MCDB 111 - Midterm 2
What specific cellular processes are regulated by growth hormone?
- Fat tissue: increased fat breakdown and lower glucose uptake (decrease in body fat) - liver : more protein synthesis, more gluconeogenesis, more IGF-I secretion - More IGF-I leads to more protein synthesis, DNA synthesis, cell size and # - Chondrocytes: more IGF-I secretion, protein synthesis, DNA synthesis, cell size and growth - Muscle: more protein synthesis, and less glucose uptake
What actions does the body take to compensate for the reduction in % hemoglobin saturation at high altitudes? How do these actions facilitate the delivery of oxygen to the tissues?
- Long term; increases # of RBC and vascularity of tissues - Rapid: increases ventilation and decreases affinity of oxygen for hemoglobin
What events in the cardiac cycle do the P wave, QRS complex, and T wave correspond?
- P-wave: atrial action potential - QRS complex: ventricular action potential - T wave: ventricular repolarization
What changes in contraction and relaxation of the L. ventricle are associated with systole and diastole? How do these relate to the corresponding terms that are used to describe the two components of blood pressure measurement?
- Systole: contraction of L. ventricle, max blood pressure - Diastole: relaxation of L ventricle. Min blood pressure
Know the effects of temperature, pH and CO2 on the affinity of oxygen for hemoglobin and the significance of these changes in the context of oxygen delivery to the tissues of the body.
- Temperature: Lower temperature = higher affinity for oxygen - pH: Lower pH = lower affinity for oxygen - CO2: higher CO2 = lower pH = lower affinity for oxygen
Know the functions of thyroid hormone
-- Cellular mechanism of action: thyroid hormone binds to a nuclear receptor and stimulates transcription of a large number of genes -- Metabolism: thyroid hormone enhances expression of many enzymes leading to an increase in basal metabolic rate. - Lipid metabolism: stimulate fat mobilization - Carbohydrate metabolism: stimulates almost all aspects carbohydrate metabolism -- Growth: necessary for normal growth in children -- Development: essential to the development of the fetal and neonatal brain. (based on experiment in endocrinology was the demonstration that tadpoles deprived of thyroid hormone) -- Cardiovascular system: increase heart rate and output. Promote vasodilation which leads to enhanced blood flow to organs. Mediated through the sympathetic NS and release of norepinephrine. -- Central nervous system: essential for the prenatal development of the nervous system and is important for the maintenance of CNS functions in adults.
Which hormones are produced by the posterior pituitary? What are their roles?
-- Vasopressin (ADH): antidiuretic hormone. 9 A.A. peptide hormone. Aquaporin insertion in kidney collecting ducts. Contraction of smooth muscle associated with blood vessels to regulate blood pressure. Regulates water retention thus regulation of ECF (extracellular fluid) volume and composition. -- Oxytocin: 9 A.A. peptide. Effects the MAMMARY gland: acts on smooth muscle to cause milk injection. (Suckling causes post. Pituitary to release oxytocin, the "let down reflex" Paracrine hormone activity: Uterus (causes uterine contraction during parturition) and testes (sperm transport and maturation) - Neurotransmitter: evokes maternal behavior, social bonding, and feeling of calm and content. - MDMA "ecstasy" promotes increased release of oxytocin into the blood and is associated with an increase of subjunctive prosocial feelings.
What are the steps involved in atherosclerotic plaque formation?
1. Absorption of oxidized LDL-C - Endothelial surface injury 2. Inflammatory response - Macrophage infiltration and foam cell formation 3. Plaque enlarges. Capped by smooth muscle 4. Cap rupture RBC and platelets are attracted, clots form, and potential thrombosis
Other than venous pressure, what factors help assure that the venous blood flow returns to the heart?
