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ANATOMY AND PHYSIOLOGY 2
CHAPTER 18
The endocrine system works with the nervous system and coordinates all the body systems.
The endocrine system uses hormones produce by endocrine structures.
-Effects are produced by these hormones
Hormones effect cells in their local environment or in distant parts of body.
Autocrine hormones- secreted by a cell and binds with that same cell
Paracrine hormones- local, secreted into the interstitial fluid of one cell and act on near body cells
Circulating hormones- hormones that travel and work over long distances (secreted into interstitial fluid, absorbed by blood stream, and carried systematically to any target cell that displays the appropriate type of receptor)
Lipid Soluble Hormones- bind with receptors in cytoplasm or nucleus of a cell
Steroid hormones- derived from cholesterol
Thyroid hormones- (T3 or T4) synthesized by attaching iodine to the amino acid tyrosine
Nitric oxide (NO) - can be both a hormone and a neurotransmitter
1) Bind with cell with receptors in cytoplasm or nucleus2) Activated receptor-hormone complex alters gene expression (turns genes on/off)3) Newly formed mRNA directs synthesis of specific proteins on ribosomes4) New proteins alter cell’s activity
Water Soluble Hormones- bind to receptors on the surface of a cell
Amine hormones- synthesized by modifying specific amino acids (melatonin/histamine)
Peptide hormones and protein hormones- amino acid polymers (longer chains of amino acids)
Eicosanoids-
Prostaglandins- important in playing a role in inflammatory response
Leukotrienes- important in playing a role in inflammatory response
Water Soluble hormones have to bind with a first messenger to get into the cell
1) Binding of hormone (first messenger) to its receptor activates G protein, which activates adenylate cyclase
2) cAMP serves as a second messenger to activate protein kinases
3) Activate protein kinases phosporlyate cellular proteins4) Millions of phosphorylated proteins cause reactions that produce physiological
responses
Prostaglandins (PGs) - hormones with local control
Important in mediation of pain, platelet aggregation, fever, inflammation
Important for smooth muscle contraction, gastric acid secretion, airway size.
Effects of Hormones
1) Hormones balance the volume and composition of body fluids2) Regulate metabolism and energy production3) Direct the rate of timing of growth and development4) Exerting physical and mental control during stress (physical trauma, starvation,
hemorrhage)5) Oversee reproductive mechanisms
Endocrine System Glands- secrete endocrine hormones into bloodstream
Exocrine- excrete products via ducts
Endocrine- when stimulated it will release hormone in frequent bursts (increases concentration of that particular hormone in the bloodstream)
Hormone secretion is regulated by impulses from nervous system, chemical changes in blood, and other hormones
Most hormonal regulatory systems work through negative feedback system
EX: (Parathyroid hormone (PTH) is important for controlling blood-calcium levels)
PTH exerts effects into body until calcium levels are leveled out
Positive feedback system- oxytocin stimulate contraction, which stimulate more oxytocin release
The endocrine systems consists of different glands throughout body (pituitary gland, thyroid glands, parathyroid glands, adrenal glands, pineal glands)
Other glands that are important in endocrine system but not endocrine function hypothalamus, thymus, pancreas, ovaries, testes
Endocrine contributions from other organs- kidneys, stomach, liver, small intestine, heart, skin.
