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244 Cards in this Set

  • Front
  • Back
Three primary techniques for examining cells
Microscopy, autoradiography, centrifugation
Microscopy Types
Compound Light = most common
diaphragm - controls amount of light
Phase Contrast - allows for visualization of living organisms
Electron - visibility down to atomic level
autoradiography used to...
study biochemical processes
plasmids
small circular pieces of DNA in prokaryotes, replicate independently of bacterial chromosome
glyoxysomes
convert fats to usable fuel (sugars) for energy in plants until photosynthesis can be performed
3 components to cytoskeleton
microfilaments (made of actin)
intermediate filaments
microtubules
four main types of tissue in body
epithelial, connective, nervous, muscle

"C-MEN , seamen"
Cell Theory
1. All living things composed of cells.
2. Cell = basic functional unit of life.
3. Cells come only from other cells.
4. Genetic material contained in DNA.
nucleoid region
where DNA is found in prokaryotes
cell adhesion molecules (CAMs)
important in cell recognition
nucleolus
where rRNA is synthesized in nucleus in euks, not surrounded by a membrane
lysosomes
break down ingested material (cell garbage dump)
can participate in apoptosis
cristae
increase surface area of mitochondria, folds of inner membrane
mitochondrial matrix
enclosed inner portion important in cellular respiration
peroxisomes
microbody that creates hydrogen peroxide and uses it to break down fats, important in detox liver rxns (alcohol)
centriole
bundle of microtubules used to organize spindle apparatus for mitosis ("highway system")
actin
important in muscle contraction where they interact with myosin
microtubules
hollow, polymers of tubulin proteins, involved in chromosomal separation during mitosis/meiosis, make up cilia and flagella
intermediate filaments
maintain overall integrity of cytoskeleton
Mv't across membranes
simple diffusion (includes osmosis)
facilitated diffusion
active transport (needs ATP)
endo- & exo- cytosis (needs ATP)
hypotonic
less solutes than on other side of membrane
hypertonic
more solutes than on other side of membrane
isotonic
same amt of solutes on both sides of membrane, does not prevent mv't
facilitated diffusion
for large, polar, and/or charged molecules to move down electrochem gradient
pinocytosis
endocytosis of fluids and dissolved particles
phagocytosis
ingest of large solids, e.g. bacteria
epithelial tissue
cover body and line cavities, protect against invasion and desiccation
connective tissue
supports, provides framework for body, e.g. blood, adipose tissue, tendons

"the bra of the body"
nervous tissue
primary cells = neurons
use electrochem gradients for cell signaling and coordinating control
muscle tissue types
skeletal, smooth, cardiac
capsid
protein coat of virus
obligate intracellular parasites
descriptor of viruses
virions
new copies that a virus has made of itself using cell machinery
bacteriophages
viruses that specifically target bacteria, don't fully enter, just inject genetic material
polyhedral tail structure with tail fibers
virus genetic information forms
circular or linear
single or double stranded
DNA or RNA
(may bring own polymerases and/or RNA replicase with them if they want to replicate & transcribe in cytoplasm)
Functions of smooth ER
transport of materials throughout cell
lipid synthesis
detoxification of drugs and poisons
ribosome function
protein synthesis
Differences bw prokaryotes and eukaryotes
- euks have nucleus & membrane-bound organelles
- euks ribosomal subunit weights are 40s and 60s, proks ribosomal subunit weights are 30s and 50s
Enzyme function
biological catalysts, lower activation E thus increasing rxn rate, pH & temp sensitive, specific

