HUMAN ORGANIZATION

The Structural Organization of Animals

•  Individual cells are grouped into tissues (cardiac muscle). •  Tissues combine to form organs (heart). •  Organs are organized into organ systems (circulatory system). •  Organ systems make up the entire organism (the woman!).

1. TISSUES In most multicellular animals, cells are grouped into tissues. A tissue is composed of similarly specialized cells that perform a common function in the body

•  4 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

A. Epithelial Tissue – Consists of tightly packed cells that form a

continuous layer

– Numerous functions •  Usually protective

•  Secretion

•  Absorption

•  Excretion

•  Filtration

Epithelial Tissue Can Be Classified according to: – Cell Shape:

• Squamous: flattened cells • Cuboidal: cubed-shaped cells • Columnar: cells resembling rectangular

pillars or columns – the Number of Layers in the Tissue

• Simple: Single layer of cells • Stratified: Multiple cell layers • Pseudostratified: appears to be layered

but each cell touches basement membrane

Glandular epithelium secretes a product

•  Gland: can be single or multiple cells – Exocrine glands – secrete products into

ducts (“exit body”)

– Endocrine glands – secrete product into bloodstream (stay in body)

Example: Pancreas is both an exocrine and endocrine gland

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basement membrane

• lining of lungs, blood vessels • protects

© Ed Reschke

Simple squamous

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cilia

• lining of trachea • sweeps impurities toward throat

goblet cell secretes mucus

basement membrane

© Ed Reschke

Columnar Pseudostratified

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• skin (epidermis) • lining of nose, mouth, esophagus, anal canal, vagina • protects

© Ed Reschke

Stratified Squamous

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basement membrane

goblet cell secretes mucus

• lining of small intestine, oviducts • absorbs nutrients

© Ed Reschke

Simple Columnar

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• lining of kidney tubules, various glands • absorbs molecules

basement membrane

© Ed Reschke

Simple Cuboidal

Which of these epithelial tissue is simple cuboidal?

A B C

Which of these epithelial tissue is simple columnar?

A B C

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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

© Ed Reschke

B. Connective Tissue Functions

– Binds organs together – Provides support and protection – Fills spaces – Produces blood cells – Stores fat

B. Connective Tissue Connective tissues have a sparse population of cells scattered through an extracellular matrix. The matrix consists of a web of molecules that "glue" the cells together in the connective tissues The structure of connective tissue correlates with its function. It binds and supports other tissues.

Components of Connective Tissue

– Matrix: noncellular material - solid, semisolid, or liquid

– Fibers: collagen, elastic, reticular – Cells: various types

•  Loose fibrous connective tissue –  Supports epithelium and many internal organs –  Forms a protective covering enclosing many internal

organs

•  Dense fibrous connective tissue –  Contains many collagen fibers –  Found in structures such as tendons and ligaments

•  Both types have cells called fibroblasts separated by a jellylike matrix with collagen and elastic fibers

Loose connective tissue (under the skin)

Blood

Adipose Tissue Fat droplets

Fibrous connective Tissue (tendons)

Cartilage (at the end of the bone)

Bone

1. Loose connective tissue: –  is the most widespread connective tissue. –  It binds epithelia to underlying tissues. –  It holds organs in place.

2. Blood: –  is a connective tissue with a matrix of liquid. – Red and white blood cells are suspended in

plasma.

3. Fibrous connective tissue: – has a dense matrix of collagen. –  It forms tendons and ligaments.

5. Cartilage –  Its matrix is strong but rubbery. –  It functions as a flexible, boneless skeleton. –  It forms the shock-absorbing pads that cushion

the vertebrae of the spinal column.

6. Bone: –  is a rigid connective tissue with a matrix of rubbery fibers hardened with deposits of calcium.

4. Adipose tissue stores fat: –  It stockpiles energy. –  It pads and insulates the body.

Blood

– Unlike other types of connective tissue in that the matrix (i.e., plasma) is not made by the cells

– Functions 1.  Transports nutrients and oxygen and removes

carbon dioxide and wastes 2.  Helps distribute heat 3.  Plays role in fluid, ion and pH balance 4.  Protects us from disease 5.  Blood clotting protects against fluid loss

Components of Blood – Plasma – 55% of volume •  Variety of inorganic and organic substances dissolved or

suspended in water – Formed elements – 45% of volume

•  Red Blood Cells (erythrocytes) » Contain hemoglobin for transport of oxygen

•  White Blood Cells (leukocytes) »  Fight infection

•  Platelets (thrombocytes) » Cell fragments involved with blood clotting

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a. Blood sample plasma

white blood cells

plasma

Formed elements: white blood cells and platelets Red blood cells

platelets

red blood cell

b. Blood smear

C. Muscular Tissue

• Muscle tissue consists of bundles of long, thin, cylindrical cells called muscle fibers. • Each cell has specialized proteins that contract when the cell is stimulated by a nerve.

– Muscles fibers contain actin and myosin filaments

•  Interaction accounts for movements

There is 3 kinds of muscle Tissue:

2. Skeletal muscle

1. Cardiac muscle

3. Smooth muscle

2. Skeletal muscle: –  is attached to bones by tendons. –  It is responsible for voluntary movements. – The contractile apparatus forms a banded

pattern in each cell or fiber. –  It is said to be striated, or striped.

1. Cardiac muscle: –  is found only in heart tissue. –  Its contraction accounts for the heartbeat.

3. Smooth muscle –  is named for its lack of obvious striations. –  It is found in the walls of various organs. –  It is involuntary.

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400 ×

a. c.

