Week 7

Question 1

what are lower and upper motor neurons? how do they interact? where are they located?

Answer 1

lower motor neurons are somatic motor neurons in brain stem/spinal cord that travel to stimulate skeletal muscle contractions. Upper motor neurons are in the brain and influence activity of the lower motor neurons (muscle sensory feedback also influences lower motor neuron activity). Lower motor neuron cell bodies (efferent) are located in the Ventral horn of the spinal cord gray matter. The Dorsal root contains sensory (afferent) fibers.

Question 2

two types of interneurons

Answer 2

commissural tracts: cross midline of CNS to synapse on opposite side
ipsilateral: conduct impulses up and down on the same side (can effect contralateral side of nervous system)

Question 3

what type of reflex is the muscle stretch reflex? give one example of the a dramatic muscle stretch reflex

Answer 3

monosynaptic. only has one synapse with CNS, sensory neuron synapses with motor neuron without any interneurons (not really monosynaptic, many other neurons are activated indirectly!)
the knee-jerk reflex (patellar tendon reflex) is a commonly evoked stretch reflex. Neurons stimulate fibers of quadriceps femoris to contract and extend knee joint.

Question 4

what is reciprocal innervation? when is it present?

what is double reciprocal innervation? when would this occur?

Answer 4

Dual stimulatory and inhibitory activity. This happens all the time in stretch reflexes. Whenever a limb is flexed, the antagonistic extensor muscles are stretched and whenever a limb is extended, the antagonistic flexor muscle is stretched. Basically, whenever agonist muscles are stimulated to contract, the motor neurons also inhibit the antagonist muscle.

Double reciprocal innervation involves muscles controlled by numerous spinal cord segments and affect muscles on the contralateral side of the cord. This occurs in the crossed extensor reflex (step on a tack reflex) where you withdraw the foot that stepped on the tack and extend the other leg.

Question 5

what are similarities between skeletal muscle and cardiac and smooth muscle

Answer 5

All contract by means of sliding thin filaments over thick filaments
Sliding is produced by myosin cross bridges
Excitation-contraction coupling involves Ca2+

Question 6

describe the structure of cardiac cells and how they synapse

Answer 6

Like skeletal muscles, myocardial cells are striated with actin and myosin filaments in sarcomeres. But, myocardial cells are short, branched, and interconnected by electrical synapses or gap junctions. Gap junctions have affinity for stain and appear as dark lines under microscope called intercalated discs. The gap junctions allow all of the myocardium to behave as a single functional unit in response to action potential. There is no summation as myocardium contracts to its full extent every time it fires.

Question 7

what produces action potentials in the heart? How does excitation translate to contraction?

Answer 7

cardiac muscle produces action potentials automatically (intrinsic rhythmicity) because of the pacemaker (sinoatrial node) cells. Rate is affected by autonomic innervation (like Vagus nerve)

Cardiac cells have RyR2 ryanodine receptors which are NOT directly coupled to voltage gated Ca2+ channels (dihydropyridine receptors) which open in response to depolarization. Instead, the dihydropyridine receptors let a small amount of calcium inside the cell and this calcium binds and opens the RyR2 receptors and releases a large amount of Ca2+ into cytoplasm, causing muscle contraction. This is Calcium Induced Calcium Release.

Question 8

where is smooth muscle found? What action can these muscles perform?

Answer 8

Tubular digestive tract, ureters (transport urine), ductus deferentia (transport sperm), uterine tubes (transport ova).
Alternate contraction of circular and longitudinal smooth muscle produce peristaltic waves, which propel contents of the tube in one direction

Question 9

describe the structure of a smooth muscle cell. how are the filaments connected? why are they connected this way?

Answer 9

NOT striated sarcomeres. They do contain lots of actin and some myosin, so high ratio of thin to thick filaments. The thin filaments are very long and attach to regions of plasma membrane of to cytoplasmic protein structures called dense bodies (analogous to Z lines). The myosin thick filaments are stacked vertically (perpendicular) so heads can form cross bridges with actin all along the length of thick filament.
All of this is to allow smooth muscle to contract even when greatly stretched!

