BIOLOGY FINAL REVIEW Flashcards
Cell theory
All living things are composed of cells
The cell is the basic functional unit of life
Cells arise only from preexisting cells
Peroxisomes
Peroxisomes contain hydrogen peroxide, they break down long chain fatty acids and participate in the synthesis of phospholipids
Microfilaments
Made of actin
Play a role in cytokinesis, form the cleavage furrow during mitosis
Microtubules
Made of hollow polymers of tubulin
Radiate throughout the cell, providing pathways for the motor proteins kinesin and dynein
Make cilia and flagella
Centrioles are found in the centrosome
cilia and flagella
cilia are for movement of materials along cell surface, flagella are for movement of the cell itself
share the same structure (9+2), only in eukaryotes
Centrioles
the organizing centers for microtubules
during mitosis, they migrate to opposite poles and organize the mitotic spindle, microtubules that attach to the chromosomes via kinetochores and pull apart the sister chromatids
Intermediate filaments
Diverse, includes keratin
Cell-cell adhesion or maintenance of overall cytoskeleton integrity, help anchor other organelles
varying protein identity
Epithelial tissue
protects against pathogen invasion
involved in absorption, secretion, sensation
tightly joined to each other and to the underlying basement membrane
constitute the parenchyma, functional parts of the organ
often polarized (facing lumen or interacts with underlying blood vessels, structural cells
Epithelial tissue classifications
Classified by layers and shape
simple has on layer of cells, stratified have multiple, pseudostratified only appears to have multiple
cuboidal are cube-shaped, columnar are long and thin, squamous are flat
Connective tissue
supports the body and provides a framework for the epithelial cells to carry out their function
constitute the stroma, support structure
bone, cartilage, tendons, ligaments, adipose tissue, blood
most produce and secrete materials to form the extracellular matrix (collagen, elastin)
Archaea
historically considered extremophiles, have ability to use alternative sources of energy
hypothesized to share an origin with eukaryotes, associate their DNA with histones like us
divide by binary fission
Bacteria
can be obligately aerobic, aerotolerant, etc
have a cell wall and phospholipid cell membrane that together are known as the envelope
Bacteria classifications
spherical = cocci rod-shaped = bacilli spiral-shaped = spirilli
Bacteria Gram negative vs positive
gram positive absorbs the violet stain, have a thick layer of peptidoglycan, contains lipoteichoic acid
gram negative absorbs the pink-red safranin counterstain, have a thin layer of peptidoglycan, have an additional outer membrane containing lipopolysaccharides (that triggers immune response)
Bacteria flagella structure
Flagella are composed of a filament, basal body, and hook
filament is hollow, helical structure composed of flagellin
basal body anchors the flagellum to the cytoplasmic membrane and serves as the motor
hook connects the filament and the basal body
Prokaryotes in general (DNA, cell membrane, ribosome)
have a single circular molecule of DNA concentrated in the nucleoid region
DNA acquired from external sources may be carrier on circular plasmids
plasmids carrier DNA not necessary for survival
Cell membrane is used for ETC and generation of ATP
contain a 30S + 50S = 70S ribosome
Binary fission
Binary fission takes less energy and proceeds more rapidly
circular chromosome attaches to cell wall and replicates while the cell continues to grow in size, eventually two exist and the cell divides along the midline
Plasmid use prokaryotes
Plasmids may carry virulence factors from external sources that increase pathogenicity
a subset of plasmids called episomes can integrate into the genome of the bacterium
Transformation, conjugation, and transduction
transformation is the integration of foreign genetic material taken from the vicinity (usually from lysed bacteria)
conjugation is sexual reproduction using a conjugation bridge made from sex pili to transfer genetic information between a donor male (+) and a female (-)
conjugation allows for rapid acquisition of antibiotic resistance or virulence factors
transduction is transfer of genetic material using a vector, usually a virus
Transposons
Transposons are genetic elements capable of inserting and removing themselves from the genome
Prokaryotic life cycle
Lag phase- adapting
exponential (log) phase- adapted
stationary phase- reduction of resources
death- out of resources
Viruses
genetic information may be circular or linear, composed of either DNA or RNA, have a protein coat known as a capsid
lack ribosomes and must use host cell
enveloped viruses are easier to kill
bacteriophages
bacteriophages are viruses that target bacteria, simply inject their genetic material inside
have a tail sheath (syringe) and tail fibers (for recognition)
positive sense vs negative sense RNA
single-stranded RNA from viruses can be positive sense (directly translate genome) or negative sense(serves as template for complementary strand which then serves as template for synthesis)
negative sense must carry an RNA replicase
retrovirus type of virus
retrovirus are enveloped, single stranded
carry reverse transcriptase
can only be removed by killing the cell
virus infection mechanism and limitations
viruses can only infect certain cells, must bind to specific receptors
enveloped viruses fuse with plasma membrane (HIV)
sometimes mistaken as useful molecule and brought into cytoplasm
viral genome must be returned to its original form before packaging
how viral progeny leave cell
progeny can either be released through the initiation of cell death or simple lysing of cell after being filled with virions, or leave by fusing with the plasma membrane (extrusion)
lytic cycle or lysogenic cycle
lytic cycle has little regard for survival of host cell (virulent)
lysogenic cycle integrates into host genome and is replicated as the bacterium reproduces
can be converted to lytic cycle by environment
prions
infections proteins, trigger misfolding of other proteins
viroids
very short circular ssRNA, typically infects plants and silence genes
Cell cycle stages
Four stages: G1, S, G2, M
first three are interphase, where cell spends most of its time
G0 phase implies no preparation for division
G1 stage
G1- Presynthetic gap
creates organelles and protein, increase size
passage into S stage is governed by restriction point, must contain proper complement of DNA
p53 controls this
S stage
S- Synthesis of DNA
replicates its genetic material, will have two identical chromatids although chromosome number has not changed
G2 stage
G2- Postsynthetic gap
checks that there is enough cytoplasm and organelles (adequate size), DNA replication proceeded correctly
p53 controls this
M stage
M- Mitosis
Prophase, metaphase, anaphase, and telophase
Cyclins and cylin-dependent kinases
Cyclins and cyclin-dependent kinases are responsible for cell cycle. Can create complex which phosphorylates transcription factors that promote transcription of genes required for next stage
Mitosis-Prophase
condensation of the chromatin into chromosomes
centriole pairs separate and move towards opposite poles, located at centrosome
centrosome-
responsible for correct division of DNA
MTOC at centrosomes form spindle fibers, asters
Mitosis-Metaphase
centriole pairs are now at opposite ends
chromosomes align at metaphase plate
Mitosis-Anaphase
centromeres split so that each chromatid has its own distinct centromere
sister chromatids separate and are pulled toward opposite poles
Mitosis-Telophase
reverse of prophase
spindle apparatus disappears
nuclear membrane reforms
nucleoli reappear, chromosomes uncoil
Mitosis-Cytokinesis
separation of cytoplasm and organelles
Meiosis 1 general concept and term
homologous chromosomes separated, generating haploid cells, known as reductional division
Meiosis 1 difference from mitosis - prophase
homologous chromosomes come together and intertwine in a process called synapsis
each synaptic pair is referred to as a tetrad
crossing over occurs if chromosomes break at point of contact (chiasma)
Meiosis 1 difference from mitosis - metaphase
tetrads align at plate, homologous chromosomes are held up with one spindle fiber (in meiosis there are two for each pair of sister chromatids)
Meiosis 1 difference from mitosis - anaphase
homologous pairs separate and are pulled to opposite poles