1. Increased activity of sympathetic nerves to veins 2. Skeletal pump 3. Blood volume 4. Inspiration movements (respiratory pump) 5. One way valves
Know steps involved in thyroid hormone production and the mechanisms that regulate thyroid hormone production and release
1. Iodine is cotransported into the follicle cell with sodium 2. Diffusion into the lumen of follicle 3. Iodine is oxidizes (via action of thyroid peroxidase) and attached to rings of tyrosines in thyroglobulin (TG) 4. An iodinated ring of one MIT or DIT is added to a DIT on another spot 5. Endocytosis of TG containing T3 and T4 molecule 6. Lysosomal enzymes release T3 and T4 from TG (TG is sent back to the lumen of follicle) 7. T3 and T4 are secreted -- Regulation: Hypothalamus secretes TRH which stimulates TSH, which aids in production of T3 and T4. (p23) This is controlled via a negative feedback loop
What three factors are the primary influences on stroke volume?
1. Preload (how much blood enters left ventricle) ventricular end diastolic volume. 2. Contractionility (how hard the heart pushes out blood) sympathetic activity 3. Afterload (decreased arterial pressure allows the heart to push blood out more easy)
Know the difference between primary and secondary hypertension
1. Primary (essential) hypertension: loss of homeostatic mechanisms that regulate MAP (genetic) - CO normal/TPR increased - MAP increased - MAP set point increased 2. Secondary Hypertension: can result from diseases that inhibit the flexibility of peripheral blood vessels or affect coronary output.
What do the two pressures, diastolic and systolic pressure represent in terms of the cardiac cycle?
1. Ventricular filling (Diastole) 2. Isovolumetric ventricular contraction (start systolic phase) 3. Ventricular ejection (systole) 4. Isovolumetric ventricular relaxation (diastoles)
What factors affect alvelolar partial pressures of oxygen and carbon dioxide
1.Atmospheric partial pressure 2. Metabolic rate 3. Ventilation
Be able to describe the path of blood flow through the heart and the vessels involved in both systemic and pulmonary circulation.
1.Vena cava 2. Right atrium 3. Right ventricle 4. Pulmonary artery 5. Lungs 6. Pulmonary vein 7. Left atrium 8. Left ventricle 9. Aorta
What is the pulse pressure if the diastolic pressure is 60 and the systolic pressure is 105 mm Hg?
105-60 = 45 mmHg = pulse pressure
How do statin drugs stop the progression of existing atherosclerotic plaques and prevent the formation of new ones?
20-30% plasma LDL reduction - Inhibition of HMG CoA reductase Direct cholesterol synthesis reduction and increase expression of LDL receptors. - Indirectly: reduces vascular inflammation and platelet aggregation, stabilization of plaques, and mild immunosuppression.
What is the mean arterial pressure if the diastolic pressure is 60 and the systolic pressure is 105 mm Hg?
60+⅓(45) = 75 mmHg = mean arterial pressure
Determine cardiac output given a heart rate of 70 beats/min and a stroke volume of 0.1 L/beat
7 L/min = cardiac output 70 * 0.1
How do alveolar and chest wall elastic recoil forces contribute to the negative intrapleural pressure that is essential for normal lung function?
According to Boyle's Law, an increase in the volume of a closed chamber must be accompanied by a decrease in pressure. The elastic recoil promotes separation of the lungs and chest wall which enlarges the intrapleural cavities resulting in a reduction of pressure relative to the pressure within the alveolar space
Briefly describe the three homeostatic mechanisms that the body can use to restore arteriolar blood flow to specified organs within the body? Add other two mechanisms
Active hyperemia: Increased metabolic activity in an organ results in a localized drop in O2 and an increase in metabolites. This promotes arteriolar dilation in the organ. Flow autoregulation: A drop in arterial pressure within an organ results in decreased blood flow to the organ causing a drop in oxygen, increased levels of metabolites, and decreased vessel wall stretch produces arteriolar dilation within the organ which restores blood flow. This response is mediated by a reduced action of the sympathetic NS and localized formation of NO in endothelial cells that results in a corresponding localized vasodilation of the blood vessel. Reactive hyperemia: A complete block in blood flow, such as caused by a blood clot produces maximal dilation of arterioles in anticipation of the return of blood flow once the blockage is removed.
What are the three biochemical classes of hormones?
Amine Hormones Peptide Hormones Steroid Hormones
What information can be obtained from an echocardiogram?
