DAT bio Chapter 11.6 and 11.7 Skeleton Flashcards
Many
invertebrates and all arthropods possess____
exoskeleton (external skeleton)
Vertebrates contain an
endoskeleton (on the inside)
endoskeleton can be divided into two parts. what are they
axial skeleton (core bones like skull, and rib cage) and the appendicular skeleton (appendages). if the endo skeleton were a tree, the axial skeleton would be the tree trunk and the appendicular skeleton would be all the branches coming off of it.
types of long bones
long bones short bones flat bones sesamoid bones irregular bones
long bone is made out of
cortical bone (compact cancellous bone (spongy)
important features of long bone include
epiphysis, diaphysis, medullary cavity,
metaphysis, and epiphyseal plate.
Epiphysis - is
end of a long bone that forms
joints with other bones and contains red
bone marrow for hematopoiesis (blood
cell synthesis).
Diaphysis
long hollow shaft in center of
bone.
Medullary cavity
located within the
diaphysis and contains red and yellow
bone marrow (area of fat storage).
Metaphysis
similar to epiphyses and
found between the medullary cavity and
epiphyseal plates.
Epiphyseal plate is
“growth plate” located between epiphysis and metaphysis. Made out of hyaline cartilage and works to lengthen the diaphysis through growth and ossification.
short bone provide what
as wide as they are long and
mainly provide support (eg. parts of the
wrist).
Flat bones -
mainly provide protection (eg.
skull).
Sesamoid bones
found within tendons to
help muscles pull (eg. kneecap).
Irregular bones
- irregularly shaped (eg.
pelvis) .
Cortical (compact) bone
dense outer layer of bone that
supports the weight of our bodies. It is composed
of many microstructures:
microstructures of cortical bone
osteons haversian canals lamella lacunae canaliculi volkmanns canals
osteons
- cortical bone’s functional unit,
composed of tiny multi-layered cylinders.
Also known as haversian systems because
they contain a haversian canal in their center.
Haversian canals
‘tubes’ that contain blood
vessels for nutrient supply.
lamellae
layers of the osteon
lacunae
small spaces between lamellae that
hold bone cells and interconnect through
canaliculi.
canaliculi
small channels that connect lacunae and the haversian canal
volksmanns canal
connect Haversian canals
to the periosteum, which provides nutrients.
what is cancellous bone
the spongy inner layer of bone
that soaks up red bone marrow via a web of
trabeculae (connective tissue that supports
cancellous bone).
what is bone remodeling
process of going back and
forth between the processes of ossification (bone
formation) and resorption (bone loss).
Types of cells involved in bone remodeling:
Osteoprogenitors
Osteoblasts
Osteocytes -
Osteoclasts
Osteoprogenitors
- immature precursor cells
that differentiate into osteoblasts.
Osteoblasts
build bone by secreting
proteins and utilizing blood calcium. They
mature into osteocytes after getting trapped
inside the bone matrix they create.
Osteocytes
live in lacunae in osteons to
maintain bone.
Osteoclasts
eat and resorb bone, bringing
calcium back into the blood. Derived from
monocytes.
Mechanisms involved in bone remodeling
parathyroid hormone
vitamid d
calcitonin
Mechanisms involved in bone remodeling S1
parathyroid hormone
increases blood
calcium levels by stimulating osteoclasts and
depressing osteoblasts. Secreted by the
parathyroid gland.
Mechanisms involved in bone remodeling S2
vitrami d
increases blood calcium levels by
raising intestinal calcium absorption. Activated
by parathyroid hormone, but provides
negative feedback on PTH production.
Mechanisms involved in bone remodeling S3
calcitonin
decreases blood calcium levels by
depressing osteoclasts, allowing osteoblasts to
build bone without competition. Secreted by
the thyroid gland.
what is osteoid
organic component of bone
containing many proteins such as collagen (gives
bone tensile strength).
what is Hydroxyapatite
inorganic mineral
component of bone that gives the bone density
and strength.
two types of embryonic ossification
intramembranous and endochondral ossification
Intramembranous ossification
bone is
created directly within fibrous membranes,
mainly for flat bones. Osteoblasts start by
secreting osteoid, which hardens and houses
osteocytes. Eventually, cortical bone is
created.
Endochondral ossification
bone is created
indirectly through a cartilage model, mainly
for long bones. The cartilage model calcifies
during fetal development, creating
ossification centers that help form the
features of long bones.
what fibers make up the fibrous connectice tissue?
tendons
ligaments
periosteum
endosteum
tendons connect what
muscle to bone.
Ligaments connect what
bone to bone
periosteum is what
- membrane that covers
cortical bone with an outer fibrous layer
(vascularized) and an inner/cambium
layer (collagen for attachment to cortical
bone)
Endosteum is what
membrane located between
cortical and cancellous bone.
