01 Lecture 01 c&t Colour

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BIOSCI 107Cellular Processes and Development1. Cells and Tissues

Dr Clive Evans

Objectives

At the end of this lecture youshould be able to:

•Name and describe the six

Organisation of the Human Body

levels of structural organisationof the human body withexamples

•Name the eleven systems of the human body and havean understanding of their components and functions

•Name the four basic tissue types and understand their originsfrom the three germ layers .

Dr. Tulp’s Anatomy Lesson(Rembrandt, 1632)

Six levels of structuralorganisation are

relevant to

The Structural Organisation of the Human Body

un ers an ng eform ( anatomy )and function(physiology ) of thehuman body.



Structural Level Description Examples

Chemical The building blocks of the body Atoms and molecules

Cellular Basic structural and functionalunits of the body

Smooth muscle cells

Tissue Tissues are groups of cells thatwork together to perform a

articular function

Muscle tissue

Six Levels of Structural Organization

Organ Organs are structures withspecific functions composed of two or more types of tissue

Stomach

System A system consists of relatedorgans with a common function.

Digestive system

Organismal All the parts of the body functiontogether to constitute a livingorganism.

The individual

The Eleven Body Systems

The human body is organised into eleven systems composed of related organs with a common function.

•Integumentary

•Muscular

•Skeletal

•Cardiovascular

•Respiratory

•Digestive

Some organs may belong to more than onesystem.The pancreas , for example, belongs to thedigestive and endocrine systems .

•Nervous

•Endocrine

•Lymphatic and Immune

•Urinary

•Reproductive

www.massgeneral.org

The Integumentary System

Major Components Principal Functions

Skin and its derivativesincluding hair, nails, and sweatand oil glands

Protective; detects sensations;vitamin D synthesis (UVBactivates a precursor tocalcitriol); thermoregulation

Calcitriol (1,25 dihydroxycholecalciferol)the main biologically active form of

vitamin D



The Muscular System


Skeletal or striated muscle(usually attached to bones).Cardiac and smooth muscle areconsidered in different systems.

Movement; posture; heat.

www.eorthopod.com

The Skeletal System

Megakaryocyte

Haematopoietic cells

Trabecular bone

Support and protection;

red bone marrow producesblood cells, yellow marrowstores lipids; stores minerals

Bones and joints; cartilage

Principal FunctionsMajor Components

Red bone marrow

http://www.bu.edu/histology/p/02006ooa.htm

The Nervous System

Detects stimuli and producesnerve impulses to regulate bodyactivities (sensory, integrativeand motor functions)

Brain, spinal cord, nerves;special sense organs e.g. eyeand ear


The nerve impulse ( http://www.freewebs.com )



The Endocrine System

Hormone producing cells andglands


Releases hormones to regulatebody activities (e.g. insulin,which decreases blood glucose)

The Lymphatic and Immune System

Defence; transport of lipids,proteins, lymphoid cells andfluid.

Lymphatic fluid and vessels;lymphatic organs e.g. spleen,thymus; tonsils, lymph nodes


The Cardiovascular System

Major Components Principal Funct ions

Blood, heart and bloodvessels

Transport of oxygen, carbon dioxide,nutrients and waste; regulation of water content, temperature and acid-base balance; defence.

Vein and artery in goat forestomach



The Respiratory System


Lungs and airways e.g.pharynx, larynx; trachea,bronchi

Transfer of oxygen and carbondioxide between blood and air;vocalization; acid-base regulation

The Digestive System


Organs of the gastrointestinaltract (mouth to anus); accessoryorgans (e.g. salivary glands,liver, gall bladder, pancreas)

Digestion and absorption of nutrients;elimination of solid waste

The Urinary System


Kidneys, urinary bladder andtheir ducts (ureters, urethra).

Urine production, storage andelimination; regulation of bloodvolume; assists in production of blood cells; acid-base balance.

Erythropoietin



The Reproductive System


Gonads (testes and ovaries) andassociated organs.The mammary gland (a modifiedsweat gland) is also part of theintegumentary system.

Production, transport andstorage of gametes (sperm oroocytes); hormones regulatea number of body processes

The Tissue Level of Organisation

The cells of the body seldom function as isolated units. Theyusually work together in groups called tissues .

A tissue is a group of similar cells (usually of a commonembryonic origin) that functions together to carry outspecialised activities.

The microscopic study of the tissues of the body is known ashistology .

The body is composed of four basic tissue types .

Tissue Description Major Functions

Epithelial Covers body surfaces, lineshollow organs, cavities andducts; forms glands

Protection; filtration;secretion; absorption;excretion

onnec ve e s n a ma r x o resand ground substance

ro ec s an suppor s;binds organs together;stores energy; transport

Muscle Contractile cells (musclefibres)

Movement

Nervous Nerve cells and supportiveneuroglia

Detects changes andgenerates nerve impulses



Germ Layer Tissue Example

Ectoderm Epithel ia l; nervous Brain, spinal cord andnerves; epithelium of skin

All four tissues of the body develop from three germ layers(ectoderm, mesoderm and endoderm).

Mesoderm Epithelial; connective;most muscle

Bone; blood

Endoderm Epithelial Lining of gastrointestinal tract(except oral cavityand anal canal) andepithelium of itsassociated glands

Origin of the Germ Layers

The formation of the germ layers is bestseen in the development of the fertilizedegg of a model organism such as theclaw-toed frog Xenopus laevis .

e e r ze egg un ergoes c eavage m o c ce v s on oyield a solid ball of 64 cells known as the morula .

A fluid filled cavity (the blastocoel ) develops, and the hollow ballof cells is now known as a blastula .

The germ layers form when the hollow blastula transforms intoa three-layered gastrula (gastrulation ).

Cells from the surface of the egg (including a deeper marginalzone ) move inwards through an opening (the blastopore ), whichforms in the embryo.



As the cells move inwards ( involution ),they occlude the blastocoel and establishanother cavity known as the archenteron(the primitive gut ), the opening of which isclosed by a yolk plug .

The cells that move inwards are replacedby other cells which spread out on thesurface ( epiboly ).

encompass the yolk, but it marks thefuture location of the anus. In thedeuterostomes (animals includingvertebrates and echinoderms) the anusforms first and the mouth second. It is theother way round in the protostomes ,which include animals such as themolluscs and annelids.

The result of gastrulation is a three-layered structure around a cavity(the archenteron or primitive gut ).

The outermost layer (which does notinvolute) forms the ectoderm .

The innermost layer of cells, whichlines the cavity, forms the endoderm .

The middle layer, derived frommarginal zone cells, forms themesoderm .

All of the tissues of the body develop from these three germ layers.

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