Question 10

describe the three functions of the circulatory system

Answer 10

1. Transportation: all substances for cellular metabolism are transported. Substances can be categorized into respiratory (red blood cells /erythrocytes transport oxygen, CO2 carried to lungs), nutritive (digestive products), and excretory (metabolic wastes carried to kidneys)
2. Regulation: hormonal and temperature.
3. Protection: clotting and immune function.

Question 11

two subdivisions of circulatory system and organs are in each

Answer 11

cardiovascular: consists of heart and blood vessels
lymphatic: includes lymphatic vessels and lymphoid tissues within spleen, thymus, tonsils, and lymph nodes. Lymphatic system drains to left and right subclavian veins (under collarbone)

Question 12

What are arteries and veins? how do they connect?

Answer 12

Arteries carry blood away from the heart and Veins carry blood to the heart. they are continuous with each other through smaller blood vessels: arterioles (small branches of arteries) connect with capillaries (thinnest and most numerous blood vessels) and then flow into venues (converge to deliver blood to the veins).

Question 13

what is the fluid in the lymphatic vessels and how does it get there?

Answer 13

Lymph. It is a product of blood plasma which passes out of the capillary walls into the tissues, forming tissue fluid or interstitial fluid. Some of this returns to capillaries and some enters lymphatic vessels to form Lymph. this fluid is returned to the venous blood at sites called Lymph Nodes.

Question 14

describe the color of blood (and why) and the normal composition of blood

Answer 14

Arterial blood is bright red because of its high oxyhemoglobin
Venous blood is a darker maroon red because it is less oxygen rich.

Blood has a cellular portion called formed elements and a fluid portion called plasma. A hematocrit (centrifuged blood sample) displays about 45% erythrocyte volume and 55% plasma volume with a thin Buffy coat (contains white blood cells and platelets)

Question 15

what does a thick Buffy coat indicate?

Answer 15

A large amount of white blood cells, indicative of a severe infection or more likely leukemia. Leukemia is also associated with a smaller amount of erythrocytes because the large number of WBCs overcrowd the blood

Question 16

*what is contained in the blood plasma (specific proteins and what they do)? what is the difference between plasma and serum?

Answer 16

Plasma contained Na+, other ions, and organic molecules. Plasma proteins are only about 7-9% of plasma, but are super important. there are three types:

1. Albumens: smallest size, produced by liver, provide osmotic pressure needed to draw water from tissue into capillaries
2. Globulins: includes alpha, beta, and gamma. alpha and beta are made by liver and transport lipids and fat soluble vitamins. gamma globulins are antibodies produced by lymphocytes
3. Fibrinogen: important clotting factor produced by liver. conversion into threads of fibrin cause clot formation. Serum does not have fibrinogen and does not clot, otherwise it’s the same as plasma.

Question 17

*how do the different plasma proteins migrate in plasma protein electrophoresis?

Answer 17

Albumin migrates the furthest towards positive pole (very small and very numerous)

Gamma globulin migrates the least distance

Question 18

*what conditions might you see in the blood if liver disease occurs and why?

Answer 18

Liver produces many plasma proteins so if liver is diseased, these proteins are not produced. If no Albumin produced = water not drawn out of tissue into capillaries = edema. If no Fibrinogen produced = no clotting = hemorrhage

Question 19

Review how plasma volume is maintained

Answer 19

If body loses water, plasma osmolality increases and osmoreceptors in the hypothalamus are activated and cause thirst sensation. Antidiuretic Hormone is released from the posterior pituitary to promote water retention in the kidneys and decrease urination

Question 20

describe the unique shape and contents of a erythrocyte. what molecule is in a high concentration in erythrocytes and what condition does a deficiency of this molecule cause?