The Hypothalamus- major link between nervous system and endocrine system
Receives inputs from many regions of brain (from thalamus/limbic system)
The Pituitary gland- the hypothalamus is mainly controlled by pituitary gland
Hangs down from hypothalamus on infundibulum
Divided into Posterior and Anterior pituitary (Anterior accounts for 75% of mass)
Posterior- (neurohypophysis)-
Anterior division (adenohypothesis) - anatomically and functionally connected to hypothalamus by blood vessels (form portal system- hypophyseal portal system)
Portal system- blood from capillary network into vein into another capillary network, then it returns to heart
Usually named to indicate the location of the second capillary network
Specialized cells in hypothalamus that secrete releasing hormones (secreted into portal system)
Tropic hormones- produced and secreted by the anterior pituitary- they target other endocrine glands (exception: hGH, Prolactin, MSH go directly to target organs)
Posterior pituitary- release, but not synthesize hormones
When stimulated neurosecretory cells in hypothalamus releases hormones like oxytocin and ADH
Oxytocin- involved in a positive feedback (birthing) – targets smooth muscle uterus/breast tissue- stimulates uterine contractions
ADH- target the collecting ducts in kidneys and sweat glands in skin. (Goal is to minimize water loss) Also causes arterials to constrict (by constricting, ADH helps increase blood pressure)
Pituitary Gland Disorders-
Acromegaly- excess hGH during adulthood) - enlargement and elongation of facial bones and hands
Diabetes Insipidus (DI)- (juvenile diabetes) caused by insufficient release of ADH from the neurohypophysis (without ADH acting on collecting duct in kidney, there is normal urine output of 1-1.5 liters a day to 2.5 liters a day- causes dehydration and loss of ions)
The Thyroid Gland-
Located inferior to larynx and anterior to trachea
There are 2 laterally placed lobes, connected by Isthmus
Spherical groups of follicular cells (thyroid follicles) store about a 100 day supply of the amount of hormone you need
Thyroid hormones-
TGB- large glycoprotein- made from oxidizing and adding iodine to molecules of amino acid (tyrosine) (hormones released- T4 and T3)
T4 and T3 are found in blood (most of T4 is released from thyroid then converted into T3)
Thyroid hormone accelerates growth (nervous and skeletal mostly)
TSH (thyroid stimulating hormone) - released from anterior pituitary gland
Goiter- enlargement of the thyroid gland (can be associated with hyperthyroidism and hypothyroidism)
The Parathyroid Glands-
Small round masses- attached to posterior surface of the left and right lobes of thyroid gland
Usually 2 attached to each lobe of thyroid gland
Calcitonin- secreted when blood calcium levels need to be lowered
Made by parafollicular cells of thyroid (C-cells)
Parathyroid hormone- is made from chief cells
Increases absorption of calcium (in GI tract)
Stimulation of osteoclasts so that calcium is released from bone into blood
Adrenal Glands-
There are 2 adrenal glands superior to each kidney (sometimes called suprarenal glands)
During embryonic development- the adrenal glands differentiate between 2 distinct/ functional regions
Adrenal Cortex- makes up 80-90% of the total weight of this gland
Subdivided into 3 separate zones that secrete a different group of steroid hormones
-Zona Glomerulosa secretes mineralocorticoids-mainly aldosterone
-Zona Fasciculata secretes glucocorticoids- mainly cortisol
-Zona reticularis secretes androgens- mainly masculinization hormones
Mineralocorticoids- function is to regulate concentration sodium and potassium in blood (affects blood volume and blood pressure) (aldosterone is one of the main hormones)
Glucocorticoids- function is to influence glucose metabolism (important to resist the effects of stress) (cortisol is one of the main hormones)
-Regulate metabolism by promoting breakdown of proteins and fats- when they are broken down they produce glucose (process is called glucogenesis- increase blood sugar levels and assist body with coping with stress) used in part of inflammatory response- because they inhibit white blood cells. They slow tissue repair and wound healing
-Glucocorticoids- used for chronic inflammatory disorders (can have long term side effects) Can be used for Lupus
-Addison’s Disease- autoimmune disorder (can become hypoglycemic easily/low sodium levels/low BP/dehydrated more easily/muscle weakness)
Androgens- masculinizing hormones (sex hormones) little effect on men, but important in the libido of women
RAAS: Renin-Angiotensin-Aldosterone System –important in increasing or decreasing blood pressure and blood volume as a response to stress (dehydration/hemorrhage) it is a 16 step process
Adrenal medulla- Deep to adrenal cortex (much smaller part of adrenal gland- about 20%)
Modified sympathetic ganglion- developed from same tissue as other sympathetic ganglion in other parts of nervous system
Secretes Epinephrine (80%) and Norepinephrine (20%)- help prolong the sympathetic response throughout body
There is a connective tissue capsule covering the outside of the adrenal gland
Pancreas
Endocrine gland and exocrine gland
Located posterior and inferior to stomach
Acini- clusters of exocrine cells-produce digestive enzymes and flow through ducts in GI tract
Pancreatic islets (islets of Langerhans) distribute along Acini (secrete 4 types of cells)
Alpha cells- secrete glucagon (important for increasing blood- glucose levels and converting glycogen into glucose)
Beta cells- secrete insulin
Delta Cells- secrete somatostatin
F cells- secretes pancreatic polypeptides
Insulin- decrease blood glucose levels- acts on hepatocytes (liver cells) converts glucose to glycogen- facilitates diffusion of glucose into cells
Somatostatin- act in a paracrine manner (local control of hormone) (inhibits both insulin and glucagon of Alpha and Beta cells) (inhibits secretion of HGH
Gonadal Hormones
Ovaries- produce several steroid hormones (2 types of estrogen/ progesterone)
Estrogen and LH and FSH control menstrual cycle
Estrogens- estradiol and estrone
Progesterone- relaxin and inhibin
Ovarian hormones- Female secondary sex characteristics- Progesterone
Testes- oval glands found in scrotum
Testosterone- androgen (male sex hormone) –important and needed for production of sperm/maintenance and development of secondary sex characteristics in males
Pineal Gland
Melatonin- secreted by pineal gland (important for maintaining internal biological clock- daily/seasonal cycles) more melatonin is secreted in darkness.
