UNIT F: HOMEOSTASIS & UNIFYING CONCEPTS OF BIOLOGY

CHAPTER 20

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

•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?

• 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

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

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

• 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

Shaft

Figure 20.1

• 20.2 Animal structure has a hierarchy

• Structure in the living world is organized in a series of

hierarchical levels

Muscle cell

A Cellular level

B Tissue level

Muscle tissue

C Organ level

Heart

E Organism levelMany organ systems

functioning together

D Organ system level

Circulatory system

Figure 20.2A–E

• 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

• Epithelial tissue functions in protection, secretion, and exchange

Basement

membrane

(extracellular

matrix)

Free surface of

epithelium

Cell

nuclei

A Simple squamous epithelium

(lining the air sacs of the lung)

B Simple cuboidal epithelium

(forming a tube in the kidney)

C Simple columnar epithelium

(lining the intestine)

D Stratified squamous epithelium

(lining the esophagus)

Layers of

dead cells

Rapidly dividing

epithelial cells

E Stratified squamous epithelium

(human skin)

Colo

rized S

EM

Figure 20.4A–E

Underlying

tissue

Cartilage-

forming

cells

Matrix

D Cartilage

(at the end of a bone)

Central

canal

Matrix

Bone-

forming

cells

E Bone

F BloodA 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

• 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

Figure 20.5A–F

• 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

contractionMuscle

fiber

Nucleus

A Skeletal muscle

Nucleus

Muscle

fiberJunction between

two cells

Muscle fiber

Nucleus

C Smooth muscle

B Cardiac muscle

Figure 20.6A–C

Cell body

Nucleus

Cell extensions

LM

33

0

Figure 20.7

• 20.7 Nervous tissue forms a communication network

• The branching neurons of nervous tissue transmit nerve signals that help

control body activities

CONNECTION

• 20.8 Artificial tissues have medical uses

• Artificial tissues can assist in the healing of several injuries

Figure 20.8

• 20.9 Several tissues are organized to form an organ

• Each organ is made of several tissues that collectively perform specific

functions

Figure 20.9

Small intestine

(cut open)

Lumen

Epithelial tissue

(columnar epithelium)

Connective tissue

Smooth muscle

tissue (2 layers)

Connective tissue

Epithelial tissue

Lumen

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

• 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

Bozeman: Organ Systems

• 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

• 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

• The integumentary system covers and protects the body

• Skeletal and muscular systems support and move the body

Figure 20.10I–K

I Integumentary system

Hair

Skin

Nails

K Muscular system

Skeletal

muscles

Cartilage

Bones

J Skeletal system

• The reproductive system perpetuates the species

Figure 20.10L

Female

Vas

deferens

Penis

Urethra

Testis

Prostate

gland

Male

Oviduct

Ovary

Uterus

Vagina

L Reproductive systems

CONNECTION

• 20.11 New imaging technology reveals the inner body

• New technologies enable us to see body organs without surgery

• X-rays

• X-rays can be used for imaging bones and teeth

• CT

• Computed tomography (CT) scans are excellent diagnostic tools

Figure 20.11A Figure 20.11B

• MRI

• Magnetic resonance imaging (MRI) allows visualization of soft tissues

• MRM

• Magnetic resonance microscopy (MRM) provides three-dimensional images

of very small structures

Figure 20.11C

• PET

• Positron-emission tomography (PET) yields information about metabolic

processes at specific locations in the body

HEARING

WORDSSEEING

WORDS

SPEAKING

WORDS

GENERATING

WORDS

MIN

MAX

Figure 20.11D

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

layersDiffusion

Mouth

Gastrovascular

cavity

• 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

FoodMouth

Animal

Body

cells

Interstitial

fluid

Anus

Unabsorbed

matter (feces)

Metabolic waste

products (urine)

Intestine

Nutrients

CO2 O2

Figure 20.12B

• The respiratory system has an enormous internal surface area

Figure 20.12C

• 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

fluctuationsLarge

fluctuations

Figure 20.13AFigure 20.13B

Bozeman: Homeostasis

• 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 36–38C

Temperature rises

above normal

Temperature falls

below normal

Temperature

decreases

Temperature

increasesThermostat shuts off

warming mechanisms

Blood vessels in skin

constrict, minimizing

heat loss

Thermostat in

brain activates

warming

mechanismsSkeletal 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

YOUR TURN!!

• To help understand the connection between the body systems

and homeostasis go to this website:

https://ats.doit.wisc.edu/biology/ap/ho/ho.htm

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?