Exam 2 Flashcards
How do osteoblasts become osteocytes?
Other osteoblasts start to build bone over them and they get stuck in the matrix of the bone
What are concentric rings?
They are compact bone being formed around blood vessels that have osteocytes in trapped between their layers
What is spongy/trabecular bone?
Less dense bone that does not aid with support against forces. This type of bone is usually broken down for calcium when the body has low levels. It also has osteoblasts cells all over its outer layer
What are chondrocytes?
Cartilage cells that formed from random tissue being compacted together
How does a cavity in the bone form?
Chondrocytes starts to undergo program death and form a cavity. Blood vessels then enter cavity and bring osteoclast and osteoblasts cells with them.
What is the epiphysis growth plate composed of?
Chondrocytes
What is the difference between epiphysis and diaphysis?
Epiphysis is the ends of the bone and diaphysis is the shaft of the bone
Where is the second ossification center located?
In epiphysis
What is the metaphysis?
It is the site where developing long bone occurs, mechanism for bone getting longer
How does cartilage turn into bone?
- Reserve bone: where Chondrocytes are resting
- Chondrocytes starts to divide rapidly
- Cells hypertrophy (grow)
- Cells are calcified in growth plate
- Cells then enter metaphysis where they encounter blood vessels and ossification/mineralization occurs (turn into bone)
In what fashion is bone built?
Born is built towards the center and then osteoclast and osteoblasts shape the bone in the metaphysis to make it longer
What causes growth plates to disappear?
Hormone slows that causes the division of Chondrocytes to slow, meanwhile osteoblast is converting all Chondrocytes into bone faster than Chondrocytes are dividing.
How does bone get longer?
Read portion from outside and building it inside in upward direction of the metaphysis
Where is the youngest and oldest part of the bone located?
Metaphysis outer layer is the youngest.
Middle of the shaft is the oldest.
Growth stages of bone
- Cartilage on outside
- Periosteum layer would start to form
- Cartilage cells would hypertrophy and ossification would begin
- Primary and second ossification centers form
- Growth plates form
- Growth plates disappear
Ossification in newborns
Ossification gets going during week of embryo and then week after birth ossification quickly speeds up to form metacarpals and skull
What is the outside layer of the bone called?
Periosteum
When does the primary ossification center appear?
During gustation in the diaphysis
When do the secondary ossification centers appear?
Appear after birth in epiphysis
When do growth plates disappear in long bone?
Late adolescence or earl adulthood (not all bones are the same) arms can still be growing when legs stopped
White fat tissue
Thy are not thermogenic. Contributes to internal and subcutaneous fat and has important metabolic functions. Produces hormone derivatives
What is leptin?
Helps regulate entry to puberty and is produced by adipocytes
How do adipocytes grow?
First few years, they increase in diameter by hypertrophy. As we get older adipocyte cells start to divide through hyperplasia.
What is fat mass?
All sources of adipose tissue (fat). This fat is found underneath skin and around organs
Due to F=ma. As fat mass increases acceleration decreases
What is fat free mass?
All organs, blood, and water (everything but fat). This correlates with the body’s ability to produce force
How does MUSCLE grow? ( not adipocytes)
First year, hyperplasia and thoughout life it then grows in diameter through hypertrophy (opposite from adipocytes)
How does estrogen effect fat mass?
Estrogen encourages fat deposition therefore increases fat mass. That’s why females tend to have higher fat mass than males. Testosterone has opposite effect ( burns fat)
Trend of percent fat overtime
High when first born (Hugh subcutaneous levels when baby, hence fat babies). It then decreases during childhood because we are gaining fat free mass faster than fat mass). During puberty girls increases due to estrogen and males increase with girls until puberty two years later where it decreases due to testosterone
Trend of fat and fat free mass
Fat mass increases throughout childhood and plateaus in boys during puberty. Fat free mass increases throughout childhood and plateaus in females
Vein appearances in babies compared to children
Subcutaneous fat high in babies hard to find veins.
Subcutaneous drops dramatically through childhood and veins are easier to find
HOW DOES INTERNAL FAT GROW THROUGHOUT LIFE?
IT STEADILY INCREASES THROUGHOUT LIFE
How long is normal human gustation?
40 weeks
What is hyaline membrane disease?