do not
- affect overall ΔG
- change equilibrium constant
- Δ from rxn
substrate of enzymatic rxn
molecule upon which enzyme acts
active site of enzymatic rxn
location within enzyme where substrate is held during rxn
lock & key theory
suggests enzyme active site (lock) is in appropriate conformation to bind to substrate (key)
induced fit theory
more accepted than lock & key theory
change in shape which takes a little E but ends up with lowered conformation energy, active site only truly complementary after substrate binds to enzyme
cofactor
nonprotein molecules that aid enzymes
apoenzymes
enzymes without their cofactors
holoenzymes
enzyme with cofactor
prosthetic groups
tightly bound factors that connect to their enzyme
coenzymes
small organic groups that are cofactors for an enzyme
Km = ? when rxn rate = ½ Vmax
[S]= ? at ½ Vmax
Michaelis-Menten eqn
rate = (Vmax * [S]) / ([S] + Km)
optimal pH of human blood
7.4
allosteric sites
site different from active site that affects active site availability
allosteric enzymes
alternate bw an active and inactive form
allosteric activators
causes conformation shift in protein that favors substrate binding
allosteric inhibitors
cause conformational shift in protein that inhibits substrate binding
Reversible inhibitions types
competitive, noncompetitive, uncompetitive
competitive inhibition
only involves occupancy of active site
noncompetitive inhibition
involves allosteric site, both the substrate bound and non-substrate bound forms of protein can be inhibited
uncompetitive inhibition
involves allosteric and active site, substrate-bound protein can be inhibited allosterically
irreversible inhibition
active site made permanently unavailable or enzyme permanently altered
zymogens
inactive forms of enzymes, regulatory domain must be removed/altered to expose active site, e.g. caspases used in apoptosis
autotrophs
derive E from sun
heterotrophs
derive E by breaking down other organisms organic molecules
Photosynthetic eqn
6 CO₂ + 6 H₂O + E ➔ C₆H₁₂O₆ + 6 O₂
Cell Respiration Eqn
C₆H₁₂O₆ + 6 O₂ ➔ 6 CO₂ + 6 H₂O + E
Intermediates used in glucose metabolism
ATP, NAD⁺, FAD
ATP
generated during glucose metabolism
7 kcal/mol E released with each Pi that leaves
NAD⁺ & FAD
coenzymes capable of accepting high-energy electrons during glucose oxidation

by accepting hydride ions, they are reduced to NADH & FADH₂, carried on inner mitochondrial membrane to ETC to get oxidized & produce ATP
glycolysis
breaks down glucose into 2 smaller orgo mols in presence or absence of O₂

Inputs: 6C-glucose, 2 ATP, 2 NAD⁺
Outputs: 2 3C-pyruvate, 4 ATP, 2 NADH
substrate-level phosphorylation
direct generation of ATP from ADP and Pi
Net rxn of glycolysis
Glucose + 2 ADP + 2 Pi + 2 NAD⁺ ➔ 2 Pyruvate + 2 ATP + 2 NADH + 2 H⁺ + 2 H₂O
fermentation fxn
to oxidize NADH for re-use, includes glycolysis step
reduces pyruvate to ethanol or lactic acid
alcohol fermentation rxn
Pyruvate (3C) ➔ CO₂ + Acetaldehyde (2C)
Acetaldehyde + NADH + H⁺ ➔ Ethanol (2C) + NAD⁺

Typical rdxn of aldehyde to alcohol from orgo
Lactic acid fermentation rxn
Pyruvate (3C) + NADH + H⁺ ➔ Lactic acid + NAD⁺
Cori cycle
when O₂ supply catches up to demand, lactic acid gets converted back to pyruvate
oxygen debt
amt of O₂ needed to catch back up to demand
3 key phases of cell respiration
pyruvate decarboxylation
citric acid cycle
ETC
Pyruvate decarboxylation
2 pyruvate(3C) + 2 CoA + 2 NAD⁺ ➔ 2 NADH + 2 Acetyl-CoA (2C) + 2 CO₂ (1C)

2 NAD⁺ mols reduced per glucose mol

no need of O₂ itself but part of chain so O₂ must be present for other parts to make this part run
What E do we have in what forms after pyruvate decarboxylation?
2 ATP (glycolysis)
2 NADH (glycolysis)
2 NADH (decarboxylation)
Citric Acid Cycle aka Krebs Cycle aka tricarboxylic acid cycle (TCA) info
Each acetyl-CoA molecule ➔ 2 NADH & 1 FADH₂

2 turns / glucose molecule

Each turn generates 1 ATP via substrate-level phosphorylation and a GTP intermediate. Does generate high-E electrons carried by NADH and FADH₂.

