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Introduction to Basic Human Anatomy Course ANAT 1010 Akram Jaffar, Ph.D. 1

Anatomy • Anatomy (ana-=up; -tomy=cutting): the study of structure and the relationships among structures. –Anatomy was first studied by dissection (dis-=apart; - section=cutting), the cutting apart of body structures to study their relationships.

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Levels of Structural Organization

• The human body consists of several interrelated levels of structural organization ranging from the least complex chemical level to the most complex organismal level: –Chemical –Cellular –Tissue –Organ –System –Organismic 3

Levels of Structural Organization – Chemical Level

• Atoms are organized into molecules that are essential for maintaining life: –Atoms include carbon, hydrogen, nitrogen, oxygen, phosphorous, and calcium.

• Organic compounds usually contain carbon and hydrogen and form complex macromolecules, i.e. proteins, carbohydrates, lipids, and nucleic acids.

• Inorganic compounds are less complex than organic compounds. 4

Levels of Structural Organization – Cellular Level

• Groups of molecules combine to form cells. • Cells are the basic structural and functional unit of an organism. 5

Levels of Structural Organization – Tissue Level

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Levels of Structural Organization – Organ Level

• Several tissues form organs, which are structures that have specific functions: –Stomach as an organ has:

• Epithelial tissue: in lining mucosa. • Muscular tissue: for food churning. • Nervous tissue: to innervate the muscles. • Connective tissue: to bind the other tissues together. 7

Levels of Structural Organization

• System level: –Collection of related organs with a common function. – In this course, you will study the following body systems: 8

Basic Anatomical Terminology

• Clinical and anatomical terminology is mainly based on a Greek or Latin root words. –Anatomical position. –Regions of the body. –Anatomical planes, sections, and directional terms. 9

Anatomical Position

• Standardized position from which to describe directional terms –standing upright –facing the observer –eyes facing forward –feet flat on the floor –arms at the sides –palms turned forward (supinated) •

• Prone position = lying face down • Supine position = lying face up 10

Common and Anatomical Regional Terms

• Names given to specific regions in the body: –The leg is not the entire lower limb; it is the region between knee and ankle.

–The arm is not the entire upper limb; it is the region between elbow and shoulder. 11

Major Directional Terms

• Arranged in pairs of opposites. • Describe the relationship of parts of the body in the anatomical position and compare the position of two structures relative to each other. 12

Proximal and Distal

• Proximal –nearer to the attachment of the limb to the trunk:

• The knee is proximal to the ankle. • Distal –farther from the attachment of the limb to the trunk:

• The elbow is distal to the shoulder. 13

Planes and Sections

• A plane is an imaginary flat surface that passes through the body for study. • A section is one of the two surfaces (pieces) that results when the body is cut by a plane passing through it. 14

Sagittal Plane

• Sagittal plane: –divides the body or an organ into left and right sides.

• Midsagittal plane: –produces equal halves.

• Parasagittal plane: –produces unequal halves. 15

Other Planes and Sections • Frontal (coronal) plane: –divides the body or an organ into front (anterior) and back

(posterior) portions.

• Transverse (cross-sectional) (horizontal) plane: –divides the body or an organ into upper (superior) and lower (inferior) portions. 16

Sagittal and Coronal Planes - Origin of Terms

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Dorsal and Ventral

• Dorsal (posterior) –At the back of the body. • e.g. the brain is posterior to the forehead.

• Ventral (anterior) –At the front of the body.

• e.g. the sternum is anterior to the heart. 18

Dorsal Body Cavity

• Near dorsal surface of body • Has two subdivisions: –cranial cavity

• holds the brain • formed by the skull –vertebral (spinal) canal • contains the spinal cord

• formed by the vertebral column 19

Ventral Body Cavity

• Near ventral surface of body • Has two subdivisions: –thoracic cavity: superior to the diaphragm. –abdominopelvic cavity: inferior to the diaphragm.