Lungs cannot inflate by themselves due to prematurity because they lack surfactant
What are the 3 different zones of the lung?
Conductive: conduct gas to and from the lung (arteries, veins, airways)
Respiratory: where gas exchange occurs (alveoli)
Transitional: oxygen and co2 end up in the capillaries (capillaries)
How many times does bronchi branch before reaching respiratory zone?
- And then 7 more times within respiratory zone
What is the purpose of bronchi?
They keep junk out of our lungs, covered in cilia that beat up bacteria. Meant to keep lungs clean
RESPIRATORY MEMBRANE NEEDS TO BE WHAT FOR OXYGEN TO REACH BLOOD CELLS?
EXTREMELY THIN!
What are type II cells?
They have lamellar bodies that secrete surfactant
When does the lung start to develop alveoli?
36 weeks. Before these are formed viable decreases
What are the four stages of lung development?
- Embryonic
- Pseudo glandular
- Canicular
- Saccular
What occurs in the embryonic stage?
Start to form the first and second generation of bronchi, larynx forms, mesenchyme tissue surround airways
What occurs in the pseudo glandular stage?
Finish forming transitional zone. has glandular appearance and lung is expanding in size. Has loose mesenchyme cells growing around bronchi. BABIES ARE UNVIABLE UNTIL CAPILLARIES ARE FORMED
What occurs in the canalicular stage?
Mesenchyme cells will start to give rise to capillaries. For the first time have a structure that holds airs. AT THE END OF THIS STAGE BABIES ARE POSSIBLY VIABLE
When do babies become viable?
After canicular stage when capillaries have formed
What occurs in the saccular stage?
Capillaries are forming still but at not close to each other yet, they are starting to migrate to epithelial membrane, so oxygen can be diffused.
ALVEOLI STILL HAVE NOT FORMED
How are alveoli formed?
Budding new septum from capillaries. Between each alveolus there are two layers of capillaries that result from septa.
How do capillaries increase oxygen diffusion rate?
The interstitial fluid between two capillaries will cause them to fuse and create on capillary that is capable of diffusing oxygen through all sides.
What are the 4 challenges premature babies face?
- Poor alveolar growth and thick membrane
- Poor surfactant production
- Poor respiratory control and responsiveness
- High pulmonary resistance
What are the 3 factors that diffusion depends on?
Concentration
Distance
Cross-sectional area
In premature babies we can only increase the concentration of air
What is the function of surfactant?
Since water is very polar and bonds to itself it has a high tension. Water causes tension on alveoli and they collapse when surfactant is not available. It reduces liquid tension between the two
Alveologenesis
Thinning of the interstitial layers by apoptosis so that two capillaries merge into one. Cells also differentiate to produce surfactant
What causes bronchi pulmonary dysplasia
Only occurs in premature babies due to a disruption in alveoli growth mechanical ventilation and supplemental oxygen
Risks of BPD
Mortality decreases with maturity between canalicular and saccular stage. Remember that babies are unviable before canalicular stage
Results of BPD
Hypoxemia (low concentrations of oxygen in the blood), difficulties eating, increase risk of respiratory infections, asthma
How are chemoreceptors different in premature babies?
Their development is suppressed and therefore cannot sense changes in arterial oxygen.
Premature babies breathing patterns
Have periodic apneas that result in arterial oxygen desaturation that effect brain development. Brain isn’t signaling breathing correctly. Will eventually grow out of it with no supplemental oxygen. High risk of dying from SIDS
Why can premature babies not travel to different altitudes?
Their chemoreceptors cannot sense the different oxygen levels and they will not be able to change breathing patterns. Supplemental oxygen also prevents chemoreceptors from fully developing
What is congenital diaphragmatic hernia
Malformation of the diaphragm hat allows the organs of the abdomen to move into the chest. This results from mesenchyme tissue not explaining in pseudo glandular stage and prevents lung from growing fully
Heart abnormalities in premature babies?
Pulmonary veins do not reattach to left atrium instead they attach to super vena cava preventing blood from the lung from reaching the systemic circulation.
Framenal valve
Window between atriums that allow exchangement of blood between both atriums to relieve high blood pressure. Close after birth
Ductus Interiosous
Connection between pulmonary artery and aorta. Allows blood to reach systemic circulation. Close after birth
Adipocyte cell division is greater in males or females?