Some ATP generated from GTP directly through substrate-level phosphorylation.
What E do we have in what forms after Krebs/TCA?
2 ATP (glycolysis)
2 NADH (glycolysis)
2 NADH (decarboxylation)
6 NADH (TCA)
2 FADH₂ (TCA)
2 ATP (TCA)
oxidative phosphorylation
·Process of releasing E from protons moving back through ATP synthases to convert ADP to ATP
·Produces more ATP during Krebs/TCA
Citric Acid Cycle aka Krebs Cycle aka tricarboxylic acid cycle (TCA) Rxn
2 Acetyl-CoA + 6 NAD⁺ + 2 FAD + 2 GDP + 2 Pi + 4 H₂O ➔ 4 CO₂ + 6 NADH + 2 FADH₂ + 2 ATP + 4 H⁺ + 2 CoA
cytochromes
enzymes that are high energy electron carriers used in ETC, contain central iron atom
cytochrome complexes
Complex I. NADH dehydrogenase
Complex III. b-c1 complex
Complex IV. cytochrome oxidase
FMN (flavin mononucleotide)
part of complex I, given electrons by NADH, then passed to ...



carrier Q
carrier Q (ubiquinone)
small hydrophobic, not an enzyme, passed electrons onto complex III
Order of ETC
Complex I (NADH dehydrogenase) & Complex II (succinate-Q oxidoreductase - FADH₂)
Carrier Q (ubiquinone)
Complex III (b-c1 complex)
Complex IV (cytochrome oxidase)
(w/in IV, cytochrome a3 protein + 2 protons make H2O)
cytochrome a3
protein in complex IV (cytochrome oxidase) that makes water with 2 protons
Each NADH in ETC generates ___ molecules ATP?
3
Each FADH₂ in ETC generates ___ molecules ATP?
2
Where does FADH₂ molecules start in ETC?
Complex II (succinate-Q oxidoreductase)
proton-motive force
the electrochemical gradient driving H⁺ passively back across the inner mitochondrial membrane into the matrix
ATP synthases
enzyme complexes that are channels for allowing charged H⁺s to move back down gradient
Location of glycolysis
cytoplasm
location of fermentation
cytoplasm
location of pyruvate to acetyl-CoA
mitochondrial matrix
location of TCA cycle
mitochondrial matrix
location of ETC
Inner mitochondrial membrane
Fatty acids introduced catabolic pathway via what molecule at what stage?
Acetyl-CoA introduced into Krebs cycle
adding H reduces/oxidizes?
reduces
Fats stored in adipose tissue in what form?
triglycerides
β-oxidation
generates acetyl CoA from fatty acids in cytoplasm, each round results in 1 NADH and 1 FADH₂
transaminases
remove amine moiety from amino acids resulting in α-keto acids which can then be converted to acetyl-CoA or are intermediates of TCA
Steps in metabolism of fats
1. Fatty acids activated in cytoplasm, requires 2 ATP
2. Transported to mitochondrial matrix to undergo β-oxidation
3. Each round of oxidation makes 1 NADH and 1 FADH₂, removes 2 C at a time from fatty acid chain
Steps in metabolism of proteins
1. Removal of amine moiety from AAs by transaminases to make α-keto acids
2. α-keto acids converted to acetyl-CoA or are intermediates of TCA cycle and enter directly
binary fission
type of asexual reproduction used by proks
euk autosomal cells
contain diploid (2n) chromosomes
euk haploid
aka germ cells
contain the n number of chromosomes
Interphase made up of...?
G1, S, G2 stages
G1 stage
aka presynthetic gap
cells create organelles for E and protein prdxn while doubling in size
Restriction points
G1 ➔ S
S Stage
aka synthesis
replication of genetic material making 2 identical chromatids bound at centromere, no Δ in ploidy
2x as much dna now as in G1
Four phases of mitosis
prophase (chromosomes condense, spindle forms)
metaphase (chromosomes align)
anaphase (sister chromatids separate)
telophase (new nuclear membranes form)
G2 stage
aka post synthetic gap
quality control check
chromatin
less condensed form of chromosomes during interphase
centrioles
specialized organelles made of tubulin, paired outside the nucleus in centrosome region, responsible for correct division
migrate to opposite poles during prophase and form spindle fibers made from microtubules
asters
attachment points for chromosomes for separation during anaphase
prophase
chromosomes condense, centriole pairs separate, spindle apparatus forms, nuclear membrane dissolves, nucleoli become less dense, kinetochores appear at centromeres
metaphase
centriole pairs at opposite poles, kinetochore fibers interact with spindle apparatus to align chromosomes on metaphase plate
anaphase
centromeres split so each chromatid has its own, telomeres are last part of chromatids to separate, sister chromatids pulled apart by kinetochore fiber shortening
telophase & cytokinesis
spindle apparatus disappears, nuclear membrane re-forms, nucleoli reappear, chromosomes uncoil, resume interphase form
Four forms of asexual reproduction
binary fission
budding
regeneration
parthenogenesis
binary fission
(think bacteria)
circular chromosome attaches to wall and replicates while cell grows in size, plasma membrane and cell wall grow inward along midline
budding
equal replication followed by unequal cytokinesis
regeneration
accomplished via mitosis, parts regrowing into whole
parthenogenesis
process whereby adult organism develops from unfertilized egg, means number of chromosomes will be haploid in resulting offspring
gametes
specialized sex cells produced via meiosis
mitosis results vs meiosis results
mitosis- 2 identical diploid daughter cells (2n)
meiosis - 4 different haploid gametes (n)
gametocytes undergo ______ where somatic cells undergo _______.
meiosis... mitosis
reductional division
First division during meiosis I generating haploid daughter cells
equational division
Second division during meiosis II resulting in separation of sister chromatids.
synapsis
first major difference bw meiosis and mitosis
during prophase I where homologous chromosomes come together and intertwine
point of synapsis = chiasma
exchange = crossing over
prophase I
each chromosome has 2 sister chromatids at this stage so each pair contains 4 chromatids making a tetrad
anaphase I
homologous pairs separate to opposite cell sides
process known as disjunction = chromosome of paternal origin separates from maternal, either can end up in either daughter cell
telophase I
each chromosome still consists of sister chromatids joined at centromere, the cells are haploid (once homologous chromosomes separate, only the n number of chromosomes is left; still 2 chromatids / chromosome)
gonads
produce sperm and ovum which fuse during fertilization to form a single-celled zygote in fallopian tubes
testes
primitive gonads develop into these in males, located in scrotum hanging below penis
2 functional components of testes
seminiferous tubes (sperm produced here, nourished by Sertoli cells)
interstitial cells (cells of Leydig) (secrete testosterone and other androgens)
Pathway of sperm from creation to ejaculation
"Seven Up"
Seminiferous tubules
Epididymis
Vas deferens
Ejaculatory duct