first law of segregation, either chromosome can end up in either daughter cell
Meiosis 1 difference from mitosis - telophase
each chromosome still consists of two sister chromatids, the cells are now haploid
Meiosis 2 general concept and term
similar to mitosis, separation of sister chromatids, equational division
X chromosome
X chromosome contains more genetic information
males only have one allowing for sex-linked disorders
Y chromosome
contains very little information
contains SRY (sex-determing region Y) which codes for the initiation of testis development. In absence all zygotes will be female
testicles
seminiferous tubulus and interstitial cells of Leydig
seminiferous tubules
sperm are produced, nourished by sertoli cells
interstitial cells of Leydig
testosterone is secreted
epididymis
sperm develop, flagella gain motility
seminal vesicles, prostate gland, and bulbourethral gland
create seminal fluid
seminal vesicles contribute fructose
prostate gland gives mild alkaline properties to protect against female reproductive acidity
bulbourethral (prostate) gland produces a cleaning and lubricating fluid
spermatogenesis order
Diploid Spermatogonia -> Diploid Primary spermatocytes -(meiotic division)-> Haploid secondary spermatocytes -> haploid spermatids -> mature spermatozoa
sperm anatomy
head (genetic material),
midpiece (mitochondria)
acrosome cap (penetrating ovum, made from Golgi Apparatus)
ovaries
produce estrogen and progesterone
located in pelvic cavity, consists of thousands of follicles
follicles
follicles are multilayered sacs that contain and nourish the eggs
oogenesis order and timing
By birth, all oogonia are considered primary oocytes, arrested in prophase 1.
One primary oocyte per month will complete meiosis I, producing a secondary oocyte and a polar body.
The secondary oocyte remains in metaphase II unless fertilization occurs.
zona pellucida
Oocytes are surrounded by zona pellucida
protects the oocyte and contains compounds for sperm cell binding
corona radiata
corona radiata surrounds the zona pellucida
Meiosis II is triggered when both layers are penetrated
hypothalamus start of puberty
At the start of puberty, hypothalamus releases GnRH which triggers the anterior pituitary gland to synthesize and release FSH and LH
FSH and LH general males
FSH stimulates Sertoli cells, sperm maturation
LH causes the interstitial cells of Leydig to produce testosterone
testosterone exerts negative feedback on hypothalamus, anterior pituitary
FSH and LH general females
Estrogens are secreted in response to FSH
Progesterone is secreted by the corpus luteum in response to LH
Menstrual cycle general definition and stages
The process of the endometrial lining growing and shedding in response to estrogen and progesterone levels
Follicular phase, ovulation, luteal phase, menstruation/pregnancy
Follicular phase
begins when the menstrual flow begins from previous cycle
GnRH increases due to decreased estrogen and progesterone, causes increased FSH and LH
these two hormones develop follicles, which begin to produce estrogen
in response to estrogen, gnRH, LH, and FSH concentrations level off.
in response to estrogen, regrowth of the endometrial lining occurs
Ovulation
in response to estrogen reaching a threshold, gnRh, LH, and FSH levels spike
the LH surge induces ovulation, the release of the ovum from the ovary into peritoneal cavity
Luteal Phase
after ovulation, the ruptured follicle forms the corpus luteum
the corpus luteum secretes progesterone
high levels of progesterone cause negative feedback on GnRH, FSH, and LH
Menstruation
if implantation does not occur, the corpus luteum loses its stimulation from LH, progesterone levels decline, and the uterine lining is sloughed off
Pregnancy (menstrual cycle)
if fertilization has occurred, the zygote develops into a blastocyst that implants in the uterine lining and secretes hCG (an analog of LH)
hCG maintains the corpus luteum, which secretes estrogen and progesterone during first trimester, keeping uterine lining in place
in second trimester hCG levels decline, the placenta can secrete enough progesterone and estrogen by itself
Menopause
ovaries become less sensitive to FSH and LH, resulting in ovarian atrophy. Menstruation stops. Blood levels of FSH and LH increase as negative feedback is removed
Fertilization steps
a secondary oocyte is ovulated on day 14, where it travels into the fallopian tube and can be fertilized up to 24 hrs after ovulation
first sperm to come into direct contact with the secondary oocyte creates the acrosomal apparatus
after penetration of sperm through cell membrane, the cortical reaction (release of calcium ions) occurs
as the zygote moves to the uterus for implantation, it undergoes rapid mitotic cell divisions. The first cleavage officially creates an embryo
Corticol reaction (fertilization)
release of calcium ions that depolarizes the cell membrane of the oocyte which prevents multiple fertilization and increases the metabolic rate of the zygote
Membrane is now called the fertilization membrane
Indeterminate cleavage vs determinate cleavage
Indeterminate cleavage results in cells that can still develop into complete organisms
determinate cleavage results in cells that are committed to differentiating
Blastulation of embryo
several divisions after the embryos first division, it becomes a solid mass of cells known as a morula
the morula forms the blastula
the blastula burrows into the endometrium
Blastulation- blastocoel
the blastula’s inner cavity is called a blastocoel
contains the trophoblast (surrounds the blastocoel and gives rise to chorion which becomes placenta, serves as an interface between the maternal blood supply and the embryo)
also contains the inner cell mass (protrudes into the blastocoel and gives rise to the organism itself)
Blastulation- development and connection of the placenta
trophoblasts form chorionic villi, which develop into placenta
the embryo is connected to the placenta by the umbilical cord
two arteries, one vein. vein is oxygenated
Blastulation- support of embryo
until the placenta is functional, the embryo is supported by yolk sac
The allantois is involved in early fluid exchange between the embryo and the yolk sac. Surrounded by the amnion membrane, which serves as a shock absorber. Chorion also forms an outer membrane around the amnion
Gastrulation definition
Once the cell is implanted it can begin the generation of three distinct cell layers
archenteron
the membrane invaginates into the blastocoel, forming the archenteron, which later becomes the gut. The opening, called the blastopore, becomes the anus in deuterostomes
Ectoderm
Ectoderm- “attracto derm”
epidermis, hair, nails, epithelia of nose, mouth, eye, nervous system
Mesoderm
Mesoderm- “means oderm”
musculoskeletal and circulatory system, excretory system, gonads, muscular and connective tissue layers, kidneys
Endoderm
Endoderm- “internal derm”
digestive and respiratory tracts, pancreas, thyroid, bladder, liver
Differentiation control
selective transcription controls differentiation
is mediated by chemical substances called inducers
responder cells must be competent to be induced
Neurulation
Once the three germ layers are formed, the notochord forms from the mesoderm
Formation of notochord
notochord induces ectoderm cells to slide inward, forming neural folds, which surround a neural groove and eventually fuse into a neural tube
neural crest cells at the tip of each fold form the peripheral nervous system
Teratogens
Teratogens are substances that interfere with development
Folic acid deficiency results in spina bifida
determination
specification
differentiation
order and description
Specification (cell is designated as a certain type) -> Determination (cell differentiation is designated) -> Differentiation
Potency and types of potent cells
Potency describes ability to differentiation
Totipotent can differentiate into any type
Pluripotent can differentiate into all but placenta
Multipotent can differentiate into all from a particular group
Autocrine signals
Paracrine signals
Juxtacrine signals
Endocrine signals
definitions
Autocrine signals - same cell
Paracrine signals - local area
Juxtacrine signals - no diffusion, directly stimulating adjacent cell
Endocrine signals - travel through blood
growth factors definition
peptides that promote differentiation
types of inducers
Reciprocal development definition
development of one induces development of the other
How does apoptosis occur?