Females
Trends of fat free and fat mass in females and males
Both increase throughout life but fat free mass accumulates faster than fat mass. And faster in males than females. More fat mass in females and more fat free mass in females
Why does percent fat decrease in childhood?
Because we are gaining fat free mass a lot faster than regular fat
Subcutaneous fat trends in females and males
In first years it increases for both genders (chubby babies). Then dramatically decreases on childhood as we quickly gain fat free mass (kids get thinner). And then it increases for girls as they enter puberty and boys follow same trend until they enter puberty two years later and then they decrease
Fat trends in puberty stages
Girls are gaining fat and boys are losing fat
Boys subcutaneous fat in extremities and trunk
Subcutaneous fat decreases in extremities but continues to increase in the trunk during puberty. Ratios increases because losing so much fat in their extremities
Females subcutaneous fat in extremities and trunk
Continues to increase over life, so ratio has a pretty constant slope
Heart size is proportional to what?
Fat free mass because those tissues need oxygen pumped to them by heart
Which side of the heart deals with oxygenated blood
The left ventricle and aorta pump out oxygenated blood and the vena cava is returning deoxygenated blood to the lungs
How does blood move in normal heart?
Deoxygenated blood is emptied into the right side of the heart by the vena cava and then pulmonary arteries into the lungs.
Then that oxygenated blood goes into pulmonary veins and into the left side of the heart and then into aorta and rest of body
How does blood move in a baby?
Oxygenated blood from umbilical vein goes up to inferior vena cava and into right side of heart. Then instead of going to pulmonary trunk it goes into left atrium through formanel valve. Little window between atriums
Ductus venosus
Where oxygenated blood from umbilical vein goes through a bypass so that it doesn’t need to get filtered by liver
Ductus arteriousous
Connection between pulmonary trunk and arch of aorta where oxygenated and deoxygenated blood mix.
Do males or females tend to have a higher heart volume?
Males because they have a higher fat free mass.
Why does heart rate decrease with age?
Because heart valves get bigger so heart doesn’t have to work as hard when you get grow. Bigger heart valves create higher stroke volumes
Why do boys have higher systolic and diastolic pressures?
Because boys have more resistance than females. They have more capillaries that create resistance for their fat free mass.
Where are nuclei located on muscle fibers?
Located on the periphery because contractile filaments are densely assembled throughout the center of the fiber
What are myofibrils?
They are a muscle unit that consist of sarcomeres that are attached to each other in a series
How many muscle fibers can a motor neuron stimulate?
Only a given type of motor neuron can stimulate a given type of fiber. One type will not control two different types of fibers
A muscle that is recruited a lot is most likely what type of fiber?
Type I, slow twitch, these muscles are resistance to fatigue ex: posture muscles. (Glycolysis are fast twitching fibers)
Steps for a muscle to contract
- Release neurotransmitter (AcH) into synaptic cleft
- Receptors on fibers must respond
- Neurotransmitter binds to receptors and ion channels open.
- Huge influx of sodium rushes in and few potassium fuse outward.
- Membrane becomes slightly positive (depolarizes) and calcium is released into contracting filament
4 major phases of muscle development?
- Axonal outgrowth
- Myogenesis (cell decides to be a muscle)
- Synaptogenesis (formation of synapses)
- Synapse elimination (eliminates extra neuromuscular connections)
Skeletal muscle develops from what type of cell layer?
Mesoderm, it also forms the notochord. The notochord also elicits signals that are critical for the formation of the neural tube and spinal cord
What are somites?
Around 30 days, somites are formed from mesoderm and are on either side of neural tube. They will develop into vertebrae abs skeletal muscle
What are precursor cells?
Theses are undifferentiated cells that can decide to be muscle and migrate to specific locations where muscle will develop. Precursor cells found in adult muscles are called satellite cells
How does a precursor cell become a muscle fiber?
It is exposed to myogenic factors. First myoD and Myrf5 tell the cell to become a muscle cell (determination). Then the cell is exposed to mfr4 and myogenin that tell cell to become certain type of fiber (differentiation)
Synaptogenesis of a precursor cell?
Acetylcholine receptors are located all over immature muscle fiber, so upon synaptogenesis, expression of those receptors becomes specific to a certain region.
