Introduction to Human Anatomy and Cell biology

Dr. Obimbo MMMBChB, MSc. Dip Felasa C, PhD (c)

Anatomical Etymology

• Anatomy- Science of the structure of body

• Greek ‘anatome’- ana – up, tome – cutting

• Latin ‘dissecare’ – dis – asunder, secare – cut (dissection)

• Anatome = dissecare

• Study of Anatomy introduces students to greater terminology

Anatomy is to Physiology, as Geography is to History

Emphasis should be placed on the Anatomy of living body ◦ Surface Anatomy

◦ Radiological Anatomy

Major divisions of Anatomy◦ Gross

◦ Microscopic

◦ Embryology

◦ Neuroanatomy

• Anatomy may be studied systematically or regionally (topographical)

• Body systems

– Name??

• Body topography

– ??

Rules Guiding etymology• 1. Each structure shall be designated by one term

• 2. Every term in official list shall be in Latin

• 3. The term shall primarily be for memory signs

• 4. No usage of eponyms

Anatomical Position and Direction

• The body standing erect, facing forward, feet together, toes pointed slightly apart, hands at one’s side, palms facing forward.

• Once the body is in this position (or imagined to be in this position,) the positional terms can be used correctly.

Terms• Medial/ lateral – nearer/away median plane

• Anterior/posterior – near front/near the back

• Superior/inferior – nearer the head/toe

– (cf, cranial/caudal/rostral)

• Proximal/ distal – limbs

• Internal and external – nearer/away from center of an organ (cf, middle)

• Superficial/deep

• Supine/prone

• Ipsilateral/contralateral

Terms of body movement

FLEXION: reduces the angle of the joint from the anatomical position. Flex elbow

EXTENSION: movement that returns you to anatomical position. Extend elbow.

◦ All these terms refer to either a body part or a joint. HYPEREXTENSION: extension beyond anatomical

position; wrist, neck. Some terms relate only to certain areas, such as the

ankle: DORSIFLEXION: lift up toes PLANTARFLEXION: move toes down INVERSION: when sole of foot points inward EVERSION: sole of foot points outward. ABDUCTION: move body part away from midline;

arm, fingers, thumb ADDUCTION: bring back to midline; arms, fingers,

thumb

ROTATION: pivot on an axis; shake head “no”; can rotate head and shoulder

CIRCUMDUCTION: to draw a circle with body part; shoulder, head

PRONATION (to lie prone is on stomach). Turn hands downward.

SUPINATION: refers to arms; want a bowl of soup, supinate

PROTRACTION: to move anteriorily; shoulders, mandible

RETRACTION: to move part posteriorly; shoulders

ELEVATION: to raise part superiorly; shoulders

DEPRESSION: to lower part; open mouth.

Main areas to be studied• Osteology and arthrology

• Myology

• Angiology

• Neurology

• Splanchnology

• Surface marking/ anatomy

Cell Structure and Function

Chapter Outline

• Cell theory

• Properties common to all cells

• Cell size and shape – why are cells so small?

• Eukaryotic cells

– Organelles and structure in all eukaryotic cell

• Cell junctions

History of Cell Theory

• mid 1600s – Anton van Leeuwenhoek– Improved microscope, observed many living cells

• mid 1600s – Robert Hooke – Observed many cells including cork cells

• 1850 – Rudolf Virchow– Proposed that all cells come from existing cells

Cell Theory

1. All organisms consist of 1 or more cells.

2. Cell is the smallest unit of life.

3. All cells come from pre-existing cells.

Observing Cells

• Light microscope– Can observe living cells in true color

– Magnification of up to ~1000x

– Resolution ~ 0.2 microns – 0.5 microns

Observing Cells

• Electron Microscopes– Preparation needed to kill the cells

– Images are black and white – may be colorized

– Magnifcation up to ~100,000

• Transmission electron microscope (TEM)

– 2-D image

• Scanning electron microscope (SEM)

– 3-D image

SEM

TEM

Cell Structure

• All Cells have:

–an outermost plasma membrane

–genetic material in the form of DNA

–cytoplasm

Cell Structure

• All Cells have:

–an outermost plasma membrane

• Structure – phospholipid bilayer with embedded proteins

• Function – isolates cell contents, controls what gets in and out of the cell, receives signals

Cell Structure

• All Cells have:

–genetic material in the form of DNA

• Eukaryotes – DNA is within a membrane (nucleus)

• Prokaryotes – no membrane around the DNA (DNA region called nucleoid)

Cell Structure

• All Cells have:

–cytoplasm with organelles

• Cytoplasm – fluid area inside outer plasma membrane and outside DNA region

Eukaryotic Cells

• Structures in all eukaryotic cells– Nucleus

– Ribosomes

– Endomembrane System • Endoplasmic reticulum – smooth and rough

• Golgi apparatus

• Vesicles

– Mitochondria

– Cytoskeleton

CYTOSKELETON

MITOCHONDRION

CENTRIOLES

LYSOSOME

GOLGI BODY

SMOOTH ER

ROUGH ER

RIBOSOMES

NUCLEUS

PLASMA

MEMBRANE

Fig. 4-15b, p.59

Nucleus

• Function – isolates the cell’s genetic material, DNA

– DNA directs/controls the activities of the cell

• DNA determines which types of RNA are made

• The RNA leaves the nucleus and directs the synthesis of proteins in the cytoplasm

