Anatomy - the study of the structure of body parts & their relationship to one
another
Physiology - the study of the function of the body's structural machinery
Fields: Renal Physiology is the study of kidney function; Neurophysiology is the study of nervous system function...
Principle of
complementarity of structure & function: the function of structure depends on its structural form
Levels of Structural
Organization in Organisms:
Chemical Level: Atoms/Elements
(carbon, hydrogen, oxygen, sodium...)
Molecules/Compounds
(sugar, salt, water...)
Macromolecules
(proteins, lipids, carbohydrates, nucleic acids)
Organelles
(mitochondrion, nucleus, plasma membrane...)
Tissue Level
Organ Level
Organ System Level
Organismal Level
Anatomical Position: standing straight, facing forward with feet slightly
apart, arms at sides & palms of the hands facing forward.
Know the definitions of
& be able to apply:
Anatomical Terms - see textbook
Planes & Sections of the
body - see textbook
Know the location of each
of the following. Also know the
subdivisions where appropriate (for example: the pleural cavity is within the
thoracic cavity, which in turn is within the ventral body cavity).
Dorsal Body Cavity
-
Cranial cavity
-
Vertebral or Spinal cavity
Ventral Body Cavity
-
Thoracic cavity
-
Abdominopelvic cavity
Abdominopelvic Quadrants
Organ Systems:
-
Integumentary System (chapter 5): skin & accessory organs
-
Support & Movement
o Skeletal System (chapter 6)
o Muscular System (chapter 7)
-
Integration &
Coordination
o Nervous System (chapter 8)
o Sense Organs (chapter 9)
o Endocrine System (chapter 10)
-
Maintenance of the Body
o Circulatory System (chapter 12)
o Lymphatic System (chapter 13)
o Respiratory System (chapter 14)
o Digestive System (chapter 15)
o Urinary System (chapter 16)
-
Reproduction &
Development
o Reproductive System (chapter 17)
Negative Feedback: the product or response shuts off or reduces the
level of the original stimulus; the variable then changes in a direction
opposite the initial change
Examples of negative
feedback mechanisms: regulation of
body temperature, the withdrawal reflex, regulation of blood glucose levels by
the hormones insulin & glucagons
Positive Feedback - the product or response enhances or exaggerates he
original stimulus such that the response is continued
Examples of positive
feedback mechanisms: blood clotting,
labor contractions during birth
Homeostatic Imbalance - some lack of ability to activate/carry out control
mechanisms - age is one factor
-
matter is composed of elements
-
states of matter: solid, liquid
or gas
Elements are composed of atoms
Atoms are composed of subatomic particles:
-
protons (+ charge)
-
neutrons (no charge)
-
electrons (- charge)
The atomic number of an atom = the number of protons in its nucleus
-
the periodic table is grouped
according to atomic number (Hydrogen (H) has an atomic number of 1, Helium (He)
has an atomic number of 2...)
The atomic mass (mass number) of an atom is the number of protons + the number
of neutrons in its nucleus
-
the mass of electrons is
negligible
-
Hydrogen (H) has a mass number
of 1 (no neutrons), Helium (He) has a mass number of 4...
The atomic weight of an element is the average of the relative weights
of all the isotopes of that
element (the atomic weight of Hydrogen is 1.008).
Isotopes are atoms of an element that have the same number of
protons (atomic number) but different mass numbers (different numbers of
neutrons).
-
Examples: 12C,
13C, 14C
-
Radioactive isotopes are unstable isotopes that spontaneously decay into
more stable forms (it can take up to thousands of years for half the atoms in
an element to decay to the stable state)
-
Radioactivity can be
detected with scanning devices, & radioisotopes can be incorporated into
biological molecules...this makes radioisotopes useful tools for biological
research & medicine).
Carbon (C), Oxygen (O),
Hydrogen (H) & Nitrogen (N) make
up > 96% of the mass of a person
-
other elements in the human
body: Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), Sodium (Na),
Chlorine (Cl), Magnesium (Mg), Iron (Fe), Iodine (I)...