Synaptic elimination in precursor cell
2-6 motor neurons may form synapses with immature muscle fiber, but during synapse elimination the most efficient neuron is only one that is kept others are eliminated
An interneuron that is attaching a small and big diameter axon is stimulated. What are the effects?
The smaller neuron is stimulate easier and faster , more frequency and will most likely be a slow twitch fiber. The bigger neuron will take more energy to stimulate and will not be stimulated as much and will therefore be a fast twitch fiber
How are muscle fiber types determined?
Primarily by the pattern of its stimulate and recruitment. By the type of neuron it is attached to. It neuron stimulated a lot likely will be type I
Why are babies born with missing muscles?
Failure of the cervical somites to differentiate
What is centeronuclear myopathies?
Caused by mutation in several genes associated with differentiation of myotubes in muscle fibers. Nuclei will be in the middle of fiber where it shouldn’t be. Causes weakness
How is Cardiac output is calculated?
Heart rate * stroke volume (strike volume increased with age)
Red blood cell count in males and females
Blood count is the same for both sexes. Increases in males during puberty because their dramatic increase in fat free mass
Hematocrite
Percentage of red blood cells in blood. High in neonatal babies decreases in childhood and increases in adolescence
LDL and HDL ratios in females and males
Constant in females and males until males reach puberty it increases. Females stay the same. Males are at risk of developing cardiovascular diseases
How are some ways you can determine a persons chronological age?
Skeletal system
Secondary sexual characteristics (no sensitivity prior to puberty)
Somatic boys maturation
First menstrual cycle
Tanners 5 stage secondary sexual characteristics chart
- Pre adolescence
2-3. Based on physical appearance - Adult
Used a lot in research, a lot easier to use than taking measurements of blood, very qualitative and subjective
Somatic body maturation
example: age at peak height or weight velocity. Should correlate with skeletal age data. Peak strength sort occurs after puberty!!
Average age to enter puberty and peak height velocity
Girls: 8.5 puberty/11.4 height
Boys: 2 years after (have height peak velocities
Testosterone anabolic or catabolic
Anabolic
What is the pattern of limb growth for height?
- Legs grow before trunk
- Lower limbs before upper limbs
- Distal before proximal
(Growth of body is not proportional to all parts)
(Coordination skills are NOT lost)
When does peak weight gain appear?
Typically 6 months after peak height velocity. there are NO peaks growths after weight gain velocity.
Experiment of MZ and DZ twins to show the role of genes
Have to compare MZ in same environment to DZ twins in same environment and show that DZ twins have a lower correlation than MZ twins. We need to compare both to make sure it’s not just the environment that is causing peak height velocities to be similar but that it’s due to genes
MZ vs DZ twins stature correlations
MZ twins always have a higher correlation than DZ twins for heights. DZ start to have higher correlations around adolescence
People with XXX,XXY, XYY chromosomes. Height compared to normal
The more chromosomes you had the taller you were compared to normal. More Ys gave a higher height too!so XYY was taller than XY and XXY. If person suffered from illness after it was cured growth made up for the lost time. Those with less chromosomes were shorter than average!!
Correlation for age of menarche in MZ DZ sisters and mothers
Height correlation for MZ>DZ>sisters>mom-daughter
Correlations in sexual maturation for DZ and MZ
Very small differences in ages for sexual maturation In MZ twins. and large differences in DZ twins
Skeletal maturation for twins
Very small differences in age for MZ and large differences for DZ.
Fat correlations in twins
correlations are low for both because fat is so influenced by environmental factors. Abdominal-subcutaneous fat is heritable and has higher correlations in MZ than DZ
Workout correlations between twins and relatives
Adopted siblings have no correlations. Brothers and sisters higher, DZ higher and MZ highest. Still not has high as other traits. That is because workout is not strongly controlled by genes
Family aggregation of the response to training
If you are born into a family that has a agent for higher vo2 max your chances for having that same trait are higher than average. But does not mean you will have same correlation as parent or sibling
Work output in twins correlation
The correlation for MZ is higher than DZ TWINs! There is a genetic cause for anaerobic metabolism
Inheritability for anaerobic and aerobic metabolism
High correlation in MZ twins for anaerobic. Not Inheritability for septic metabolism
Vo2 max correlations
No difference in correlations between DZ and MZ. There is not strong genetic inheritable for aerobic metabolism
Endocrine vs paracrine
Endocrine- gland secretes hormone into blood stream circulation and will only effect target cells with specific receptors for that hormone.