An "echo" provides a way of measuring stroke volume and can also be useful in detecting cardiac valve defects.
What general types of information can be obtained from an electrocardiogram?
An ECG tells you if there is any abnormality in the electrical currents that give rise to contractile rhythm of the heart, such as a heart block or ventricular fibrillation. - Changes in heart rate - Abnormalities in heart rhythm - Possible location of damage in the heart - Effects of drugs on cardiac function
What does the ECG actually measure?
An ECG trace is a summation of the coordinated firing of cardiac muscle cells as the action potential spreads from atria to ventricles in a wave-like manner. It is actually a measure of the current flow from the heart into the intracellular fluid.
How do the action potentials of cardiac cells differ from those of neurons?
An action potential in a neuronal cell occurs as a consequence of opening and closing of Na+ and K+ channels. In cardiac nodal/pacemaker cells, calcium channels have a direct role in the depolarization phase of the action potential. In cardiac contractile cells the opening of calcium channels significantly delays repolarization and gives rise to the force of heart contraction. The prolonged depolarization gives rise to a long refractory period which helps to assure the directionality of action potential propagation and prevents tetanus.
Know the diseases associated with the adrenal gland
Autoimmune adrenal atropy, primary and secondary adrenal insufficiency give rise to cortisol deficit. Tumors of the pituitary and adrenal gland often result in cortisol excess. Pheochromocytoma is an adrenal gland tumor that originates in the chromaffin cells of the adrenal medulla, resulting in dangerously high levels of circulating epinephrine which can lead to a stroke due to the resulting elevated blood pressure.
How is calcium metabolism regulated and what diseases result from abnormal levels of this ion?
Calcium metabolism is regulated by vitamin D and many organs. Parathyroid hormone stimulates the enzyme required to convert vitamin D to its active form, 1,25 hydroxy Vitamin D which is needed for the absorption of calcium from the intestine and urine. Parathyroid hormone also stimulates the activity of osteoclasts which deminearalize bone, allowing calcium to be reabsorbed into the blood. -- Hypercalcemia: primary hyperparathyroidism, humoral hypercalcemia, excessive Vitamin D -- Hypocalcemia: primary hypoparathyroidism (parathyroid gland removal), pseudohypoparathyroidism (resistance to effects of parathyroids hormones), secondary hyperparathyroidism (failure to absorb calcium and decreased kidney function)
What is meant by cardiovascular compliance?
Compliance is a measure of the elasticity of a blood vessel, ΔV/ΔP. The greater the volume changes as blood pressure increases, the greater the compliance.
Know the functions regulated by the adrenal gland and the hormones it releases
Contributes to the overall stress response. Releases epinephrine and norepinephrine (rapid response to stress) and cortisol (long term adaptation to stress) . Increased heart rate, blood flow to muscles, increased respiration, and decreased blood flow to skin and major organs. Metabolic effects vary dependent on short vs long term stress. Short term: glycolysis; long term gluconeogenesis, glycogen synthesis, inhibition of fat formation, immunosuppression. Hormones include epinephrine and cortisol. Also vasopressin which is released in response to the renin-angiotensin pathway.
Know the hypophysiotropic hormones and the hormones that each controls.
Corticotropin-releasing hormone: stimulates the secretion of ACTH Thyrotropin-releasing hormone (TRH): stimulates the release of TSH Growth hormone-releasing hormone (GHRH): stimulates the release of GH Somatostatin(SS): Inhibits release of GH Gonadotropin-releasing hormone (GnRH): stimulates the release of LH and FSH. Dopamine (DA): inhibits secretion of prolactin
What are the two major downstream effects of hormones on cellular metabolism?
Cytoplasmic enzyme activation and transcriptional activation
What agents increase arteriolar compliance?
Decreased blood pO2, elevated levels of K+, CO2, H+, nitric oxide, and epinephrine released from the adrenal gland (acting on arterioles with adrenergic β2 receptors)
What are the two types of glands that release hormones?
Endocrine glands and Exocrine glands release hormones. Endocrine glands release into the bloodstream and exocrine glands secrete into the lumen of the organ to work on endodermal cells.