Molecules: 2 or more atoms held together by chemical bonds
-
when 2 or more atoms of the same element bind, they form a molecule
of that element
-
when 2 or more different atoms bind, they form one molecule of a compound
Chemical Bonds:
Electrons
of an atom differ in amount of potential (stored)
energy
-
electrons closest to the nucleus have the least potential energy (nonbonding electrons)
-
electrons farthest
from the nucleus have the greatest potential energy (valence or bonding electrons)
First
energy level can contain a maximum
of 2 bonding electrons
Second energy level, and all additional energy levels, can contain a maximum
of 8 bonding electrons
Octet rule: except for the first energy level, the
outermost energy level is most stable when it has 8 bonding electrons
(the first energy level is most stable with its maximum of 2 bonding electrons)
Bonding:
Ionic Bonding: transfer of electrons from one atom to another
-
results in ions: charged particles resulting from charge
imbalance
(greater or fewer electrons than protons) due to electron transfer
-
Examples: NaCl,
MgCl2, Na2O
-
Chemical formulas of compounds
based on # of valence electrons
(example: from above: MgCl2,
Mg has 2 valence electrons to donate, while Cl can
only accept 1, so two Cl atoms are needed to accept the 2 valence electrons
donated by one Mg atom)
Covalent bonding: sharing of electrons between 2 or more atoms
-
each atom acquires an octet of
valence electrons (electrons in outermost shell). Examples: CH4,
O2, H2, C6H12O6
-
water, H2O is formed by a polar covalent bond (unequal sharing
of electrons)
Hydrogen Bonding:
-
bond between a slightly
positive hydrogen atom of one molecule, and a slightly negative atom (usually oxygen or nitrogen)of the same or another molecule
-
weak bonding compared to ionic and covalent bonding, but
many bonds increases strength
-
good example is water
molecules
Biochemistry:
Inorganic Molecules:
Molecules which do not contain carbon and hydrogen (e.g.: salts, strong
acids and bases, metal compounds)
- usually ionic-bonding
Characteristics of Water:
-
resists changes in temperature (in part due to hydrogen bonding)
-
water has a high heat of
vaporization
⋅ high boiling point (100 degrees Celsius)
⋅ energy needed to break hydrogen bonds
⋅ water absorbs a lot of heat before evaporating
releases heat as it cools - helps keep body temperature constant
-
water is cohesive (water molecules stick together, also due to hydrogen
bonding)
⋅ cohesiveness allows water to fill tubular vessels in
body to transport & distribute molecules
-
water is the universal
solvent:
a. ionic
compounds : salts
b. polar covalent compounds
-
water dissociates or ionizes to release hydrogen ions and hydroxide ions
Electrolytes: substances that ionize, or break apart & release ions, when put into water
-
Acid:
molecules that release hydrogen ions (H+) when dissolved in
water
-
acids are hydrogen ion
(proton) donors
-
Base:
molecules that release hydroxide (OH-) ions , or increase the
number of hydroxide ions available, when dissolved in water
-
bases are hydrogen ion
(proton) acceptors
-
Salt: ionically-bonded molecule that dissociates into
cations & anions in solution
-
in the body, salts are electrolytes
that conduct electricity (important for nerve & muscle cells) & provide
essential chemical elements in body fluids (blood, lymph & interstitial
fluids)
pH scale (power of hydrogen): indicates acidity or basicity of
solution
-
ranges from 0 (strong acid) to
14 (strong base)
-
pH < 7 is acidic; pH > 7
is basic; pH = 7 is neutral
-
water ionizes to release equal numbers of hydrogen ions and
hydroxide ions (neutral)
Buffers:
maintain stable pH of solution (resist changes in pH)
-
Buffers can take up excess
hydrogen or hydroxide ions
-
Buffers have acidic and basic components
-
Blood uses carbonic acid (acidic) - bicarbonate ion (basic) buffer system
-
normal pH of blood is between
7.35 & 7.45
-
acidosis: blood pH < 7.35
-
alkalosis: blood pH > 7.45
-
Bicarbonate ions take up added
hydrogen ions, and carbonic acid takes up excess hydroxide ions
Organic Molecules: Carbon-based molecules
- Carbon
atoms are bonded mainly to atoms of hydrogen, oxygen,
