The Human Body: An Orientation

Anatomy – the study of structure Physiology – the study of function

Chemical level Atoms combine to form molecules Cellular level Cells are made up of molecules Tissue level Tissues consist of similar types of cells 5 Organ system level Organ systems consist of different organs that work together closely Organ level Organs are made up of different types of tissues 6 Organismal level The human organism is made up of many organ systems Atoms Molecules Smooth muscle cell Smooth muscle tissue Connective tissue Smooth muscle tissue Epithelial tissue Blood vessel (organ) Heart Blood vessels Cardiovascular system Levels of Structural Organization

1. Carbohydrates: Sugars Empirical formula: CH 2 O Three forms: Monosaccharide, Disaccharide, Polysaccharide Quick Energy in body Glucose, Sucrose, Starch, Glycogen 4 Types of Organic Molecules

2. Lipids: Monomers - fatty acids and glycerol Hydrophobic Make waterproof coverings (part of cell membrane)

3. Proteins: Monomers - amino acids (20 naturally occurring) Bonded by peptide bonds Includes enzymes (lock and key model)

4. Nucleic Acids: Monomers-Nucleotides DNA and RNA Genetic Expression and protein synthesis

Life Functions of Humans Maintaining boundaries: Keeping internal and external environments separate Cells use the cell membrane Humans use integumentary system Movement: Moving muscles, bones, blood, urine…etc Responsiveness: Also called irritability Sensing stimuli and responding to them

Digestion: Breaking down polymers to use as energy Hydrolysis Metabolism: All chemical reactions that happen in the body Excretion: Moving wastes out of body Includes digestive system and respiratory system

Reproduction: Making a new organism or new cells (mitosis/meiosis) Growth: Increase in body size

Homeostasis Maintaining a constant internal environment Every cell, tissue and organ in the human body contributes toward total body homeostasis

Ex: Blood cells carry wastes from various tissues toward kidneys which filters blood and then sends waste materials toward excretory system

Homeostatic Control Mechanisms Control mechanisms are the way that the body maintains homeostasis Variable: The event that is being regulated Receptor: A sensor that monitors the environment Stimuli: Changes in environment

Control Centers: Analyze the stimuli and determines the course of action Effector: Provides the control center’s response to the stimuli (also called output)

Feedback Systems Negative feedback: Output turns off or reduces stimulus Variables are changed opposite to stimulus

Ex: Body is cold, you begin to shiver to raise body temperature Ex: Your body needs oxygen, your respiration rate increases to meet this O 2 need

Positive Feedback: Response to stimulus enhances so the output is raised Usually control infrequent events Ex: Labor contractions and blood clotting

Homeostatic Imbalance: Negative feedback is overwhelmed and harmful positive feedback takes over. Ex: If heart muscles fail to contract and negative feedback can not control the muscles, positive feedback takes over and heart failure can occur

Anatomical Position Body erect, feet slightly apart, palms facing forward, thumbs point away from body Language of Anatomy

Body Region Terms: Axial - Makes up the main ‘axis’ of the body-head, neck and trunk Appendicular - Appendages that are attached to the axis

 Superior – toward the head  Inferior – away from the head Directional Terms:

 Anterior – toward the front of the body  Posterior – back of the body

 Medial – toward the midline  Lateral – away from the midline

 Proximal – closer to the origin of the body  Distal – farther from the origin of the body

 Superficial – toward or at the body surface  deep – away from the body surface; more internal

Human Body Planes: Sectioned along a flat surface into the following divisions: Sagittal: Vertical plane, divided into left and right sides

Frontal Plane: Vertical plane that divides body into anterior and posterior sections. Transverse or horizontal plane: Divides body into superior and inferior parts. Also called cross section

Body Cavities 1. Dorsal Body Cavity - Protects nervous system organs Includes cranial cavity that encases brain

2.Ventral Body Cavity - Largest body cavity, holds the internal organs Thoracic Cavity - Superior portion of cavity Pericardial cavity - Encloses heart Pleural cavity - Encloses each lung

Abdominopelvic Cavity - Inferior portion of cavity separated from thoracic cavity by diaphragm Abdominal cavity: stomach, intestines, spleen, liver…etc Pelvic cavity: bladder, reproductive organs, rectum

Four Types of Tissues 1.Epithelial tissue: Covering tissue 2.Connective tissue: Support tissue 3.Muscle tissue: Movement tissue 4.Nervous tissue: Control tissue

Covers body surface or lines body cavities Outer layer of skin, open cavities, cardiovascular system (veins/arteries), digestive system, respiratory system, covers walls of organs, forms glands Epithelium

Functions of epithelial tissue 1.Protection 2.Absorption 3.Filtration 4.Excretion 5.Secretion 6.Sensory Reception

Special characteristics of epithelial tissue 1. Supported by connective tissues Epithelial tissue rests upon connective tissue that forms a basement membrane

3. Regeneration Epithelial tissue goes through mitosis quickly-this tissue is replaced quickly 2. Avascular Epithelial tissue has no blood vessels (only capillaries) Epithelial tissues does have nerves

