Basic Structure of the Human Body

Cell Cell Reproduction Tissues

Introduction

 Human body is an efficient, organized machine  Disease occurs when the machine does not function correction  Health care workers must understand normal function of the body before understanding the disease processes

Anatomy

 The study of the form and structure of an organism

Physiology

 Study of the processes of living organisms or why and how they work

Pathophysiology

 Study of how disease occurs and response of the body to disease process

Protoplasm

 Basic substance of all life  Material that makes up all living things  Made of ordinary elements, such as carbon, oxygen, hydrogen,sulfur, nitrogen and phosphorus  Scientist can combine these elements, but they are not able to give it the characteristics to produce life.

Cells

 Basic unit of structure and function of all living things; made of protoplasm  Microscopic organisms that carry on all functions of life  Take in food and oxygen      Produce heat and energy Move and adapt to their environment Eliminate waste Perform special functions Reproduce to create new identical cells

Human body contains trillions of cells.

Cells vary in shape and size and perform many different functions.

Basic parts of the cell Cell membrane

 Outer protective covering of cell  Also called the plasma membrane or plasmalemma  Semipermeable allows certain substances to enter and leave cell while preventing the passage of other substance

Basic cell structure Cytoplasm

 Semifluid inside the cell membrane but outside the nucleus  Contains water (70 to 90 percent), proteins, lipids, carbohydrates, minerals and salts  Site for all chemical reactions in cell

Basic Structure Organelles

 Cell structure that help a cell to function  Located in cytoplasm  Main organelles include the nucleus, mitochondria, ribosome, lysosomes, centrioles, golgi apparatus and endoplasmis reticulum

Basic Structure Nucleus

 Mass in cytoplasm  Separated from cytoplasm by a nuclear membrane and contains pores to allow substances to pass between the nucleus  Often called the brains of the cell  Controls many cell activities, including the process of mitosis or reproduction

Basic Structure Nucleolus

 One or more small round bodies located inside the nucleus  Important in reproduction of the cell  Ribosomes made of ribonucleic acid (RNA) and protein are manufactured in the nucleolus  Ribosomes move to cytoplasm to aid in synthesis (production) of protein  Ribosomes can exist freely in the cytoplasm or be attached to the endoplasmic reticulum

Basic Structure Chromatin

 Located inside the nucleus  Made up of deoxyribonucleic aid (DNA) and protein  Chromatin condenses to from rod-like structure called chromosomes during cell reproduction

Chromosomes

 Human cell has 46 chromosomes or 23 pairs  Each chromosome contains between 30,000 and 45,000 genes, the structures that carry inherited characteristics  Each gene has a specific and unique sequence of about 1000 base pairs of DNA

Genes

 Each gene has a specific and unique sequence of about 1000 base pairs of DNA • DNA carries genetic coding that allows for exact duplication of the cell • DNA sequence on genes is unique for each individual • DNA is used as an identification tool similar to fingerprints but much more exact

Genome

 Total mass of genetic instruction humans inherit from their parents  Consists of strings of DNA nucleotides  Human beings have about 3 billion nucleotides in their genome  Order of nucleotides on DNA sequences provide instructions for body to build all of its parts, everything from permanent structures such as teeth and brain cells to short lived substances such as blood and hormones

Basic Structure Centrosome

 Located in cytoplasm near the nucleus  Contains two centrioles important in reproduction  During mitosis, or cell division, the centrioles separate  Thin cytoplasmic spindle fibers form between the centrioles and attach to the chromosomes  Creates an even division of the chromosomes in the two new cells.

Basic Structure Mitochrondria

 Rod-shaped organelles located throughout the cytoplasm  Called furnaces or powerhouses of the cell  Break down carbohydrates, proteins and fats to produce adenoside triphosphate (ATP) which is major energy source of the cell  Cell can contain just 1 to over 1000 mitochrondria depending on how much energy the cell requires.

Cell Structure Golgi Apparatus

 Stack of membrane layers located in cytoplasm  Produces, stores, and packages secretions for discharge from the cell  Cells of salivary, gastric, and pancreatic glands have large numbers of Golgi appartus

Cell Structure Endoplasmic reticulum

     Fine network of tubular structures in cytoplasm Allows for transport of materials into and out of the nucleus Also aids in synthesis and storage of proteins Rough endoplasmic reticulum contains ribosomes which are the sites for protein synthesis Smooth endoplasmic reticulum does not contain ribosomes and is not present in all cells; but it does assist with cholesterol synthesis, fat metabolism and detoxification of drugs

Cell Structure Vacuoles

 Pouch like structures found throughout cytoplasm  Have a vascuolar membrane with same structure as cell membrane  Filled with watery substances, stored food or waste products

Cell Structure Lysosomes

 Oval or round bodies found throughout the cytoplasm  Contain digestive enzymes that digest and destroy old cells, bacteria, and foreign materials  Fuse with stored food vacuoles to convert food to a form that can be used by mitochondria

Cell Structure Pinocytic vesicles

 Pocketlike folds in the cell membrane  Allow large molecules such as protein and fat to enter the cell  When molecule is inside the cell, the pocket closes to form a vacuole, or bubble, in the cytoplasm  When cell needs energy, vesicles fuse with lysosomes to allow proteins and fats to be digested and used by mitochondria to produce ATP(energy).