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Thoracic Cavity

• Contains two other cavities: –Pericardial cavity: encloses the heart. –Pleural cavities: enclose the lungs. 21

Abdominal Quadrants and Regions

• Used to describe locations of organs or source of pain. • A simple way to divide the abdominal cavity is into four quadrants. • A more detailed way is to divide it into nine regions.

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The Cellular Level of Organization

Part One

Akram Jaffar, Ph.D.

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Cytology

• The study of cellular structure and function. 3

The Cell

• Basic, living, structural, and functional unit of the body. –compartmentalization of chemical reactions within specialized structures. –regulate inflow and outflow of materials. –use genetic material to direct cell activities. 4

Main Cell Structures

• Cell consists of three main parts: –Plasma membrane (cell membrane): flexible but sturdy membrane that surrounds cytoplasm. –Nucleus: contains most of the genetic material of cell. –Cytoplasm: everything between the membrane and the nucleus:

• Cytosol: intracellular fluid. • Organelles: subcellular structures with specific functions. 5

The Plasma Membrane

• Is a flexible yet sturdy barrier that surrounds and contains the cytoplasm. • Has a common overall structure consisting of: –Lipids –Proteins –Carbohydrates

• Its structure is described using the fluid mosaic model. 6

Fluid Mosaic Model

• Sea of lipids in which proteins may float like icebergs or anchored at specific locations like islands.

• Lipids form a barrier to entry or exit of polar substances. • Proteins are “gatekeepers”: regulate traffic. • Carbohydrates provide attachment points and protection.

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Functions of the Plasma Membrane

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Lipids of the Cell Membrane

• Phospholipids –Contain phosphorus. –Comprise most of the lipids. –Phospholipid bilayer:

• The basic framework of the cell membrane. • Two parallel layers of molecules. • Glycolipids • Cholesterol 9

Lipids of the Cell Membrane

• Glycolipids: –Carbohydrate groups attach to the phospholipid heads on the side of the membrane facing the extracellular fluid. –Forms part of the glycocalyx.

• Cholesterol: –Interspersed among the other lipids in both layers. –Important for strengthening the cell membrane and making it flexible. 10

Types of Membrane Proteins

• Integral proteins –Firmly embedded in the membrane. –Extend into or completely through the cell membrane (transmembrane protein). –form a channel for transport of substances.

• Peripheral proteins • Glycoproteins 11

Types of Membrane Proteins

• Integral proteins • Peripheral proteins: –Related to either inner or outer surface of cell membrane. –Not firmly attached.

• Glycoproteins: –Proteins with attached sugars.

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–Sugar portion faces the extracellular fluid to form part of the glycocalyx. 12

Glycocalyx

• Functions –Cell recognition: acts like a molecular signature. –Creates a stickiness that enables cells to adhere to one another. –Protects cells from being digested by enzymes. 13

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Functions of Membrane Proteins

• Formation of channels (pores) –passageway to allow specific substance to pass through (especially non-lipid soluble substances). •

• Transporter (carrier) proteins –bind a specific substance, change their shape and move the substance across membrane.

• Receptor proteins –cellular recognition site: bind to a ligand and alter cell function in some way.

• Ligand: specific molecule that binds to a receptor. 15

Functions of Membrane Proteins

• Act as enzyme –speed up chemical reactions. –

• Linkers –anchor proteins in cell membrane of other cells or protein filaments inside and outside the cell.

• cell shape and stability. •

• Cell Identity Marker (glycoproteins)

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–allow cell to recognize other similar cells. 16

Selective Permeability of the Cell Membrane

• Lipid bilayer: –permeable to molecules such as oxygen, carbon dioxide, water, and steroids. –impermeable to ions and large molecules such as glucose. 17

Selective Permeability of the Cell Membrane

• Transmembrane proteins that act as channels: –Selectively permeable to small- and medium-sized charged substances (including ions) that cannot cross the lipid bilayer without help. • Macromolecules, such as proteins, cannot pass through the plasma membrane except by the processes of endocytosis and exocytosis. 18

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Transport Across the Plasma Membrane

• Plasma membranes regulate fluid movement from intracellular to extracellular compartments. 20

Transport Across the Plasma Membrane Substances cross membranes by a variety of processes: A.Passive Transport –moves substances down their concentration gradient with only their kinetic energy. B.Active Transport –uses ATP to drive substances against their concentration gradients.