Thymus Gland
Thymosin- promotes proliferation and maturation of T cells (type of white blood cell-destroy microorganisms and foreign substances in body)
Lymphocyte-
General Adaptation Syndrome- (stress response)
Three stages-
Alarm reaction- short lived fight or flight response (initiated by hypothalamus- mediated by sympathetic division of ANS) (when we are in this reaction there are large amounts of oxygen and glucose in brain/lungs/skeletal muscles)
Resistance reaction- initiated by hypothalamic region- release hormones that are longer lasting- cortisol/thyroid hormones- tells our tissues to sustain metabolic)
Exhaustion- occurs when the body’s reserves become so depleted that it can no longer sustain the resistance reaction (large amounts of cortisol can cause muscles to waste) Suppression of the immune system happens as well/ ulceration in GI tract
1) What are functions of hormones (regulate chemistry composition/volume of internal environment/ regulate metabolism/ secretion of glands/ control growth and development)
2) Local hormones- paracrine/ Autocrine and circulating hormones3) Water-soluble/ lipid soluble hormones- steroids4) How to circulate hormones (signals from nervous system/ chemical changes in blood/
releasing of other hormones/ combination of above)5) The different Glands (pituitary -7 types of hormones-anterior/posterior/how
hypothalamus controls release of hormones/ Thyroid/Parathyroid gland- thyroid stimulating hormone (TSH) T3 and T4- feedback systems- how we get calcium in and out of blood and controlling high or low levels in blood/ Pancreas- islet cells (alpha and beta cells- glucagon) Feedback systems in pancreas (insulin/sugar)/ Rest of glands
6) General Adaptation System
CHAPTER 19
The Blood
Blood is important for contributing to homeostatic balance
-It transports repertory gases/ nutrients/ circulating hormones
It is body wide
Regulates body pH and temperature
Provides protection (plotting mechanisms/immune defenses)
About 5 Liters of blood in body (a little less than 1 and half gallons)
Blood is considered a connective tissue
Many different kind of cells that are suspended in salt water solution (plasma)
Little more viscous/dense than water
Blood is slightly warmer than body temperature
Blood is slightly more alkaline (more basic- 7.3-7.4 pH)
When blood sits out (it coagulates) (pinning in centrifuge separates quicker into:
Cellular portion-
Sediment-
55% blood plasma and 45% formed elements
Plasma- 92% water/ dissolved solutes other 8% (proteins/electrolytes/ gases)
Red blood cells (RBCs) - far more numerous than WBCs, interspersed together
Normal RBC mass/volume is called hematocrit (H-CT) (women-38-46/men 40-58)
The range is due to individual physiology/ physical fitness levels
They outnumber WBCs 700 to 1
Shaped- biconcave – important functionally because it increases surface area (more oxygen)
Because they don’t have mitochondria- they don’t use any of the oxygen they carry
They can form and fit into tight spaces
Mature RBC will not have a nucleus or other protein making machinery
Have a life span of about 120 days (much longer than platelets)
Since they don’t have a nucleus they are not really cells at that point (they really are the remnants of cells)
Purpose is to carry oxygen to all of body tissues
Reticulocytes- immature RBCs (low retic count (-.5%) indicates low rate of erythropoiesis)
As they begin to mature they become smaller in shape (nucleus/machinery disappears)
Allows more hemoglobin (HGB) to be present
HGB- protein molecule that is adapted to carry oxygen
Each RBC will have about 280 million HGB molecules
Each HGB molecule consists of 4 large globin proteins (each contains heme center (iron containing))
Anemia- condition where there is insufficient RBC (hemoglobin) in quantity/quality
Often results from low iron intake/ sometimes of autoimmune diseases/blood loss/ lack of production of RBC in bone marrow
Polycythemia- opposite of anemia (excess of RBCs)
Can occur in response to hypoxia/response to shots of EPO/dehydration.
