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Organization and Regulation of Body
Systems
Tissues:
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Group of similar cells
Connective tissue binds and supports body parts
Muscular tissue moves the body
Nervous tissue receives stimuli and conducts nerve impulses
Epithelial tissue covers body surface and lines body cavities

Cancer:
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Classified according to their tissue from which they start
Sarcomas in muscular or connective tissues (bone and cartilage)
Leukemias in blood
Lymphomas in lymphoid tissue
Carcinomas in epithelial tissue
Cancer Is related to rate of cell division => carcinomas and leukemia are most common since
blood cells and epithelial cells divide quickly

Connective tissue
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Made of: specialized cells, ground substance and protein fibers
Ground substance: noncellular material that separates cells
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Protein fibers:
o White collagen fibers: contain collagen which gives flexibility and strength
o Reticular fibers: thin collagen fibers, highly branched, supporting networks
o Yellow elastic fibers: contains elastin, not as strong as collagen but more elastic
Diseases (inherit genes that do malformed fibers)
o Marfan Syndrom: mutations in the fibrillin gene (FBN1) => decreases in elasticity in
connective tissues
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Fibrous connective tissue:
o Loose (areolar tissue): have fibroblasts separated by jelly ground substance with white
collagen fibers and yellow elastic fibers (Matrix=ground+fibers)
 Supports epithelium and internal organs
 In expanding organs like lungs, bladder and arteries
 Protective cover for blood vessels, nerves and muscles
 Ex
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Little extracellular matrix
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Releases leptin hormone
which regulates appetite
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Dense: contain many collagen fibers
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Supportive connective tissue: like cartilage and bone
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Cartilage more flexible because no minerals in matrix
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Matrix formed by chondroblasts and chondrocytes
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Types:
 Hyaline: common, only fine collagen fibers, glassy translucent appearance
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Fetal skeleton at first then replaced by bone
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 Fibrocartilage: has strong collagen in matrix
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o Bone: most rigid connective tissue
...
collagen) in matrix => rigid
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Matrix
formed by osteoblasts and osteoclasts
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Made of cylindrical structural units called
osteons
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Bone cells in
lacunae between rings
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Thin
extensions of bone cells connect cells to each other and to canal
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Surrounds bone marrow cavity which is
covered by compact bone forming a sandwich
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Solid portions follow lines of stress
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Tissue fluid bathes cells and
removes wastes
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 Red blood cells: small, biconcave, disks, no nuclei
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Hemoglobin has 4 units (each is protein globin and complex iron structure
called heme) which carry Oxygen
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Leukocytes are translucent
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Generalists fight all invaders, ex
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others more specific and produce antibodies to bind and deactivate certain
agents
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Seal damages vessels and injured tissue
helps
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Has WBC
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Absorb fats in small intestine
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Nodes grow when infection
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Muscle fibers contain actin and myosin filaments which interact to move
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Attached by tendons to bones
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Several cells fuse
=> multiple nuclei at periphery of muscle
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Smooth muscles: no striations
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Involuntary
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Slower than skeletal but withstands more
contraction time
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Between smooth and skeletal
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Single central nucleus
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Bound end to end
by intercalated disks (adhesion and gap junctions)
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Function: sensory input, integration
of data and motor output
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Axons covered by myelin,
white fatty substance
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Neuroglia: x9 than neurons
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Might communicate with
neurons and themselves even without extensions
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Epithelial tissue:
Tightly packed cells that form a continuous layer
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Protective function
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Exposed to environment
from one side and bounded by basement membrane (different than plasma membrane) from
other side
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Simple epithelia: single layer of cells
o Squamous: flattened cells
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Allow
exchange of material
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In glands and ovaries and kidneys where urine is formed
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Increase surface area of cells
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o Columnar: cells like rectangular pillars with nuclei at bottom
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Also found in
oviduct
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In
windpipe and trachea
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Smoking makes cilia motion stop => chronic inflammation => bronchitis

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If COLUMNAR or PSEUDOSTRATIFIED secret => called glandular
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Exocrine glands carry secretion to surface like sweat
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Stratified Epithelia: layers of cell piled up
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Outer layer of skin
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When bladder is full, epithelium stretches and outer cells become
squamous (flatten)
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Plays important role in homeostasis
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Epidermis: made of stratified squamous epithelium
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If injury destroys stem cells, skin can’t repair
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Auto
grafting from same person vs
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Skin cells harden because they produce keratin,
waterproof protein => keratinocytes
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A thick layer of
dead keratinized cells forms the finger
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Carotene is another pigment, makes Asians yellow
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Vitamin D escapes skin and regulates calcium and phosphorus in body
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Curable
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Dermis: dense fibrous connective tissues under epidermis
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Both decrease with age and sun
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If temperature rises, vessels dilate and more blood comes to cool
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Loose connective and
adipose to store fat => thermal insulation and padding protection
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Nail, hair and glands are structures of epidermal origin
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They grow from epithelial
cells (nail root)
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Lunela (light part of nail) is due
to thick layer of cells
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o Hair follicles: starts at bulb in dermis and grow through epidermis
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If melanin has iron or sulfur => blond or
ginger
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Air trapped in hair shaft => white
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o Oil glands at hair follicle (sebaceous glands, secretes sebum)
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If blocked by keratinocytes =>
white heads
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Acne is inflammation due to
hormonal changes of the glands
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Activated by high temperature
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Epithelium over loose fibrous connective
tissue
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Mucus protects from bacteria => more is
made when person sick
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Serous: line lungs, heart and abdominal cavity and internal organs
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Support organs and makes compartments
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Pericardium = heart
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(its infection is peritonitis)
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Synovial: loose connective tissue lines free joints
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Lubricates
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Meninges: dorsal cavity
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Infection is
meningitis
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Nervous system sends fast
commands as electrochemical signals
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Positive feedback: change in same direction
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Giving birth to baby and secretion of lubricants
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Negative feedback: prevents change in same direction

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