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73 terms

Human Biology Chapter 4

From Cells to Organ Systems
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Epithelial Tissues
consist of sheets of cells that line or cover various surfaces and body cavities
ex: (skin, lining of the mouth, inner surface of digestive track, lungs, bladder, blood vessels, and tubules of kidnesy
Glands (glandular epithelia)
form the body's glands. epithelial tissues that are specialized to synthesize and secrete a product.
Exocrine glands
(exo- means "outside" or "outward") secrete their products into a hollow organ or duct.
ex: secrete saliva, sweat glands in your skin, and glands in your stomach that produce digestive acid.
Endocrine Glands
(endo- means "within") secrete substances called hormones into the blood stream.
ex: thyroid gland, which secretes several hormones that help your body's growth and metabolism.
tissues
groups of specialized cells that are similar in structure and that perform common functions.
4 major types of tissues
1. Epithelial
2. Connective
3. Muscle
4. Nervous
Squamous epithelium
consists of one or more layers of flattened celled. (squama means "platelike") (appears "squashed flat"
- forms outer surface of skin and lines the inner surfaces of the blood vessels, air sacs of the lungs, mouth and throat and vagina
- permits exchange of nutrients, wastes, and gases.
cuboidal epithelium
composed of cube-shaped cells
- forms the kidney tubules, glands, and covers the surface of the ovaries
- secretes and reabsorbs water and small molecules.
Columnar Epithelium
composed of tall, rectangular (column-shaped) cells.
- lines parts of the digestive tract, certain reproductive organs, and the larynx
- goblet cell within the simple columnar secrete mucus, a thick fluid that lubricates the tissues and traps bacteria, viruses, and irritating particles.
- absorbs nutrients, produces mucus.
Stratified squamous
- outer layer of skin, mouth, vagina
- protects against abrasion, drying out infection
Stratified cuboidal
- Lines ducts of sweat glands
- secretes water and ions
Stratified columnar
- lines epididymus, mammary glands, larynx
- secretes mucus
Basement membrane
directly beneath the cells of an epithelial tissue is a supporting non-cellular layer
cell junctions
1. tight junction
2. Adhesion junctions
3. Gap junctions
Tight junctions
- form leak-proof seals between cells.
- tight junctions are particularly important in epithelial layers that must control movement of substances into or out of the body.
- cells that line the digestive tract (which bring in nutrients), bladder (which stores urine), cells that form the tubules of the kidneys (which remove waste products from the body)
Adhesion junction
-sometimes called spot desmosomes
-looser in structure
- protein filaments of adhesion junctions
- allows for some movement between cells, gives the tissues the ability to stretch and bend
- found in the epithelium of your skin
Gap Junctions
represent connecting channels mad of ptoteins the permit movement of ions or water between two adjacent cells
-found in the epithelial cells in the liver, heart and some muscle tissue
Connective tissue
supports the softer organs of the body against gravity and connects the parts of the body together.
Collagen fibers
made of protein, confer strength and are slightly flexiable.
Elastic Fibers
most fibrous connective tissues also contain thinner coiled elastic fibers, made primarily of the protein elastin, which can stretch without breaking.
Fibrous Connective Tissue
1. Loose
2. Dense
3. Elastic
4.. Reticular (lymphoid)
Specialized Connective Tissues
1. Cartilage
2. Bone
3. Blood
4. Adipose tissue
Loose Fibrous Connective Tissue
- also called areolar connective tissue
- Mostly collagen and elastin fibers in no particular pattern; more ground substance
- Flexible but only moderately strong
- Surrounds internal organs, muscles, blood vessels
Dense Fibrous Connective Tissue
- Mostly collagen in a parallel arrangement of fibers; less ground substance.
- Strong
- In tendons, ligaments, and lower layers of skin.
Elastic Fibrous Connective Tissue
- High proportion of elastin fibers
- Stretches and recoils easily
- Surrounds hollow organs that change in shape or size regularly
Reticular (lymphoid) Fibrous Connective tissue
- Mostly thin, interconnecting reticular fibers of collagen
- Serves as a flexible internal framework.
- In soft organs such as liver, spleen, tonsils, and lymph glands.
Specialized Connective Tissues - Cartilage
- Primarily collagen fibers in a ground substance containing a lot of water
- Maintains shape and resists compression
- Embryonic tissue that becomes bone. Also the nose, vertebral disks, and the lining of joint cavities.
Specialized Connective Tissues - Bone
- Primarily hard mineral deposits of calcium and phosphate.
- Very Strong
- Forms the skeleton
Specialized Connective Tissues - Blood
- Blood cells, platelets, and blood fluid called plasma
- Transports materials and assists in defense mechanisms
- Within cardiovascular system
Specialized Connective Tissues - Adipose Tissue
- Primarily cells called adipocytes filled with fat deposits
- Stores energy in the form of fat
- Under the skin, around some internal organs.
Reticular Fibers
Fibrous connective tissue contains thin fiber of collagen, called reticular fibers, that interconnect with each other
Fibroblasts
are the cells responsible for producing and secreting the proteins that compose the collagen, elastic, and reticular fibers.
Muscle Tissue
Consists of cells that are specialized to shorten, or contract, resulting in movement of some kind.
Muscle tissue is composed of tightly packed cells called muscle fibers.