Urethra
Penis
epididymis
where sperm go as they mature and develop flagella, stored here until ejaculation
seminal fluid produced by...
seminal vesicles (contribute fructose)
prostate gland (makes fluid mildly alkaline)
bulbourethral gland

seminal fluid + sperm = semen
where does spermatogenesis occur?
seminiferous tubules
spermatogonia
diploid stem cells in males
Steps of spermatogenesis
spermatogonia (2n) ➔
1° spermatocytes (2n) ➔
via meiosis I form..
2° spermatocytes (n) ➔
via meiosis II form..
spermatids (n) ➔
spermatozoa (n)
How many sperm does one spermatogonium create?

How many ovum does one oocyte create?
4

1
Sperm parts
Head (containing genetic material)
Midpiece (to generate E from fructose)
Flagellum (motility)
Acrosome (cap over sperm head, derived from Golgi to penetrate ovum)
Ovaries
female gonads that produce estrogen and progesterone, consisting of follicles (sacs) to nourish ova
Fallopian tube
aka oviduct, lined with cilia to usher egg along from peritoneal sac to uterus (site of fetal development)
vaginal canal
where sperm is deposited during intercourse and then moves through cervix into uterus
primary oocytes
pre-differentiated 2n cells in females frozen in prophase I
Steps of oogenesis
1° oocyte (2n) ➔
via meiosis I, 2° oocyte (n) + polar body ➔
2° oocyte gets frozen in metaphase II until fertilization ➔
fertilization leads to meiosis II ➔
ovum (n)
What is unequal cytokinesis in oogenesis?
ample cytoplasm given to one daughter (2° oocyte) and nearly none to other (polar body)
Cell layers surrounding oocytes
zona pellucida
corona radiata
Meiosis II triggered when sperm penetrate these.
zygote
fused haploid cells resulting in restoration of diploid chromosome number during fertilization
How does the sperm get inside the egg?
1. Acrosomal enzymes digest corona radiata and penetrate zona pellucida.
2. Sperm hits cell membrane; acrosomal apparatus forms to penetrate.
3. Nucleus enters ovum.
4. Ovum undergoes cortical rxn with Ca2+ release leading to..
5. Formation of fertilization membrane. (impenetrable to other sperm)
Upon ovulation, the oocyte is released into...
the abdominal cavity near the entrance of the fallopian tubes.
cleavage
process of rapid mitotic cell division of the zygote, first cleavage officially creates an embryo
Types of cleavage
indeterminate (results in cells that develop into full organisms)
determinate (commits cells to differentiating)
Key time points in embryo development
1st cleavage - 32 hpf
2nd - 60 hpf
3rd - 72 hpf
arrives at uterus