What is the resistance to flow if the pressure at one end of an artery is 110 mm Hg and 80 at the other end and the flow rate is 10 ml/min?
F = ΔP/R . . . so . . . R = ΔP/F = 110-80 / 10 = 3 mm Hg ml-1 min -1
What factors regulate growth hormone release?
Factors that regulate growth hormone release: stimulus - exercise, fasting, low plasma glucose, sleep makes hypothalamus release more GHRH. SS inhibits GH. More GH and IGF-I stimulates SS and inhibits GHRH.
What type of growth is primarily regulated by growth hormone?
Height (linear growth) - long bone growth. Growth is restricted to epiphyseal growth plate.
How can changes in respiration rate lead to respiratory alkalosis?
Hyperventilation causes respiratory alkalosis
What is the baroreceptor response?
Located in the aortic arch and carotid arteries, the baroreceptors sense the blood pressure. Stroke volume, cardiac output, and mean arterial pressure go down in response to a hemorrhage. Baroreceptors increase everything to make up for loss.
Know the functions that are regulated by the hypothalamus
Most important brain center for regulating homeostasis. Receiving many inputs and outputs can be hormonal or neural. Works through the posterior and anterior pituitary. Regulates: hunger, body temperature, thirst, osmolarity, reproduction, lactation, metabolic rate, circadian cycles, fatigue, emotion, and more.
anterior pituitary
Not neural cells, a collection of endocrine cells that are regulated by the hypothalamus or more specifically the neurosecretory cells.
What inputs does the medullary respiratory center receive that enable it to make appropriate decisions for regulating respiration rate?
Peripheral chemoreceptors are sensitive to blood gases, especially oxygen. Sends signals to the medulla to act accordingly. Very sensitive to pH changes but the medullary cell will respond more strongly to carbon dioxide in the bloodstream than protons.
What are the functions of the pleural cavities? Why are there two instead of just one?
Pleural cavities are the two sacs of fluid surrounding the lungs that act to protect the lungs and keep a set pressure around them. They are not together because they independently help each lung.
How is cortisol secretion regulated?
Regulated by the hypothalamus and the pituitary gland. It is subject to negative feedback. (p24) Release promoted by CRH (hypothalamus) and ACTH (pituitary).
What is gluconeogenesis?
Supplies the plasma glucose needed between meals. stimulated by the diabetogenic hormones (glucagon, growth hormone, epinephrine, and cortisol). Gluconeogenic substrates include glycerol, lactate, propionate, and certain amino acids.
What is a surfactant and why is it important for lung compliance?
Surfactant is a detergent-like substance that breaks the surface tension in alveoli which leads to less alveolar collapsing. Keeps the alveoli roughly the same size so it is less likely that a small alveoli will collapse into a larger one.
In what ways do the sympathetic and parasympathetic NS alter heart function?
Symp: Increase rate and force of contraction. ParaS: Primary effect is to reduce rate. Can also decrease force of atrial contraction
What enables pacemaker cells to undergo spontaneous contractions?
The If Na+ channels initiate the action potential at a less negative voltage than is the case for other excitatory cells. When K+ channels repolarize the membrane, they do so gradually such that there is no steady resting potential.
What are the effects of the autonomic NS and adrenal gland on the cardiovascular system?
The adrenal gland and ANS increase cardiac output due to the raised contractility. - Parasympathetic vagus nerves: decrease heart rate with acetylcholine - Sympathetic: Thoracic spinal nerves increase rate and force of the heart with norepinephrine. Blood brings epinephrine which does this
What factors determine the rate of blood flow?
The difference in pressure between two points and the resistance to flow
Does the rate of blood flow increase or decrease as arterioles become capillaries? What is the physical reason for this change and why is this important?
The rate of movement is decreased in the capillaries due to Poiseulle's Law which states that resistance to flow is inversely proportional to the 4th power of the radius. Thus as radius decreases, resistance increases and flow decreases. The reduced velocity of blood flow through the capillaries increases the efficiency of gas, nutrient, and waste exchange between the circulation and the surrounding tissues.