Iron deficiency anemia- (most common in U.S.) low iron levels in body
Menstruating women- this happens most often with them (20%)
Only about 2% of men have this type of anemia
Hemorrhagic anemia- pretty dramatic and traumatic
Result of very fast and sudden blood loss (Decrease in hematocrit levels and HGB content and low RBC count)
Sickle-cell disease- autosomal recessive disorder (genetic)
Defect in DNA sequence which causes production of a faulty HGB chain (beta chain in particular) – RBC take on a very rigid and sickle-cell shaped
This makes it difficult for RBC to fit through tiny capillary beds/ less oxygen carried
Shortened life expectancy
RBC life cycle-
About 2 million cells a second created/destroyed
RBC life span Is about 120 days
Ruptured Red blood cell removed from circulation- death and phagocytosis Found in lymphatic tissues (spleen and liver) When it’s broken down its product is recycled. The recycled bits are used in formation of brand new blood cells
1) Red blood cell death and phagocytosis (macrophage in spleen/liver/ or red bone marrow)
2) Heme in HGB3) Globin is broken down into amino acids4) Iron is removed from Heme portion that forms Fe3 (associated with transferrin)- serves
as transporter for iron in the blood stream5) Microphages from spleen and liver detach Fe3 from transferrin that becomes ferritin
(iron storage proteins)6) Release from storage site or absorption from GI tract- more Fe3 attach to transferrin
7) The iron-transferrin complex carried to red bone marrow (where RBC precursor cells take up Fe3- transferrin complex through receptors through endocytosis)Take in complex and used in HGB synthesis (iron is needed to add to heme group in HGB- amino acids form globin in HGB) (Vitamin B12 is needed for this as well)
8) Erythropoiesis happens in red bone marrow (these RBC enter into circulation)9) Iron removed from heme group, then non-iron portion of heme converted into
billiverdin (green pigment) then converted into bilirubin (yellowish pigment) (bilirubin is put into blood and transported to liver)
10) ) (bilirubin is put into blood and transported to liver)11) Bilirubin in transported from liver into bile12) From small intestine into large intestine (bacteria converts it into urobillinogen) (some
urobillinogen is converted back into blood and converted into urobiligen that is secreted into urine)
13) Converted into stercobilin (brownish color) gives feces its brownish color
White blood cells (WBCs) - 5 different kinds (with varying functions) (leukocytes)
They have nuclei (unlike RBC) and other organelles like in most cells
Has no HGB (no oxygen carrying)
Divided into 2 different groups (whether or not they have chemical filled granules in their plasma membranes) (we can stain the cells to see if they have them)
Granulocytes- Have chemical filled granules in plasma membrane
Eosinophil- (2-4% of all leukocytes) Phagocytize antigen-antibody complexes. Also destroy some types of a parasitic worms
Basophil- (1/2-1% of all leukocytes) Release histamine and other chemical defenses. Play a role in allergic reactions. When basophils leave the bloodstream and enter the tissues, they are called mast cells.
