Midterm 3 Flashcards
What is the primary function of the endocrine system?
Integration and regulation of growth and development
What are the four chemical classifications of hormones?
Amines: derived from tyrosine and tryptophan
Polypeptides and proteins
Glycoproteins: long polypeptides bound to a carbohydrate
Steroids: lipids derived from cholesterol
What are the major endocrine glands?
Hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, ovary/testis
Describe how hormones are classified
polar: water soluble, must be injected if used as a drug
Nonpolar: insoluble in water, called lipophilic hormones, can enter target cells directly, can be taken orally in pill form
Distinguish prohormones and prehormones
Prohormones-inactive hormones that must be cut and spliced together to be active (proinsulin –> insulin)
Prehormones–inactive hormones that must be modified within their target cells
Distinguish synergistic, permissive, and antagonistic effects of hormones
Synergistic–occurs when 2 or more hormones work together to produce a particular effect. May be additive or complementary.
Permissive–occurs when one hormone makes the target cell more responsive to a 2nd one.
Antagonistic–occurs when hormones work in opposite directions
Describe hormone half life
Most hormones are removed within minutes to hours, thyroid hormones take days
Describe the significance of hormone concentration
Tissues only respond when hormone concentration is at a certain “normal” level. At higher concentration, effects may be different, which may result in binding of hormones to receptors of related hormones, sometimes causes widespread side effects.
what do flexor muscles do? what do extensor muscles do?
Flexor: decrease angle between bones
Extensor: increase angle between bones
What is a motor unit composed of?
Neuromuscular junction and somatic motor axon
What are the components of muscle fiber striations
I bands (light) and A bands (dark)
What are the two types of muscle fibers and what are they composed of?
Thick: protein myosin
thin: protein actin
What is the sliding filament theory
A and I bands do not shorten. Thin filaments slide towards each other, H bands DO shorten
What is a skeletal muscle twitch?
When muscle quickly contracts and relaxes after electrical shock
What is tetanus?
Increase in frequency of electrical shocks decreases relaxation time. Complete tetanus: no relaxation
What is treppe?
As voltage increases, # of muscle fibers uses increases. Staircase effect: when fresh muscle is stimulated with several shocks at max voltage and twitches are stronger
Distinguish isotonic and isometric contractions
Isotonic: muscle fibers shorten, tension is greater than load
Isometric: muscle fibers can’t shorten, load too great, can be voluntary.
Distinguish concentric vs eccentric contraction
Concentric: muscle fiber shortens
Eccentric: muscle fbier lengthens, ex. lowering dumbell after concentric contraction
List four muscle strength determinants
- # s of fibers recruited to contract
- frequency of stimulation
- Thickness of each muscle fiber
- Initial length of fiber at rest
Where do muscles get their energy?
Rest and mild exercise–fatty acids
Moderate exercise–glycogen
Heavy exercise–blood glucose (GLUT4 channels inserted into sarcolemma)
Differentiate between slow and fast twitch fibers
Slow-(type 1) slower contraction speed, can sustain contraction for long periods without fatigue, rich capillary supply, more mitochondria, more respiratory enzymes, more myoglobin
Fast (type 2)–faster contraction speed, fatigue fast, fewer capillaries, mitochondria, respiratory enzymes and less myoglobin
Intermediate (type 2a)–fast twitch but with high oxidative capacity
What are causes of muscle fatigue
- -Accumulation of extracellular K+, reducing membrane potential
- -Depletion of stored glycogen
- -reduced SR calcium release
- -lactic acid accumlation and lower pH
- -Increased concentration of PO4 due to phosphocreatine breakdown
- -Lack of ATP
- -Buildup of ADP
- -Fatigue for upper motor neurons, called central fatigue
What is hypertrophy?
Type 2 muscle fibers become thicker due to increased amount of actin and myosin (more sarcomeres)
What do satellite cells do?
Fuse to damaged muscle cells and repair them or fuse to each other to form new fibers
why does muscle decline with aging?
Reduced muscle mass and capillary blood supply, few satellite cells and increased myostatin production
What are the functions of the circulatory system?
Transportation, regulation and protection
What are the components of the circulatory system?