the cell undergoes changes in morphology and divides into apoptotic blebs
apoptotic blebs become apoptotic bodies, which are digested by other cells
placental barrier and placenta in fetal circulation
Placental barrier serves for immunity, placenta serves nutrient, gas, and waste exchange functions
oxygenation in fetal circulation
Oxygenation occurs at placenta
Umbilical arteries carry blood away from fetus like all arteries
deoxygenated
Umbilical veins carry blood towards the fetus
oxygenated, from placenta
foramen ovale
connects the right atrium to the left atrium, bypassing right ventricle
ductus arteriosus
shunts leftover blood from the pulmonary artery to the aorta
ductus venosus
shunts blood returning from the placenta via the umbilical vein directly into the inferior vena cava, bypassing the liver
First trimester
heart begins to beat, cartilaginous skeleton begins to harden into bone, by 8 weeks most of organs have formed, the brain is fairly developed, and the embryo becomes known as the fetus
Second trimester
fetus undergoes tremendous growth, takes on a human appearance
Third trimester
rapid growth, antibodies are transferred to fetus at highest rate, eventually growth rate slows in ninth month
Birth
coordinated by prostaglandins and oxytocin
water breaking is the amniotic sac rupturing
myelin purpose and production
prevents signal loss or crossing of signals
produced by oligodendrocytes (CNS) or Schwann cells (PNS)
tracts (nervous system)
only one type of information
cell bodies of neurons in the same tract are grouped into nuclei
Glial cells- Astrocytes
nourish neurons and form the blood-brain barrier
Glial cells- ependymal cells
produce cerebrospinal fluid
Glial cells- microglia
phagocytic cells for the CNS
Glial cells- oligodendrocytes and Schwann cells
Oligodendrocytes (CNS) and Schwann cells (PNS) produce myelin
Action potential
Na+ influx open in response to reaching the threshold, causing depolarization
positive potential triggers Na+ channels to inactivate and K+ channels to open, causing repolarization
hyperpolarization occurs as K+ overshoots
Na+/K+ ATPase acts to restore resting potential and sodium potassium gradients
Neurotransmitters release
when action potential reaches the nerve terminal, Ca+ channels open, triggering fusion of the membrane-bound vesicles and exocytosis of the neurotransmitters
Neurotransmitters breakdown
Three main mechanisms for breakdown enzymatic reactions (ex: acetylcholinesterase) reuptake carriers (ex: serotonin, dopamine, norepinephrine) simple diffusion
White matter
axons encased in myelin sheaths
located deep in the brain but shallow in the spinal cord
Grey matter
unmyelinated cell bodies and dendrites
shallow in the brain but deep in the spinal cord
Spinal cord order
Cervical, thoracic, lumbar, sacral (top to bottom)
Somatic vs autonomic nervous system nerve setup
in autonomic system, peripheral component contains two neurons
in somatic nervous system motor neuron goes directly from spinal cord to muscle
Autonomic nervous system branches and general mechanism
ANS consists of sympathetic and parasympathetic
Parasympathetic uses acetylcholine, vagus nerve is responsible for much of it
Sympathetic nervous system uses acetylcholine in preganglionic neurons, norepinephrine in postganglionic neurons
Reflexes, two types
bypassing the brain and use interneurons
monosynaptic
single synapse between sensory and motor neuron
knee-jerk reflex
polysynaptic
at least one interneuron between sensory and motor neurons
withdrawal reflex
Peptide hormones
made from AAs, derived from larger precursor polypeptides
charged, so cannot pass through plasma membrane and must use secondary messenger system
generally water soluble, do not require carriers
Steroid hormones
derived from cholesterol, so nonpolar
can easily cross cell membrane
not water soluble, must use carriers
which hormones are peptide which are steroid
Peptide- FSH, LH, ACTH, TSH, Prolactin, Endorphins, GH, ADH, Oxytocin, Calcitonin, PTH, Glucagon, Insulin, Somatostatin, Melatonin, Erythropoietin, ANP, Thymosin
Steroid- cortisol/cortisone, aldosterone, testosterone, estrogen, progesterone
-(end in one or ol or en)
tyrosine derived hormones; types and binding location
epinephrine, norepinephrine
bind to G protein-coupled receptors
triiodothyronine, thyroxine
bind intracellularly
Hypothalamus
bridge between nervous and endocrine systems
sleep-wake cycles, blood osmolarity, appetite and satiety
regulated by negative feedback
interacts with anterior pituitary through hypophyseal portal system
interacts with posterior pituitary directly
hypophyseal portal system hormone relationships (hypothalamus -> anterior pituitary)
hints: GnRH GHRH TRH CRF
Gonadotropin-releasing hormone (GnRH) ->
Follicle-stimulating hormone (FSH), Luteinizing hormone (LH)
Growth hormone-releasing hormone (GHRH) -> Growth hormone (GH)
Thyroid-releasing hormone (TRH) ->
Thyroid-stimulating hormone (TSH)
Corticotropin-releasing factor (CRF) -> Adrenocorticotropic hormone (ACTH)
Anterior pituitary tropic hormones
Follicle-stimulating hormone and Luteinizing hormones act on the gonads
Adrenocorticotropic hormone acts on the adrenal cortex
Thyroid stimulating hormone acts on the thyroid
Anterior pituitary direct hormones
Prolactin stimulates milk production during pregnancy in response to elevated estrogen and progesterone
dopamine from the hypothalamus decreases its secretion
Growth hormone promotes the growth of bone and muscle
-prevents glucose uptake in certain tissue and stimulates the breakdown of fatty acids
Endorphins decrease pain
Posterior pituitary hormones
Antidiuretic hormone -response to low blood volume, works on the the collecting duct to increase water reabsorption from filtrate
Oxytocin- bonding, coordinated contraction of smooth muscle (breasts when lactating, uterus)
unique for its positive feedback look
Thyroid hormones
controlled by thyroid-stimulating hormone
T3 and T4
- mediate basal metabolic rate, higher amounts lead to increased cellular respiration
- high levels decrease the amount of TSH (anterior pituitary) and TRH (hypothalamus)
- made from iodine
calcitonin
- produced from C-cells (parafollicular cells)
- decreases plasma calcium levels
Calcitonin mechanism (kidneys, gut, bone)
increasing calcium excretion from the kidneys
decreasing calcium absorption from the gut
increasing storage of calcium in the bone
Parathyroid glands hormones
four small glands on posterior surface of thyroid
Parathyroid hormone (PTH)
- antagonistic to calcitonin, increases plasma calcium levels
- activates vitamin D, required for the absorption of calcium and phosphate in the gut
Adrenal CORTEX hormones
Corticosteroids: Glucocorticoids and Mineralocorticoids, cortical sex hormones
Glucocorticoids increase plasma glucose levels in response to stress
-cortisol and cortisone
Mineralocorticoids regulate salt and water homeostasis, particularly on kidneys
-aldosterone increases sodium reabsorption in the distal convoluted tubule and collecting duct, water follows
Cortical sex hormones
- Androgens and estrogens