Answer 20

7 µm diameter, flattened and biconcave because they lack nuclei and mitochondria. Therefore they only use anaerobic metabolism (to avoid using the oxygen they are transporting). Erythrocytes contain tons of hemoglobin. The heme iron is mostly from recycled sources - transferrin carries iron to the RBCs in bone marrow. Some dietary iron is needed as well. If there is a deficiency in dietary iron, iron-deficiency anemia can result. Anemia is defined as a reduced RBC count and/or hemoglobin count. Anemia can also result from vitamin B12 deficiency

Question 21

Describe the structure of leukocytes and what this structure allows them to do (specific name for the action)

Answer 21

Leukocytes contain nuclei and mitochondria and can move in an amoeboid fashion. They can squeeze through capillary walls and move to the site of infection. This action is called Diapedesis or Extravasation and is what creates pus at an injury.

Question 22

*Name the granular leukocytes. what do they each do? which is the most numerous one and what is its unique structure?

Answer 22

Eosinophils: stain pink with eosin stain. present in allergic reactions and parasitic response

Basophils: stain blue with basic stain. present in allergic reactions

Neutrophils: no stain affinity. Most abundant type of leukocyte and function as phagocytic cells. immature neutrophils have sausage nuclei and are called band cells. mature neutrophils have 2-5 lobed nuclei and are called Polymorphonuclear Leukocytes (PMNs).

Question 23

*Name the agranular leukocytes. what do each of them do and what do they look like?

Answer 23

Lymphocytes: second most numerous leukocyte. small cells with round nuclei and little cytoplasm. Involved in specific immunity or Acquired Immunity as they produce gamma globulins (aka antibodies). lymphocytes include B cells and T cells. The B cells produce Plasma cells which then produce antibodies.

Monocytes: largest leukocytes with “cerebriform” appearance meaning nucleus is kind of brain shaped. These are phagocytic cells

Question 24

How are platelets formed? what roles do they play in blood and *what would low platelet count cause? name this condition

Answer 24

Platelets aka Thrombocytes are actually cytoplasmic fragments of large cells called megakaryocytes. They lack nuclei but are capable of amoeboid movement and play important role in clotting blood. When they clot, they release serotonin which stimulates blood vessel constriction and reduces flow of blood to the injured area. They also secrete growth factors with maintain blood vessel integrity.

Low platelet count, Thrombocytopenia, causes blood vessels to leak blood into tissues, aka spontaneous hemorrhage. Petechiae are pinpoint bleeds and Purpura is bruising that occurs with thrombocytopenia.

Question 25

describe the structures in the female reproductive system and how they connect (ovaries, uterus, vagina, cervical mucus, urethra, labia minora, labia majora, hymen, and clitoris)

Answer 25

two ovaries (almond sized) are partially covered by fimbriae of the uterine (fallopian) tubes. Fimbriae catch the egg during ovulation. Lumen of the uterine tubes is continuous with the uterus (womb) which is pear shaped muscle. Uterus narrows to form vagina, a physical plug of cervical mucus is the only barrier between uterus and vagina. Vaginal opening is posterior to the urethra opening and both are covered by labia minora (inner fold) and labia majora (outer fold w/ pubic hair). vagina may be closed by a ring of tissue called the hymen, which is ruptured by sexual intercourse or other action. The clitoris erectile tissue has a small visible portion anterior to labia minora and a much larger, wishbone shaped portion inside the pelvic region.

Question 26

layers of the uterus. which one is shed during menstruation?

Answer 26

Outer layer perimetrium is connective tissue
middle layer myometrium is smooth muscle
inner layer endometrium is epithelial. Has a stratum basale (basal layer), and stratum functionale (functional layer) which is the only layer that thickens and sheds at menstruation.

Question 27

What is a common form of cancer in women? What is one common cause of this cancer and how do we detect the cancer and treat it?

