cecie starr | beverly mcmillan chapter 4 tissues, organs, and organ systems

Cecie Starr | Beverly McMillan

Chapter 4

Tissues, Organs, and Organ Systems

Key Concepts•Types of Body Tissues•Organs and Organ Systems•Homeostasis

Tissues, Organs, and Organ Systems 4

Tissues, Organs, and Organ Systems 4

• Stem cells– Embryonic stem cells:

controversy– Adult stem cells

p67

4.1 Epithelium: The Body’s Covering and Linings

• Epithelial tissues cover the body surface or line it’s cavities and tubes

Types of Body Tissues


• Epithelium – Simple: one layer of cells– Stratified: several layers of cells

• Shape of the cells at the tissue’s free surface– Squamous epithelium– Cuboidal epithelium– Columnar epithelium

• Basement membrane

There are two basic types of epithelia.


simple squamous epithelium

basement membrane

connective tissue

free surface of epithelium

Flattened simple squamous epithelium

Squarish simple cuboidal epithelium

Tall simple columnar cellsFigure 4-1 p68


• Gland– Make and release specific products– Derived from epithelial tissue

• Classification– Exocrine gland

• Substances released through ducts or tubes– Endocrine gland

• Substances released directly into the extracellular fluid

Glands form from epithelium.


parotid gland(secretes saliva)

Exocrine gland

parotid duct (deliverssaliva to mouth)

thyroid gland (secreteshormones into blood)

Endocrine gland

bloodvessel

cell that secreteshormone

Figure 4-2 p69

Take home message

What are epithelial tissues?

4.2 Connective Tissue: Binding, Support, and Other Roles

• Connective tissue connects, supports, and anchors the body’s parts

• Makes up more of your body than any other tissue

• Fibrous and specialized types

• Matrix– Ranges from hard to liquid


• Fibrous connective tissue

• Loose connective tissue– Flexible

• Dense connective tissues– Less flexible; stronger

• Elastic connective tissue– Stretchy due to elastin

Fibrous connective tissues are strong and stretchy.

Table 4-1 p69

Table 4-2 p70


collagenous fiberfibroblastelastic fiber

Type Loose connective tissue Description Fibroblasts, other cells, plus fibers loosely arranged in semifluid matrix Common Locations Under the skin and most epithelia Function Elasticity, diffusion

collagenous fibers

Type Dense, irregular connective tissue Description Collagenous fibers, fibroblasts, less matrix Common Locations In skin and capsules around some organs Function Support

Figure 4-3 p70


• Cartilage– Hyaline cartilage– Elastic cartilage– Fibrocartilage

• Bone tissue

• Adipose tissue

• Blood

Special connective tissues include cartilage, bone, adipose tissue, and blood.


collagenous fibers

fibroblast

Type Dense, regular connective tissue Description Collagen fibers in parallel bundles, long rows of fibroblasts, little matrix Common Locations Tendons, ligaments Function Strength, elasticity

ground substance with very fine collagen fiberscartilage cell (chondrocyte)

Type Cartilage Description Cells embedded in pliable, solid matrix Common Locations Ends of long bones, nose, parts of airways, skeleton of embryos Function Support, flexibility, low-friction surface for joint movement Figure 4-3 p70


compact bone tissue

nucleusblood vessel

cell bulging with fat droplet

bone cell (osteocyte)

Type Bone tissue Description Collagen fibers, matrix hardened with calcium Common Locations Bones of skeleton Function Movement, support, protection

Type Adipose tissue Description Large, tightly packed fat cells occupying most of matrix Common Locations Under skin, around heart, kidneys Function Energy reserves, insulation, paddingFigure 4-3 p70

4.3 Muscle Tissue: Movement

• Cells in muscle tissue can contract, allowing muscle to move body parts

• Muscle tissue- contracts and shortens when stimulated by an outside signal


• Skeletal muscle- striated; usually attached to bone; voluntary; multinucleated

• Smooth muscle- tapered; walls of internal organs; involuntary; uninucleated

• Cardiac muscle- cardiac wall; branching: special cellular junctions (intercalated discs); involuntary; uninucleated

Take home message

What is muscle tissue?

