The Human Body An Orientation The Human Body
The Human Body: An Orientation
The Human Body: An Orientation Anatomy – the study of structure Physiology – the study of function
Levels of Structural Organization Smooth muscle cell Molecules 2 Cellular level Cells are made up of molecules Atoms Smooth muscle tissue 3 Tissue level Tissues consist of similar types of cells 1 Chemical level Atoms combine to form molecules Heart Cardiovascular system Epithelial tissue Smooth muscle tissue Connective tissue 4 Organ level Organs are made up of different types of tissues Blood vessel (organ) 6 Organismal level The human organism is made up of many organ systems 5 Organ system level Organ systems consist of different organs that work together closely
4 Types of Organic Molecules 1. Carbohydrates: • Sugars • Empirical formula: CH 2 O • Three forms: Monosaccharide, Disaccharide, Polysaccharide • Quick Energy in body • Glucose, Sucrose, Starch, Glycogen
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
Language of Anatomy Anatomical Position Body erect, feet slightly apart, palms facing forward, thumbs point away from body
Body Region Terms: • Axial - Makes up the main ‘axis’ of the body-head, neck and trunk • Appendicular - Appendages that are attached to the axis
Directional Terms: § Superior – toward the head § Inferior – away from the head
§ 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 • Pleural cavity - Encloses each lung • Pericardial cavity - Encloses heart
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. 2. 3. 4. Epithelial tissue: Covering tissue Connective tissue: Support tissue Muscle tissue: Movement tissue Nervous tissue: Control tissue
Epithelium 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
Functions of epithelial tissue 1. 2. 3. 4. 5. 6. Protection Absorption Filtration Excretion Sensory Reception
Special characteristics of epithelial tissue 1. Supported by connective tissues • Epithelial tissue rests upon connective tissue that forms a basement membrane
2. Avascular • Epithelial tissue has no blood vessels (only capillaries) • Epithelial tissues does have nerves 3. Regeneration • Epithelial tissue goes through mitosis quickly-this tissue is replaced quickly
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 1. Connective Tissue Proper – “loose connective tissues” a. Areolar Connective Tissue: • Supports and joins fibers of other tissues “universal packing material of tissues” • Holds body fluids
• 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: • Fat storage tissue • Adipocytes (fat cells) 90% of tissue mass, large, rounded, with large fat droplets, faint outlines • High amount of veins, arteries, metabolic activity, nutrient storage ability
• 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 systemcauses 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
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