How do we differentiate epithelial tissue? 1. Layers Simple: Thin layer usually used for absorption Stratified: Thick layer of 2 or more cells used for protection (skin)

2. Shape of cells: All polyhedral shape, allows for close connection of cells Cell nuclei conform to shape 3 shapes 1. Squamous cells - flat and scale like

2. Cuboidal cells - box-like or blunt pyramids 3. Columnar cells - tall and column shaped

Simple Squamous Epithelium: Cells flattened laterally, not much cytoplasm Found where filtration and the exchange of substances by diffusion is needed Kidneys and lungs

Simple Cuboidal Epithelium Secretion and absorption cells Walls of small ducts of glands Kidney tubules Looks like strings of beads when viewed microscopically

Simple Columnar Epithelium Layers of tall cells with closely packed membranes Lines digestive tract from the stomach to the rectum Absorption and secretion cells

Modifications of columnar: Microvilli: Projections that increase absorption Goblet cells: Secrete protective mucus

Pseudostratified Columnar Epithelium Layers of different height cells that rest on a basement membrane (appears layered) Secretes or absorbs Ciliated version are goblet cells that line the respiratory tract

Stratified Epithelial Tissue Stratified Squamous Tissue: Most widespread type (areas of wear and tear) Skin Stratified Cuboidal Tissue: Rare in body, usually found in glands (mammary and sweat) Stratified Columnar Tissue: Pharynx, male urethra

Connective Tissue Found everywhere, most abundant of primary tissues Skin is mostly connective tissue 4 classes of connective tissue 1. Connective tissue proper 2. Cartilage 3. Bone Tissue 4. Blood

3 elements make up connective tissue 1. Ground Substance Material that fills in space between cells, also called matrix 2. Fibers Provide support Collagen Fibers: Very strong, high tensile strength, also called white fibers Elastic Fibers: Stretchy fibers made of elastin, found in lungs, blood vessels, also called yellow fibers

Reticular Fibers: Fine network of collagen found around capillaries

3. Cells: Blast = forming (baby or developing cells) Cyte = cell (adult cells) Fibroblast/Fibrocyte: Cells in connective tissue proper Chondroblast/Chondrocyte: Cartilage cells Osteoblast/Osteocyte: Bone cells Hematopoietic Stem Cells: Blood developing cells

Types of Connective Tissue a. Areolar Connective Tissue: Supports and joins fibers of other tissues “universal packing material of tissues” Holds body fluids 1. Connective Tissue Proper – “loose connective tissues”

Defends against infection- when an area is inflamed, this tissue soaks up extra body fluids-called edema Stores nutrients in fat Most widespread connective tissue

b. Adipose Tissue: High amount of veins, arteries, metabolic activity, nutrient storage ability Fat storage tissue Adipocytes (fat cells) 90% of tissue mass, large, rounded, with large fat droplets, faint outlines

Acts as a shock absorber, insulator and energy storage site 18% of an average person’s body weight is this type of tissue Can be deposited around organs such as the heart, lymph nodes and various muscles

c. White Fibrous Connective Tissue - “Dense Regular Connective Tissue” Tendons and ligaments Matrix of regular arranged collagenous fibers

2. Cartilage: Resists tension and compression Tough, flexible tissue Avascular, no nerve fibers Receives nutrients from blood vessels located in the connective tissues that surround it

Ground substance is collagen Chondroblasts in growing cartilage until maturity-becomes chondrocyte

Types of Cartilage 1. Hyaline “gristle” Most abundant cartilage in body Matrix appears bluish-white Trachea, lungs, nose, rib attachment to sternum, growth plate (epiphyseal plate), embryonic skeleton

2. Elastic Elastin fibers External ear, epiglottis

3. Fibrocartilage Compressible, resists tension Support and pressure Intervertebral discs, cartilage of knee

3. Bone Tissue Support and protect body Provide cavities for fat storage and the synthesis of blood cells Matrix includes calcium salts Cells: Osteoblasts (develop bones) Osteocytes (mature bones)

4. Blood Tissue Consists of red blood cells, white blood cells, lymphocytes, monocytes, eosinophils, basophiles Is considered connective tissue, but it doesn’t “connect” anything

Muscle Tissue Responsible for body movement Three types: skeletal muscle, cardiac muscle, smooth muscle

Nervous Tissue Main component of nervous system (brain, spinal cord, nerves) Cells: Neurons

Tissue Repair Process: 1. Inflammation Tissue trauma causes inflammation chemicals to be released Is a negative feedback system- causes capillaries to dilate to accommodate WBC’s and clotting factors Clot forms, the part of the clot that is exposed to air becomes a scab

2. Organization Clot is replaced by granulation tissue which becomes scar tissue 3. Regeneration and fibrosis Regeneration: New tissue (same type) takes the place of the damaged tissue

Fibrosis: Fibrosis connective tissue (scar tissue) takes the place of the damaged tissue

Tissue Development Tissues develop from three germ layers 1.Ectoderm 2.Mesoderm 3.Endoderm

By second month of development, all tissues have appeared and all organs are formed

Tissue cells (except neural cells) remain mitotic until adulthood is reached As adults only blood and skin cells are highly mitotic Skin cells can go through mitosis once a day