4.2 The small size of cells relates to the need to exchange materials across the plasma membrane Cell size must –be large enough to house DNA, proteins,

4.2 The small size of cells relates to the need to exchange materials across the plasma membrane

Cell size must

– be large enough to house DNA, proteins, and structures needed to survive and reproduce, but

– remain small enough for a SA:volume ratio that will allow for adequate exchange with the environment.

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Figure 4.2A

3

3

1

1

Total volume

Total surfaceareaSurface-to-volume ratio

2

54 units2

27 units3 27 units3

162 units2

6

20.3 Tissues are groups of cells with a common structure and function

Tissues

– are an integrated group of similar cells that perform a common function and

– combine to form organs.

Animals have four main categories of tissues:

1. epithelial tissue,

2. connective tissue,

3. muscle tissue, and

4. nervous tissue.

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Extracellular Matrix in Animals

Animal cells synthesize and secrete an elaborate ECM

– Composed of sugar-protein polymers

– helps hold cells together in tissues and

– protects and supports the plasma membrane.

© 2012 Pearson Education, Inc.

EXTRACELLULAR FLUID

CYTOPLASMMicrofilamentsof cytoskelton

Plasmamembrane

Integrin

Connectingglycoprotein

Glycoproteincomplexwith longpolysaccharide

Collagen fiber

ECM is glue that holds animal cells together!!

4.20 Cell junctions are found in animal tissues

Allow adjacent cells to communicate, interact, and adhere together.

– Tight junctions prevent leakage of extracellular fluid across a layer of epithelial cells.

– Anchoring junctions fasten cells together into sheets.

– Gap junctions are channels that allow molecules to flow between cells.

© 2012 Pearson Education, Inc.

Animation: Tight Junctions

Animation: Gap Junctions

Animation: Desmosomes

Figure 4.20

Tight junctionsprevent fluid frommoving between cells

Tight junction

Anchoringjunction

Gap junction

Plasma membranesof adjacent cells

Extracellular matrix

4.21 Cell walls enclose and support plant cells

Cell wall

– protects and provides skeletal support that helps keep the plant upright against gravity and

– is primarily composed of cellulose.

Plant cells have cell junctions called plasmodesmata that serve in communication between cells.

© 2012 Pearson Education, Inc.

Figure 4.21

Vacuole

Plant cellwalls

Plasmodesmata

Cytoplasm

Primary cell wallSecondary cell wallPlasma membrane

20.3 Tissues are groups of cells with a common structure and function

– Tissues combine to form organs.

Epithelial tissuecovers the body andlines its organs andcavities.

Connectivetissue binds andsupports othertissues.

Muscletissue functionsin movement.

Nervous tissueforms acommunicationnetwork.

Sheets of closelypacked cells

Sparse cells in extra-cellular matrix

Long cells (fibers)with contractileproteins

Neurons withbranching extensions;supporting cells

Columnar epithelium Loose connective tissue Skeletal muscle Neuron

Ex

am

ple

Str

uc

ture

Fu

nc

tio

n

Figure 20.4

Stratified squamousepithelium

Pseudostratifiedciliated columnarepithelium

Simple columnarepithelium

Simple cuboidalepithelium

Simple squamousepithelium

Basallamina

Underlyingtissue

Apical surface ofepithelium

Cell nuclei

Epithelial tissue covers the body and lines its organs and cavities

Figure 20.5

Cellnucleus

Collagenfiber

Elasticfibers

Loose connective tissue(under the skin)

Cell nucleus

Collagenfibers

Fibrous connectivetissue (forming a tendon)

Fat droplets

Adiposetissue

White bloodcells

Red bloodcell

PlasmaBlood

Centralcanal

Matrix

Bone

Bone-formingcells

Cartilage-formingcells

Matrix

Cartilage(at the endof a bone)

Figure 20.6

Unit ofmusclecontraction

Musclefiber(cell)

Nuclei

Skeletalmuscle

Musclefiber

Nucleus

Junctionbetweentwo cells

Cardiacmuscle

Musclefiber

Smoothmuscle

Nucleus

Figure 20.7

Dendrites

Cell body

Axon

Organs are made up of tissues Each tissue performs

specific functions.

The small intestine

– is lined by a columnar epithelium,

– includes connective tissues that contain blood vessels, and

– has two layers of smooth muscle that help propel food.

© 2012 Pearson Education, Inc.

Small intestine

Lumen

Epithelial tissue(columnar epithelium)

Connective tissue

Smooth muscletissue (two layers)

Connective tissue

Epithelial tissue

Figure 20.10_L

Bloodvessels

Heart

Circulatorysystem

Respiratorysystem

Nasalcavity

Pharynx

Larynx

Trachea

Bronchus

Lung

Bone

Cartilage

Skeletal system

Muscular system

Skeletal muscles

Integumentary system

Hair

Skin

Nails

Urinarysystem

Digestivesystem

Urinarybladder

Smallintestine

Largeintestine

Kidney

Ureter

Urethra

Mouth

Esophagus

Liver

Stomach

Anus

Figure 20.10_R

Endocrine system

Thymus

Adrenalgland

Pancreas

Testis(male)

Hypothalamus

Pituitary gland

Thyroid gland

Parathyroidgland

Ovary(female)

Lymphatic andimmune systems

Lymphnodes

Appendix

Bonemarrow

Thymus

Spleen

Lymphaticvessels

Reproductivesystem

FemaleOviduct

Ovary

UterusVagina

Male

Seminalvesicles

Prostategland

Vasdeferens

Penis

UrethraTestis

Nervous system Brain

Sense organ(ear)

Spinal cord

Nerves

EXTERNAL ENVIRONMENT

MouthFood

CO2 O2

ANIMAL

Digestivesystem

Respiratorysystem

Circulatorysystem

Urinarysystem

HeartInterstitialfluid

Bodycells

Intestine

Anus

Unabsorbedmatter (feces)

Metabolic wasteproducts (urine)

Nutrients

Blo

od

respiratory system exchanges gases between the external environment and blood.

digestive system acquires food and eliminates wastes

excretory system eliminates metabolic waste

circulatory system- distributes gases,nutrients, and wastesthroughout the body

- exchanges materialsbetween blood andbody cells through theinterstitial fluid

Every organism must exchange energy and nutrients/wastes with surroundings

Terminal bud

Shootsystem

Rootsystem

LeafBlade

Petiole

Axillary bud

Stem

Taproot

Flower

Node

Internode

Epidermal cell

Root hair

Root hairs

Root hairs

Plants have 3 Organ Systems:

– Roots

– Water and nutrient absorption; storage

– Shoots (stems)

– Support, structure, storage

– Leaves

– Photosynthesis; gas exchange (O2 / CO2)

Dermal tissue system

Ground tissue system

Vascular tissue system

Key

Sheath

Stoma

Guardcells

VeinPhloem

Xylem

Eudicot leaf Cuticle

Upper epidermis

Lower epidermis

Mesophyll

Dermal = protective coveringGround = photosynthetic cells, storage, fillerVascular = transport

xylem: water from roots to leavesphloem: leaves to roots

Dermal = protective coveringGround = photosynthetic cells, storage, fillerVascular = transport

xylem: water from roots to leavesphloem: leaves to roots