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Diffusion

• Random mixing of particles in a solution as a result of the particle’s kinetic energy –more molecules move away from an area of high concentration to an area of low concentration. • When the molecules are evenly distributed, equilibrium has been

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reached. • Important for absorption of nutrients, excretion of wastes, exchange of gases within the lungs.

• Nonpolar, hydrophobic molecules: –oxygen, carbon dioxide, nitrogen, fatty acids, steroids, small alcohols, ammonia and fatsoluble vitamins (A, E, D and K) • 22

Osmosis

• Net movement of water through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration –Diffusion through lipid bilayer. –Diffusion through integral proteins (pores) called aquaporins. 23

Filtration

• A process in which substances move across a plasma membrane down a pressure gradient

• Not to be confused with diffusion (concentration gradient) 24

Facilitated Diffusion • Substance binds to specific transporter protein.

• Transporter protein moves substance across cell membrane –Too large to fit into the protein pores. –Insoluble in lipids.

• Facilitated diffusion occurs down concentration gradient only. • If no concentration difference exists, no net movement across membrane occurs 25

Active Transport

• Movement of substances against their concentration gradient mainly through a transporter protein.

• Energy-requiring process. –energy from hydrolysis of ATP. • Na+, K+, H+, Ca+2, I- and Cl-, amino acids, and monosaccharides

• Vital for conducting a nerve impulse: –High concentration of intracellular K +. –High concentration of extracellular Na+.

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Vesicular Transport of Particles

• Vesicle: small, spherical, membranous sac formed by budding off from a cell membrane.

• Active process that requires energy. –Endocytosis: materials move into a cell in a vesicle:

• Receptor-mediated endocytosis • Phagocytosis • Pinocytosis • Transcytosis –Exocytosis 27

Receptor-Mediated Endocytosis

• Selective input. • Substance (ligand) binds to receptor on cell membrane before being ingested (e.g. low density lipoproteins (LDL) and hormones).

• Desired substance binds to receptor protein in clathrin-coated pit region of cell membrane causing membrane to fold inward and form a vesicle.

• Clathrin and the receptors are recycled. • Ligands are digested by lysosomal enzymes. 28

Phagocytosis

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Pinocytosis

• • • •

Cell drinking. No pseudopods form. No receptor proteins are involved.

Nonselective drinking of extracellular fluid with all solutes dissolved in (also called bulk-phase endocytosis). • Plasma membrane folds inwards  vesicle  detach into cytoplasm  lysosome fuses  enzymes degrade solutes. 30

Transcytosis

• Transport in vesicles to successively move a substance into (endocytosis), across, and out of a cell (exocytosis). –Materials to move between blood plasma and interstitial fluid. 31

Exocytosis

• Materials move out of a cell in a vesicle.

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• Vesicles form inside cell, fuse to cell membrane to release their contents: –digestive enzymes, hormones, neurotransmitters or waste products. 32

The End

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The Cellular Level of Organization

Part Two

Akram Jaffar, Ph.D. 2

Cytoplasm

• Can be divided into –Cytosol:

• Intracellular fluid. • Inclusion bodies. –Cytoplasmic organelles. 3

Cytosol

• Intracellular fluid • 55% of cell volume • Jelly-like substance composed of 75-90% water with dissolved components: –Large organic molecules (proteins, carbohydrates, and lipids). –Small organic molecules (simple sugars) –Ions.

• Site of many important chemical reactions: –Production of ATP. –Synthesis of building blocks. 4

Cytoplasmic Inclusions

• Aggregates of non-living organic molecules in the cytosol.

• Diverse in composition, shape, and longevity.

• Examples include granules of melanin (in skin), glycogen (in liver), and lipid droplets (in fat cells). 5

Cell Organelles

• Specialized structures within a cell that have characteristic shapes and perform specific functions.

