1. Chapter 20. Unifying concepts of animal structure and function
2018 Biology2
Chapter 20. Unifying concepts of animal structure and function

2. 20.1 Structure fits function at all levels of organization in the animal body
The correlation between structure and function is one of biology’s most fundamental concepts
Anatomy: the study of the structure of an organism
Physiology: the study of the functions an organism performs

3. Structural hierarchy of an animal’s body

4. 20.3 Tissues are groups of cells with a common structure and function
Tissue: a cooperative unit of many similar cells that perform a specific function
Animals have four major categories of tissue
Epithelial tissue (상피조직)
Connective tissue
Muscle tissue
Nervous tissue

5. 20.4 Epithelial tissue covers the body and lines its organs and cavities
Epithelial tissue (epithelium) occurs as sheets of closely packed cells : tight junction
It covers surfaces and lines internal organs and cavities
Examples: epidermis, stomach lining
The structure of each type of epithelium fits its function
The one side of an epithelial tissue is anchored to underlying tissues by a basement membrane (basal lamina)
Basement membrane: a dense mat of extracellular matrix consisting of fibrous proteins and sticky polysaccharides

7. Classification
According to the number of cell layers
Simple epithelium: a single layer of cells
Stratified epithelium: multiple layers of cells
According to the cell shape
Squamous epithelium
Cuboidal epithelium
Columnar epithelium

9. The structure of each type of epithelium fits its function
e.g., simple squamous epithelium
 exchange of materials by simple diffusion
lining capillary, alveolus
Cuboidal and columnar epithelia
secretion과 absorption에 적합 (formation of the mucous membrane)
lining digestive tracts, airways (trachea, bronchus)

10. 20.5 Connective tissue binds and supports other tissues
Connective tissue is characterized by sparse cells scattered through an extracellular matrix
The cells manufacture and secrete an extracellular matrix
The matrix is composed of fiber proteins (collagen, elastin, fibronectin, laminin) embedded in a liquid, solid, or gel containing proteoglycan

11. Animal cells
Embedded in an extracellular matrix that binds cells together in tissues
It is a sticky layer of collagen and glycoproteins embedded in a network woven from proteoglycans
It binds cells together in tissues
It protects and supports cells

12. Collagen
Proteoglycan
complex
Polysaccharide
molecule
EXTRACELLULAR FLUID
Carbo-
hydrates
Fibronectin
Core
protein
Integrins
Proteoglycan
molecule
Plasma
membrane
Proteoglycan complex
Micro-
filaments
CYTOPLASM

13. E. CARTILAGE (at the end of a bone)
There are six major types of connective tissue
Figure 20.5
Cell
A. LOOSE CONNECTIVE TISSUE (under the skin)
Collagen fiber
Other fibers
B. ADIPOSE TISSUE
Fat droplets
Cell nucleus
C. BLOOD
White blood cells
Red blood cells
Plasma
D. FIBROUS CONNECTIVE TISSUE (forming a ligament)
Collagen fibers
E. CARTILAGE (at the end of a bone)
Cells
Matrix
F. BONE
Central canal

14. Loose connective tissue
The most common type of connective tissue
Its matrix is a loose weave of fibers made largely of collagen
Tissue들을 서로 연결하고 지지하는 역할 (fibroblast)
Surround the blood vessels and nerves
Hold organs in place
2. Adipose tissue
Large, closely packed adipose cells held in a sparse matrix of fibers
Each adipose cells contains a large fat droplet
It pads and insulates the body and stores energy

15. 3. Blood
Connective tissue with a fluid matrix
Blood cells + plasma (blood matrix)
Transportation of substances (O2, CO2, nutrients, wastes)
Immunity
4. Fibrous connective tissue
A matrix of densely packed parallel bundles of collagen fibers
e.g., tendon (힘줄): attach muscles to bone
ligament (인대): join bones together

