches the data with normal values. If the value is not at the set point or is outside the normal range, the control center sends a signal to the effector The effector is an organ, gland, muscle, or other structure that acts on the signal from the control center to move the variable back toward the set point Negative Feedback Negative Feedback Negative Feedback promotes stability in a system and ensures they do not deviate to far from the set point However there are some disadvantages: I. Negative feedback control is initiated after variable has been disturbed it is not anticipatory (compare toe feed forward systems) II. The amount of correction to be applied is determined by magnitude of error signal this can lead to incomplete correction III. Overcorrection oscillations in controlled variable Positive Feedback In a positive feedback loop feedback serves to intensify a response until an endpoint is reached Self-reinforcing loop Positive feedback in the body is normal only when there is a definite end point. Generally moves the system away from its starting point Examples: Blood Clotting and Childbirth