Figure 4-4 p71

white blood cell

platelet

red blood cell


nucleus

VOLUNTARY

A Skeletal muscle

nucleus

INVOLUNTARY

B Smooth muscle

adjoining ends of abutting cells

C Cardiac muscle

Figure 4-5 p72

4.4 Nervous Tissue: Communication

• Nervous tissue makes up the nervous system– Neurons (nerve cells)– Neuroglia (support cells)

• Communication lines; carry messages


• Glial cells (neuroglia) – 90% of the cells of the

nervous system– Bring nutrients to the

neurons– Physically support neuron– Remove debris– Myelin Sheath

(Schwann cells)• Provide insulation

p73


• Neurons have a cell body that contains a nucleus and cytoplasm

• Cell processes– Dendrites– Axons

p73

Take home message

What is nervous tissue?

4.5 Healing with Stem Cells and Lab-Grown Tissues

• “Reverse engineering” mature cells to convert them back to stem cells

• Introduce “cured” stem cells to replace faulty stem cells

• Use stem cells from bone marrow and umbilical cords

• Use a cultured skin substitute

stemcell

stemcell

stemcell

stemcell

stemcell

or

or

celltype 1

celltype 2

celltype 3

cells divide cells specialize

p73

Figure 4-6 p73

4.6 Cell Junctions: Holding Tissues Together

• Junctions between the cells in a tissue knit the cells firmly together, stop leaks, and serve as communication channels


• Tight junctions– Block leaking between adjoining cells

• Adhering junctions– Desmosomes– Cement cells together

• Gap junctions – Channels that connect the cytoplasm of neighboring cells– Abundant in smooth and cardiac muscle

Take home messageWhat do cell junctions do?


cell

basementmembrane

Figure 4-7 (top) p74


Tight JunctionA Adhering JunctionB

cytoskeletonfilaments

plasmamembraneof one cell

Gap JunctionC

channel

Figure 4-7 p74

4.7 Tissue Membranes: Thin, Sheet-like Covers

• Thin, sheet-like membranes cover many body surfaces and cavities

– Some provide protection– Others both protect and lubricate organs


• Mucous membranes– Designed to secrete and/or

absorb substances– Most have glands– Line tubes and cavities

• Serous membranes– Occur in paired sheets; line

the thoracic cavity and enclose the heart and lungs

– Secrete a fluid; no glands

• Cutaneous membranes– Dry membrane; skin

• Synovial membranes– Line cavities of the body’s

movable joints– Lubricate the ends of moving

bones– Prevent friction between a

bone and a moving tendon

Take home message

What are the functions of membranes?


B serous membrane C cutaneous membrane (skin)

D synovial membrane

A mucous membrane

Figure 4-8 p75

4.8 Organs and Organ Systems

• Organ

• Body cavities– Cranial cavity– Spinal cavity– Thoracic cavity– Abdominal cavity– Pelvic cavity

Organs and Organ Systems

4.8 Organs and Organ SystemsOrgan system: A set of organs that interacts to carry out a major body function

Organ: Body structure that integrates different tissues and carries out a specific function

Stomach

Epithelial tissue: Protection, transport, secretion, and absorption

Connective tissue: Structural support

Muscle tissue: Movement

Nervous tissue: Communication, coordination, and controlFigure 4-9a p76


cranial cavity

spinal cavity

thoracic cavity

abdominal cavity

pelvic cavity

Figure 4-9b p76


Organ systems:

Integumentary System

Nervous System

Skeletal System

Muscular System

Circulatory System

Endocrine System

Figure 4-10a p77


Organ systems:

Lymphatic System

Digestive System

Reproductive System

Respiratory System

Urinary System

Figure 4-10a p77

4.9 The Skin: An Example of an Organ System

• Skin– Largest surface area of any organ– Functions

• Oil glands

• Sweat glands

• Hair

• Nails

Skin and structures that develop from it make up the integument- the body’s covering.


