The human body is organized at multiple levels: 1) Cells are the basic unit and come together to form tissues like muscle and bone. 2) Tissues combine to create organs like the heart and lungs. 3) Organs work together in organ systems that carry out vital functions like nutrition, interaction, and reproduction. 4) Organ systems are coordinated by the nervous and endocrine systems to keep the body functioning as a whole.

1. 3º ESO
The organization of the
human body

2. Organisation of living matter

3. Organisation of living matter
Human beings are living things:
• Composed of biomolecules (proteins, lipids and carbohydrates)
• Made of cells (60 trillions cell). So they are multicellular organisms
• Eukaryote cells: these have organelles and DNA enveloped
by a cover
• They perform the three vital functions:
• Nutrition: they feed on other living things (heterotrophic)
• Interaction
• Reproduction

4. Levels of organisation of the human being
especializadas
de varios tipos
Mismo tipo de tejido Distinto tipo de tejido

5. Cell Types
• Prokaryotic
• Eukaryotic

6. Characteristics of All Cells
• A surrounding membrane
• Cytoplasm– cell contents in thick fluid
• Control center with DNA (Nucleus)

7. Representative Animal Cell

8. Cytoplasm
• Viscous fluid containing organelles
• components of cytoplasm
– Interconnected filaments & fibers
– Fluid = cytosol
– Organelles (not nucleus)
– storage substances

9. Nucleus
• Control center of cell
• Double membrane
• Contains
– Chromosomes
– Nucleolus

10. Nuclear Envelope
• Separates nucleus from rest of cell
• Double membrane
• Has pores

11. Nucleolus
• Most cells have 2 or more
• Directs synthesis of RNA
• Forms ribosomes

12. Rough Endoplasmic Reticulum
• Ribosomes attached to surface
– Manufacture protiens
– Not all ribosomes attached to rough ER
• May modify proteins from ribosomes

13. Smooth Endoplasmic Reticulum
• No attached ribosomes
• Has enzymes that help build molecules
– Carbohydrates
– Lipids

14. Golgi Apparatus
• Packaging & shipping station of cell

16. Lysosomes
• Contain digestive enzymes
• Functions
– Aid in cell renewal
– Break down old cell parts
– Digests invaders

17. Vacuoles
• Membrane bound storage sacs
• More common in plants than animals
• Contents
– Water
– Food
– wastes

18. Mitochondria
• Break down fuel molecules (cellular respiration)
– Glucose
– Fatty acids
• Release energy
– ATP

19. Cytoskeleton
• Made of proteins
• Supports cell shape and function
• Keep organelles organized

20. Centrosome
• Near the nucleus.
• Formed by two tubular structures: centrioles
(made of proteins)
• Coordinate cytoesqueleton movement and
cell division

21. Exchange with the environment
• Cells have to exchange substances to live through its
semipermeable membrane:
– Diffusion: movement of small molecules from greater
to lower concentration.
– Osmosis: passage of water from the more diluted to
the more concentrated medium
– Active transport: movement of substances from
lower to greater concentration
– Endocytosis: cell sometimes incorporates large
particles by membrane collapsing . The opposite
process is called exocytosis.

22. Cellular differentiation
• After fertilization , egg cell begin to divide on identical cells (stem cells) till
gastrulation stage on 3rd week
Specialised cells (muscle ones for instance):
• Makes a particular job. Muscle cells contract and relax to produce movement
• Develop a characteristic shape. Muscle cells are usually very long .
• There are changes in their cytoplasm .In muscle cells are abundant
mitocondria for energy-producing and cytoskeletal filaments .
Those 60 trillion cells in a human body have the same nucleus DNA

23. Types of tissues
Epithelial tissues: cells arranged very closely together
• Epithelium tissue Lining the surface of the body (skin and hollow cavities inside
the body)
• Glandular epitheliumreleases substances with different functions (pancreas and
liver). Sometimes form structures called glands (saliva glands)
Type of cells
Intercellular substance among them

24. Types of tissues
Connective tissues: supports and/or connects other tissues. Produce a lot of extracellular
substances.
• Connective tissue Located in the deepest layer of our skin (dermis) and “stuffing”
between organs
• Adipose tissueenergetic reserve. Thermal insulating.
• Bloodtransports nutrients and oxygen
• Bone tissuerigid tissue because of mineral salts it contains in its matrix
• Cartilaginous tissue protects joints from the bones, and strengthens some structures.

25. Types of tissues
Muscle tissue
• Composed of elongated cells called muscle fibres
• These muscle cells contract and relax causing the body to move
• Three different muscle tissues:
• Striated muscle tissue: contract voluntary (locomotor system)
• Smooth muscle tissue: contract involuntary (stomach or intestine)
• Cardiac muscle tissue: striated but contract involuntary

26. Types of tissues
Nervous tissue
• Composed of cells called neurons.
• Coordinates the functioning of the organism.

27. Organ

28. Systems
Nutrition
• Digestive systemPrepares food to be used by cells
• Respiratory systemSupplies O2 to the blood and takes away
CO2
• Circulatory systemBlood distribute nutrients and oxygen. Picks
up waste products
• Excretory systemPicks up waste products from blood and
discharges them from the body. Regulates wáter content.

29. Systems
Reproduction
• Reproductive system Ensures our survival over time. Involves both,
male and female reproductive organs

30. Systems
Interaction (to internal and external enviroment)
• The sensory organs Pick up information and enable the body to
adapt and survive
• The nervous systemReceives information from outside and inside
the body. Coordinates all the body functions
• The endocrine systemMade up of glands, special organs that
release substances (hormones) to the blood. Different effects on the
body.
• The skeletal and muscular systems (locomotor system) Formed by
bones and muscles respectively. Responsible for a person’s
movement.

31. Systems
Notice that:
• The nervous and endocrine systems coordinate all the systems in the
body
• Sense organs perceive internal and external stimuli
• The nervous system sends orders to the organs in order to respond to
those stimuli
• The endocrine system controls many of the reactions that take place
inside cells