Cartilage is ______ (lacks blood vessels)
and is not innervated (as opposed to bone
which is highly vascular and innervated).
avascular
what builds cartilage
chondroblasts
how does chondroblasts build cartilage?
by secreting
collagen and elastin.
Hyaline cartilage is
slightly flexible and
important in providing support and
stability to joints.
Fibrous cartilage
high rigidity and resists
tension, found in intervertebral discs and
knee meniscus.
Elastic cartilage -
highly flexible and
found in ears and epiglottis.
Joints are ____ and _____
vascularized and innervated. They
are found between bones.
types of joints
__Synarthroses - dense, fibrous joints that do
not move.
___Amphiarthroses- - cartilaginous joints that
partially move.
___Diarthroses - synovial joints that fully
move. Typically contain hyaline cartilage.
hormones can be secreted in how may ways
● Endocrine - through the bloodstream. ● Exocrine - through ducts. ● Paracrine - to neighboring cells. ● Autocrine - onto the same cell that is secreting the hormone.
3 types of hormones
1. peptide hormones 2. steroid hormones 3. amino-acid derived hormones.
peptide hormone is produced where
rough ER and made
of amino acids connected by peptide bonds.
what does peptide hormones do?
binds to cell surface receptors because
they cannot pass freely through the cell
membrane as a result of being water-soluble
(and not lipid-soluble). The process of hormone
function is an indirect stimulation.
The two
ways the signal can be received in peptide hormone
secondary messengers or
ligand-gated ion channels.
secondary messengers are initiated by
G protein coupled receptors (GPCRs) which are cell
surface receptors
how does secondary messengers work
after binding to a peptide
hormone extracellularly. A G protein is coupled
to the receptor and dissociates into subunits
(alpha (α), beta (β) and gamma (γ)) after
activation. These subunits then act upon
intracellular second messengers to propagate
the signal.
another way of initiating second messenger response upon binding to a peptide hormone.
Receptor tyrosine kinases (RTKs) are another
cell surface receptor that dimerizes
how does receptor tyrosine kinases work?
The intracellular
domains of RTKs cross-phosphorylate each
other and initiate second messenger signaling
within the cell.
The second messenger system of peptide
hormone signaling allows for _____ and
_____physiological changes.
quick and immediate
Ligand-gated ion channels change _____ upon
binding to peptide hormones, allowing ___ to flow
across the ______. No second messengers
are involved.
shape
ions
cell membrane
where are steroid hormones made
smooth ER and
made up of a fused 4-ring structure.
how does steroid hormones work?
requires a protein carrier to travel
through the bloodstream due to being lipophilic.
Freely crosses the cell membrane, and binds to
receptors either in the cytoplasm or the nucleus to
form molecule-receptor complexes that bind to
DNA, and influence gene transcription. This
process is known as direct stimulation.
Steroid hormones cause ___ and _____
physiological changes.
slow and gradual
- Amino-acid derived hormones:
Can have what kind of properties?
properties that are similar to both
peptide hormones and steroid hormones.
where is amino acid derived hormones made?
produced in rough ER and cytosol.
Mainly derived from the amino acid tyrosine.
function of hypothalamus
coordinates the body’s
internal environment and maintains homeostasis.
where is the pituitary gland located and is composed of how many lobes
is under the
hypothalamus and is composed of two lobes -
the anterior pituitary and posterior pituitary.
- Posterior pituitary is also known as
the neurohypophysis because it is
made of neuronal tissue. It is a direct neuronal
extension of the hypothalamus.
what two hormones are stored and released by the posterior pituitary?
Anti-diuretic hormone (ADH aka
vasopressin)
Oxytocin
Anti-diuretic hormone (ADH aka
vasopressin) - functoin
decreases urination by
increasing water retention. Targets nephrons,
increasing the number of aquaporins for
water reuptake.
oxytocin function
causes uterine contractions during
child labor and the release of milk during
breastfeeding (mammary gland).
Anterior pituitary is also known as
adenohypophysis, it is made of
glandular tissue, and produces its own hormones.
anterior pituitary is connected to the hypothalamus through ____
hypophyseal portal system, which allows for
quick diffusion of hormones through a portal
vein. Hypothalamic-releasing hormones are
released by the hypothalamus to stimulate the
anterior pituitary to release other hormones.
types of hormones released by anterior pituitary
GnRh
TRH
CRH
GRH
GnRH (gonadotropin-releasing hormone) function
release of luteinizing hormone (LH)
and follicle stimulating hormone (FSH).
TRH (thyrotropin-releasing hormone)
causes
release of thyroid stimulating hormone (TSH).
CRH (corticotropin-releasing hormone)
causes release of adrenocorticotropic
hormone (ACTH).
GRH (growth hormone-releasing hormone)
causes release of growth hormone (GH).