and nitrogen, as well as some other atoms
- Always contain carbon and hydrogen
-
Always covalent-bonding
Synthesis &
degradation reactions used by organic macromolecules (carbohydrates, proteins, lipids, & nucleic
acids)
-
Dehydration synthesis
(condensation) reactions: formation
of a bond with removal of
water
-
Hydrolysis reactions: breaking of a bond by the addition of water
Carbohydrates: (contain carbon, hydrogen, and oxygen atoms)
Monosaccharides: simple
sugars with a backbone of 3 to 7 carbon atoms
-
Glucose is a 6-carbon sugar (hexose) found in the blood of animals, and Fructose is a hexose found in fruits
-
Ribose is a 5 carbon sugar (pentose) found in RNA (in DNA,
the pentose sugar is deoxyribose)
Disaccharides: 2 monosaccharides joined by condensation
-
Maltose (a disaccharide in the digestive tract) = glucose
+ glucose
-
Lactose ( a disaccharide in milk) = glucose + galactose (another hexose)
-
Sucrose (a disaccharide in fruits & vegetables) =
glucose + fructose
Polysaccharides:
-
Glycogen is a highly branched polymer of glucose, and is the storage form of carbohydrates in animal
cells (stored in liver cells)
-
Starch is a more moderately branched polymer of glucose, and is the storage form of carbohydrates in plant
cells
-
Cellulose is an unbranched polymer of glucose,
with adjacent chains held together by hydrogen bonds, giving it a very rigid structure. It is the major structural component of
plant cell walls
Lipids:
In
the form of neutral fats (fats or oils)
One
triglyceride = Glycerol + 3 fatty acids
-
Glycerol has 3 carbon atoms and 3 hydroxyl groups
-
Fatty acids have a long hydrocarbon (carbon + hydrogen) chain
with a carboxylic acid group at one end
-
Condensation joins a fatty acid to each of the hydroxyl groups in
glycerol
-
The condensation reaction
removes the ionizable functional groups from fatty acids and glycerol; hence,
these molecules are very hydrophobic
Saturated
fatty acids: each carbon atom in
the fatty acid molecules have the maximum number of bonded hydrogen
atoms (each carbon is saturated
with hydrogen atoms); there are no C=C double bonds
Unsaturated
fatty acids: one or more carbon
atoms in the fatty acid molecule has less than the maximum number of
bonded hydrogen atoms; there are one or more C=C double bonds
In
animal cells, neutral fats are in
the form of fats
-
fats are solid at room
temperature
-
fats contain more saturated
fatty acids
In
plant cells, neutral fats are in
the form of oils
-
oils are liquid at room
temperature
-
oils contain more unsaturated
fatty acids
Phospholipids = Glycerol + 2 fatty acids + 1 polar (phosphate-containing) head group (instead of
third fatty acid in triglyceride)
-
allows molecules to have hydrophobic end (2 fatty acids) and hydrophilic (phosphate) end
-
these molecules are the subunits of biological membranes in cells (e.g.: plasma membrane): the polar head group is in contact with
water on the inside and outside of the cell, and the hydrophobic fatty acid
chains are buried in the center of the membrane
Steroids are composed of 4 fused carbon
rings plus some variable
functional side group
-
Cholesterol is a structural
component of the plasma membrane
in animals, and is used in the synthesis of vitamin D and bile salts
-
Cholesterol is a precursor form of steroid that is modified to
produce several other types of steroids
-
Steroids function as hormones in animal cells
-
Accumulation of large amounts
of these bulky molecules in animals can lead to reduced blood flow and
hypertension (high blood pressure)
Proteins:
Proteins are composed of chains of amino acid monomers
-
There are 20+ different amino acids in cells of living organisms
-
Amino acids have a basic
core structure plus an
additional functional side chain
-
Each amino acid has a central
carbon bonded to an amino group,
a carboxylic acid group, a hydrogen
atom, and the remaining side chain (R
group); it is the R group that
differs in different amino acids
-
R groups can be nonpolar & hydrophobic, or polar
& hydrophilic, depending on the
atoms present
-
some proteins function as enzymes - organic catalysts that speed up chemical reactions
Polypeptide: a chain of many amino acids joined by peptide bonds
-