• Epidermis– Stratified squamous

epithelium– Keratinocytes– Melanocytes

• Role in skin color– Langerhans cells– Granstein cells

• Dermis– Dense connective tissue– Elastin and collagen fibers– Blood vessels and nerve

endings– Oil and sweat glands– Hair follicles

Epidermis and dermis are the skin’s two layers.


smooth muscle

sebaceous gland

hair follicle

sweat gland

epidermisstratifiedsquamousepithelium

dermis mainlydenseconnectivetissue hypodermis mainly adipose tissue and loose connective tissue

pressuresensitivesensoryreceptor

bloodvessel

duct ofsweatgland

hair

Figure 4-11a p78


outer flattened epidermal cells

cells being flattened

dividing cells

dermis

epidermisstratifiedsquamousepithelium

dermis mainlydenseconnectivetissue

Figure 4-11b p78


• Hypodermis: layer beneath dermis– Loose connective– Fat: insulator and cushion


• Sweat glands – Location of glands– Chemical composition of sweat– Role in evaporative cooling

• Oil glands– Location– Sebum: softens and lubricates hair– Effect on bacteria

• Hair– Keratinized cells

Sweat glands and other structures develop from epidermis.


• Blisters• Acne• Cold sores

• Vitiligo

• Cancer– Squamous cell carcinoma– Malignant melanoma

• Effect of ultraviolet radiation on the skin

Skin disorders are common.

Malignant melanoma

Squamous cell carcinoma

Figure 4-12 p79 p79

Take home message

What is the integumentary system?

4.10 Homeostasis: The Body in Balance

• Cells and more complex body parts function properly only when conditions inside the body are stable

Extracellular fluid


• Extracellular fluid– ~15 liters– Mostly interstitial fluid– Blood plasma

• Homeostasis– Mechanisms to maintain

stability in the volume and chemical makeup of extracellular fluid

The internal environment is a pool of extracellular fluid.

Interstitial (tissue) fluidCell Blood

Blood vessel

p80

Figure 4-13 p80

Sensors: Cells inthe eyes, ears, skin,and elsewhere

Integrator:The brain

Effectors: Musclesand glands


• Sensory receptors– Translate the stimulus into a signal that can be sent to

the brain• Stimulus

– Specific change in the external and internal environment

• Integrator– Brain

• Effectors– Muscles and glands

Homeostasis requires the interaction of sensors, integrators, and effectors.


Stimulus(change in the environment)

In negative feedback, the response of the system cancels or counteracts theeffect of the original change.

Sensor(for example,nerve endingin the skin)

Effector(a muscle

or a gland)

Integrator(such as

the brain)

Response

Figure 4-14 p81


• Negative feedback– An activity alters a condition in the internal

environment and triggers a response that reverses the altered condition

– Example: keeping body temperature within a normal range

Negative feedback is the most common control mechanism in homeostasis.


• Positive feedback– A chain of events intensify a change from the original

condition that reverses the change– Example: childbirth

Positive feedback is the plays a role outside of homeostasis.

Homeostasis

Take home message

What are homeostatic controls?

4.11 How Homeostatic Feedback Maintains the Body’s Core Temperature

• Controls over the body’s core temperature provide good examples of negative feedback loops


• Humans are endotherms.• Core temperature

– 37°C (98.6°F)– Controlled by metabolic activity and negative

feedback loops• What happens to enzyme activity if the body gets too

hot? Too cool?

Body’s core temperature.


Change in skin temperature Change in core temperature

peripheral thermoreceptors in skin

central thermoreceptors in hypothalamus, abdominal organs, and elsewhere

hormonal signals from “thermostat” centers in hypothalamus

motor neurons

skeletal muscles

smooth muscle in arterioles in skin

sweat glands

voluntary changes in behavior

muscle tone, shivering

vasoconstriction, vasodilation sweating

adjustments in heat gain or heat loss

adjustments in muscle activity (in metabolic heat output)

adjustment in loss or conservation of metabolic heat

adjustment in heat loss

Figure 4-15 p82


• Hypothalamus- neurons and endocrine cells• Peripheral vasodilation • Activation of sweat glands followed by evaporation of the

sweat• Hyperthermia

– Heat exhaustion– Heat stroke

Excess heat must be eliminated.

Table 4-3 p83


• Hypothalamus• Peripheral

vasoconstriction • Pilomotor response• Non-shivering heat

production and “brown fat”• Hypothermia and frostbite

Several responses counteract cold.

Metabolic activityat 22°C (72°F)

Metabolic activity aftertwo hours at 16°C (61°F)

Figure 4-16 p83

Take home message

How is body temperature regulated?

Table 4-4 p85

cecie starr | beverly mcmillan chapter 4 tissues, organs, and organ systems

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rolesconnective tissue

liningsepithelial tissues

body surface

bodys partsmakes

solid matrix common

stem cellsembryonic

organs function supportfigure

liningsepithelium simple