- females are much more sensitive, in males testicles make most androgens
Aldosterone release pathway
decreased blood pressure -> juxtaglomerular cells of the kidney secrete renin -> renin cleaves angiotensinogen to angiotensin I -> converted to angiotensin II by angiotensinconverting enzyme (ACE) -> angiotensin II stimulates release of aldosterone
Glucocorticoids release pathway
under control of adrenocorticotropic hormone (ACTH) from anterior pituitary in response to corticotropin-releasing factor (CRF) from the hypothalamus
Adrenal MEDULLA hormones
Catecholamines
sympathetic hormones epinephrine and norepinephrine
glycogenolysis in liver and muscle
increase basal metabolic rate
increase heart rate, dilate the bronchi, shunt blood flow to sympathetic systems, vasodilation and vasoconstriction to appropriate system
Pancreas (endocrine)
islets of langerhans contain alpha, beta, and delta cells
alpha secretes glucagon
-times of fasting, triggers glycogenolysis, gluconeogenesis, -degradation of protein and fat
beta secretes insulin
- antagonistic to glucagon, store glucose as glycogen
- in excess causes hypoglycemia, not enough is diabetes
delta secretes somatostatin
- inhibitor of both insulin and glucagon
- in response to high blood glucose and AA concentrations
- produced by hypothalamus
Types of diabetes
type I is autoimmune destruction of beta cells
type II is resistance to insulin
in both excess water excretion due to the water being more osmotically active
Gonads endocrine function
testes secreted testosterone in response to LH and FSH
ovaries secrete estrogen and progesterone in response to LH and FSH
Pineal gland endocrine function
melatonin
circadian rhythm
kidneys endocrine function
kidneys produce erythropoietin
stimulates bone marrow to increase production of RBCs
heart endocrine function
heart release atrial natriuretic peptide
help regulates salt and water balance, excretion of sodium increases urine volume
antagonistic to aldosterone
thymus endocrine function
thymus releases thymosin
important for T-cell development
Lungs
two mainstem bronchi separate air flow
membranes known as pleurae surround each lung, surface adjacent to lung is known as the visceral pleura and the outer part is the parietal pleura
Inhalation and exhalation mechanisms
inhalation- external intercostal muscles and diaphragm expand the thoracic cavity to decrease pressure in lungs
exhalation- passive process unless using the internal intercostal muscles during active tasks
Lung volumes TLC RV VC TV ERV IRV
TLC- total lung capacity, maximum volume in lungs
RV- residual volume, volume remaining after a full exhale
VC- vital capacity, total lung capacity minus residual volume
TV- tidal volume, normal breaths worth of air
ERV- additional air that can be exhaled after a normal exhalation
IRV- additional air that can be inhaled after a normal inhalation
breathing regulation
primarily regulated by the ventilation center in the medulla oblongata
- contains chemoreceptors that respond to carbon dioxide concentration
- more CO2 = more respiration
Gas exchange lungs to circulatory system
pulmonary arteries originate from right ventricle, go to lungs, deoxygenated
pulmonary veins returns to the left atrium of the heart, oxygenated
immune function respiratory system
nasal cavity has small hairs, lysozyme (attacks peptidoglycan walls of gram positive bacteria)
cilia on internal airways propel mucus up the respiratory tract
-mucociliary escalator
lungs contain macrophages and mast cells (have preformed antibodies)
Bicarbonate buffer system and regulation of blood pH
CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) + HCO3- (aq)
more CO2 = more H+
blood ph is normally between 7.35 and 7.45
higher respiratory rate = more CO2 loss
kidneys work slower to modulate secretion and reabsorption of acid and base
Heart anatomy
Right side accepts deoxygenated blood and moves it to the lungs by way of pulmonary arteries (pulmonary circulation)
Left side accepts oxygenated blood and forces out through the body (systemic circulation)
Electrical conduction in heart
Sinoatrial node (SA) -> atrioventricular node (AV) -> bundle of His -> Purkinje fibers
As the depolarization wave spreads from SA node, it causes the two atria to contract simultaneously
atrial systole (contraction) results in an increase in atrial pressure that forces more blood into ventricles -called the atrial kick
once the signal reaches the AV node, it is delayed to allow the ventricles to fill, then travels down bundle of His
Purkinje fibers distribute the electrical signal through the ventricular muscle
-muscle cells are connected by intercalated discs which contain many gap junctions
Systole/Diastole
During systole, ventricular contraction and closure of the AV valves occurs and blood is pumped out of ventricles
-higher pressure due to contraction
During diastole, the ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles
-lower pressure due to relaxation
Cardiac output and calculation
Cardiac output is the total blood volume pumped by a ventricle in a minute
CO = HR x SV (volume per stroke)
Veins, capillaries, arteries similarities and differences
Both veins and arteries have endothelial cells and smooth muscle
arteries have much more smooth muscle and are elastic, maintaining high pressure
capillaries are a single endothelial cell layer thick to allow for diffusion
veins are thinner than arteries, they are able to stretch to accommodate larger volume of blood (75% of blood is in the veins)
how veins deal with low pressure
larger veins contain valves due to low pressure
failure leads to varicose veins, where blood pools
most veins are surrounded by skeletal muscle which forces blood against gravity
Circulation pathway
right atrium -(tricuspid valve)-> right ventricle -(pulmonary valve)-> pulmonary artery -> lungs -> pulmonary veins -> left atrium -(mitral valve)-> left ventricle -(aortic valve)-> aorta -> arteries -> arterioles -> capillaries -> venules -> veins -> vena cava -> right atrium
hepatic portal system
blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver
hypophyseal portal system
blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary
renal portal system
blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta
Blood composition
plasma + erythrocytes, leukocytes, and platelets
red blood cells rely entirely on glycolysis for ATP
hematocrit is a measure of how much of the blood sample consists of red blood cells
Leukocytes
white blood cells comprising less than 1 percent of blood
Granular leukocytes vs Agranulocytes
Granular leukocytes
- contain cytoplasmic granules which contain a variety of compounds that are toxic to invading microbes
- neutrophils, eosinophils, basophils
- involved in inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites
Agranulocytes
lymphocytes
- specific immune response
- B-cells mature in bone marrow, responsible for antibody generation
- T-cells mature in thymus, responsible for killing virally infected cells and activating other immune cells
monocytes
-become macrophages