hpf = hours post fertilization
morula
solid mass of cells after several divisions during embryo development
blastula
formed by blastulation, characterized by fluid-filled cavity known as blastocoel
blastocyst & 2 cell groups of it
mammalian blastula
1. trophoblast (surrounds blastocoel, gives rise to chorion & placenta)
2. inner cell mass
endometrium
"soil" where blastocyst settles, settling promoted by progesterone which proliferates mucosal layer in uterus
gastrulation
generation of 3 distinct cell layers in gastrula (indented 2 layer cup)
Parts of gastrula
endoderm (inner cell layer and inside of cup)
ectoderm (outer cell layer)
archenteron (cavity, later makes gut)
blastopore (opening into archenteron)
mesoderm (third middle layer)
deuterosomes (humans) vs. protosomes
(d) blastopore = anus
(p) blastopore = mouth
Ectoderm generates...
integument (skin, hair, nails, epithelium of nose mouth and anal canal, eye lens, nervous system
*adrenal medulla of kidney system
Mesoderm generates...
Musculoskeletal system, circulatory system, excretory system, gonads, muscle and connective tissue coats of digestive & respiratory tracts
*kidneys
Endoderm generates...
epithelial linings of digestive & respiratory tracts, lungs, parts of liver, pancreas, thyroid, bladder, distal urinary and reproductive tracts
neurulation
creation of nervous system, occurs post gastrulation formation of 3 germ layers
Steps of neurulation
1. Notochord
2. Neural folds surrounding neural groove
3. Fusion into neural tube (gives rise to central nervous system)
4. Neural crest cells (at top of folds) migrate outward to form peripheral nervous system
5. Ectodermal cells form cover
Specialized structures for fetal nutrient/gas xchange?
placenta (formed from chorion)
umbilical cord (provides chorion attachment & nutrition for fetus)
chorion
develops from trophoblast cells
extra-embryonic membrane

chorionic villi eventually grow into placenta and support gas exchange
3 extra-embryonic membranes
allantois (surrounded by amion)
amnion (filled with amniotic fluid)
yolk sac (site of early blood vessel development)
fetal shunts
keep blood within heart and away from fetus lungs
1. foramen ovale (connects right and left atria, pushed by pressure differential opposite of adults)
2. ductus arteriosus (shunts leftover blood from pulmonary artery to aorta)
ductus venosus
reroutes blood returning from placenta to inferior vena cava instead of the liver
arteries vs. veins
Arteries take blood Away from heart
Veins take blood towards (veni, vedi, vici)
First trimester
major organs begin to develop
heart starts beating at about 22 days
skeleton starts to harden
embryo becomes fetus by about 8 weeks
Second trimester
lots of growth
starts moving
lengthening of toes and fingers
Third trimester
rapid growth, further brain development
antibodies selected and transferred in via active txport
less active, less room
Birth
coordinated by prostaglandins & peptide hormone oxytocin
3 phases:
1. cervix thins, amniotic sac ruptures
2. strong uterine contractions
3. afterbirth = placenta & umbilical cord expelled
Placenta releases what hormones?
LH (luteinizing hormone)
hCG (human chorionic gonadotropin)
estrogen
What can cross placental barrier?
Smaller molecules such as ethanol, drugs, and hormones.
induction
influence of a specific group of cells on the differentiation of another group of cells
Blood pressure in inferior vena cava after birth..?
Blood pressure decreases, causing decrease in pressure in right atrium.
true-breeding plants
offspring will only ever have same traits as parents
Mendel's Law of Segregation
1. genes have alternate forms (alleles)
2. An organism has 2 alleles for each gene, one from each parent.
3. 2 alleles segregate during meiosis, resulting in gametes carrying only one allele for any inherited trait.
4. If 2 alleles differ, one will be dominant, the other recessive.
F (filial) generation
F1, F2, etc. mark what generation we're looking at. F1 = P (parent) generation.
other term for test crosses
back crosses
Mendel's (2nd Law) Law of Independent Assortment
Each gene's inheritance/assortment is independent of inheritance of other genes. True only for unlinked genes.
TtPp self-cross gives what phenotypic ratios?
9:3:3:1
How do you determine likelihood of two unlinked traits both happening?
Probability of one * probability of other = likelihood
genetic map
1 map unit corresponds to 1% chance of recombination occurring
Four variations on mendelian genetics
incomplete dominance (color mix result 1:2:1 distribution)
codominance (complete expression of both genes)
penetrance (all or nothing) & expressivity (variable)
inherited disorders
hemizygous
where males express an x-linked mutation, cuz they only got one x chromosome
pedigrees
males = squares
females = circles
affected = shaded
carrier = half shaded
aneuploid
individuals with diploid chromosome number other than 46
nondisjunction
most common cause for aneuploidy
deletion
can result in...
duplication (fragment joining homologous chromosome)
translocation (joining another chromosome)
inversion (joining back in where it was but backwards)
homozygous dominant crossed with heterozygous gives what phenotypic ratio?

