1. 13/11/11 1 1 1

2. Organization of the human body
13/11/11
Organization of the human body 2
© Zanichelli editore 2016 2 2

3. Organization of the body in animals
13/11/11
Organization of the body in animals
Animals present some characteristics that distinguish them from unicellular organisms and provide specific advantages:
cells are specialized;
there is hierarchical organization; cells are organized into tissues which compose organs that work together in systems;
cells communicate and cooperate. 3
© Zanichelli editore 2016 3 3

4. The human body The human body has four types of tissues:
13/11/11
The human body
The human body has four types of tissues:
epithelial tissue;
connective tissue;
muscle tissue;
nervous tissue.
These tissues form organs which are organized into eleven systems. 4
© Zanichelli editore 2016 4 4

5. 13/11/11
Epithelial tissues
Epithelial tissues are formed by one or more layers of cells of regular shape that don’t contain blood vessels.
They cover the surfaces of organs and blood vessels.
The epithelium rests on a basement membrane and its cells are continuously replaced.
epithelium 5
© Zanichelli editore 2016 5 5

6. Functions of epithelial tissues
13/11/11
Functions of epithelial tissues
Epithelial tissues have different functions:
protection and covering;
controlled exchange of substances;
secretion (endocrine and exocrine glands);
sensory reception (receptors). 6
© Zanichelli editore 2016 6 6

7. 13/11/11
Connective tissues
Connective tissues fill and connect different parts of the body.
They are formed by cells dispersed in a solid, semi-solid or fluid matrix.
They are divided into connective tissues – proper and special connective tissues.
Proper connective tissues include:
loose connective tissue;
dense connective tissue;
fat tissue. 7
© Zanichelli editore 2016 7 7

8. Special connective tissues
13/11/11
Special connective tissues
Type of tissue
Functions
Matrix
bone tissue
protection, support, storage of calcium and phosphorus
solid matrix
cartilage
protection of joints in response to friction and tension
resistant, strong and flexible matrix
blood
supply oxygen and nutrients to tissues, waste removal, immunological function, regulation of body temperature
fluid matrix (plasma) 8
© Zanichelli editore 2016 8 8

9. 13/11/11
Muscle tissues
Muscle tissues are formed by elongated cells, called fibers, that can contract and relax, facilitating movement.
There are different types of muscle tissues:
skeletal or striated muscle which contracts voluntarily;
smooth muscle which contracts involuntarily;
cardiac muscle (in the heart) which contracts involuntarily. 9
© Zanichelli editore 2016 9 9

10. Nervous tissue Nervous tissue is formed by neurons and glial cells.
13/11/11
Nervous tissue
dendrites
Nervous tissue is formed by neurons and glial cells.
Neurons are cells that present:
a cell body, containing the nucleus;
dendrites, specialized in the reception of stimuli ;
an axon, that transports nervous signals from the cell to other neurons or organs.
cell body
axon 10
© Zanichelli editore 2016 10 10

11. 13/11/11
Integumentary system
The integumentary system covers and protects the body.
It consists of skin and accessory organs (glands, nails, hair, sensory receptors and free nerve endings).
epidermis
The skin is formed by two main layers:
epidermis;
dermis.
Below the dermis is the hypodermis – a layer of fat tissue.
dermis
hypodermis 11
© Zanichelli editore 2016 11 11

12. 13/11/11
Skeletal system
The skeletal system supports and protects the internal organs, supports muscles, produces (in the red bone marrow) blood cells, and is involved in calcium equilibrium.
axial skeleton
The skeleton is divided into the:
axial skeleton (skull, rib cage, vertebral column);
appendicular skeleton (upper and lower limbs, shoulder girdle, pelvic girdle).
appendicular skeleton 12
© Zanichelli editore 2016 12 12

13. 13/11/11
Skeleton and muscles
The skeleton provides rigid support for mucles, with which it forms an integrated system.
Bones act as levers, producing ordered movements with help from coordinated action of different muscles. 13
© Zanichelli editore 2016 13 13

14. 13/11/11
Homeostasis
Homeostasis is the body’s ability to maintain a stable inner environment even when external conditions change.
To maintain homeostasis, cells communicate via signal molecules.
There are two mechanisms used to maintain homeostasis:
positive feedback;
negative feedback. 14
© Zanichelli editore 2016 14 14

15. 13/11/11
Thermoregulation
Body temperature control (thermoregulation) is an important part of homeostasis.
Humans are endothermic, with a body temperature around 37 °C. Thermoregulation occurs by controlling the production of internal heat and the exchange of heat between the body and the environment (perspiration, vasoconstriction, vasodilation, muscle activities).
The control center of body temperature is the hypothalamus. 15
© Zanichelli editore 2016 15 15

16. Stem cells and cell differentiation
13/11/11
Stem cells and cell differentiation
Stem cells are undifferentiated cells that can proliferate, generating copies of themselves or specialized cells.
Stem cells can be divided into:
totipotent cells;
pluripotent cells;
multipotent cells;
unipotent cells.
totipotent
pluripotent
multipotent
unipotent 16
© Zanichelli editore 2016 16 16

17. Regulation of cell growth and death
13/11/11
Regulation of cell growth and death
The growth and regeneration of cells is regulated by several signal molecules. When cells proliferate without control, it is possible to develop hyperplasia or tumors.
Cell death can occur through two mechanisms:
apoptosis - a controlled death;
necrosis - caused by trauma. 17
© Zanichelli editore 2016 17 17