a protein can be composed of one or several polypeptide chains
-
condensation of two amino acids in a growing polypeptide chain
results in the formation of a peptide bond
-
hydrolysis of peptide bonds occurs between specific
amino acids in a protein by the activity of specific enzymes (e.g.: pepsin)
Protein
Structure
-
primary structure: the sequence of amino acids in a polypeptide chain
-
secondary structure: the
formation of discrete structures (alpha helices or beta pleated sheets) involving several amino acids within a polypeptide
chain (held together by hydrogen bonds)
-
tertiary structure: the
conformation of the polypeptide chain following interactions of regions of secondary
structure
o if the protein only consists of 1 polypeptide, this
is the final structure of the protein
-
quaternary structure: structure following interaction and bonding between two or more (the same or different) polypeptide chains
o hydrogen or ionic bonding between polypeptide chains
Denaturation:
disruption of specific 3D structure of a protein by increasing temperature (boiling) or changing pH
- may
be reversible (remember: the structure of a given
polypeptide is specific as well as consistent and reproducible)
Nucleic Acids:
Nucleic Acids are polymers
of nucleotide monomers
- a
nucleotide = a pentose
sugar + a phosphate + a nitrogenous (nitrogen-containing) base
- In RNA (Ribonucleic Acid), the pentose is ribose
- In DNA (Deoxyribonucleic Acid), the pentose is deoxyribose (missing a hydroxyl group at carbon # 2 relative to
ribose)
DNA:
DNA is the genetic material of the cell (inherited from parents)
-
composed of a sequence
of four different nucleotides
-
the 4 nucleotide
subunits of DNA are named after the nitrogenous base each contains; the 4 bases are : adenine (A)
cytosine (C)
guanine (G)
thymine (T)
-
DNA forms a double-helical structure
(DNA is double-stranded),
in which two chains bond together;
the sugar and phosphate groups are on the outside, and the nitrogenous
bases interact by hydrogen bonding in the middle of the double helix
-
A pairs with T through 2
hydrogen bonds; C pairs with G through 3 hydrogen bonds (stronger)
- the 2 strands (nucleotide chains) of the double helix are complementary:
RNA:
-
RNA is synthesized from 1 strand of DNA
-
RNA does not
form a double helix (no pairing of complementary bases between 2
strands); RNA is single-stranded
-
RNA also uses 4 nucleotide subunits; however, uracil (U) replaces thymine in RNA
-
major forms of RNA in
cells are: messenger RNA (mRNA), transfer RNA (tRNA) & ribosomal RNA (rRNA)
Genes in DNA code
for polypeptides: the sequence of
bases in DNA serves as a code for directing the sequence of bases in mRNA, and
then the sequence of amino acids in a protein
Chapter 3: Cells: The Living Units
Cells:
-
contain organelles: small,
membrane-bounded bodies with a specific structure & function (e.g.:
mitochondria, chloroplasts, lysosomes) in cytosol (semifluid medium between nucleus and plasma membrane)
-
cell wall in plant cells, fungi, protists, bacteria... for this
course we'll focus on animal cells, which have no cell wall
Plasma membrane: outer
boundary of cells (except plant cells - also cell wall)
-
phospholipid
bilayer: semipermeable and selectively permeable
-
functions in regulation
of passage of molecules into and out of the cell
-
fluid mosaic model: the
membrane is a fluid phospholipid bilayer, capable of lateral movement of
membrane components, in which various protein molecules are either partially or
wholly embedded
-
membrane
components:
-
phospholipids: create
bilayer
-
have polar &
nonpolar parts
-
glycolipids:
protective function, and cell identity (specific for cell type)
-
cholesterol: bulky;
controls (reduces) permeability
-
proteins: also glycoproteins; can be transmembrane (spans the entire membrane) or
embedded in either the cytoplasmic or extracellular side of the membrane
-
glycoproteins (and glycolipids) function in cell-cell recognition (cell fingerprint); important in transplantation
-
fluidity: Both
phosholipids and membrane proteins are capable of lateral movement
in the plasma membrane
-
phospholipids rarely
change from cytoplasmic to extracellular side of the bilayer, or vice-versa,