homozygous recessive crossed with heterozygous gives?
3:1

1:1
cytoplasm vs. cytosol
area contained by plasma membrane but excluding nucleus
vs. fluid component of that area — "sol"ution (all of inside of proks)
glycosylation
process that takes place in golgi where proteins are modified with sugar groups
movement of cilia vs. flagella
whip-like
wave-like
intercellular junctions
tight (membranes of neighboring cells attached)
anchoring (eg desmosomes, in cells subject to mech stress)
gap (direct connxn bw cytoplasms of 2 cells formed by connexins)
gram-positive
bacteria with thick cell wall made of peptidoglycan
gram-negative
bacteria with thinner cell wall sandwiched b/w layers of periplasm & coated with lipopolysaccharide and protein
bacteria shapes
cocci - round/spherical
bacilli - rod-shaped
spirilla - curly
polycistronic
mRNA's in proks that contain more than one coding region
methods by which proks txfer genetic material
transformation (DNA taken up from environment)
transduction (via virus, generalized (all chromosome of another bacterium) & specialized (piece of chromosome with viral mix))
conjugation (via temporary connection of extended sex pili forming conjugation bridge)
Hfr cells
"High frequency of recombination" cells
Proks that have recombination of genetic material with F plasmid integrated into chromosome
retroviruses
need reverse transcriptase to copy DNA from RNA (not found in animal cells), then gets integrated and txcribed to make mRNA
Methods of bacteriophage reprdxn
lytic cycle (virus takes control of host cell machinery)
lysogenic cycle (integrates viral DNA into bacterial genome in prophage form, remains dormant)
fungi
cell walls of chitin
heterotrophs
multicell ones have hyphae, the whole = mycelium

mushrooms
molds (some reproduce asexually)
yeasts (unicellular, reproduce via budding)
lichens (symbiotic mix of algae and fungi)
fungi reproduction
asexual - earlier, haploid spores= sporangia or conidia
sexually - later, 2 haploid nuclei in plasmogamy (fusion) -dikaryotic stage, followed by karyogamy in diploid stage
Endoskeleton structure info
axial (skull, vertebral columns, ribcage: i.e. basic framework)
appendicular (arms, legs, pelvic & pectoral girdles)
2 major components: cartilage & bone
Cartilage
Made of chondrin matrix secreted by chondrocytes.
("chondro-" always relates to cartilage)
relatively avascular
Two Bone types
Compact bone ➔ gives strength
Spongy/cancellous bone ➔ lattice structured w/spicules known as trabeculae
Bone marrow
Red - Filled w/hemapoietic cells (generates blood)
Yellow - mostly fat, relatively inactive