Answer 27

Cancer of the cervix can be caused by human papilloma virus, a sexually transmitted disease which does have a vaccine. Early detection of cervical cancer is possible by a Papanicolaou smear where a few cells are removed from the cervix for microscopic examination. Removal of the uterus may be recommended, this is called Hysterectomy (also commonly done in response to uterine fibroids)

Question 28

Describe each developmental stage of the follicle and the number/type of oocytes contained in them. From embryonic to newborn to puberty

Answer 28

Embryonic: 6-7 million oogonia in Primordial Follicles. most die, the remaining oogonia begin meiosis at end of gestation time and are called Primary Oocytes.

Newborn: 2 million oocytes each wrapped in a Primordial Follicle

Puberty: 400,000 oocytes remain, only 400 of which will ovulate during a woman’s life. Follicles become larger and are now called Primary Ovarian Follicles. FSH stimulation causes follicles to get larger and divide to produce Granulose Cells that surround oocyte and fill the follicle. Some are stimulated to grow even more and develop vesicles, these are called Secondary Follicles. Growth of these and fusion of its vesicles forms a cavity called an antrum, now the follicle is a Mature or Graafian follicle. Graafian follicles contain Secondary oocytes (arrested at metaphase II)

Question 29

Describe the the process of oogenesis, especially note the timing. What happens to ova in old age?

Answer 29

At embryonic development the Primary Oocytes begin meiosis (oogenesis) and then are arrested in early meiotic division while they are still diploid. Oocytes are connected to granulosa cells by gap junctions. The granulosa cells pass cGMP to the primary oocyte and this inhibits meiosis. Luteinizing hormone (which causes ovulation) stimulates granulosa cells to lower cGMP and therefore oocyte cGMP lowers and meiosis resumes. The first meiotic division completes and forms one Secondary Oocyte and one polar body. Second meiotic division starts, but is arrested at metaphase II. This division completes only after an oocyte is ovulated and then fertilized!

Question 30

what structures are present around a secondary oocyte and what are they developed from? which ones stay after ovulation?

Answer 30

The secondary oocyte is in a Graafian follicle where some granulosa cells form a mound called the cumulus oophorus to support the oocyte. Other granulosa cells form a ring around the oocyte called a corona radiata. Between this layer and the oocyte is the zone pellucida layer of gel-like proteins. The corona radiata and zone pellucida remain around the oocyte after ovulation and play roles in fertilization.

Question 31

what cells in females are similar to the Leydig cells because of their response to Luteinizing Hormone?

Answer 31

Cells of the Theca Interna in the ovarian follicles. these produce testosterone in response to LH. The testosterone diffuses to granulosa cells which have the enzyme aromatase to convert testosterone to estradiol. FSH stimulates increased aromatase and increased estradiol as FSH causes the follicles (which are what form granulosa cells) to grow

Question 32

what cells allow hematopoiesis to be possible and what organ are they located in in fetus and adult? what procedure would they be used for?

Answer 32

Hematopoietic stem cells give rise to all types of blood cells. The originate in the yolk sac of embryo and then reside in the liver of a fetus. Shortly after birth they migrate to bone marrow. Hematopoietic stem cells are self renewing and don’t deplete, although they are low in number. These are the ONLY cells capable of restoring complete hematopoietic ability (producing all cell lines) in a bone marrow transplant, where a recipient is first depleted of all their stem cells and then given a donors to replenish the blood supply.

Question 33

*where does hematopoiesis occur?

Answer 33

Myeloid tissue, the red bone marrow of the long bones (upper ends of bones in arms and legs), ribs, sternum, pelvis, spine vertebrae, and skull

Question 34

what is the source of lymphocyte production?

Answer 34

Lymphoid tissue includes lymph nodes, tonsils, spleen, and thymus. All of these make lymphocytes through cells that originated in the bone marrow!