Skeletal muscle tissue
Connects to tendons, which attach to bones.
When skeletal muscles contract, they cause body parts to move.
The individual fibers are thin cylinders.
Cardiac muscle tissue
(Greek kardia, the heart) is found only in the heart. The individual cells are much shorter than skeletal muscle fibers, they only have one nucleus.
Arranged parallel to each other.
Smooth muscle tissue
surrounds hollow organs and tubes, including blood vessels, digestive tract, uterus, and bladder.
These slim cells are much smaller than skeletal muscle cells, and have only one nucleus, like cardiac muscle.
Nervous tissue
consists primarily of cells that are specialized for generating and transmitting electrical impulses throughout the body.
Neurons
Nervous tissue cells that generate and transmit electrical impulses are called neurons.
1. the cell body - where the nucleus is located
2. dendrites - numerous cytoplasmic extensions the extend from the cell body and receive signals from other neurons
3. axon - the long extension the transmits electrical impulses over long distances
Glial cell
another type of nervous tissue that does not transmit electrical impulses.
Organs
structures composed of two or more tissue types joined together that perform a specific function or functions.
Organ systems
groups of organs that together serve a broad function that is important to survival either of the individual organism (such as respiration, movement, or excretion of waste) or of the species (reproduction).
Integumentary System
-Protects us from injury, infection, and dehydration
-Participates in temperature control
-Receives sensory input from the external environment.
Skeletal System
-Protects, supports, and anchors body parts
-Provides the structural framework for movement
-Produces blood cells
-Stores minerals
Muscular system
-produces movement or resists movement
-Generates heat
nervous system
-Detects both external and internal stimuli
-Controls and coordinates rapid responses to these stimuli
-integrates the activities of other organ systems.
Endocrine system
-Produces hormones that regulate many body functions
-participates with the nervous system in integrative functions
Digestive system
-Provides the body with water and nutrients
-(the liver) synthesizes certain proteins and lipids for the body
-(the liver) inactivates many chemicals, including hormones, drugs, and poisons.
Circulatory system
-transports materials to and from all cells
-participates in the maintenance of body temperature
-participates in mechanisms of defense against disease and injury.
Lymphatic system
-returns excess tissue fluid to the circulatory system
-participates in both general and specific (immune) defense responses
Respiratory system
-Exchanges gases (oxygen and carbon dioxide) between air and blood.
-Participates in the production of sound (vocalization)
Urinary system
- Maintain the volume and composition of body fluids
- excretes some waste products
Reproductive system
- Female: Produces eggs
-Female: Nurtures the fertilized egg, developing embryo, and fetus until birth
-Male: Produces sperm
-Male: Participates in the delivery of sperm to the female
Tissue Membranes
consisting of a layer of epithelial tissue and a layer of connective tissue line each body cavity and form our skin.
1. Serous membranes
2. Mucous membranes
3. Synovial membranes
4. Cutaneous membrane
Serous membranes
line and lubricate body cavities to reduce friction between internal organs
Mucous membranes
line the airways, digestive tract, and reproductive passages. Goblet cells within the epithelial layer secrete mucus, which lubricates the membrane's surface and entraps foreign particles.
Synovial membranes
Line the very thin cavities between bones in movable joints. These membranes secrete a watery fluid that lubricates the joint.
Cutaneous membrane
Our outer covering. known as the skin and it serves several functions.
integumentary system
(form the Latin integer, meaning "to cover"). the proper name fo rthe skin and it accessory structures such as hair, nails, and glands.
Epidermis
the outer layer of the skin's epithelial tissue
Dermis
the inner layer of connective tissue
Hypodermis
(hypo- means "under"), consisting of loose connective tissue containing fat cells. This is a supportive layer which supports the dermis and epidermis.
Keratinocytes
the more numerous of the two types of skin cells. the cells produce a tough, waterproof protein called keratin. sometimes called basal cells
Melanocytes
less numerous cells, located near the base of the epidermis produce a dark-brown pigment called melanin.
Papillae
the surface of the dermis has many small projections called papillae that contain sensory nerve ending and small blood vessels.
Internal environment
the environment that surrounds the cells of a multicellular organism (their external environment)
interstitial fluid
the internal environment if a clear fluid. (the Latin noun interstitium means "the space between", in this case the space between cells)
Homeostasis
relative constancy of the conditions within the internal environment. (homeo- means "unchanging" or "the same" and -stasis means "standing")
Negative feedback
in living organisms, homeostasis is maintained by negative feedback control systems
controlled variable
a controlled variable is any physical or chemical property that might vary from time to time and that must be controlled to maintain homeostasis.
Sensor
(or receptor). the sensor monitors the current value of the controlled variable and sends the information (via either nerves or hormones) to the control center.
Control Center
the control center receives input from the sensor and compares it to the correct, internally set value of the controlled variable, this is sometime called the set point. Signals are sent via either nerves or hormones.
effector
the effector takes the necessary action to correct the imbalance, in accordance with the signals it receives from the control center
hypothalamus
a neural struture lying below the thalamus; it directs several maintenance activities, helps govern the endocrine system via the pituitary gland, and is linked to emotion
Positive feedback
control systems are relatively uncommon in living organisms. In positive feedback, a change in the controlled variable sets in motion a series of events that amplify the original change, rather that returning it to normal.