Cardiovascular and lymphatic systems
What is the blood composition? Volume, fluid portion, and cellular portion
5 L or 8% of body weight
Fluid portion: plasma 55% of total blood volume
Cellular portion: formed elements 45%
What makes up plasma?
plasma proteins, serum, gamma globulins
What are the characteristics of erythrocytes?
They are red blood cells, they carry oxygen, have a 120 day life span, contain hemoglobin and transferrin
What are the characteristics of leukocytes?
White blood cells, granular vs. aggranular, leukemia: increased number of immature leukocytes
What are the characteristics of platelets?
thrombocytes: smallest formed element, 5-9 day life span, clot blood, release serotonin
What is hematopoiesis? How many cells are produced in a day and where?
Process of blood formation. 500 billion cells produced a day in bone marrow.
What are some characteristics of hematopoeietic stem cells?
Undifferentiated, multipotent
What is leukopoiesis?
White blood cell formation, in myeloid and lymphoid tissues, interleukin
What is erythropoeisis?
Red blood cell formation, 2.5 million produced per second, erythropoietin
What is hepcidin?
Regulates iron metabolism
What are antigens?
Agglutinogens, found on surface of cells to help immune system recognize self cells. E.g. type A blood has the A antigen
What are antibodies?
Agglutinins, secreted by lymphocytes in response to foreign cells
What is the Rh factor?
antigen D, Rh-positive or -negative
Describe the process of blood clotting
Hemostasis–cessation of bleeding when a blood vessel is damage. Fibrinogen converted to fibrin via 2 pathways:
- -Intrinsic: activated by exposure to collagen, factor VII activates cascade of other blood factors. Then calcium and phospholipids convert prothrombin to thrombin.
- -Extrinsic: initiate by factor III, more direct pathway, vitamin K needed for both pathways
What are anticoagulants?
Aspirin, calcium chelators, heparin and coumarin
What are the AV valves?
tricuspid and bicuspid/mitral
What are the SL valves?
pulmonary and aortic
What are the heart sounds and when do they occur?
Lub (AV vlaves close) and dub (SL valves close)
What is a heart murmur what does it denote?
Abnormal heart
Mitral stenosis
Incompetent valves
Septal defects
What is the cardiac cycle
Isovolumetric contraction: QRS wave
Ventricular ejection: stroke volume and cardiac output
Isovolumetric relaxation: end systolic volume (ESV)
Ventricular filling
Atrial contraction: P wave, end diastolic volume (EDV)
What affects the electrical activity of the heart?
SA node–pacemaker. Epinephrine and norepinephrine increase production of cAMP, keeps Na+, speeds heart rate.
Parasympathetic neurons secrete acetylcholine, opens K+ channels, slows heart rate.
What is an electrocardigram? Describe its components (what it reads)
records electrical activity of heart Pwave: atrial depolarization QRS wave: ventricular depolarization--LUB S-T segment: plateau phase T wave: ventricular repolarization--DUB
What are bipolar limb vs unipolar limb leads
Bipolar leads have one positive and one negative pole. In a 12-lead ECG, the limb leads (I, II and III) are bipolar leads. Unipolar leads also have two poles, as a voltage is measured; however, the negative pole is a composite pole made up of signals from lots of other electrodes
List the kinds of blood vessels
Arteries, arterioles, capillaries, venules and veins (lower pressure)
What are the layers in arteries and veins
Tunica intima, tunica media, tunica externa
What are the two kinds of arteries?
Elastic and muscular
What are the different kinds of capillaries?
Continues, fenestrated, discontinuous
What is atherosclerosis?
Plaques form in response to damage due to endothelium of a blood vessel caused by smoking, high blood pressure, diabetes and high cholesterol, now believed as inflammatory disease
What is Ischemic Heart Disease?
Inadequate oxygen due to reduced blood flow
What are the names for speeds of abnormal heart rhythms?
Bradycardia (slow) vs tachycardia (fast)
What is the difference between flutter and fibrillation?
Flutter: extremely fast but coordinated contractions. Fibrillation: uncoordinated pumping, atrial vs ventricular
What are the functions of the lymphatic system?