since the polar head group would have difficulty moving through the hydrophobic
center
-
the amount of movement
is dependent on composition of phospholipids, glycolipids, & cholesterol
Types of Membrane
Proteins:
Channel Proteins: create
transient hydrophilic
channel for small molecules & ions to flow into & out of cell
Carrier Proteins: selectively interact with small molecules or ions to assist them
across the membrane
Cell Recognition
Protein: Cell Identity; individual-specific groups of proteins on extracellular side of membrane (e.g.: MHC/HLA
(Human Leukocyte Antigen) - important to match with donor to avoid rejection of
transplanted organ or tissue)
Receptor Protein:
Interacts with specific molecule to transmit some type of signal or
communication (electrical, chemical or contact) between cells (e.g.: hormone receptors)
Enzymatic Protein:
Catalyzes (speeds up) some specific reaction which results in a cellular
response
Plasma Membrane is semipermeable and selectively permeable: some molecules may pass through freely (e.g.: water); others must be
assisted across
Microvilli: very small, fingerlike projections that project from
a free surface of some cells
-
increases surface for
absorption
Nucleus: stores genetic information in all eukaryotic cells
-
DNA is organized into distinct chromosomes
-
Chromosomes are packaged with proteins to form chromatin
-
Chromatin exists in a semifluid medium called nucleoplasm
-
Dark regions within the
nucleus are nucleoli (1 or more
per cell)
-
Within each nucleolus, ribosomal RNA is produced and joins with ribosomal
proteins to form ribosomes
-
The nucleus is bounded
by a porous membrane, the nuclear envelope, which regulates passage of
molecules into & out of the nucleus
-
The structure of
the nucleus is maintained by the nuclear matrix, which contains a protein network called the nuclear
lamina, which also provides chromatin
attachment sites to maintain organization
Cytosol: consists of cytoplasm (the fluid within the cell outside the nucleus) &
organelles
Ribosomes: site
of protein synthesis in the cell
-
free in cytoplasm
(polyribosomes) or associated with rough endoplasmic reticulum
-
2 subunits (large &
small); mRNA is threaded through subunits during translation (protein
synthesis)
Gene
Expression:
-
Transcription: DNA is transcribed to RNA in the nucleus
-
transcription is carried
out by a 5' to 3' RNA Polymerase, as well as additional protein factors
-
the result is messenger
RNA (mRNA)
-
Translation: mature
mRNA is translated to protein in the cytoplasm
-
translation occurs at
the ribosomes
-
tRNA molecules carry amino acids to the ribosome during
translation (a tRNA for each amino acid)
-
rRNA along with proteins comprise the structure of the 2
subunits of the ribosome
Endomembrane System: includes Golgi apparatus, endoplasmic reticulum,
vesicles, and nuclear membrane
Endoplasmic Reticulum:
(ER)
-
Rough ER:
associated with ribosomes; proteins translated on ribosomes associated
with the rough ER will be transported and/or secreted outside cell
- begins processing &
modification of these proteins
-
Smooth ER:
synthesizes phospholipids in all cells; various other cell type-specific
functions
- synthesizes steroid hormones in
testes, and detoxifies drugs in liver cells
Golgi Complex: completes modification of proteins from rough ER (proteins
transported to Golgi in vesicles)
-
modification of proteins & lipids (addition of carbohydrate
chains (glycosylation))
-
also transports organic
molecules in vesicles; some become lysosomes
Lysosomes:
vesicles with digestive enzymes to break down macromolecules & cell
debris
-
loss of some or all
lysosome function in inherited disorders (Tay-Sachs disease) may lead to
accumulation of unwanted molecules (& related toxicity)
Microbodies: smaller
version of lysosomes with specific enzyme activities
-
Proteasomes: destroy unneeded, damaged or faulty proteins in cell
-
Peroxisomes are microbodies that contain enzymes for oxidizing certain organic molecules with the release of hydrogen
peroxide (toxic, but breaks down into water & oxygen)
Vacuoles: larger
membrane-bounded organelles
-
function in storage
Mitochondria: produces