Neutrophil- (60-70% of all leukocytes) phagocytic cells. Destroy bacteria
Agranulocytes- No chemical filled granules
Lymphocyte- (20-25% of all leukocytes) several subtypes exist. Two subtypes, B cells and T cells, make antibodies as part of the specific immune response. Other subtypes kill a wide variety of microbes. Others are helper cells, aiding in antibody production. (Lymphocytosis- increase in number of them- can be able to see if there are viral infection if cell count goes up) (Includes fluid lymph in lymphatic system and in blood)
Monocyte- (3-8% of all leukocytes) Leave the bloodstream and enter the tissues, where they are called macrophages. Primarily act as phagocytic cells. (Very numerous in peripheral tissues)
Leukocytosis- any amount of WBC more than 10,000 per ml cubed can indicate infection or cancer (elevation in WBC count)
leukopenia- WBC count of less than 5,000 per ml cubed (usually indicated some sort of severe disease, like AIDS, Bone marrow failure, Severe mal-nutrition, or as a result of Chemotherapy)
WBC Differential- a more specific diagnostic test where we break the 5 different blood cells into their specific percentages
Platelet- formed by really large cells (megakaryocytes- splinter into thousands of fragments)
Happens when there in the Red bone marrow
Each splintered fragment is called a platelet (enclosed inside plasma membrane)
-Leave red bone marrow and enter into circulation as an irregularly shaped disc
Many vesicles but no nucleus
In general platelets have a short life span (5-9 days) not much mass to them
Little specs interspersed among many RBCs
Important because they have granules on membrane that when they are released assist in blood clotting
Hematopoiesis- process of formed elements in blood forming
Cells formed in Red bone marrow by pluripotent stem cells
Mature in bone marrow/lymphoid tissues (thymus/spleen/tonsils/lymph nodes)
Pluripotent stem cells- the beginning of all other Red bone marrow cells
Erythropoiesis- specifically dealing with production of RBCs
Increase in state of hypoxia (low oxygen concentration) stimulates kidneys to release protein-Erythropoietin (EPO) - circulates in red bone marrow (helps speed up maturation and release of immature RBCs)
Thrombopoetin- hormone released that shows a lot of promise in stopping the depleting of platelets (depleting of platelets- side effect of chemotherapy)
Plasma
Makes up about 55% of blood
It is made up of formed elements
Mostly water
Has electrolytes/hormones/proteins/dissolved gases/glucose/ other nutrients
Albumin- major protein found in plasma (simple water soluble protein- synthesized in liver- contributes the viscosity of blood- helps body to maintain blood pressure)
Can be a transport molecule (transport qualities)
Globulins- act a transporters
Alpha globulins- carry steroids/ bilirubin
Beta globulins-carry copper and iron
Gama globulins- (immunoglobulins) antibodies
Hemostasis-
Three mechanisms reduce blood loss (has to be fast and localized and carefully controlled on damaged region)
1) Vascular spasm- occur when a damaged blood vessel constricts
Constriction slows blood flow
2) Formation of a platelet plug- platelets adhering to damaged epithelial tissues of blood vessel (form a plug and prevent blood from passing through that area quickly)
a. Platelet adhesion- platelet sticks to damaged vessel b. Platelet release reaction- helps activate the platelets (characteristics change-
many projects that help increase surface area- allows more arrow to have contact with other substances within blood)
c. Platelet aggregation- platelets become sticky (stick to each other) Accumulation of platelets- once they build up a large enough mass they form the plug that slows down blood flow to area)
3) Blood clotting (coagulation)- coagulation factors activated in sequence (result in a cascade of reactions)
Common pathway- clotting factors start off as soluble then become insolubleOne of the goals is to produce fibrin threads Consolidation of fibrin threads Is called a clot reactionAs the clot reacts the fibrin threads act to pull damaged vessel together
(decreases risk for more damage to occur/repairs vessel lining)Clots have a tendency to enlarge
Fibrinolitic system- dissolve small or inappropriate clots (dissolves clots where we have had damage after damaged is repaired)
a. Extrinsic pathway (shorter- very few steps- occurs rapidly- within seconds)b. Intrinsic pathway (more complex- responds a little more slower- responds to
damaged epithelial cells and there reaction with the platelets)
Thrombosis- clotting in an unbroken vessel (usually a vein)
Clot is called the thrombus (form for a lot of reasons- sometimes they can be caused by roughened endothelial cells in blood vessels atherosclerosis/trauma/infection)
Embolus- when a blood clot (air bubble/ piece of fat/ other debris) is transported by blood stream. (What happens after a thrombus is dislodged and starts to move around circulatory system)
Pulmonary embolism or stroke- emboli obstruct blood vessels
Blood transfusion- process of transferring blood from one person to another.