Transports excess interstitial fluid (lymph) from tissues to the veins. Produces and houses lymphocytes for the immune response. Transports absorbed fats from intestines to blood.
Describe the vessels of the lymphatic system
Lymphatic capillaries: smallest, found in most organs. Lymph ducts: formed from merging capillaries, lymph filtered through lymph nodes. Thoracic trunk and right lymphatic trunk: from merging lymphatic ducts, deliver lymph into right and left subclavian veins
What are the organs of the lymphatic system?
Tonsils, thymus and spleen: sites for lymphocyte production
What is the cardiac output? How do you calculate it? What is the average cardiac output?
Volume of blood pumped each minute by each ventricle. Cardiac output = stroke volume x heart rate. AVerage = 5.5 L per min
Describe the regulation of cardiac rate
Spontaneous depolarization at SA node when HCN channels open, Na+ goes in. Sympathetic norepinephrine and adrenal epinephrine keep these channels open, increasing heart rate. Parasympathetic acetylcholine opens K+ channels, slowing heart rate. Controlled by cardiac center of medulla oblongata.
What is End diastolic volume (EDV)?
volume of blood in the ventricles at the end of diastole.
What is total peripheral resistance?
frictional resistance in the arteries.
What is contractility?
strength of ventricular contraction
What is the Frank-Starling Law?
Increased EDV increases contractility and thus increases stroke volume
What is intrincsic vs extrinsic control of contraction strength?
Intrinsic: due to myocardial strength. Extrinsic: sympathetic norepinephrine and adrenal epinephrine can increase contractility
What are the factors of venous return?
Highest pressure in venules vs. lowest pressure in veins closest to heart. Sympathetic nerve activity to stimulate vasoconstriction. Skeletal muscle pumps squeezes veins during muscle contraction. Pressure difference between abdominal and thoracic cavities. Blood volume.
What is the body water distribution?
66% cell, last 1/3 = 80% interstitial space, 20% blood plasma
What is net filtration pressure?
HSP(B)-HSP(FC)
What is edema and what does it result from?
Excessive accumulations of interstitial fluids. High arterial pressure. Venous obstruction, leakage of plasma proteins into interstitial space. Myxedema–excess production of particular glycoproteins caused by hyperthyroidism. Decreased plasma protein concentration. Obstruction of lymphatic drainage.
Describe the regulation of blood volume by kidneys
Formation of urine begins with filtration of fluid through capillaries in the kidneys called glomeruli. 180 L of filtrate is moved across glomeruli every day, 1.5 L is actually removed as urine. Antidiuretic hormone (ADH) – produced by hypothalamus and released when osmoreceptors detect increased plasma osmolality (more concentrated).
Describe vascular resistance to blood flow
Cardiac output is distributed unequally to different organs. Blood flows from a region of higher pressure to a region of lower pressure. Mean arterial pressure and vessel radius are important factors in blood flow.
What is total peripheral resistance?
Sum of all vascular resistance in systemic circulation. Blood flow to organs run parallel to each other
What is extrinsic regulation of blood flow?
Sympathetic nerves: increases total peripheral resistance through release of norepinephrine onto smooth muscles of arterioles to stimulate vasoconstriction. ACetylcholine is released onto skeletal muscles, results in vasodilation to these tissues.
Parasympathetic nerves: acetylcholine stimulates vasodilation, limited to digestive tract, external genitalia and salivary glands
Paracrine control: molecules produced by one tissue control another tissue within the same organ.
What is intrinsic regulation of blood flow?
Used by some organs to promote constant blood flow when there is fluctuation of blood pressure, called autoregulation
Describe the regulation of blood flow through skeletal muscles
arterioles have high vascular resistance at rest
Adrenal epinephrine stimulates vasodilation and thus vascular resistance during exercise
Vasodilation is enhanced by intrinsic metaboli control mechanisms
Describe circulatory changes during exercise
Vascular resistance to skeletal and cardiac muscle decrease due to: increased cardiac output. Metabolic vasodilation. Diversion of blood away from viscera and skin.