energy
-
site of cellular
respiration (ATP production from
carbohydrates)
-
also have folded
membrane system (folds are cristae,
inner fluid-filled space is the matrix)
-
extensive membrane
systems are important in both chloroplasts and mitochondria for ATP production
Centrosome: located near nucleus; consists of centrioles &
pericentriolar material
-
centrioles: cylindrical structures composed of 9 clusters of
three microtubules (triplets) arranged in circular pattern
-
pericentriolar
material consists of hundreds of
tubulin complexes
-
involved in organization
of spindle fibers for chromosome movement during mitosis
Cilia and Flagella: composed of microtubules (9 + 2 pattern); used in
movement
-
Cilia present in some unicellular protists (Paramecium)
and cells of respiratory tract in animals
-
Flagella present in some unicellular protists (Euglena)
and sperm cells
Plasma membrane
transport:
Diffusion: movement of molecules from a region of higher
concentration to a region of lower concentration (down concentration gradient)
-
lipid soluble molecules,
gases (oxygen, carbon dioxide) and water can diffuse across the plasma membrane
Osmosis:
diffusion of water across a differentially permeable membrane (plasma
membrane)
- important in water retention
Tonicity: the strength (solute concentration) of a solution in
relation to osmosis
-
in cells, the solute concentration of a solution with respect
to that solute concentration inside the cell
-
isotonic (isoosmotic)
solution: the net solute
concentration of the solution equals that inside the cell
-
hypotonic
(hypoosmotic) solution: the net
solute concentration of the solution is less that inside the cell; animal cells
swell (& eventually will burst - hemolysis)
-
hypertonic
(hyperosmotic) solution: the net
solute concentration of the solution is greater that inside the cell; animal
cells shrink - crenation
Facilitated
Diffusion: passage of small molecules (glucose, amino acids)
across the plasma membrane even though they may not be lipid-soluble
-
a carrier protein assists
movement of molecules down concentration gradient
-
no energy
is required
Filtration: a pressure gradient pushes solute-containing fluid
(filtrate) from area of high pressure to area of low pressure
-
forces water &
solutes through membrane or capillary wall by hydrostatic pressure
Active Processes:
Active Transport: movement
of small molecules or ions across membrane assisted by carrier protein and against
concentration gradient - from
region of lower concentration to region of higher concentration
-
requires energy
(ATP)
-
(e.g.: sodium-potassium pump)
-
secondary active
transport: uses energy derived
from primary active transport to drive other substances across membrane
Vesicular
(membrane-assisted) transport:
-
transport of macromolecules into or out of cell in vesicles
-
vesicle: small, spherical sac that has budded off existing membrane
-
requires energy
-
Exocytosis: moves
macromolecules out of cell through vesicles budding off plasma membrane
-
Endocytosis: moves macromolecules into cell through vesicles budding off plasma membrane
-
Phagocytosis: endocytosis of large food particles or invading cells (bacteria)
- Common in macrophages of the immune system
-
Pinocytosis
(bulk-phase endocytosis): endocytosis of a liquid or very small particles (sampling of
extracellular environment)
- Receptor-mediated
endocytosis: endocytosis involving a receptor protein and its ligand (molecule it binds)
-
receptor proteins
cluster together in clathrin-coated pits
Cell Division:
-
cell division involves
nuclear division and cytokinesis (division of cytoplasm)
-
normally, most
eukaryotic cells have two
copies of each chromosome (2n, or diploid state); the 2 chromosomes of each
pair are called homologous chromosomes or homologs
-
the reproductive cells
(or gametes) have only one copy of each chromosome (n or haploid state)
-
human somatic cells have
23 pairs of chromosomes; gametes have 23 chromosomes
Cell Cycle: consists of Interphase and Mitosis
-
the time required for
cell division is relatively constant for a given cell type of a given organism
(usually between 14 and 24 hours)
Interphase:
consists of G1, S, and G2 stages.