Both come from hematopoietic stem cells
Thrombocytes
platelets
cell fragments released from cells in the bone marrow known as megakaryocytes
assist in blood clotting
erythroblastosis fetalis
if a mother has an Rh+ child, any subsequent pregnancy will present a problem because the mother has anti Rh+ antibodies
in the first pregnancy the mother will not produce antibodies until the child is born
Blood pressure, resistance calculation
ratio of systolic (contraction) to diastolic (relaxation)
resistance in blood vessels can be calculated same as any pipe
Resistance = 8L(viscosity)/ (pi)r^4
regulated using baroreceptors and chemoreceptors
Bohr effect
increased CO2 results in right shift in bicarbonate buffer equation, resulting in H+ increase, these protons bind to hemoglobin and reduce affinity for oxygen (release their oxygen load)
what causes left shift of hemoglobin binding curve
Fetal hemoglobin, carbon monoxide, INCREASED pH
less oxygen unloading
what causes right shift of hemoglobin binding curve
Carbon dioxide, 2,3-BPG, Temperature, exercise
more oxygen unloading
Fluid balance control mechanisms (pressure definitions); at capillaries
Fluid balance is controlled by the opposing hydrostatic and osmotic pressure
hydrostatic pressure is the pressure of the blood against the vessel walls
osmotic pressure is the sucking of solutes as they attempt to draw water into the bloodstream
mostly due to plasma proteins, thus called oncotic pressure
at arteriole end of capillary bed, hydrostatic pressure is much larger and water leaves; at venule end of capillary bed, hydrostatic pressure is lower and water enters back into circulation
Coagulation
when the endothelium is damaged, it exposes tissue factor. platelets sense this and release their contents and aggregate. Coagulation factors sense tissue factor and issue an activation cascade
activation cascade: prothrombin -> thrombin by thromboplastin. fibrinogen -> fibrin by thrombin
clot is broken down by plasmin, which is generated from plasminogen
Innate immunity definition
Innate immunity is always active against infection but lacks the ability to target specific invaders, also known as non-specific immunity
Noncellular defenses of innate immunity
- antibacterial enzymes called defensins found on the skin, sweat
- mucous membranes produce lysozyme
GI Tract
Complement system
Interferons
role of GI tract innate immunity
GI Tract
- acid
- bacteria in gut compete potential invaders
role of complement system innate immunity
complement system
- number of proteins in the blood that act as nonspecific defense, activated through a classical pathway (binding of antibody to pathogen) or alternative pathway (does not require antibodies)
- punches holes in cell walls of bacteria
role of interferons innate immunity
interferons
- proteins that prevent viral replication and dispersion
- cause nearby cells to decrease production of both viral and cellular proteins, also decreases the permeability these cells
- upregulate MHC I and class II molecules
Cellular defenses of innate immunity
Macrophages
Natural Killer cells
Granulocytes
role of macrophages innate immunity
a type of agranulocyte
activate when a bacterial invader enters a tissue
first phagocytizes the invader, then digests the invader using enzymes, then presents to other cells using MHC
release cytokines, which stimulate inflammation and recruit additional immune cells
Macrophages and dendritic cells also have pattern recognition receptors such as toll-like receptors which recognize the category of the invader and allows for production of appropriate cytokines
role of MHC I and II, types of antigen presenting cells
MHC binds to an antigen and carries it to the cell surface, where it can be recognized by the adaptive immune system
MHC I is present in all nucleated cells of the self
endogenous pathway
MHC II is displayed by antigen-presenting cells like macrophages in response to invaders
exogenous pathway
antigen-presenting cells include macrophages, dendritic cells, some B-cells, certain activated epithelial cells
role of natural killer cells innate immunity
detect downregulation of MHC and induce apoptosis in these virally infected cells
therefore help with cancer
role of granulocytes innate immunity
neutrophils are phagocytic, follow bacteria using chemotaxis, also detect bacteria once they have been opsonized (marked for death with antibody from B-cells)
eosinophils are primarily involved in allergic reactions and parasitic infections, release histamine (inflammatory response)
inflammation is particularly useful against extracellular pathogens
basophils are involved in allergic responses, least populous
mast cells are closely related but have smaller granules
adaptive immunity definition
Adaptive or specific immunity is slower but can target specific pathogens and remember them
split into humoral immunity (B-cells) and cell-mediated/cytotoxic immunity (T-cells)
Humoral immunity
May take up to a week to become fully effective
Antibodies are produced by B cells
Naive B cells wait in the lymph for their particular antigen. Upon exposure proliferate into plasma and memory B-cells
Possible antibody responses
Opsonization- attract other leukocytes to phagocytize
Agglutination- antibodies cause pathogens to clump together
Neutralization- block the ability of a pathogen to invade tissue
general structure of antibody, matching mechanism
disulfide linkages and noncovalent interactions hold the heavy and light chains together
B-cells undergo hypermutation at the antigen-binding region, trying to find the best match for the antigen
clonal selection in antibodies
only those that can bind the antigen with high affinity survive and replicated
Secondary response of humoral immunity
Upon exposure B-cells proliferate into plasma and memory B-cells
plasma cells produce large amounts of antibodies
memory B-cells wait in the lymph node for reexposure to the same antigen
primary response takes a week or so
secondary response is more rapid, from the memory B-cells
Cell mediated/cytotoxic immunity cell types roles
helper, cytotoxic, regulatory, memory
Helper T-cells
- CD4+, secrete lymphokines that recruit other immune cells and increase their activity
- Th1 release interferon gamma which activates macrophages
- Th2 activate B-cells
-MHC II cells (bacterial, fungal, parasitic infections)
Cytotoxic (killer) T-cells
CD8+, directly kill virally infected cells
MHC I cells (viruses, intracellular infection)
Suppressor (regulatory) T-cells
CD4+, Foxp3, tone down the immune response, turn off self-reactive lymphocytes
Memory T-cells
wait until next exposure to same antigen
T cells (clonal) selection
T-cells undergo both positive and negative selection in the thymus
positive selection- allows only the cells that can respond to the presentation of antigen on MHC
negative selection- causes apoptosis in cells that react to the self
maturation is facilitated by thymosin from the thymus
Production immune system
bone marrow, spleen, thymus, lymph nodes, digestive system
Bone marrow produces all of the leukocytes