Describe cerebral circulation
Brain cannot tolerate much variation in blood flow
Describe myogenic control of cerebral blood flow
When blood pressure falls, cerebral vessels dilate, and vice versa. Decreased pH of CSF causes arterial dilation.
Describe cutaneous blood flow
Skin can tolerate the greatest fluctuations in blood flow.
What is thermoregulation?
Increased blood flow to capillaries in the skin releases heat when body temperature increases, sweat produced to aid in heat loss, bradykinins in the sweat glands also stimulate vasodilation in the skin.
What do arteriovenous anastomoses do?
shunt blood from arterioles directly to venules
How does cutaneous blood flow operate at average temperatures?
Vascular resistance in skin is high, blood flow is low
What factors affect blood pressure?
Increases in blood/stroke volume, total peripheral resistance or cardiac rate will increase blood pressure
What is the baroreceptor reflex?
Activated by changes in blood pressure detected by baroreceptors in the aortic arch and carotid sinuses. Vasomotor center controls vasodilation and constriction. Cardiac center controls heart rate. Fall in BP results in increase of sympathetic and decrease in parasympathetic activity, resulting in increased HR and TPR
What are atrial stretch reflexes?
Activated by increased venous return to:
- -stimulate tachycardia
- -inhibit ADH release
- -Stimulate secretion of atrial natriuretic peptide
What is hypertension?
What percentage of Americans have hypertension? What are treatments?
High blood pressure. Can increase risk of cardiac disease and stroke. 20% of Americans have hypertension. Most people fall into the essential hypertension category. Treatments: lifestyle modification, K+ supplements, diuretics, beta blockers and ACE inhibitors
What is Circulatory Shock?
occurs when there is inadequate blood flow to match oxygen usage in tissue, sometimes leads to death. Causes also include severe allergic reactions, spinal cord injury and cardiac failure
What is hypovolemic shock?
Due to low blood volume from an injury, dehydration or burns
What is septic shock?
Dangerously low blood pressure due to infection (sepsis), high mortality rate (50-70%)
What is congestive heart failure and what is its cause?
Occurs when CO is not sufficient to maintain blood flow required by the body. Caused by myocardial infarction, congenital defects, hypertension, aortic valve stenosis.
Describe the target axis of LH/FSH
HYPOTHALAMUS—GnRH,
ANTERIOR PITUITARY–FSH/LH,
TARGET TISSUE–Ovaries and Testis,
FUNCTION–FSH: growth of ovarian follicles and sperm cells
LH: production of estrogen, progesterone, and testosterone,
HYPOSECRETION–Failure or decreased rate of sexual maturation,
HYPERSECRETION–Increased rate of sexual maturation
Describe the target axis of GH
HYPOTHALAMUS–GHRH/GHIH, ANTERIOR PITUITARY–GH, TARGET TISSUE–Liver, Muscle, Bone, Cartilage, FUNCTION–Stimulates protein synthesis in muscle, breakdown of glycogen in liver, fat absorption, and growth/cell division. Increases blood glucose level, HYPOSECRETION–Dwarfism in children [GHRH/GH], HYPERSECRETION–Gigantism in children, acromegaly in adults
[GHRH/GH]
Describe the target axis of prolactin
HYPOTHALAMUS–PRH/PIH, ANTERIOR PITUITARY—PRL, TARGET TISSUE—Breast, FUNCTION–Stimulates lactation, HYPOSECRETION–Decrease in lactation [PRH/PRL], HYPERSECRETION–Increase in lactation or milk production
[PRH/PRL]
Describe the target axis of thyrotropin releasing hormone,
HYPOTHALAMUS—TRH, ANTERIOR PITUITARY—TSH, TARGET TISSUE—Thyroid, FUNCTION–Stimulates release of thyroid hormones, regulates metabolic rate, HYPOSECRETION–Cretinism in children, myxedema in adults, HYPERSECRETION–Grave’s disease
Describe the target axis of ACTH
HYPOTHALAMUS—CRH, ANTERIOR PITUITARY—ACTH, TARGET TISSUE–Adrenal Cortex, FUNCTION–Stimulates release of glucocorticoids and androgens, HYPOSECRETION–Addison’s Disease, HYPERSECRETION–Cushing’s Disease