poiesis (Gr. root) = "to make"
Long bones
Characterized by cylindrical shafts (= "diaphyses", full of marrow) & dilated ends (= "epiphyses", sponginess for dispers° of F)
Compact on outside, separat° from inside with epiphyseal plate (site of growth)
Fibrous sheath = periosteum ➔important for growth/repair
Pic 6.2
Bone matrix
Source of bone strength
orgo cmpnts: collagen, glycoproteins
inorgo cmpnts: Ca, P, OH form hydroxyapatite crystals
Continuous bone re-modeling, vascular & enervated
Structure: osteons = Haversian systems Pic 6.3
Haversian system
Makes up bone matrix
aka osteons
osteons encircle Haversian canals which is surrounded by circles of lamellae
Spaces = lacunae which house osteocytes (mature bone cells involved in bone maintenance interconnected by canaliculi)
Bone formation
via hardening of cartilage = endochondral ossification
Also formed through intramembranous ossification (from embryonic connective mesenchymal tissue)
Key concept: Bone remodeling
What builds? What resorbs bone?
Osteoblasts build bone.
Osteoclasts resorb/destroy bone.
Joints
Made of connective tissue (like bone & cartilage)
2 Major varieties = Movable & immovable
Movable ("hinges") strengthened by ligaments, make up synovial capsule that encloses joint cavity.
Articular cartilage & synovial fluid help w/lube.
Immovable ("braces") = in skull
Three types of muscle
skeletal, smooth, cardiac
Skeletal muscle
Enervated by somatic nervous system.
Basic contractile unit = sarcomere
Put end to end = myofibrils
Surrounded by covering of sarcoplasmic reticulum (SR, specialized ER)
Sarcoplasm = modified cytoplasm in cells
Cell membrane = sarcolemma, capable of generating action potential
Connected to system of T-tubules, oriented ⊥ to myofibrils.
Contrast red & white fibers.
Part of skeletal muscle.
Red (slow twitch, high myoglobin content (binds strongly to O₂) & white fibers (fast twitch, anaerobic).
Sarcomere structure
Basic unit of muscle fiber.
Made of thick (organized bundles of myosin) & thin (made up of actin, troponin, & tropomyosin) filaments.
Z-lines define sarcomere boundaries (reason for striat°)
M-line runs down sarcomere ctr.
I-band, exclusively thin bands
H-zone, exclusively thick filaments
A-band (size remains constant, "A"ll of thick fibers) contains thick filaments in entirety even where overlap w/thin
Contraction (of muscle cells) steps
1. Initiation (signal via motor neuron to nerve terminal/synaptic bouton, releasing NT into synapse -neuromuscular jxn)
2. Shortening of sarcomere (Massive release of Ca²⁺, binding and exposing myosin-binding sites on actin (Pic 6.8), free glob heads move toward & bind exposed actin sites, allowing myosin to give actin a pull, power stroke E given by ATPase activity) Pic 6.10
3. Relaxation (once SR receptors no longer active, Ca²⁺ falls
** ATP required for both contraction & release
Muscle stimulus
all-or-none response, must reach threshold value
Tonus
constant state of low-level muscle contraction, necessary for some voluntary & involuntary muscles
Periods of a muscle twitch
Latent (time bw reaching threshold & contraction onset)
(refractory period - absolute (∅ response ∅ matter the input) & relative (calls for higher input than normal to get response))
Contraction (, relaxation
Frequency summation & tetanus
Freq summation = freq / prolonged stim leading to combined contractions
If no time to relax = tetanus
Key concept: smooth muscle
exhibits myogenic activity = responds to nervous system input but doesn't require external signals to contract
Smooth muscle
controlled by autonomic nervous system
Have single, centrally placed nuclei.
Capable of longer & more sustained contractions.
Cardiac muscle
uninucleate & involuntary
striated
May also have myogenic activity.
Energy reserves
Muscles can get E from common places but also...
Creatine phosphate - stores allow for immed creat° of ATP
Myoglobin - holds onto O₂ more tightly than hemoglobin, helps keep aerobic metabolism going
Connective tissue
To bind & support other tissues.
Contains three types of proteinaceous fibers:
Collagenous (collagen, tensile strength)
Elastic (elastin, give resilience)
Reticular (branched woven fibers, join C.T. to adjoining)

2 Major cell types:
Fibroblasts (secrete components of xtracell fibers)
Macrophages (engulf bacteria & dead cells)
Dense connective tissue
High proportion of collagenous fibers organized in parallel bundles (great tensile strength)
Form tendons (attach muscle to bone) & ligaments (hold bones together at joints)
Origin
End of muscle attached to stationary bone.
In limb muscles, corresponds to proximal end.
Insertion
End of muscle attached to bone that moves during contraction.
In limb muscles, corresponds to distal end.
Synergistic muscles
Assist principal muscles during movement.
Classification of muscles by mv't type coordinated.
Flexor (contract to ↓ ∠ of joint)
Extensor (contract to straighten joint)
Abductor (moves a part of the body away from midline)
Adductor (moves a part of the body towards midline)