Mitosis

     Asexual reproduction process used by most cell Cells reproduce by dividing into two identical cells Skin, blood forming, and intestinal tract cells reproduce continuously Muscle cells reproduce only every few years, but muscle tissue can be enlarged with exercise.

Some specialized cells do not reproduce after birth   Includes nerve cells in brain and spinal cord If these cells are damaged or destroyed, others are not formed to replace them

Process of mitosis

Meiosis

 Process by which sex cells (gametes) reproduce  Process uses two separate cell divisions to produce four new cells  When female cells (ova) or male cells (sperm) divide by meiosis, the number of chromosomes is reduced to 23 or one half the number found in cells created by mitosis.

 When oven and sperm join, zygote or new cell, has 46 chromosomes or 23 pairs  -- 23 chromosomes from ovum or maternal cell  23 chromosomes from sperm or paternal cell  Creates new individual with 23 pairs half from mother and half from father.

Meiosis

Zygote begins period of rapid mitotic division

 Within four to five days, the zygote is a hollow ball like mass of cells called a blastocyst  Within this blastocyst are embryonic stem cells  Stem cells have the ability to transform themselves into any of the body’s specialized cells and perform many different functions.

Controversial area of research

 Scientists attempting to determine whether stem cells can be transplanted into the body to cure diseases such as diabetes mellitus, Parkinson’s, heart disease, oseteoporosis, arthritis and spinal cord injuries

Stem Cells

 Embryonic cells  Umbilical cord blood cells  Adult tissues such as bone marrow and liver (but these cells do not have the ability to evolve into every kind of cell; these stem cells evolve into more cells of their own kind.)

Tissue

 Cells of the same type join together for a common purpose  60 – 99 percent water with various substances dissolved in it  Fluid called tissue fluid    Slightly salty by nature Dehydration: insufficient amount of tissue fluid Edema: Excess amount of tissue fluid; swelling

Four groups of tissues

 Epithelial tissue  Connective tissue  Nerve tissue  Muscle tissue

Epithelial Tissue

 Covers surface of body and main tissue in skin  Forms lining of intestinal, respiratory, circulatory, and urinary tracts and other body cavities  Forms body glands where it specializes to produce specific secretions for the body, such as mucus and digestive juices

Connective Tissue

 Supporting fabric of organs and other body parts  Soft connective tissue   Adipose or fatty tissue: stores fat as reserve food or source of energy, insulates the body, fills the area between tissue fibers, and acts as padding Fibrous connective tissue: includes ligaments and tendons that help hold body structures together

Connective Tissue

 Hard connective tissue - Cartilage: tough, elastic material found between bones of spine and at end of long bones where it acts as a shock absorber and allows for flexibility; also found in nose, ears, and larynx to provide form or shaping - Bone: similar to cartilage but has calcium salts, nerves, and blood vessels; frequently called osseous tissue; helps form body structure

Connective Tissue

 Blood and lymph (liquid connective tissue or vascular tissue)  Blood carries nutrients and oxygen to body cells and metabolic wastes away from cells  Lymph transport tissue fluid, proteins, fats and other materials from the tissues to the circulatory system

Nerve Tissue

 Made of special cells called neurons  Controls and coordinates body activities by transmitting messages throughout the body  Nerves, brain and spinal cord are composed of nerve tissue.

Muscle Tissue

 Produces power and movement through contraction of muscle fibers  Three main kinds:  Skeletal: attaches to bones and provides movement  Cardiac: causes the heart to beat  Visceral: located in walls of the respiratory, digestive, urinary tract and blood vessels

Organs

 Two or more tissues join together for a specific function  Examples include: heart, stomach, lungs, and kidneys

Systems

 Organs and other parts that join together for a particular function  Includes: integumentary, skeletal, muscular, circulatory, lymphatic, nervous, respiratory, digestive, urinary or excretory, endocrine, and reproductive

Summary

 Protoplasm is basic substance of life  Protoplasm forms structural units called cells  Cells combine to form tissues  Tissues combine to form organs  Organs and other parts combine to form systems  Systems work together to create miracle of human body.