-
DNA is duplicated &
cell synthesizes proteins for mitosis & cell division
Mitosis: M stage
-
Prophase:
chromatin condenses and the nuclear membrane begins disintegration.
⋅
spindle fibers form to move chromosomes in cell
-
Metaphase: Chromosomes
align at metaphase plate attached
to spindle fibers
-
Anaphase:
Chromosomes move toward opposite poles of the cell due to disassembly of spindle fibers
-
Telophase:
Chromosomes are at opposite poles of the cell; nuclear envelope reforms
around each set of chromosomes, and spindle disappears. Cytokinesis begins...
Cytokinesis: cells divide by means of a cleavage furrow
Meiosis: nuclear/cell division that reduces the chromosome
number in a cell to one half its normal number (in humans, from 46 chromosomes
to 23 chromosomes)
-
only occurs in
reproductive tissues; forms gametes (sperm & egg cells)
-
spermatogenesis: meiosis in testes in males to form sperm cell
-
oogenesis: meiosis in ovary in females to form egg cell (ovum)
-
fertilization: fusion of sperm & egg cell to form zygote
⋅
restores chromosome
number to 46
⋅
begins formation of
embryo (new individual)
Chapter 4: Body Tissues & Membranes
Body Tissues
Tissue: a group of similarly specialized cells that work
together to perform a common function in the body
-
4 major tissue types: epithelial,
connective, muscular & nervous
Epithelial Tissue
(epithelium): a sheet of cells that
lines a body cavity or covers a body surface
-
covering & lining
epithelium: skin & lining of body
cavities
-
glandular epithelium:
forms glands
-
many functions:
protection (against water loss, injury & infection), absorption, secretion,
excretion, filtration, sensory reception
Classification of
Epithelia:
-
squamous (flattened), cuboidal (cube-shaped), & columnar (column-shaped) cells
-
simple (1 layer) or stratified (multiple layers)
Simple Squamous
Epithelial Tissue: single layer of
flattened cells with disc-shaped nuclei & little cytoplasm
-
locations: in kidney glomeruli, air sacs of lungs, heart lining,
blood vessels & lymphatic vessels, lining of ventral body cavity
-
functions: diffusion & filtration; secretes lubricating
substances in serosae
Simple Cuboidal
Epithelial Tissue: single layer of
cube-shaped cells with large spherical nuclei
-
locations: in kidney tubules, ducts of small glands, ovary
surface
-
functions: secretion & absorption
Simple Columnar
Epithelial Tissue: single layer of
column-shaped cells with oval nuclei; some have cilia or microvilli; may
include goblet cells
-
locations: nonciliated in most of digestive tract, gallbladder
& excretory ducts of some glands; ciliated in small bronchi, some regions of uterus
-
functions: absorption, secretion of mucus, enzymes...; ciliated
propels mucus, reproductive cells
Pseudostratified
Columnar Epithelial Tissue: single
layer of mostly column-shaped cells with different heights (some don't reach
apical surface) & nuclei at different levels; some have cilia; may include
goblet cells
-
locations: nonciliated in male sperm-carrying ducts &
ducts of large glands; ciliated
type lines trachea & most of upper respiratory tract
-
functions: secretion & propulsion of mucus
Stratified Squamous
Epithelial Tissue: multiple layers;
basal layer cuboidal or columnar - carry out metabolism & mitosis; outer
layers are keratinized
-
locations: nonkeratinized in most of digestive
tract, gallbladder & excretory ducts of some glands; ciliated in small
bronchi, some regions of uterus
-
functions: protects underlying tissues
Stratified Columnar
Epithelial Tissue: several layers -
basal layer usually cuboidal
-
locations: male urethra & some large ducts of glands
-
functions: protection, secretion
Transitional Epithelial
Tissue: several layers - basal layer
cuboidal or columnar; surface cells dome-shaped or squamous-like (depending on
stretch)
-
locations: ureters, bladder & part of urethra
-
functions: stretches & distends urinary organ
Connective Tissue: most abundant primary tissue
-
connective tissue cells