Hypothalamic-inhibiting hormones are released
by ______ to _____ the the release of other
hormones by the anterior pituitary.
hypothalamus
inhibit
anterior pituitary produces what 2 hormones
tropic and direct
Important
examples of hormones released from the anterior pituitary:
FSH
LH
ACTH
TSH
FSH (follicle stimulating hormone)
follicle
growth (females) and sperm maturation
(males) in the gonads.
LH (luteinizing hormone) -
stimulates
ovulation, corpus luteum formation (females),
and testosterone production (males) in the
gonads.
ACTH (adrenocorticotropic hormone)
stimulates release of glucocorticoids from the
adrenal gland to fight stress.
TSH (thyroid stimulating hormone)
stimulates
T3 and T4 production by the thyroid gland to
increase metabolism.
what is the largest endocrine organ
thyroid gland
where is the thyroid gland located?
trachea
3 main hormones of the thyroid
Triiodothyronine (T3)
Thyroxine (T4)
Calcitonin
Triiodothyronine (T3) function
released in response
to TSH and increases metabolism in the
body. Has a negative feedback effect on
TSH secretion.
Thyroxine (T4)
function
performs the same actions
as T3 above. However, T4 has one more
iodine and gets converted into T3 upon cell
uptake. It is much less potent than T3 but is
more stable in the blood.
Calcitonin function
secreted by the parafollicular cells to decrease blood calcium levels. Stimulates osteoblasts to use up blood calcium to build bone and inhibits osteoclasts. Also decreases calcium uptake in intestines and kidneys.
Hypothyroidism describes
over-secretion of
T3 and T4, resulting in increased levels of
metabolism in the body.
what two things can lead to goiter?
hypothyroidism and hyperthyroidism
Hypothyroidism causes
over-secretion of TRH to compensate for low T3
and T4, enlarging the thyroid gland, while
hyperthyroidism itself results from a
hyperactive thyroid gland.
The parathyroid gland secrets
parathyroid
hormone (PTH)
parathyroid hormone (PTH) function
performs in the opposite
way as calcitonin. It stimulates osteoclasts and
decreases calcium uptake by bones. Parathyroid
hormone increases blood calcium levels.
what two tissues does the pancreas contain?
exocrine and endocrine
Exocrine tissue secretes
digestive enzymes
through the pancreatic duct to the small intestine.
endocrine tissue (the islets of Langerhans) secretes
glucagon, insulin and somatostatin.
These three hormones are each secreted by a
different cell type as listed below: alpha/beta/delta
alpha cells secrete what
glucagon in response
to low blood glucose levels. Glucagon raises
glucose levels by stimulating the liver and fat
tissue to release their glucose storages.
beta cells secrete what
insulin in response to
high blood glucose levels. Insulin lowers
glucose levels by stimulating the liver,
muscle, and fat tissue to store glucose.
Delta (δ) cells - secrete
somatostatin, which
inhibits growth hormone. It also inhibits the
secretion of glucagon and insulin.
how many adrenal gland does our body have
2
adrenal gland structure
Each adrenal
gland has an outer cortex and an inner medulla.
They mainly help the body deal with stress.
function of adrenal cortex
Deals with longer term stress.
● Stimulated by secretion of ACTH from the
anterior pituitary.
● Releases steroid hormones.
● Produces glucocorticoids (i.e. cortisol) to
raise blood glucose levels for immediate fuel
during periods of long-term stress. However,
this also lowers our immune response.
● Produces mineralocorticoids (i.e.
aldosterone) to increase blood volume and
blood pressure by raising reabsorption of
Na
+
. Water passively gets reabsorbed with
Na
+ due to osmosis.
● Produces a small amount of male sex
hormones (androgens).
function of Adrenal medulla:
● Deals with short-term stress.
● Stimulated by sympathetic nervous system.
● Releases amino-acid derived hormones.
● Produces catecholamines (epinephrine and
norepinephrine) to initiate “fight or flight”
response by increasing heart rate and the
breakdown of glucose. Also increases blood
flow to brain/muscles and air flow to lungs.
After stimulation by LH and FSH, what do the ovaries and testes produce?
ovaries
produce progesterone and estrogen, while the
testes produce androgens such as testosterone.
LH function in females
LH - during menstrual cycle, the LH surge
causes ovulation. This results in the
formation of a corpus luteum, which
produces progesterone and estrogen.
FSH function in females
FSH - stimulates follicle growth in ovaries,
which results in the increased production of
progesterone and estrogen.
LH function in males
LH - triggers testosterone production by
Leydig cells.
FSH function in males
FSH - stimulates sperm maturation.
Hormonal control relies on
feedback systems,
which fall under positive and negative feedback
loops.
Positive feedback
the change causes the
amplification of itself, forming a loop that
continues to intensify. You can think of it as
promoting exponential growth.
Negative feedback
the change causes the
inhibition of itself, forming a loop that
prevents hormone overproduction. You can
think of it as promoting stability in the body