Paracrine- cell secretes hormone and only diffuses to near by target cells (local system)
What happens to the amount of hormone and receptors with age?
Decreases
What does the hypothalamus do?
Control center for pituitary gland, sends signals to pituitary to stimulate other glands. Usually releases stimulus in burst not steadily
What is the role of the pituitary gland?
It secretes growth hormone and secrete tropins to stimulate other glands to secrete their hormone
What does the adrenal gland do?
Secrete steroid hormones and androgens. Androgens contribute to growth spurt and muscle growth in females and males. Has a small effect in males since they have testosterone. Do not play a huge role in either sex during puberty because of gonads
How does pituitary and hypothalamus regulate hormones?
Hypothalamus and pituitary gland have receptors that can sense the levels of hormones and hypothalamus can then stop stimulating pituitary gland and this will stop stimulating the other glands
Insulin growth factor 1
When growth hormone reaches liver cells, they produce IGF1 which stimulates anabolic reactions. Has a particular effect on cartilage and Chondrocyte division in growth plate of bones. Let’s bone grow without the plate disappearing
Growth hormone during puberty
Growth hormone levels are highest before puberty so that tissues have enough time to respond and make appropriate adjustments
How does growth hormone increase during puberty?
Each pulse is secreting greater amounts of growth hormone, not more pulses!
IGF 1 during puberty.
Increases in childhood, peak in puberty and then falls but does not disappear
What does the thyroid do?
Secretes thyroxine which is responsible for skeletal maturation and growth of other systems. Without thyroxine growth factor would have a BLUNTED effect
What does the parathyroid do?
Participated in the feedback loop that regulated calcium absorption and reabsorption
Androgens can be produced by what, besides adrenal gland?
Are produced by peripheral tissues like adipocytes and other cells
What causes growth hormones a blunted effect?
Absence of thyroxine and insulin blunt the effects of grower hormone
What do FSH and LH do?
Stimulate ovaries and testes to secrete estrogen and testosterone. Females: FSH- growth of follicles LH- maturing of those follicles Males: FSH- Soren production LH- testosterone production
FSH and LH levels during puberty
Both steadily increase through the stages of puberty
What are the roles of gonadal hormones?
Regulate final stages of growth and maturation especially primary and secondary sexual characteristics
How does testosterone effect growth hormone?
Increases growth hormone, increases IGF 1, increases bone growth
Testosterone and estrogen effects on subcutaneous fat
Testosterone mobilizes fat in extremities.
Estrogen drives fat deposition in extremities and trunk (also weaker anabolic steroid, so not as much muscle and bone growth)
Estrogen effects on bone growth
Males with no estrogen production of receptors tend to have growth plates a lot longer after puberty and continue to grow
What produces leptin? And how does it correlate to fat
Hormones produced by adipocytes, proportional to fat mass. Increases in females and decreases in males after puberty.
How does leptin effect weight?
Hypothalamus has leptin receptors. When body has low leptin levels means low fat mass and food intake increases. Also gain leptin during puberty because usually gain weight then
Results of inactivated leptin receptors
Causes severe obesity because body thinks we need more food. Also decreases gonad function (sterile)
Anterior pituitary glands secretes what to glands?
Tropin hormones
Positive feedback loops
Rapidly increase the size of something, good during puberty.
Hormone sensitivity throughout life
- Early childhood really high sensitivity to gonadotropin (so low levels in body)
- Later childhood less sensitivity, higher levels of gonadotropin
- Puberty gonadotropin hormone is increasing though positive feedback. Stimulates hypothalamus instead of regulating it
- Adult, remains positive feedback for males and cyclical for females
Balancing between boys and girls
Girls have more balance in past data. More recent data shows more similar results for both sexes
What does strength depend on?
The ability to recruit all muscle fibers needed to perform. Takes longer to see difference in muscle size but strength increases instantly
T/F: strength is only dependent on muscles
False, brain can effect strength and performance
What does Newton’s second law explain?
F=ma. Acceleration depends on a persons mass. Acceleration is usually slower in females after puberty because their percent fat increases
Peak weight and strength velocities compared to height velocity
Occur after height, strength peak is usually a year after
