From Cells to Organ Systems Flashcards
Tissue
▪ Tissue
* A group of cells of similar type that work together to
serve a common function
primary tissue types do humans have
4 types : muscle, nerve, epithelial squamous
Epithelial tissue
Covers the body surfaces
▪ Lines cavities and organs
▪ Forms glands
All epithelial tissues share two structural characteristics: a free surface, a basement membrane
Connective tissue
▪ Provides support and protection for organs
▪ Serves as a storage site for fat
▪ Participates in our immunity
Muscle tissue
for body movement
Nervous tissue
▪ Conducts nerve impulses through the bodyMovement of fluids through the body
▪ The three basic shapes of epithelial cells are suited to their functions
* Squamous epithelium
* Cuboidal epithelium
* Columnar epithelium
▪ These cells can be either
* Simple: a single layer of cells
* Stratified:multiple layers of cells
Epithelial cells
- Squamous epithelium
* Has flattened cells
* Shape allows for diffusion of materials and can provide a slick surface to reduce friction - Cuboidal epithelium
* Hascube-shapedcells
* Specialized for secretion and absorption - Columnar epithelium
* Hastall,column-shapedcells
* Specialized for secretion and absorption
* Lines the small intestine
- A gland is composed of epithelial tissue that secretes
a product
▪ Exocrine gland
▪ Exocrine glands secrete into ducts leading to body surfaces, cavities, or organs (exo: out)
▪ Endocrine gland
▪ Endocrine glands lack ducts and secrete their products, hormones, into spaces just outside the cells but in the body (endo: inside)
(is ther Pancreas an endocrine or a exocrine gland)
Epithelial glands
▪ Cells are contained in an extracellular matrix of protein fibers and ground substance
* Protein fibers
▪ Collagen, elastic, and reticular fibers
▪ Produced by fibroblasts, which are also responsible for tissue repairone
* Ground substance
▪ Non-cellular material
▪ May be solid (bone), fluid (blood), or gelatinous (cartilage)
Connective tissue
Types of connective tissue
▪ Connective tissue proper
* Loose connective tissue (areolar connective tissue, adipose tissue)
▪ Contains many cells and fewer, loosely woven fibers
▪ Cushions organs and provides insulation
▪ Connective tissue proper
* Dense connective tissue (in ligaments, tendons, dermis)
▪ Made of tightly woven fibers
Specialized connective tissue
Cartilage:* Tough but flexible
* Serves as a cushion between bones
* Lacks blood vessels and nerves
▪ Heals more slowly than bone
* Three types differ in flexibility and location
blood: * Liquid matrix of plasma, where elements of red blood cells, white blood cells, and platelets are suspended
* Transports various substances dissolved in plasma
bone: * Protects and supports internal structures
* Facilitates movement along with muscles
* Stores lipids (within yellow marrow), calcium, and phosphorus
* Produces blood cells in red marrow
Muscle
▪ Three types of muscle tissue that vary in structure, location, and whether voluntary or involuntary
* Skeletal * Cardiac * Smooth
▪ Nervous tissue makes up the brain, spinal cord, and nerves
▪ Neurons
* Generate nerve impulses and conduct them to other neurons, muscle cells, or glands
▪ Neuroglia
* Support, insulate, and protect neurons
Nervous tissue
Cell Attachments Between cells
- Creates an impermeable junction that prevents the exchange of materials between cells
- Found between epithelial cells of the digestive tract, where they prevent digestive enzymes and microorganisms from entering the blood
ADHESION JUNCTION:
Holds cells together despite stretching
* Found in tissues that are often stretched, such as the skin and the opening of the uterus
GAP JUNCTION:
* Allows cells to communicate by allowing small molecules and ions to pass from cell to cell
* Found in epithelia in which the movement of ions coordinates functions, such as the beating of cilia; found in excitable tissue such as heart and smooth muscle
▪ Have small holes connecting the cytoplasm of adjacent cells
▪ Found between cardiac muscle cells
Organs
▪ Organs
* Composed of two or more different tissues that work
together to perform a specific function
- Composed of organs with a common function
- There are eleven major organ systems in the human body
Organ system
▪ The integumentary system is composed of
* Skin
* Derivatives of the skin
▪ Hair
▪ Nails
▪ Sweat glands
▪ Oil glands
▪ Wax glands
▪ The skin is our largest organ
Skin: An organ system
Functions of the skiN
- Protects against bacterial invasion, UV radiation, and physical and chemical stress
- Prevents water loss
- Regulates body temperature
- Synthesizes vitamin D
- Receives stimuli
The layers of the skin
- Epidermis (epi: on, over)
▪ Thin outer layer - Dermis
▪ Thicker inner layer containing nerves, blood vessels, and glands - Hypodermis or subcutaneous layer
▪ Layer of loose connective tissue just below the epidermis and dermis
Epidermis
▪ The epidermis consists of several layers of epithelial cells
* Outer surface is made up of dead skin cells
* Deepest layer composed of rapidly dividing cells
▪ No blood vessels
* Cells receive nourishment from the dermis but die as
they move toward the surface
▪ Protective properties come from keratin
▪ The epidermis gives rise to diverse structures
* Hair
* Nails
* Oil glands
* Sweat glands
* Waxglands
* Teeth
▪ The dermis consists primarily of connective tissue
* Has blood vessels, nerves, glands, and hair follicles
* Does not wear away
* Collagen and elastic fibers are found in the lower layer, which allows the skin to stretch and return to its original shape
Dermis
Hypodermis
▪ Hypodermis also called subcutaneous level
▪ Anchors skin to the tissues of other organ systems
that lie beneath
▪ Functions:
* Protection
* Temperatureregulation
* Fat storage
▪ Not usually considered part of the skin
▪ Skin color is determined by melanin
bloodflow
- Distribution and quantity of the pigment melanin
▪ Melanin - Produced by melanocytes at the base of the epidermis
- Comes in two forms
▪ Yellow-to-red
▪ Black-to-brown - In tanning, the melanocytes respond to UV radiation by increasing production of melanin
Homeostasis is the constant adjustment made by the organ systems to respond to changes in the internal and external environments while limiting too large variations of the internal condition required for life
* Depends on the nervous and endocrine systems, which are mostly responsible for internal communication
* Maintained primarily through negative feedback mechanisms
▪ Negative feedback mechanisms
* Corrective measures that slow or reverse variation
from a normal value
* Once the normal value is reached, corrective measures cease
▪ Negative feedback mechanisms
▪ Homeostatic mechanisms have three components
* Receptor that detects a change in the internal or external environment
* Control center (such as the brain) that integrates the information coming from all receptors and selects an appropriate response
* Effector (such as a muscle or gland) that carries out the response
Homeostasis
Hypothalamus and body temperature
▪ An example of homeostatic regulation of body temperature by negative feedback mechanisms
▪ In this system
* Receptors=thermoreceptors
* Control center = hypothalamus, a region of the brain
* Effectors = sweat glands, blood vessels in the skin, as well as skeletal muscles