What is the purpose of heart valves?
Their purpose is to keep the blood going in one direction. It prevents mixing of oxygenated and deoxygenated blood.
What pathological conditions are associated with too much or too little growth hormone?
Too much: Before puberty - gigantism. After puberty - acromegaly (bones in hands, feet, and jaw can still grow) Too little: dwarfism prior to puberty
Know the five drug classes given in lecture that are commonly used to treat hypertension and be able to give a one to two sentence description of how they work
Treatment: calcium channel blockers: Prevent opening of L-type calcium channels in cardiac myocytes Beta blockers-block beta 1 receptors in cardiac myocytes, reduce cardiac output through phosphorylation of troponin and calcium channels in cardiac myocytes ACE inhibitors: inhibit ACE which converts angiotensin I to the active angiotensin II which elevates BP through promoting aldosterone release and other mechanisms ARB's: block binding of angiotensin II to angiotensin II type I receptors blocks the actions of angiotensin II diuretics:promote water loss from the body and as a result reducing blood volume. Most work by blocking Na+ channels in kidney tubules
What is the primary determinant of stroke volume?
Venous pressure
Hyperprolactinemia
a pituitary tumor that secretes prolactin or a tumor that prevents the regulation of prolactin production. Can cause galactorrhea, amenorrhea, and decreased sex drive in men. Can cause lactation at a time other than pregnancy.
What are the roles of secondary messengers in signal transduction pathways?
allow a hormone signal to be transmitted to multiple target molecules and provide an effective means of signal amplification.
What physiological parameters are typically altered in response to hypotension?
baroreceptor afferent activity decreases, sympathetic activity increases, and parasympathetic activity decreases. Stroke volume, heart rate, cardiac output, TPR, and MAP.
Hypothyroidism
caused by inadequate iodine in diet or autoimmune thyroiditis "hashimotos disease". Symptoms: thyroid hypertrophy, cold intolerance, myxedema due to overproduction of glycosaminoglycans, fatigue, depression, high risk of mental retardation of child born to mothers with low iodine Treatments: T4 tablets "levothyroxine" iodine added to salt
Hyperthyroidism
causes Graves disease or thyroid or pituitary tumors (rare). Symptoms: thyroid hypertrophy, heat intolerance, weight loss, anxiety, tachycardia, hypertension Treatment: drugs that block adrenergic receptors, methimazole (thyroid peroxide inhibitor), radioactive iodine.
How are proteins exchanged between blood in capillaries and the ECF?
endo and exocytosis
Hypopituitarism
from a variety of causes including tumors, trauma, decreased pituitary blood supply, infection, sarcoidosis, an autoimmune process, radiation, surgical removal of the pituitary or a side effect of pituitary surgery; result in a general decrease in pituitary hormone production.
Growth Hormone deficiency
from a variety of causes; in children it causes delayed growth and short stature; in adult it can lead to muscular weakness, fatigue, decreased bone mass, and obesity
What are hypophysiotropic hormones?
hormones from the hypothalamus that act on the anterior pituitary. Tropic hormones: have other endocrine glands as their target. Trophic hormones: have a growth effect on their target cells.
Pituitary tumors
may be hormone-secreting or non-secreting. Most are benign. May cause visual disturbances and headaches as they grow and compress surrounding tissues.. May produce an excessive amount of one pituitary hormone and decrease others.
specificity
one molecule will bind to a specific target and the ability to distinguish between the small differences of molecules/ligands (hormones and neurotransmitters)
posterior pituitary
release 2 hormones: Connected to hypothalamus through axons leading to neuroendocrine secretion. Vasopressin (ADH) Antidiuretic hormone (diuretic: promotes promotes water loss which lowers blood pressure) Oxytocin
Empty sella syndrome
the sella is the structure that surrounds the pituitary gland; it may increase in size and put pressure on the pituitary gland causing the gland to shrink. Leading to hypopituitarism.
affinity
the tightness of binding between two things
What two variables can be multiplied together to determine mean arterial pressure (MAP)?
total peripheral resistance (TPR) and cardiac output (CO).