Spleen stores and activates B-cells
T-cells mature in the thymus
lymph nodes provide a place for immune cells to communicate and mount an attack, B-cells can be activated
Digestive system has gut-associated lymphoid tissue (GALT)
-tonsils, adenoids, peyer’s patches in the small intestine, lymphoid aggregates in the appendix
Self and autoimmunity
Self-antigens signal to immune cells that the body is foreign and should not be attacked. Autoimmunity occurs when these fail
Active vs passive immunity
Active immunity occurs when the immune system is stimulated to produce antibodies against a specific pathogen
Passive immunity results from the transfer of antibodies to an individual
Lymphatic system
B-cells proliferate and develop within the lymphatic system in collections called germinal centers
Vessels carry lymph and join to form a thoracic duct in the posterior chest, which delivers the fluid into the left subclavian vein near the heart
Lymph nodes provide a space for the cells of the immune system to be exposed to possible pathogens
transports fats from the digestive system into the bloodstream using lacteals (small lymphatic vessels)
Digestive system pathway
Oral cavity-> Pharynx -> Esophagus -> Stomach -> Small intestine -> Large intestine -> rectum
Enteric nervous system
Enteric Nervous system is a collection of neurons that trigger peristalsis (rhythmic contractions)
ADH, Aldosterone, glycogen, gherkin, leptin, cholecystokinin role in drive
ADH and aldosterone trigger the sensation of thirst, Glucagon and ghrelin stimulate feelings of hunger. Leptin and cholecystokinin stimulate satiety
Oral cavity digestion
Chemical digestion begins with enzymes from salivary glands
like all digestive tract glands, innervated by the parasympathetic NS
salivary amylase, lipase
Parts of pharynx
Nasopharynx (behind nasal cavity)
Oropharynx (back of the mouth)
Laryngopharynx (above the vocal cords)
Stomach- divisions and associated glands
can be divided into four main anatomical divisions
fundus and body (gastric glands) (top)
antrum and pylorus (pyloric glands) (bottom)
gastric glands (mucous, chief, parietal)
respond to signals from the vagus nerve
mucous cells
-produce the bicarbonate-rich mucus that protects the muscular wall from the harshly acidic environment
chief cells
-secrete pepsinogen, activated by acidity
parietal cells
-secrete HCl (H+), intrinsic factor (proper vit B12 absorption)
chief and parietal cells together produce gastric juice
pyloric glands
contain G-cells, secrete gastrin
-gastrin induces the parietal cells to secrete more HCl and signals the stomach to contract
Duodenum
first part of small intestine, responsible for the majority of chemical digestion
food enters through the pyloric sphincter
brush-border enzymes break down dimers and trimers of biomolecules into absorbable monomers
Duodenum secretions
disaccharidases, which digest disaccharides
Enteropeptidase activates trypsinogen to trypsin
Secretin causes pancreatic enzymes to be released into the duodenum, reduces HCl secretion from parietal cells
enterogastrone, slows motility through digestive tract
Cholecystokinin stimulates the release of bile and pancreatic juices and promotes satiety
Bile salts
bile salts are derived from cholesterol, facilitate the chemical digestion of lipids
- have hydrophobic and hydrophilic regions, serve as bridge between aqueous and lipid environments
- like soap, emulsify fats and cholesterol into micelles
Pancreas functions digestive system
accessory organ with exocrine and endocrine functions
endocrine
insulin, glucagon, somatostatin (all for blood sugar)
exocrine
bulk of the pancreas is made of acinar cells that produce pancreatic juices
amylase, peptidases, lipases
-transferred to the duodenum via a duct system
enteropeptidase is the master switch for other zymogens
Liver
bile production
synthesizes certain proteins necessary for proper body function
-albumin (plasma oncotic pressure), clotting factors
receives all blood draining from the abdominal portion of the digestive tract through the hepatic portal vein
this blood is processed by the liver before draining into the inferior vena cava
- includes taking up excess sugar to create glycogen or storing fats as triacylglycerols, or the reverse of those processes
- detoxifies endogenous and exogenous compounds
bile pathway and bilirubin
bile ducts connect the liver with both the gallbladder and the small intestine
bile produced in the liver travels down these bile ducts where it may be stored in the gallbladder or secreted into the duodenum
major pigment of bile is bilirubin, a byproduct of the breakdown of hemoglobin
Gallbladder
located beneath the liver, stores and concentrates bile
upon release of CCK, contracts and pushes bile out into the biliary tree
common site of cholesterol or bilirubin stone formation
Jejunum and Ileum (digested/absorbed compounds and mechanism)
while the duodenum is primarily responsible for digestion, the jejunum and ileum are involved in the absorption of nutrients
simple sugars are absorbed by secondary active transport and facilitated diffusion into the epithelial cells lining the small intestine
blood passing by the epithelial cells creates a concentration gradient allowing the simple carbohydrates and amino acids to diffuse into the capillaries
-short chain fatty acids follow the same process
triglycerides and esterified cholesterol molecules are packaged into chylomicrons, and enter the lymphatic circulation through lacteals (small vessels that form the beginning of the lymphatic system)
-these lacteals converge and enter the venous circulation at the thoracic duct
Vitamins are absorbed by the small intestine
- fat soluble vitamins (ADEK) dissolve directly into chylomicrons
- water soluble vitamins are taken up across the endothelial cells of the small intestine, passing directly into the plasma
Water is absorbed by the small intestine
- the fluid of the chyme must be reabsorbed through osmosis
- water passes transcellularly (across cells) and paracellulary (between cells) to reach the blood
Large intestine
primarily involved in water absorption
Cecum
- an outpocketing that accepts fluid exiting the small intestine through the ileocecal valve
- where the appendix attaches
Colon
- ascending, transverse, descending, sigmoid
- mainly functions to absorb water and salts
- concentrates the remaining material to form feces
Rectum
- storage site for feces
- many bacteria (produce vitamin K)
kidneys anatomy
cortex, medulla, renal hilum
cortex (outer) and medulla (inner)
renal hilum is a deep slit in the center of its medial surface
renal artery, renal vein, and renal ureter enter and exit through hilum
Kidney portal system
renal artery branches out, passes through the medulla, and enters the cortex as afferent arterioles
- glomeruli are derived from these afferent arterioles
- -Bowman’s capsule surrounds the glomerulus, and leads to a long tubule
after passing through a glomerulus, the efferent arterioles form a second capillary bed
-known as the vasa recta, surrounds the loop of Henle