Question 35

Name the types of blood cells in order of their life span

Answer 35

Longest life span - shortest

erythrocytes (120 days), agranular leukocytes (100-300 days), granular leukocytes (0.5-3 days)

Question 36

what hormone (cytokine) stimulates production of red blood cells? What medical use does this hormone have and what banned use?

Answer 36

Erythropoietin (EPO), secreted by the kidneys, stimulates RBC production. Therefore it increases oxygen and aerobic capacity and elevates a hematocrit. Can treat anemia, especially anemia arising from kidney disease in patients undergoing dialysis. Also needed at high elevations

Blood doping: EPO can improve athletic performance by increasing aerobic capacity. Athletes inject EPO months prior to competition then remove and concentrate the RBCs. Reinfusion of the EPO containing blood then gives them an athletic advantage. It also makes blood viscous and causes clots leading to stroke and heart failure.

Question 37

*when is thrombopoietin produced

Answer 37

constantly! thrombopoietin is constantly manufactured by the liver and kidneys at a steady rate. A self regulating system is in place where low platelet count triggers a decrease in bound thrombopoietin and an increase in unbound thrombopoietin, causing more stimulation of megakaryocytes (mature into platelets). High platelet count triggers the opposite.

Question 38

*what molecules regulate leukopoiesis

Answer 38

cytokines known as Granulocyte colony-stimulating factor (G-CSF) stimulates neutrophils

Granulocyte Monocyte colony stimulating factor (GM-CSF) stimulates monocytes and eosinophils

Question 39

define antibody and antigen

Answer 39

Antigens: substances that generate immune response and antibody production (ANTIbody GENerating substance)

Antibody: specific proteins secreted by B cell lymphocytes that bond to specific antigens

Question 40

what antigens and antibodies are present in each blood type

Answer 40

A: only A antigens. has B antibodies
B: only B antigens, has A antibodies
AB: both A and B antigens, has no antibodies
O: no antigens, both A and b antibodies

Question 41

explain forward and reverse blood typing.

Answer 41

Forward typing: identify the antigens on the RBCs by adding reagent anti-A antisera to one sample and reagent anti-B antisera to another sample. If agglutination occurs then the blood contains that antigen. (if the anti-A antisera sample agglutinates then the blood has A antigens = type A. anti-B antisera agglutinates = B. both agglutinate = AB. neither agglutinate = O)

Reverse typing: identify the antibodies in the plasma by adding reagent A cells and reagent B cells. If agglutination occurs, then the sample contains antibodies for that cell and does NOT have the antigen and is NOT that type. (if the A cells agglutinate = type B. if the B cells agglutinate = type A. if both agglutinate = type O. neither agglutinate = type AB)

Question 42

what is the name of the final type test done before transfusion? what result occurs if they do not match?

Answer 42

Major Crossmatch is done before transfusion by mixing recipient serum with donor blood cells. If they don’t match, then the antibodies attach to the red blood cells antigens and form bridges (because of the two arms of the antibody) that cause cells to clump together or Agglutinate. If transfusion is done with the wrong blood type, agglutination can lead to blockage of blood vessels and cause rupture of red blood cells (hemolysis). Also causes fever, shills, kidney failure, shock, clotting, and a sense of impending doom and death

Question 43

which blood types are universal donors and recipients? why?

Answer 43

O is the universal donor because it has no antigens and so the recipients antibodies cannot cause agglutination of the donor cells. However, plasma has to be removed because type O plasma contains both A and B antibodies and would agglutinate A, B, and AB blood. “Packed cells” are RBCs with plasma removed

AB is universal recipients because there are not anti-A or anti-B antibodies, so agglutination does not occur. However plasma could agglutinate the recipient cells by introducing A or B antibodies. Packed cells are again the solution

Question 44

what is the term for removal of the uterus? what is the main reason for this procedure?