• Some are membranous: surrounded by lipid bilayer membrane that helps to separate functions: –One layer: e.g. vesicles –Two layers: e.g. mitochondria

• Some are non-membranous and are in direct contact with the

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cytoplasm: e.g. cytoskeleton. 6

Nucleus

• Most cells have a single nucleus. • Some cells are anucleate (RBC’s). •

• Some cells are multi-nucleate (skeletal muscle). •

• Large organelle with double membrane (nuclear envelope): –outer membrane is continuous with the rough endoplasmic reticulum (ER). –perforated by nuclear pores.

• Function of nuclear membrane: –Control movement of substances between nucleus and cytoplasm:

• Passive diffusion of small molecules and ions. • Active transport of large proteins and ribosomes. 7

Chromosomes

• There are 46 chromosomes in human somatic cells. • Each chromosome is a long coiled molecule of chromatin formed by: –DNA (in the form of double helix) –Proteins –some RNA • Genes (about 30K in humans) are arranged along chromosomes.

• Genome: the total genetic information carried in a cell. • Function of genes: –Control cellular structure and cellular activity by giving directions for the synthesis of a specific protein. –Hereditary units that replicate during cell division. 8

Nucleolus

• Spherical, dark bodies (one or more) within the nucleus. • Has no membrane. • Function: site of ribosome production. 9

Ribosomes

• Packages of ribosomal RNA (rRNA) and proteins. • Assembled in the nucleolus.

• Function: –Sites of protein synthesis where mRNA from the nucleus is translated into a chain of amino acids (protein). • Types: –Free ribosomes are loose in cytosol:

• synthesize proteins found inside the cell. –Membrane-bound ribosomes: • attached to endoplasmic reticulum or nuclear membrane. • synthesize proteins needed for plasma membrane or for export. 10

Protein Synthesis

• Instructions for making specific proteins are found in the DNA (genes), involves: • Transcription –transcribe DNA information onto a messenger RNA molecule (mRNA).

• Translation –translate the “message” into a sequence of amino acids in order to build a protein molecule on a ribosome. –transfer RNA (tRNA) carries amino acids to ribosomal RNA (rRNA) for protein synthesis. 11

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Endoplasmic Reticulum

• Network (reticulum) of membranes forming flattened sacs or tubules. • Rough ER: –Continuous with nuclear envelope. –Covered with attached ribosomes. –Function: • Protein synthesis.

• Processing (e.g. folding and beginning of glycosylation). 13

Endoplasmic Reticulum

• Smooth ER:

–Continuous with the rough ER. –No attached ribosomes = no protein synthesis. –Function:

• Synthesizes fatty acids and steroids. • Detoxifies harmful substances (e.g. alcohol). • Calcium ion storage in muscle cells; its release initiates muscle contraction. 14

Golgi Complex

• • • •

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Flattened, curved membranous sacs called cisterns. Convex side faces rough ER and concave side faces cell membrane. Contains enzymes. Function: –Receives transport vesicles from rough ER. –Processes proteins  glycoproteins and lipoproteins. –Sorts and packages proteins into vesicles for export, lysosomes, and membrane proteins.

Packaging by Golgi Complex

• Proteins pass from rough ER to Golgi complex in transport vesicles. • Processed proteins pass from entry cistern to medial cistern to exit cistern in transfer vesicle.

• Finished proteins exit Golgi as vesicles: –Secretory: exocytosis. –Membrane: replace lost parts. –Transport: to other organelles e.g. lysosomes. • 16

Lysosomes

• • • •

Membranous vesicles. formed in Golgi complex. Filled with digestive enzymes. Functions: –Digest large molecules and microbes. –Recycles own worn-out organelles (autophagy). –Digestion of the entire cell (autolysis) e.g. after death. –Extracellular digestion e.g. during fertilization.

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Peroxisomes

• Membranous vesicles. • Resemble but smaller than lysosomes. • Function: –Contain enzymes (oxidases) involved in metabolic breakdown of fatty acids  H2O2 as a cytotoxic by-product:

• Used in liver to detoxify toxic...