Bladder anatomy
has a muscular lining known as the detrusor muscle
has an internal and external urethral sphincter
-micturition reflex causes internal to relax
filtration by kidney
20% of the blood that passes through the glomerulus enters Bowman’s space. This blood is now known as filtrate. This fluid movement is government by starling forces
- Starling forces are the pressure differentials between hydrostatic and oncotic pressure. The hydrostatic pressure in the glomerulus is higher than Bowman’s space, so the fluid moves into the nephron
- Pathogens can cause derangements of this flow
- Filtrate is similar to blood but without cells or proteins
secretion by kidney
the nephrons can secrete (take out of circulation) salts, acids, bases, and urea directly into the tubule through either active or passive transport
-the quantity and identity of secreted substances depends on the needs of the body
reabsorption by kidney
some compounds that are filtered or secreted may be taken back up via reabsorption
- glucose, AA, vitamins are always reabsorbed
- antidiuretic hormone and aldosterone can alter the quantity of water reabsorbed to maintain blood pressure
nephron summarized function and anatomy
the kidney keeps what the body needs and lose what it doesn’t, and concentrates the urine to conserve water
proximal convoluted tubule, loop of Henley, distal convoluted tubule, collecting duct
Proximal convoluted tubule
in this region, amino acids, glucose, water-soluble vitamins, and the majority of salts are reabsorbed along with water
secretion of waste products, including hydrogen ions, potassium ions, ammonia, and urea also occurs here
loop of henle (descending)
descending limb is permeable only to water, increasing concentration with more depth into the medulla favors the outflow of water, which is reabsorbed by the vasa recta
countercurrent multiplier system
together the vasa recta and nephron create a countercurrent multiplier system
opposite flows, the filtrate is constantly being exposed to hypertonic blood
maximum reabsorption of water
loop of henle (ascending)
the ascending limb is permeable to salts and is impermeable to water, therefore maximizes salt reabsorption by taking advantage of of decreasing medullary osmolarity (opposite of descending limb)
diluting segment can produce urine that is more dilute than blood
-important during overhydration
distal convoluted tubule
responds to aldosterone, which promotes sodium reabsorption; water follows
site of waste product secretion like the proximal convoluted tubule
collecting duct
responsive to both aldosterone and ADH
almost always reabsorbs water, to varying degrees
anything that is not reabsorbed from the tubule by the end of the collecting duct will be excreted
blood pressure regulation role of excretory system
Aldosterone is a steroid hormone that is secreted by the adrenal cortex in response to decreased blood pressure
in response to renin, ACE; as discussed earlier
distal convoluted tubule and collecting duct to reabsorb sodium
Antidiuretic hormone (ADH) is a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary directly alters the permeability of the collecting duct
osmoregulation role of excretory system
kidneys control by modulating the reabsorption of water and by filtering and secreting dissolved particles
acid-base balance role of excretory system
kidneys are able to selectively increase or decrease the secretion or reabsorption of hydrogen ions and bicarbonate
slower than respiratory response but highly effective
epidermis layers, shallowest to deepest
(Come Lets Get Sun Burned)
stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale
stratum corneum
contains several dozen layers of flattened keratinocytes, forming a barrier that prevents invasions by pathogens and that helps to prevent loss of fluids and salt
stratum lucidum
only present in thick, hairless skin; nearly transparent
sole of the foot or the palms
stratum granulosum
the keratinocytes die and lose their nuclei
stratum spinosum
where keratinocytes become connected to each other, also the site of Langerhans cells
-These are the macrophages, capable of presenting antigens to T-cells
stratum basale
contains stem cells and is responsible for proliferation of keratinocytes that produce keratin
melanocytes produce melanin here, which is transferred to the keratinocytes
-skin color is caused by varying levels of activity of the melanocytes
dermis layers, shallowest to deepest and purpose
papillary layer
loose connective tissue
reticular layer
sweat glands, blood vessels, hair follicles
most sensory receptors are also located here
Merkel cells
Meissner’s corpuscles
Ruffini endings
Pacinian corpuscles
Merkel cells (deep pressure and texture) Meissner’s corpuscles (light touch) Ruffini endings (stretch) Pacinian corpuscles (deep pressure and vibration)
hypodermis
layer of connective tissue that connects the skin to the rest of the body
contains insulating fat and fibrous tissue
Thermoregulation role of skin
sweating controlled by the autonomic nervous system
arrector pili muscles contract, causing piloerection
brown fat in infants has a much less efficient electron transport chain, causing more heat loss
Skeletal muscle
voluntary movement, striated due to sarcomeres, multinucleated
consists of red fibers and white fibers
Red fibers and white fibers
red fibers
- slow twitch
- high myoglobin and mitochondria to carry out oxidative phosphorylation
white fibers
- fast twitch
- low myoglobin and mitochondria
Smooth muscle unique characteristics
uninucleated
contain actin and myosin, but the fibers are not as well-organized so striations cannot be seen
can sustain contractions
-tonus
can contract without nervous system input in myogenic activity
-in response to stretch or other stimuli
Cardiac muscle
uninucleated
appears striated
cardiac muscle cells are connected by intercalated discs, which contain many gap junctions
Sarcomere definition and makeup
basic contractile unit of skeletal muscle
made of thick and thin filaments
-thick are made of myosin
-thin filaments are made of actin, troponin and tropomyosin
-titin anchors the actin and myosin filaments together
Myofibrils
Sarcomeres are attached end-to-end to form myofibrils
myofibrils are covered with sarcoplasmic reticulum that contains a high concentration of Ca2+ ions
Myocyte, sarcolemma
a myocyte is made from many myofibrils arranged in parallel, also called muscle fiber
the cell membrane of a myocyte is known are the sarcolemma
-capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle using a system of transverse tubules (T-tubules) orientated perpendicularly to the myofibrils
Regions of a sarcomere (Z,M,I,H,A)
Z-line defines the boundaries of each sarcomere
M-line runs down the center of the sarcomere
I-band is only thin filaments
H-zone is only thick filaments
A-band is entire thick filament, including part of thin filament
muscle contraction pathway
contraction starts at the neuromuscular junction, where the nervous system communicates with muscles via motor neurons