Answer 44

Hysterectomy
Uterine fibroids or Leiomyomas are benign tumors that arise in the myometrium smooth muscle. Their growth is stimulated by progesterone and estradiol. Symptoms include abdominal pain, profuse menstrual bleeding, urinary incontinence, and loss of pregnancy. these are extremely common, 70-80% of women have one by age 50

Question 45

what causes amyotrophic lateral sclerosis? what are the two forms of this disease?

Answer 45

mutations in the gene for superoxide dismutase, which plays a role in removing toxic free radicals. free radicals, mutant protein, RNA toxicity, and inability to transport lactate for energy contribute to neurodegeneration. This produces muscle weakness, atrophy, and spastic paralysis, usually leading to death via respiratory failure in about 5 years
Familial ALS is the type that can be caused by this mutation
Sporadic ALS is not inherited genetically

Question 46

what does damage to lower motor neurons cause? what about damage to upper motor neurons?

Answer 46

Lower or spinal nerves: flaccid paralysis or reduced muscle tone, depressed stretch reflexes and atrophy

Upper: first produces spinal shock and flaccid paralysis. then is followed by spastic paralysis after a few weeks characterized by increased muscle tone and exaggerated stretch reflexes. Clonus occurs where agonist and antagonist muscles contract in alternating movements

upper motor neurons must therefore have an inhibitory effect!

Question 47

what is the preferred test for myocardial infarction

Answer 47

cardiac specific troponin T or troponin I. This test is more sensitive and specific than the test for CPK-MB

myocardial infarction is a heart attack btw (infarction = area of tissue with blood supply cut off)

Question 48

What calcium channel blockers are used in the heart and how do they work? what do they treat?

Answer 48

Dihydropyridines are a category of calcium channel blockers that are relatively specific to vascular smooth muscle. This leads to vasodilation which lowers blood pressure as treatment for hypertension

Verapamil and diltiazem (cardizem) are more heart specific drugs that are NOT dihydropyridines that also lower blood pressure via vasodilation to treat hypertension and slow heart rate

Question 49

What are the types of anemia (three)

Answer 49

Iron deficiency anemia is the most common form and is caused by low iron which is needed for the hemoglobin molecule. Low iron can be caused by heavy menstruation, ulcers, other intense bleeding, low dietary iron, pregnancy, or an inability to absorb iron (eg celiac).

Pernicious anemia is caused by insufficient B12 vitamin, needed for hemoglobin synthesis. This is usually due to lack of secretion of intrinsic factor from stomach glandular mucosa suffering autoimmune attack and atrophy. Without intrinsic factor, B12 is not absorbed. Can also be caused by Crohn’s disease or inadequate dietary B12

Aplastic anemia: destruction of bone marrow and multipotent stem cells of myeloid tissue. Caused by chemotherapy and radiation therapy for cancer or toxins or mutations

Question 50

why does anemia cause weakness/fatigue?

Answer 50

Anemia is low RBC count. this results in low oxygen and low ATP production, causing weakness.

Question 51

What conditions cause high or low hematocrits? (name terms for high and low erythrocyte and high and low WBCs)

Answer 51

Polycythemia: high erythrocyte (high altitude)
Anemia: low erythrocyte (lots of causes, see other card)
Leukocytosis: high leukocytes (leukemia)
Leukopenia: low leukocytes (cancer irradiation treatment)

Question 52

what is the term for elevated platelet count? what causes it?

Answer 52

Thrombocytosis. Liver makes more thrombopoietin in response to cancer, blood loss, inflammation, or other condition

Question 53

how are stem cell transplants done from peripheral blood? what are the two main categories of hematopoietic stem cell transplants

Answer 53

Stem cells can be isolated from peripheral blood by injecting granulocyte colony-stimulating factor (G-CSF) and granulocyte-monocyte colony-stimulating factor (GM-CSF) which stimulate bone marrow to release more stem cells.

Autologous transplants: obtained from same patient before bone marrow depleted

Allogenic transplants: obtained from different person, usually sibling or other close genetic match.