Chapter 11

Human Organization

Structure fits Function

Palm

Finger 2

Finger 3

Shaft

Barb

Barbule

Hook

Feather structure

Wrist

Forearm

Finger 1

Internal bone structure

Shaft

Figure 20.1

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 level Many organ systems functioning together

D Organ system level

Circulatory system

Tissues are groups of cells with a common structure and function

•  Tissues are groups of many similar cells

–  That perform a specific function

Four Types of Tissues in the Human Body

•  Epithelial: covers body surfaces and lines cavities

•  Connective: supports and binds body parts

•  Muscular: moves the body and its parts

•  Nervous: receives stimuli, processes that information, and conducts impulses

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

cilia

Pseudostratified, ciliated columnar • lining of trachea

• sweeps impurities toward throat

basement membrane

Simple cuboidal • lining of kidney tubules, various glands

• absorbs molecules

basement membrane basement

membrane

goblet cell secretes

mucus

Simple columnar • lining of small intestine, oviducts

• absorbs nutrients

basement membrane

goblet cell secretes

mucus

basement membrane

Simple squamous • lining of lungs, blood vessels

• protects

Stratified squamous • skin (epidermis)

• lining of nose, mouth, esophagus, anal canal, vagina

• protects

Functions in protection, secretion, and exchange

Epithelial Tissue Connective tissue binds and supports other tissues

•  The various types of connective tissue

–  Are characterized by sparse cells in an extracellular gel matrix

Cartilage- forming cells Matrix

D Cartilage (at the end of a bone)

Central canal

Matrix 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

–  Binds and supports other tissues

Connective Tissue 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

Nucleus

Muscle fiber Junction between

two cells

Muscle fiber Nucleus

C Smooth muscle

B Cardiac muscle

Muscle Tissue

Cell body

Nucleus

Cell extensions

LM 3

30×

•  forms a communication network

•  The branching neurons of nervous tissue

–  Transmit nerve signals that help control body activities

Nervous Tissue

Artificial tissues have medical uses

•  Artificial tissues

–  Can assist in the healing of several injuries

CONNECTION 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)

Connective tissue

Epithelial tissue

Lumen

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

•  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

•  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)

•  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

•  The reproductive system

–  Perpetuates the species

Female

Vas deferens

Penis

Urethra

Testis

Prostate gland

Male

Oviduct

Ovary

Uterus

Vagina

L Reproductive systems

EXCHANGES WITH THE EXTERNAL ENVIRONMENT

Structural adaptations enhance exchange between animals and their environment

•  An animal must exchange materials

–  With its environment

•  Small animals with simple body construction

–  Have enough surface area to meet their cells’ needs

Diffusion

Two cell layers Diffusion

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

Food Mouth

Animal

Body cells

Interstitial fluid

Anus

Unabsorbed matter (feces)

Metabolic waste products (urine)

Intestine

Nutrients

CO2 O2

•  The respiratory system

–  Has an enormous internal surface area

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

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 36–38οC

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