Fractionated- allows us to break blood up into its units (RBC/ Plasma/WBC/Platelets)
Can pull out individual proteins (Albumin/coagulation factors/antibodies)
Serum- liquid part of blood coagulated
Way we refer to plasma without clotting factors
We might need it so it won’t coagulate in machine to test blood
Antigens (surface markers) RBC have proteins that are associated with its surface
Proteins act as Antigens (ways we can identify different kinds of cells)
Antigens from one individual are not necessarily compatible with another individual
AB Antigens- we can determine if a cell has A or B antigens
ABO Blood Group System
RH Antigens- another important group because 85% of population usually has them (15% doesn’t have them)
Universal recipients- Type AB (because neither A or B antibodies in serum)
Universal donors- Type O (RBC have no antigens on surface)
Blood typing- done with a few drops of blood with different antibodies to see how it reacts
Agglutination- with anti-serum (indicates the presence of one of the antigens on the RBC)
Rh incompatibility- normally blood plasma will not contain anti Rh antigens
Individuals who have Rh antigens are Rh positive
It can cause problems in a blood transfusion if you are incompatible
Most common reason to screen for it involved crossing over of antigens during pregnancy (it can result in hemolytic disease of the newborn- Rh positive baby is developing in an Rh negative women)
Hemolysis- what happens in a blood transfusion if a recipient gets the wrong type of blood
Refers to the rapid destruction of the RBC
Would result in fever/ serious renal failure/ shock
Most common cause is clerical error
CHAPTER 20
THE HEART
The pump of the circulatory system
In an average human, it’s the size of the fist
Beat 10,000 per day (300,000 times a month)
Heart and vessels are important for transporting blood/constituents of blood
Circulatory system is useful for regulating body temperature/blood pH/facilitating functions of immune system
Mediastinum- where heart is located (extends from sternum posteriorly to vertebral column/ lies medially to 2 lungs)
Heart is located in middle mediastinum
Most of hearts mass is located just left of midline
Base of heart is tipped medially and posteriorly
Apex is project inferiorly and laterally
Pericardium- around the heart (membrane that surrounds the heart)
Holds the hearts position in the mediastinum
Allows room to move for the heart to expand and contract
Fibrous pericardium- dense and non-flexible tissue (protect and anchor the heart
Serous pericardium (inner layer of pericardium) (parietal layer and visceral layer)
Parietal layer- adhering to fibrous pericardium
Visceral layer- touching the heart muscle
Space between visceral and parietal pericardium (pericardial fluid- helps keeps heart lubricated so it can move around in the fibrous sac)
Myocardium- actual heart muscle
Epicardium- (most superficial layer) a thin and transparent outer layer of the heart wall (synonymous the visceral layer of serous pericardium)
Myocardium- (middle layer) thick layer composed of cardiac muscle
Endocardium- (deepest layer) thinner layer than myocardium, made of simple squamous epithelium (endothelium)
Endothelium- continuous with veins and arteries in circulatory system
Chambers of the heart
There are 4 chambers
Atria- upper 2 chambers (right and left)
Ventricles- lower 2 chambers (right and left)
Right heart- superior and inferior vena cava brings blood back to heart into right atria (deoxygenated blood) - goes to right ventricle through the tricuspid valve into pulmonary artery (carrying deoxygenated blood) to the lungs. This blood becomes oxygenated and comes back to heart (in pulmonary vein- newly oxygenated)
Blood leaving the heart the right ventricle- through pulmonary artery (deoxygenated)
Travels back to the heart in pulmonary vein (oxygenated blood)
Left heart- comes into the left atrium to the left ventricle through bicuspid valve to the atrium to the rest of the body.
Left ventricle has more muscle (because right ventricle only pumps blood to lungs, however blood from left ventricle goes to the rest of circulatory system)
Top part of the heart- considered a relatively weak pump (consists left and right atria)
Preloading from atria that is called atrial kick before the ventricles enter a contraction
Bottom part of the heart- left and right ventricles (main chambers that send blood to pulmonary circuit or systemic circuit)
Even without atrial function there is passive movement of blood going into ventricles (gravity)
Atrial kick- responsible for about 20% of increase of blood flow
Chronic atrial fibrillation- no atrial kick (common condition as people get older)
Blood flows from high pressure to low pressure
In our bodies is dictated by pressure differences- these operate the valves of our heart
Valves open in pairs
Atrioventricular valves (AV valves) –when they are open they allow blood to flow from atria to ventricles
Outflow (semilunar) valves- allow blood to flow from ventricles through outflow vesicles (pulmonary artery or aorta)
Right AV valve- (Tricuspid valve) - it has 3 little cusps- connects right atria to right ventricle
Left AV valve- (Mitral valve) - a.k.a bicuspid valve- connects left atria to left ventricle
Right outflow valve (pulmonary valve) - positioned at the entrance to pulmonary trunk that becomes the pulmonary artery
