Studied by 3 peoplehierarchy of structural organization in the body
atoms - molecules - organelles - cells - tissues - organs - organ system - organism
tissues
made of many cells functioning together
organs
made up of many tissues
organ systems
made up of many organs working together
organisms
made up of many organ systems working together
anatomical position
body up right
standing erect facing the observer
heads and eyes facing forward
feet flat on the floor and facing forward
upper limbs to the sides
palms turned forward
superior
toward the head, above
inferior
toward the feet, below
anterior/ventral
toward the front
posterior/dorsal
toward the back
medial
toward the midline
lateral
away from the midline
proximal
near the point of attachment to the body
distal
away from the point of attachment to the body
superficial
close to the surface
deep
far from the surface
ipsilateral
on the same side of the body
contralateral
on opposite side of the body
frontal/coronal plane
divides the body into anterior and posterior parts
horizontal/transverse plane
divides the body into superior and inferior parts
median/sagittal plane
divides the body into left and right parts
parasagittal plane
divides the body into left and right but not perfect halves, uneven
what are the smallest living units in the body?
cells
3 main structural components of cells
plasma membrane
cytoplasm
nucleus
fluid mosaic model
the cell membrane is not a rigid structure but a fluid membrane of phospholipids and embedded proteins
phospholipids
amphipathic, bilayer, 75% of membrane lipids
cholesterol
helps maintain the proper membrane fluidity
glycolipids
assist in cell recognition and adhesion
tight junctions
connects two adjacent cells together with a nearly impenetrable barrier that prevents molecules from passing between them
desmosomes
filamentous junctions between two cells that provide a strong physical linkage between them and withstand stretching without tearing
gap junctions
when two adjacent cells are connected by membrane proteins (connexons) that form small channels between the cells that allow ions and small molecules to pass through
cilia
motile projections that assist in moving the cell or moving items along the surface of the cell, move objects across the surface using wiggling motions
flagella
motile projections that assist in moving the cell or moving items along the surface of the cell, use whip-like motions to move objects along the surface
microvilli
finger-like projections on the outside of the cells whose role is to increase the surface area
ribosomes
site of protein synthesis
mitochondria
the powerhouse of the cell, site of cellular respiration, converts energy stored in the bonds of organic molecules to ATP through redox reactions
endoplasmic reticulum
the network that extends from the nuclear envelope that comes in two forms
rough ER
studded with ribosomes and closest to the nucleus, involved in protein synthesis, cisternae
smooth ER
does not have ribosomes, making or breaking down fats and calcium storage, tubules
golgi apparatus
the part of the cells that receives the products of the ER, modifies, sorts and ships them to the rest of the cell or outside of the cell via transport vesicles
lysosomes
sacs of hydrolytic enzymes that break down large molecules and thus act as the site of intracellular digestion
peroxisomes
responsible for removing toxic wastes by using special enzymes
centrosome
the microtubule organizing center consisting of centrioles, the place where microtubules for cilia and flagella are formed, important role in cell division during mitosis
tissue
a group of cells that live and work together for a common function
extracellular matrix
component of all tissues that gives them their consistency, provides structural and biochemical support to surrounding cells
four main tissue types and their one word function
epithelial - covering
connective - support
muscle - movement
nervous - control
epithelial tissue
found on body surfaces and linings, cells arranged in sheets
a free surface - on surface is always exposed to an area of no cells
cellularity - tightly packed, little extracellular matrix
avascularity - no blood vessels, receives nutrients from other cells and tissues
specialized contacts - specific proteins that allow them to link together tightly
simple squamous epithelium
a single layer of flattened cells with disk-shaped central nuclei and sparse cytoplasm allows passage of materials by diffusion and filtration in sites of no protection
Kidneys, air sacs of lungs, blood vessels, the lining of the heart, lining of the ventral body cavity
simple cuboidal epithelium
a single layer of cubelike cells with large spherical central nuclei, secretion, and absorption
Kidney tubules, ducts of glands, ovary surface
simple columnar epithelium
a single layer of tall cells with round to oval nuclei, some have cilia, a layer may contain goblet cells, absorption, secretion of mucus
nonciliated - lines the digestive tract, gallbladder, excretory ducts
ciliated - lines small bronchi, uterine tubes, uterus
pseudostratified columnar epithelium
a single layer of cells of differing heights, may contain mucus-secreting goblet cells and bear cilia, secretion
nonciliated - sperm-carrying ducts, ducts of large glands
ciliated - lines trachea and upper respiratory tract
stratified squamous epithelium
thick membrane composed of several cell layers, the top layer is squamous, lower layers are active in mitosis, protects underlying tissues in abrasion areas
nonkeratinized - esophagus, mouth, vagina
keratinized - forms the epidermis
stratified cuboidal epithelium
generally two layers of cube-like cells, protection
largest ducts of sweat glands, mammary glands, and salivary glands
stratified columnar epithelium
several cell layers, basal usually cuboidal, protection and secretion
rare in the body, small amounts in making urethra and in some large gland ducts
what is the most abundant and diverse type of tissue?