250 × 250 ×

• has branching, striated cells, each with a single nucleus. • occurs in the wall of the heart. • functions in the pumping of blood. • is involuntary.

intercalated disk nucleus

• has cells with a single nucleus. • cells have no striations. • occurs:

•  in blood vessel walls • walls of the digestive tract.

• functions in movement of substances in lumens of body. • is involuntary.

nucleus smooth muscle cell

nucleus striation

• has striated cells with multiple nuclei. • occurs in muscles attached to skeleton. • functions in voluntary movement of body.

b. a, c: © Ed Reschke; b: © The McGraw- Hill Companies, Inc./Dennis Strete, photographer

Skeletal muscle Smooth muscle Cardiac muscle

D. Nervous Tissue Nervous tissue makes communication of sensory information possible.

• Sensory input is received and processed. • Motor output is then relayed to make body

parts respond. Nervous tissue is found in the brain and spinal cord. The basic unit of nervous tissue is the neuron, or nerve cell. Neurons can transmit electrical signals rapidly over long distances.

•  Dendrites •  Cell body •  Axon – may have myelin sheath to increase

speed

Neuron structure

Dendrite (receives signals)

nucleus

cell body

Neuron

Astrocyte (provide nutrients) Microglia

(engulf bacterial and cellular debris) Oligodendrocyte

(forms myelin sheaths) myelin sheath (increase speed)

Axon (sends signals)

Capillary

a. Neuron and neuroglia

b. Micrograph of a neuron

b: © Ed Reschke

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200 x

2. Body Cavities

– Ventral Cavity or Coelom •  Thoracic cavity – Lungs and heart •  Abdominal cavity

– Separated from thoracic cavity by diaphragm – Stomach, liver, spleen, gallbladder, and most of

the small and large intestines •  Pelvic cavity

– Bladder, rectum, internal reproductive organs

– Dorsal Cavity •  Cranial cavity - Brain •  Vertebral canal - Spinal cord

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Dorsal cavity

Cranial cavity

Thoracic cavity

Ventral cavity

Abdominal cavity

Pelvic cavity

vertebrae

spinal cord

diaphragm

Vertebral canal

Body Membranes

Line cavities and the internal spaces of organs and tubes that open to the outside

1.  Mucous membranes 2.  Serous membranes 3.  Synovial Membranes 4.  Meninges

Mucous Membranes

•  Line tubes of the digestive, respiratory, urinary, and reproductive systems

•  Epithelium overlies loose fibrous connective tissue

•  Goblet cells produce mucus – Protective function

Serous Membranes •  Line thoracic and abdominal cavities

•  Epithelium and loose fibrous connective tissue

•  Secrete watery fluid for lubrication •  Specific names according to location

– Pleurae- lines thoracic cavity and lungs – Pericardium-encloses heart – Peritoneum- lines abdominal cavity and covers

organs •  Mesentery supports abdominal organs and attaches

them to abdominal wall

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peritoneum

pleura

pericardium

3. Synovial membranes • Loose connective tissue • Line freely movable joints • Secrete synovial fluid

4. Meninges • Line the dorsal cavity • Protect brain and spinal cord • Connective tissue

3. ORGANS

The next level in the structural hierarchy is the organ.

– An ORGAN consists of 2 or more tissues packaged into one working unit that performs a specific function.

– Examples: heart, liver, stomach, brain, and lungs

Example of an Organ: THE SMALL INTESTINE

Epithelial Tissue

Connective Tissue (blood and lymph vessels)

Smooth muscle Tissue (2 layers)

Connective Tissue Epithelial Tissue

The organs of humans and most other animals are organized into organ systems. Organ systems are teams of organs that work together to perform a vital bodily function.

4. ORGAN SYSTEMS

Which of the following are listed in the correct hierarchical order, from least complex to most complex? A) cell, tissue, organ B) tissue, organ, cell C) organ, tissue, cell D) cell, organ, tissue E) tissue, cell, organ

A

Groups of cells that perform a similar function are known as: A) organs. B) organ systems. C) control centers. D) organisms. E) tissues.

A

Blood is a type of: A) epithelial tissue. B) muscle tissue. C) collagen. D) connective tissue. E) nerve tissue.

D

Which organ system is NOT essential for survival of an individual? A) digestive system B) respiratory system C) muscular system D) nervous system E) reproductive system

E

The skin is an example of a(n): A) organ. B) cell. C) ligament. D) tissue. E) organ system.

A

Muscular system Endocrine system

Integumentary system • protects body. • receives sensory input. • helps control temperature. • synthesizes vitamin D.

• ingests food. • digests food. • absorbs nutrients. • eliminates waste.

Digestive system Cardiovascular system • transports blood, nutrients, gases, and wastes. • helps control tempe rature, fluid, and pH balance .

Urinary system

• excretes metabolic wastes. • helps control fluid balance. • helps control pH balance.

Respiratory system

• maintains breathing. • exchanges gases at lungs and tissues. • helps control pH balance.

• helps control fluid balance. • absorbs fats. • defend against infectious disease.

Lymphatic and immune systems

Reproductive system • produces gametes. • transports gametes. • produces sex hormones. • in females, nurtures and gives birth to offspring.

• produces hormones. • helps coordinate organ systems. • responds to stress. • helps regulate fluid and pH balance. • helps regulate metabolism.

Nervous system • receives sensory input. • integrates and stores input. • initiates motor output. • helps coordinate organ systems.

Skeletal system • supports the body. • protects body parts. • helps move the body. • stores minerals. • produces blood cells.

• maintains posture. • moves body and internal organs. • produces heat.

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