1. Unit f: Homeostasis & Unifying Concepts of Biology
Unit f: Homeostasis & Unifying Concepts of Biology
Chapter 20

2. Unit f Standards
I can describe the structural hierarchy of the body: cell, tissue, organ, organ system and organism
I can describe the structure and function of the 4 types of tissues: epithelial, connective, muscle and nervous
I can state the structures (organs) of the 12 organ systems
I can describe the function of the 12 organ systems
I can explain how and why animals regulate their bodies via homeostasis
I can provide examples of negative feedback loops at work in the human body and explain why they function to maintain homeostasis

3. Climbing the Walls
Spiderman is a familiar character known for his ability to climb walls
Geckos, small lizards commonly found in the tropics can walk up a wall and across ceilings, but how do they do this?

4. The explanation relates to hairs called setae, on the gecko’s toes containing many split ends called spatulae
The ability to “stick” to surfaces results from attractions between molecules on the spatulae and the surface on which the gecko is crawling
Rows of setae on
a gecko’s foot
Spatulae coming
from a single seta

5. A little Hank  Intro to Anatomy and Physiology
Tissues Part 1: Intro, Nervous and Muscle
Tissues Part 2: Epithelial
Tissues Part 3: Connective
Tissues Part 4: Types of Connective

6. THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL
THE HIERARCHY OF STRUCTURAL ORGANIZATION IN AN ANIMAL
Correlation between structure and function is one of biology’s most fundamental concepts
20.1 Structure fits function in the animal body
Anatomy is the study of structure
Physiology studies how structures function

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

8. 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

9. 20.3 Tissues are groups of many similar cells with a common structure and that perform a specific function
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

10. 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

11. 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
Connective tissue binds and supports other tissues
Cartilage- forming cells
Matrix
D  Cartilage      (at the end of a bone)
Central canal
Bone- forming cells
E  Bone
F Blood
A  Loose connective tissue      (under the skin)
Elastic fibers
Collagen fiber
Cell
Collagen fibers
Cell nucleus
B  Fibrous connective tissue      (forming a tendon)
White blood cells
Red blood cell
Plasma
C  Adipose tissue
Fat droplets
Figure 20.5A–F

12. 20.6 Muscle tissue functions in movement
Skeletal muscle is responsible for voluntary body movements
Cardiac muscle pumps blood
Smooth muscle moves the walls of internal organs such as the stomach
The three types of muscle tissue
Unit of muscle contraction
Muscle fiber
Nucleus
A  Skeletal muscle
Junction between two cells
C  Smooth muscle
B  Cardiac muscle
Figure 20.6A–C

13. 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

14. CONNECTION 20.8 Artificial tissues have medical uses
Artificial tissues can assist in the healing of several injuries
Figure 20.8

15. 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
Small intestine (cut open)
Lumen
Epithelial tissue (columnar epithelium)
Connective tissue
Smooth muscle tissue (2 layers)
Epithelial tissue
Figure 20.9

16. 20.10 Organ systems work together to perform life functions
Each organ system has one or more functions
The digestive and respiratory systems gather food and oxygen
A  Digestive system
Mouth
Esophagus
Liver
Stomach
Small intestine
Large intestine
Anus
B  Respiratory system
Nasal cavity
Larynx
Trachea
Bronchus
Lung
Figure 20.10A, B
Bozeman: Organ Systems

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

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

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

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

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

22. X-rays
X-rays can be used for imaging bones and teeth

23. CT Computed tomography (CT) scans are excellent diagnostic tools
Figure 20.11A
Figure 20.11B

24. MRI
Magnetic resonance imaging (MRI) allows visualization of soft tissues

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

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

27. EXCHANGES WITH THE EXTERNAL ENVIRONMENT
20.12 Structural adaptations enhance exchange between animals and their environment
Small animals with simple body construction have enough surface area to meet their cells’ needs
Diffusion
Two cell layers
Mouth
Gastrovascular cavity

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

29. The respiratory system has an enormous internal surface area
Figure 20.12C

30. 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
Homeostatic mechanisms
External environment
Internal environment
Small fluctuations
Large fluctuations
Figure 20.13B
Figure 20.13A
Bozeman: Homeostasis

32. 20.14 Homeostasis depends on negative feedback
Negative feedback mechanisms
Keep internal variables fairly constant, with small fluctuations around set points
Homeostasis: Internal body temperature of approximately 36–38C
Temperature rises above normal
Temperature falls below normal
Temperature decreases
Temperature increases
Thermostat shuts off warming mechanisms
Blood vessels in skin constrict, minimizing heat loss
Thermostat in brain activates warming mechanisms
Skeletal muscles rapidly contract, causing shivering, which generates heat
Thermostat in brain activates cooling mechanisms
Sweat glands secrete sweat that evaporates, cooling body
Blood vessels in skin dilate and heat escapes
Thermostat shuts off cooling mechanisms
Figure 20.14

35. Your Turn!!
To help understand the connection between the body systems and homeostasis go to this website:
and proceed through the 3 topics in order
1. Ben’s Bad Day
2. Ben’s Homeostasis: The Inside Story
3. Does Ben Have Diabetes?