Nucleus

• Structure

–Nuclear envelope

• Two Phospholipid bilayers with protein lined pores

–Each pore is a ring of 8 proteins with an opening in the center of the ring

–Nucleoplasm – fluid of the nucleus

Nuclear pore bilayer facing cytoplasm Nuclear envelope

bilayer facing nucleoplasm

Fig. 4-17, p.61

Nucleus

• DNA is arranged in chromosomes

–Chromosome – fiber of DNA and the proteins attached to the DNA

–Chromatin – all of the cell’s DNA and the associated proteins

Nucleus

• Structure, continued

–Nucleolus

• Area of condensed DNA

• Where ribosomal subunits are made

– Subunits exit the nucleus via nuclear pores

Endomembrane System

• Series of organelles responsible for:

–Modifying protein chains into their final form

– Synthesizing of lipids

–Packaging of fully modified proteins and lipids into vesicles for export or use in the cell

Endomembrane System

• Endoplasmic Reticulum (ER)

–Continuous with the outer membrane of the nuclear envelope

– Two forms - smooth and rough

• Transport vesicles

• Golgi apparatus

Endoplasmic Reticulum

• Rough Endoplasmic Reticulum (RER)

• Network of flattened membrane sacs create a “maze”

• Ribosomes attached to the outside of the RER make it appear rough

Endoplasmic Reticulum

• Function RER

• Where proteins are modified and packaged in transport vesicles for transport to the Golgi body

Endomembrane System

• Smooth ER (SER)

– Tubular membrane structure

– Continuous with RER

– No ribosomes attached

• Function SER

– Synthesis of lipids (fatty acids, phospholipids, sterols..)

Endomembrane System

• Additional functions of the SER

– In muscle cells, the SER stores calcium ions and releases them during muscle contractions

– In liver cells, the SER detoxifies medications and alcohol

Golgi Apparatus

• Golgi Apparatus

– Stack of flattened membrane sacs

• Function Golgi apparatus

– Completes the processing substances received from the ER

– Sorts, tags and packages fully processed proteins and lipids in vesicles

Golgi Apparatus

– The proteins and lipids are modified as they pass through layers of the Golgi

– Molecular tags are added to the fully modified substances

• These tags allow the substances to be sorted and packaged appropriately.

• Tags also indicate where the substance is to be shipped.

Transport Vesicles

• Transport Vesicles

– Vesicle = small membrane bound sac

– Transport modified proteins and lipids from the ER to the Golgi apparatus (and from Golgi to final destination)

Endomembrane System

• Putting it all together

–DNA directs RNA synthesis RNA exits nucleus through a nuclear pore ribosome protein is made proteins with proper code enter RER proteins are modified in RER and lipids are made in SER vesicles containing the proteins and lipids bud off from the ER

Endomembrane System

• Putting it all together

ER vesicles merge with Golgi body proteins and lipids enter Golgi each is fully modified as it passes through layers of Golgi modified products are tagged, sorted and bud off in Golgi vesicles …

Endomembrane System

• Putting it all together

Golgi vesicles either merge with the plasma membrane and release their contents OR remain in the cell and serve a purpose

Vesicles

• Vesicles - small membrane bound sacs

– Examples

• Golgi and ER transport vesicles

• Peroxisome

– Where fatty acids are metabolized

– Where hydrogen peroxide is detoxified

• Lysosome

Lysosomes

• The lysosome is an example of an organelle made at the Golgi apparatus.

– Golgi packages digestive enzymes in a vesicle. The vesicle remains in the cell and:

• Digests unwanted or damaged cell parts

• Merges with food vacuoles and digest the contents

Mitochondria (4.15)

• Function – synthesis of ATP

– 3 major pathways involved in ATP production

1. Glycolysis

2. Krebs Cycle

3. Electron transport system (ETS)

Mitochondria

• Structure:

– ~1-5 microns

– Outer membrane

– Inner membrane - Highly folded

• Folds called cristae

– Intermembrane space (or outer compartment)

– Matrix

• DNA and ribosomes in matrix

Mitochondria

Cytoskeleton (4.16, 4.17)

• Function

– gives cells internal organization, shape, ability to move and polarity

• Structure

– Interconnected system of microtubules, microfilaments, and intermediate filaments

• All are proteins

Cytoskeleton

Cell Junctions

• Plasma membrane proteins connect neighboring cells - called cell junctions

– Plant cells – plasmodesmata provide channels between cells

Cell Junctions (4.18)

• 3 types of cell junctions in animal cells

1. Tight junctions

2. Anchoring junctions

3. Gap junctions

Cell Junctions

1. Tight junctions – membrane proteins seal neighboring cells so that water soluble substances cannot cross between them

• Seen between stomach cells

Cell Junctions

2. Anchoring junctions – cytoskeleton fibers join cells in tissues that need to stretch

• See between heart, skin, and muscle cells

3. Gap junctions – membrane proteins on neighboring cells link to form channels

• This links the cytoplasm of adjoining cells

Gap junction

Anchoring

junction

Tight junction

Cell specializationSpecialized cell Function Modification

Muscle cell Contraction Myofilaments

Pancreatic acinar cell Synthesis and secretion of

enzymes

RER

Kidney tubular cells Ion transport Basal membrane infoldings

Macrophages Intracellular digestion Lysosomes

Sensory cells Transformation of stimuli

into nerve impulses

Membrane receptors

Leydig Testicular cells Synthesis and secretion of

testosterone

SER

Tissues

• Tissues are collection of cells that subserve specific function

• Four fundamental types:

– Epithelial

– Supporting

– Propulsion

– Nervous

– Composed of cells, intercellular matrix and tissue fluid

Scope of microscopic Anatomy

• Cytology

• Histology

• Organology

The end....

• “ No man should marry until he has studied anatomy and dissected at least one woman”

Honore de Balzac

Thank you!!