Left outflow valve (aortic valve) - open from left ventricle into aortic arch
To prevent damage of heart valves the AV valves are tethered to wall of ventricle by cordae tendinae (attached to papillary muscles)
Papillary muscles- pull on AV valves via cordae tendinae
Outflow valves (semilunar valves) - have firm cusps that look like half moons
Each cusp makes up about a third of a valve
Arteries- vessels that are directing blood away from heart (most often arteries contained oxygenated blood) (except pulmonary arteries)
Thick muscular walls (because they allow arteries endure high pressures and high forces that are exerted on them)
Veins- vessels that bring blood back to the heart (deoxygenated) (most veins are thins walled and exposed to low pressures and minimal forces acting on them)
Valves in veins work from pressure produced in body to return blood back to heart
Major Arteries-
Arch of Aorta- right of off heart
Pulmonary trunk- left and right pulmonary arteries come off of it (carry blood from right ventricle to lungs)
Coronary Arteries- supply heart muscle itself with oxygenated blood
Major Veins-
Inferior/superior vena cava- bring blood from body into right atrium
Pulmonary Veins- bringing blood from lungs back to heart (oxygenated blood)
Coronary sinus- found on back of the heart
Systemic Circuit- take blood from aorta into systemic arteries
Systemic circulation powered mostly by left side of heart (left ventricle)
Left ventricle is highly musclularized so it can happen
Pulmonary Circuit- powered by right side of heart
LOOK AT SCHEMATIC ABOUT BLOOD FLOW
Left and right coronary arteries-
LCA (left coronary artery)
RCA (right coronary artery)
Coronary veins- blood collects in coronary sinus- empties into right atrium (where deoxygenated blood joins in right atrium)
Gap junctions in intercalated discs- cells connecting and communicating to each other through gap junctions (found in intercalated discs)
Cardiac muscle is striated- the fibers are shorter and they branch- only one nucleus
Cardiac conduction system- during development a network or pathway developing (specialized myocytes- muscular cells- they are special because they have the ability to spontaneously depolarize)
Autorhythmicity- the rhythmical electrical activity that myocytes produce (important because it doesn’t need central nervous system to sustain action- no need to think about pumping the heart)
Once one group of myocytes reaches their threshold, an action potential is generated (then all of the cells in that region of the heart depolarize)
Forming the conduction system- myocytes form the conduction system of the heart and act as pacemakers in that system
Sinoatrial (SA) node- normal pacemaker of heart (located in right atrial wall, just below where the superior vena cava enters into right atria)
Spontaneous depolarization happens every .8 seconds
Moves from SA node to AV node
Once at AV node the signal is slowed (allows atrium to move blood into ventricles)
At AV noted, the electrical signal passes through AV bundle- heads towards apex of heart
(Divided into left and right branches) then spread to perkinje fibers
Perkinje fibers- rapidly conduct Action potential through ventricles (.2 seconds after AV contraction)
Each functional unit is called a functional syncytium
Atrial muscle syncytium contract as a single unit (forces blood into ventricle)
Syncytium of ventricles contracts- starts at apex and squeezed upward and exits through Aortic Valve
Autonomic nervous system Innervation-
Many sympathetic and parasympathetic points of innervation
Many alter heart rate and heart contraction
Role of ANS is to regulate changes in blood pressure/blood flow/blood volume
To put out enough blood to fill all the organs at one time
Medulla- cardio exceletory center- where there is sensory information going here (collected from carotid arteries- takes information about blood pressure and blood flow)
Sympathetic nerves are presented throughout the atria (especially in SA node and ventricles)
In addition to cardio exceletory center, there is a cardio inhibitor center (baroreceptor information comes from peripheral baroreceptors) When stimulated the parasympathetic fibers travel along vagus nerve (release ACh- decrease heart rate and force of contraction)
LOOK AT SCHEMATIC IN BOOK
Cardiac Action Potentials-
Action potential is initiated by SA node- travels through conduction system to excite working contractile muscles (found in atria and ventricles)
Action potential propagating throughout heart via opening of sodium and potassium channels
The refractory period in cardiac muscle is longer than contraction itself
Another contraction cannot being until relaxation is under way (so the heart can check and balance itself)
Blood flow would stop if there was a maintained contraction.
Mechanism of contraction is same as skeletal muscle (Sliding filament theory)
The electrocardiogram (ECG)
A way for us to monitor or record electrical changes on surface of body
Records depolarization and repolarization of myocardium
Can measure the presence or absence of certain waveforms (can measure side and time intervals of waves)
By taking an ECG we can quantify the electrical activity of heart (normal or abnormal ECG rating)
P wave- major wave deflection (atrial depolarization)
P-Q interval- time it takes for the atrial kick to fill ventricles
Q-R-S complex- tells information about ventricular depoliorization
Q wave-
R wave-
S wave-
T wave-