1. Unifying Concepts of Animal Structure and Function
Chapter 20
Unifying Concepts of Animal Structure and Function

2. THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL
20.1 Structure fits function in the animal body
Anatomy is the study of structure
Physiology studies how structures function

3. The functions of specific structures
Result from their specific structures
Forearm
Wrist
Finger 1
Palm
Shaft
Internal bone structure
Finger 2
Finger 3
Shaft
Barb
Feather structure
Barbule
Hook
Figure 20.1

4. 20.2 Animal structure has a hierarchy Structure in the living world
20.2 Animal structure has a hierarchy
Structure in the living world
Is organized in a series of hierarchical levels
A  Cellular level
Muscle cell
B  Tissue level
Muscle tissue
C  Organ level
Heart
D  Organ system level
Circulatory system
E  Organism level
Many organ systems functioning together
Figure 20.2A–E

5. 20.4 Epithelial tissue covers the body and lines its organs and cavities
Epithelial tissue occurs as sheets of closely packed cells
That cover surfaces and line the cavities and tubes of internal organs

6. Epithelial tissue Functions in protection, secretion, and exchange
Free surface of epithelium
Basement membrane (extracellular matrix)
Underlying tissue
Cell nuclei
A  Simple squamous epithelium (lining the air sacs of the lung)
D  Stratified squamous epithelium (lining the esophagus)
B  Simple cuboidal epithelium (forming a tube in the kidney)
Layers of dead cells
Rapidly dividing epithelial cells
Colorized SEM
E  Stratified squamous epithelium (human skin)
C  Simple columnar epithelium (lining the intestine)
Figure 20.4A–E

7. 20.5 Connective tissue binds and supports other tissues
The various types of connective tissue
Are characterized by sparse cells in an extracellular gel matrix

8. Connective tissue Binds and supports other tissues
Fat droplets
Cartilage- forming cells
C  Adipose tissue
Matrix
Cell nucleus
D  Cartilage      (at the end of a bone)
Collagen fibers
Central canal
B  Fibrous connective tissue      (forming a tendon)
Cell
White blood cells
Matrix
Collagen fiber
Bone- forming cells
Red blood cell
Elastic fibers
E  Bone
Plasma
Figure 20.5A–F
A  Loose connective tissue      (under the skin)
F Blood

9. 20.6 Muscle tissue functions in movement
Skeletal muscle attaches bones by tendons and is responsible for voluntary movements of the body.
Cardiac muscle forms the contractile tissues of the heart.
Smooth muscle found on the walls of digestive tract, urinary bladder, arteries, and other internal organs.

10. The three types of muscle tissue
Muscle fiber
Unit of muscle contraction
Junction between two cells
Muscle fiber
Nucleus
Nucleus
Muscle fiber
Nucleus
B  Cardiac muscle
A  Skeletal muscle
C  Smooth muscle
Figure 20.6A–C

11. 20.7 Nervous tissue forms a communication network
The branching neurons of nervous tissue
Transmit nerve signals that help control body activities
Cell body
Nucleus
Cell extensions
LM 330
Figure 20.7

12. Small intestine (cut open)
20.9 Several tissues are organized to form an organ
Each organ is made of several tissues
That collectively perform specific functions
Lumen
Small intestine (cut open)
Lumen
Epithelial tissue (columnar epithelium)
Connective tissue
Smooth muscle tissue (2 layers)
Connective tissue
Figure 20.9
Epithelial tissue

13. 20.10 Organ systems work together to perform life functions
Each organ system
Has one or more functions

14. The digestive and respiratory systems Gather food and oxygen
Mouth
Nasal cavity
Larynx
Esophagus
Liver
Trachea
Stomach
Bronchus
Small intestine
Lung
Large intestine
Anus
A  Digestive system
B  Respiratory system
Figure 20.10A, B

15. The circulatory system, aided by the lymphatic system
Transports the food and oxygen
The immune system
Protects the body from infection and cancer
Bone marrow
Heart
Thymus
D  Immune system
Spleen
E  Lymphatic system
Lymph nodes
Blood vessels
Lymph vessels
C  Circulatory system
Figure 20.10C–E

16. Disposes of certain wastes The endocrine and nervous systems
The excretory system
Disposes of certain wastes
The endocrine and nervous systems
Control body functions
Pituitary gland
F  Excretory system
Thyroid gland
Thymus
Kidney
Adrenal gland
Ureter
Pancreas
Testis (male)
Urinary bladder
Urethra
Ovary (female)
G  Endocrine system
Figure 20.10F–G

17. The integumentary system Covers and protects the body
Skeletal and muscular systems
Support and move the body
Hair
Cartilage
Skin
Skeletal muscles
Nails
Bones
I  Integumentary system
J  Skeletal system
K  Muscular system
Figure 20.10I–K

18. The reproductive system Perpetuates the species
Male
Female
Prostate gland
Vas deferens
Oviduct
Ovary
Urethra
Uterus
Penis
Vagina
Testis
Figure 20.10L
L  Reproductive systems

19. 20.11 New imaging technology reveals the inner body
CONNECTION
20.11 New imaging technology reveals the inner body
New technologies
Enable us to see body organs without surgery

20. X-rays Can be used for imaging bones and teeth

21. CT Computed tomography (CT) scans Are excellent diagnostic tools
Figure 20.11A
Figure 20.11B

22. MRI Magnetic resonance imaging (MRI)
Allows visualization of soft tissues

23. MRM Magnetic resonance microscopy (MRM)
Provides three-dimensional images of very small structures
Figure 20.11C

24. PET Positron-emission tomography (PET)
Yields information about metabolic processes at specific locations in the body
MAX
HEARING WORDS
SEEING WORDS
MIN
SPEAKING WORDS
GENERATING WORDS
Figure 20.11D

25. EXCHANGES WITH THE EXTERNAL ENVIRONMENT
20.12 Structural adaptations enhance exchange between animals and their environment
An animal must exchange materials
With its environment

26. Small animals with simple body construction
Have enough surface area to meet their cells’ needs
Mouth
Diffusion
Two cell layers
Diffusion
Gastrovascular cavity
Figure 20.12A

27. Larger, complex animals
Have specialized structures that increase surface area
Exchange of materials between blood and body cells
Takes place through the interstitial fluid
External environment
Mouth
Food
CO2 O2
Animal
Respiratory system
Digestive system
Interstitial fluid
Nutrients
Circulatory system
Body cells
Intestine
Excretory system
Anus
Figure 20.12B
Unabsorbed matter (feces)
Metabolic waste products (urine)

28. The respiratory system Has an enormous internal surface area
Figure 20.12C

29. Homeostatic mechanisms
20.13 Animals regulate their internal environment
In response to changes in external conditions
Animals regulate their internal environment to achieve homeostasis, an internal steady state
External environment
Internal environment
Homeostatic mechanisms
Small fluctuations
Large fluctuations
Figure 20.13A
Figure 20.13B

30. 20.14 Homeostasis depends on negative feedback
Negative feedback mechanisms
Keep internal variables fairly constant, with small fluctuations around set points
Sweat glands secrete sweat that evaporates, cooling body
Thermostat in brain activates cooling mechanisms
Blood vessels in skin dilate and heat escapes
Temperature rises above normal
Thermostat shuts off cooling mechanisms
Temperature decreases
Homeostasis: Internal body temperature of approximately 36–38C
Temperature increases
Thermostat shuts off warming mechanisms
Temperature falls below normal
Blood vessels in skin constrict, minimizing heat loss
Thermostat in brain activates warming mechanisms
Skeletal muscles rapidly contract, causing shivering, which generates heat
Figure 20.14