the signal travels down until it reaches the nerve terminal, where acetylcholine is released into the synapse
acetylcholine binds to receptors on the sarcolemma, causing depolarizations
depolarization triggers an action potential, which spreads down the sarcolemma to the T-tubules
The action potential travels down the t-tubules into the muscle tissues to the sarcoplasmic reticulum
Ca2+ is released from the sarcoplasmic reticulum
The calcium ions bind to a regulatory subunit in troponin, triggering a change in the conformation of tropomyosin, to which troponin is bound
This exposes the myosin-binding site on the actin filament
the free globular heads of the myosin form an actin-myosin bridge
myosin carrying hydrolyzed ATP is able to bind with the myosin-binding site
The release of the inorganic phosphate and ADP in rapid succession provides the energy for the power stroke and results in sliding of the actin filament over the myosin filament
ATP binds to the myosin head, releasing it from actin
This ATP is hydrolyzed to ADP and P which recocks the myosin head so that it is in position to initiate another cross-bridge cycle
acetylcholine is degraded in the synapse by acetylcholinesterase
-allows the sarcolemma to repolarize
Simple twitch
all-or-nothing response of a single muscle fiber to a brief stimulus
Tetanus
Tetanus is the result of too frequent summations that the muscle is unable to relax at all
Creatine phosphate
Creatine phosphate is created by transferring a phosphate group from ATP to creatine during times of rest
ATP + creatine creatine phosphate + ADP
Oxygen debt and muscle fatigue of skeletal muscle
Fast-twitch muscle fibers have fewer mitochondria and rely on glycolysis and fermentation to make ATP under most circumstances
High concentrations of oxygen are required for muscle cells, especially slow-twitch (red)
-eventually even red muscle fibers must switch to anaerobic metabolism and produce lactic acid, at which point the muscle begins to fatigue
Skeletal system axial and appendicular
Axial skeleton consists of the skull, vertebral column, ribcage, and hyoid bone (in anterior neck, used for swallowing)
Appendicular skeleton consists of the bones of the limbs, pectoral girdle, and pelvis
Compact bone
makes up the diaphysis
strength comes from bony matrix which contains hydroxyapatite (calcium, phosphate) crystals
Composed of osteons/haversian systems
Osteons
cylindrical structures that contain concentric circles of bony matrix called lamellae surrounding a central microscopic channel, which contains blood vessels, nerve fibers, and lymph vessels
longitudinal channels are known as Haversian canals
transverse channels are known as Volkmann’s canals
between the lamellar rings are lacunae, which house mature bone cells known as osteocytes and are interconnected by canaliculi that allow for nutrient and waste exchange
peristeum
a fibrous sheath that surrounds the long bone to protect it as well as serve as a site for muscle attachment
Spongy/Cancellous bone
found at the core of vertebral bones and at the epiphysis
composed of trabeculae instead of osteons, which contain red bone marrow
Diaphysis, Metaphyses, epiphyses locations
Diaphyses (length) swells at the end to form metaphases, the epiphyses are on both ends
Bone remodeling
Osteoblasts build bone
-Calcitonin
Osteoclasts resorb bone
- polynucleated resident macrophages of bone
- Parathyroid hormone
- Vitamin D
- -encourages the growth of new, stronger bone
Cartilage
consists of a firm but elastic matrix called chondrin that is secreted by cells called chondrocytes
avascular and not innervated
most are the bones in the body are produced by endochondral ossification from cartilage
Immovable joints
bones that are fused together to form sutures
-those of the skull
Movable joints
strengthened by ligaments, connect bones to one another
consist of a synovial capsule, which encloses the joint cavity
- a layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures
- the articular cartilage coats the articular surfaces of the bone so as to restrict the impact to the lubricated joint cartilage
Muscle attachment to bone
The end of muscle with a larger attachment to bone is called the origin
The end with the smaller attachment to bone is called the insertion
Types of muscle movement (flexor, extensor, abductor, adductor)
Flexor muscle decreases angle (biceps)
Extensor muscle increases angle (triceps)
abductor
moves a part of the body away from the midline (deltoid)
adductor
moves a part of the body toward the midline (pectoralis major)
Codominance vs incomplete dominance
Codominance
more than one dominant allele; AB blood typing
Incomplete dominance
heterozygote is intermediate between the two homozygous genotypes
Penetrance vs expressivity
Penetrance is the proportion of individuals who express the phenotype; population level
Expressivity is the variance of phenotype; individual level
Mendelian laws
First law of segregation
two alleles segregate during anaphase I of meiosis, resulting in gametes that carry only one allele for any inherited trait
Second law of independent assortment
two sister chromatids separate independently during prophase I of meiosis
Frederick Griffith
exposed mice to strains of virulent bacteria under different conditions
when both dead virulent and live nonvirulent bacteria were injected into the mouse, the mouse died
Avery, Macleod, McCarty
separated the subcellular components of the bacteria into different extracts
When the DNA was degraded but not the protein, the mice lived, and vice versa
Hershey and Chase
radiolabeled DNA and protein on bacteriophages
no radiolabeled protein entered the cells, but radiolabeled DNA did
Genetic leakage
the flow of genes between species
-hybrid species
Genetic drift
changes in the composition of the gene pool due to random chance
more pronounced in small populations
Test cross
used to determine an unknown genotype by crossing it with a homozygous recessive
Gene mapping:
chiasma, recombination frequency, map unit
The further apart two genes are, the more likely a point of crossing, called a chiasma will occur between them
-this likelihood is called a recombination frequency
- -roughly proportional to the distance between the genes
- -in a genetic map, one map unit or centimorgan corresponds to a 1 percent chance of recombination occurring between two genes
Five criteria for Hardy Weinberg
population is very large (no genetic drift)
no mutations
no sexual selection
no migration
all genes are equally successful at being reproduced
Modern synthesis theory and differential reproduction
Neo-darwinism
adds knowledge of genetic inheritance and changes in the gene pool to Darwin’s original theory
When mutation or recombination results in a chance that is favorable to the organism’s reproductive success, that change is more likely to pass on to the next generation; the opposite is also true
-differential reproduction
Inclusive fitness
an organism can be evolutionary successful by being altruistic in his group
Punctuated equilibrium
changes in some species occur in rapid bursts