connective tissue
connective tissue
consists of a small number of cells and a large amount of extracellular matrix and the composition determines the properties
collagen fibers
large, thick, strong, rope-like fibers that provide tensile strength and withstand pulling forces, strongest, abundant, and widest type
elastic fibers
long fibers with intermediate diameter, branch off and form networks that make them stronger, allow the tissue to recoil
reticular fibers
smallest fibers, cluster into networks to become stronger, support
skeletal muscle
longest cells that run the length of the cell, striated, multiple nuclei, involved in voluntary body movements
cardiac muscle
striated, one nucleus, shorter, branched, high protein intercalated discs cellular junctions, only in the heart, involuntary
smooth muscles
not striated, arranged into sheets, center nuclei, propel things along internal pathways, walls of hollow organs, involuntary
nervous tissue
found in the brain, spinal cord and nerves, consists of two types of cells (neurons and neuroglia)
neurons
basic nervous cell, soma (cell body), axon and dendrites
neuroglia/glial cells
support cells for neurons
is the skin an organ?
yes, the skin is an organ because it consists of many types of tissues working together
layers of the skin
epidermis and dermis
epidermis
consists of epithelial tissue
dermis
consists of connective tissue
hypodermis
technically not a part of the skin, loose connective tissue lies deep to the dermis and primarily composed of adipose cells
what cells are hair and nails are made of?
keratinized epidermal cells, keratinocytes
hair shaft
visible portion of the hair
hair root
the portion that penetrates the skin and lies below the skin surface
hair follicle
the sheath surrounding the hair root in the skin
hair bulb
found at the base of the hair follicle
papilla of the hair
indentation of the hair bulb that consists of capillaries, connective tissue, and nervous tissue
arrector pili muscle
small, smooth muscle that attaches to the hair follicle
matrix of the hair follicle
the portion where the cells divide and produce new hair cells
sebaceous gland
skin glands that produce sebum (oily substance) on to the hairs, found a lot in the face and scalp but found everywhere but soles of feet and palms of hands
eccrine sweat glands
exist on the palms of the hands, soles of the feet, and forehead, produce true sweat directly onto the skin that serves to cool the skin during evaporation
apocrine sweat glands
found in anal, genital, and axillary areas, produce milky sweat that is viscous and odorous through the hair follicle ducts, used to neutralize harmful bacteria with its chemicals
periosteum
thick membrane found on the outside of bones that consists of two layers
superficial layer - dense irregular connective tissue
deep layer - osteogenic containing osteoblasts and osteoclasts
perforated fibers/sharpey’s fibers
collagen fibers that wedge themselves into bone tissue and attach the periosteum to the bone, found in greatest numbers where muscles attach
endosteum
thin membrane found on the inside of the bones lining the trabeculae of spongy bone in the medullary cavity, osteon central canals, and epiphyses, osteogenic, highly vascularized
epiphyseal plate
hyaline cartilage grows on the epiphysis side and then replace by bones on the diaphysis side until the cartilage stops growing and this structure is formed
joint
the point at which rigid elements of the skeleton come together
Note
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