separated by extracellular matrix (collagen or elastin fibers; calcium
phosphate (bone)
Connective Tissue Fibers:
-
collagen (white
fibers): flexibility &
strength
-
elastic (yelloe
fibers): not as strong as
collagen; more elastic
-
reticular fibers: very thin; highly branched collagenous fibers that
form networks
Connective Tissue Types:
Loose Connective Tissue:
-
Areolar Connective
Tissue: gel-like matrix with all 3
fiber types; fibroblasts, mast cells, macrophages & some white blood cells
-
location: under many epithelia (forms lamina propria); around
organs & capillaries
-
functions: cushions organs; many immune cells regulate immunity
-
Adipose Connective
Tissue: gel-like matrix with all 3
fiber types; closely packed adipocytes (fat cells with large fat droplet)
-
location: under skin, around kidneys & eyeballs, within
abdomen, breasts
-
functions: cushions organs; reserve food fuel, insulation
-
Reticular Connective
Tissue: reticular fiber network in
loose ground substance; reticular cells
-
location: lymphoid organs
-
functions: internal skeleton for support of other cell types
Dense Regular (Fibrous)
Connective Tissue: dense (primarily)
parallel collagen fibers, few elastin fibers; fibroblasts
-
location: tendons, ligaments, aponeuroses
-
functions: attaches muscles to bone & other muscles,
attaches bones to bones; withstands high stress
Hyaline Cartilage: amorphous firm matrix; collagen fibers form glassy
(invisible) network; chondrocytes in lacunae
-
location: embryonic skeleton, covers long bones in joints,
costal cartilage of ribs, cartilage of nose, trachea & larynx
-
functions: support, cushioning, resists stress
Elastic Cartilage: similar to hyaline cartilage, with elastin fibers in
matrix
-
location: external ear (pinna), epiglottis
-
functions: maintains shape while adding flexibility
Fibrocartilage: similar to hyaline cartilage, less firm with thick
collagen fibers in matrix
-
location: intervertebral discs, pubic symphysis, knee joint
discs
-
functions: tensile strength, absorbs shock
Bone: hard calcified matrix, many collagen fibers,
well-vascularized, osteocytes in lacunae
-
location: bones
-
functions: support, levers for muscles, calcium storage, blood
cell formation (hematopoiesis) in red bone marrow
Blood: red blood cells (erythrocytes) & white blood cells
(leukocytes) in fluid matrix (plasma)
-
location: in blood vessels
-
functions: transports oxygen & carbon dioxide, nutrients,
wastes & other substances
Muscle Tissue:
Smooth Muscle: uninucleate, spindle-shaped cells; centrally located nucleus; nonstriated;
involuntary muscle
-
location: lines hollow
passageways such as: walls of blood vessels, airways to lungs, stomach,
intestines & bladder
-
function: contraction
helps constrict or narrow lumen of blood vessels, break down & move food
through GI tract, move fluids & eliminate wastes
Skeletal Muscle: multinucleate, long cylindrical cells with peripheral
nuclei; striated; voluntary muscle
-
location: attached to bones of skeleton
-
function: contraction helps move bones
Cardiac Muscle: one centrally located nucleus (usually); striated;
branched; intercalated discs (desmosomes & gap junctions) between cells
-
location: myocardium of heart
-
function: contraction helps propel blood from heart to tissues
Nervous Tissue: neurons
& supporting cells
-
location: brain, spinal cord & nerves
-
functions: transmit electrical signals from sensory receptors to
effectors
Body Membranes:
Epithelial: skin
Mucous: lines body cavities (digestive tract, respiratory
tract)
- specialized cells
(glands) may secrete mucus
Serous: fluid membrane surrounding organs... pleura (lungs),
pericardium (heart), peritoneum (digestive organs)
-
visceral & parietal
Synovial Membranes: line cavities of freely movable joints
- areolar CT with elastic fibers & adipocytes
- joint (synovial) cavity: potential space with synovial fluid
- synovial membrane lines all internal joint surfaces except hyaline cartilage
- synovial fluid: occupies free spaces in joint cavity; reduces friction