16. 5. Cartilage
Matrix: many collagen fibers embedded in a rubbery substance (chondroitin sulfate)
Chondrocyte
Cartilage commonly surrounds the ends of bones
It supports the nose and the ears
It forms the cushioning discs between our vertebrae
6. Bone (osteoblast, osteon)
Matrix: collagen fibers embedded in calcium phosphate salts
Rigid connective tissue

17. 20.6 Muscle tissue functions in movement
Muscle tissue consists of bundles of long cells called muscle fibers
The most abundant tissue in animals
Three types of muscle tissue
Skeletal muscle
Cardiac muscle
Smooth muscle

18. Unit of muscle contraction
A. SKELETAL MUSCLE
Muscle fiber
Nucleus
B. CARDIAC MUSCLE
Junction between two cells
C. SMOOTH MUSCLE

19. Skeletal muscle
It is attached to bones by tendons
Voluntary muscle
Striated muscle
Muscle fiber with multiple nuclei

20. Sliding-filament model of muscle contraction

21. 2. Cardiac muscle
The contractile tissue of the heart
The cell is striated and branched
Involuntary muscle

22. 3. Smooth muscle
No striation
It occurs in the walls of the digestive tract, urinary bladder, arteries and other internal organs
The cell is spindle-shaped
It contracts more slowly than skeletal muscles, but it can sustain contractions for a long period of time
Involuntary muscle

23. 20.7 Nervous tissue forms a communication network
Nervous tissue functions in the receipt, processing, and transmission of information
Nervous tissue contains neurons and glial cells
Neuron: nervous cell which transmits nerve impulse
Glia:
To surround neurons and hold them in place
To supply nutrients and oxygen to neurons
To insulate one neuron from another
To destroy pathogens and remove dead neurons.

24. The functional unit of nerve tissue : nerve cell (neuron)

25. neurotransmitter

26. 20.8 Organs are made up of tissues
Each organ is made of several tissues that cooperate to perform specific functions

27. 20.10 Organ systems work together to perform life’s functions
The level of organization higher than an organ is an organ system
Each organ system has one or more functions
Digestive system
Respiratory system
Circulatory system
Lymphatic and immune system
Excretory system
Endocrine system
Nervous system
Integumentary system
Reproductive system
Skeletal system
Muscular system

28. 20.12 The integumentary system protects the body
Integumentary system: skin, hair, nail
Skin:
Skin consists of two layers: epidermis and dermis
Epidermis: stratified squamous epithelium
The epidermal cells accumulate keratin and release a waterproofing glycolipid, and eventually die
Dermis: the inner layer of the skin
The dermis consists of a connective tissue with many elastic and collagen fibers
It contains hair follicles, oil and sweat glands, mucles, nerves, sensory receptors, blood vessels

30. 20.11 New imaging technology reveals the inner body
New technologies enable us to see body organs without surgery (X-ray, ultasound imaging)
Computed tomography (CT) – X-ray이용

31. Magnetic resonance imaging (MRI)
Visualize the soft tissues well (magnetic field)
Positron-emission tomography (PET)
Measuring metabolic activities
Tracer: fluorodeoxyglucose
Figure 20.10C, D

32. CT
PET
CT-PET

33. 20.13 Structural adaptations enhance exchange between animals and their environment
Animals are not closed systems
An animal must exchange materials and heat with its environment
This exchange must extend to the cellular level

34. Small animals with simple body construction have enough surface to meet their cells’ needs
Hydras can exchange materials with the environment through direct diffusion
Mouth
Gastrovascular cavity
Diffusion
Two cell layers
Figure 20.11A

35. Larger, complex animals
Specialized exchange surfaces
Circulatory system

36. 20.14 Animals regulate their internal environment
In response to changes in external conditions, animals regulate their internal environment
They must do this to achieve homeostasis (항상성), an internal steady state by negative feedback mechanism

37. Homeostasis depends on negative feedback