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What is the order an action potential travels through the heart?
- SA Node
- AV Node
- Atrioventricular bundle (bundle of hiss)
- Bundle branches (right and left)
- Purkinje Fibers
What are the characteristics of the SA Node?
- Depolorizes spontaneously
- Pacemaker of the heart
- 100% more permeable to NA ions than other cells
- Without modification runs at 100 BPM
What two systems modify pace?
- Nervious System: Sympathetic (fight or flight) speed up Parasympathetic (rest digest) slow down
- Hormones: Catecholamines like epi and nor epi
- cortisol increases sensitivity
What are the 4 properties of cardiac muscle fibers
- Contract like skeletal muscle
- short fat branches that are interconnected
- many mitochondria
- calls (branches) connect at interclated disks
What is cardiac output?
The amount of blood pumped by each ventricle in one minute
Heart rate x stroke volume = cardiac output
How much blood in the heart is pumped out?
What is stroke volume
How much blood is pumped out by the ventricle in one beat
What are the three components of stroke volume regulation
Preload, contractility, afterload
What is preload?
Stretch of fibers prior to contraction. Increase stretch = increased stroke volume
What is contractility?
Increased contractility = increased stroke volume
What is afterload?
- Presure needed to push blood past semilunar valves
- Increase afterload = decrease in stroke volume
What is a tunic
Layer in blood vessel
What is the most internal tunic
Tunica interna (endothelium)
What is the middle layer of tunic
Tunica media: Smooth muscle and elastic connective tissue
What is the most external layer of tunic?
Tunica Externa: Collegen fibers and protein
What are the three types of arteries?
Elastic, Muscular, Arterioles
What are elastic arteries?
- Have large expansion properties
- close to the heart due to pressure from the heart
- thick walled
- large lumen
- withstand and smooth out BP fluctuations
What are muscular arteries
- Deliver blood to body organs
- more smooth muscle and control over lumen size and flow
- Controlled by nervous system
What are arterioles
- Smallest of arteries
- Control flow into capillaries
- Smooth muscle
What is a cappilary
- Smallest blood vessel, 1 cell thick (squamous)
- 1 RBC pass at a time
- Many have pores or capillary exchange (gasses / nutrients / waste diffuse along concentration gradients
What is a venule?
- Drain blood from capillaries
- thin walled
- begin the return of blood to the heart (deoxygenated)
What are the properties of Veins?
- More elastic tissue
- Contain 65% of blood
- Lower BP than arteries
What 4 aspects aid in the return of blood to the heart?
- Large diameter lumens (less resistance to flow)
- Muscle contraction (milks blood toward hearts)
- Valves (once blood passes it cannot go back)
- Pressure changes in the body (breathing etc)
What is blood pressure?
Force per unit exerted on the blood vessel by blood
What is the order of the pressure gradient in the heart
- highest in aorta
- lowest in vena cava
- zero in right atrium
What 3 factors influence blood pressure
- Cardiac output
- Blood volume
- Vascular resistance
What influences vascular resistance (3 items)?
- Blood viscocity (Increase thickness=increase resistance)
- Blood vessel length (increase length = increase resistance)
- Blood vessel diameter (lower diamter = increase in resistance)
What is the function of Atrial Natiuretic Peptide hormone (ANP)?
Released by cells of atria casues vasodilation, decrease in BP, and loss of salt / H20 in urine
What are the 5 components of the lymbic system?
- bone marrow
- lymph nodes
What are the functions of the lyphatic system?
- Drain interstitial fluid
- Protect against invasion
- Transport dietary fats
What is lymph
Intersitial fluid that moves into lymphatic vessels through pressure gradient
Describe lymphatic vessels
- Have terminal ends
- Allow tissue fluid in but not out
- capillaries join to form vessels
- lymph flows through lymph nodes toward heart
What is the destination of lymph
It is dumped into subclavain veins and becomes plasma
What are lymph nodes?
- reticular connective tissue
- located along lymphatic vessels
- network of fibers
- contain WBC's
What are lymphatic nodules
Located in small intestine, appendix, tonsils: Help with filtration
What happens in the thymus gland?
WBC become specialized into T Cells
What is the function of the spleen?
- Contains RBC / WBC / Platelets.
- Filters worn out cells
What is a pathogen?
A disease producing microbe
What are the 2 broad areas of disease resistance?
specific and nonspecific
What are the 6 mechanisms of nonspecific resistance to disease?
- Physical and chemical barriers of the skin
- antimicrobe substances
- natural killer cells
What are the 2 main mechanisms in which the skin acts as a barrier of defense?
physical and chemical barriers
What are natural killer cells
Lack membrane molecules but have the ability to kill a wide variety of infected body cells
What is phagocytosis
Process by which phagocytes ingest and destroy microbes, cell debris, and other foreign matters
What are the 5 phases of mechanism of action of phagocytosis
- 1) Chemotaxis
- 2) Adherence
- 3) Ingestion
- 4) Digestion
- 5) Killing
What is inflammation?
Nonspecific defensive response to tissue damage
4 symptoms of inflammation?
Heat, Pain, Redness, Swelling
What are the 3 stages of inflammation?
- Acute: Swelling
- Subacute: Regenerative stage
- Chronic: Scar tissue rematuration and remodeling stage
Trace a drop of blood
Superior Vena Cava > Right atrium > Tricuspid Valve > right ventricle > Pulmonary Valve > Pulmonary artery > Lungs > pulmonary vein > Left atrium > mitral valve > Left ventricle > Aortic valve > aorta
What is pericardium?
Double walled sac that contains the heart and the roots of the great vessels
What is epicardium?
Outer layer of the pericardium made of connective tissue (protectve coating)
What is Myocardium:
Middle of the three layers forming the walls of the heart
What is endocardium:
Inner tissue that lines the chambers of the heart made of epithelium tissue
What is the function of the left atrium?
recieve oxygenated blood from the pulmonary veins and pump it to the left ventricle via teh artioventricular valve
What is the function of the right atria?
Receive deoxygenated blood from the superior and inferior vena cava and pump it to the right ventricle via the tricuspid valve
What is the function of the left ventricle?
Recieve oxygenated blood from the left atria (via mitral valve) and pump it to the aorta via aortic valve
What is the function of the right ventricle?
Recieves deoxygenated blood from the right atria via the tricuspid valve and pumps it to the pulmonary artyer via the pulmonary valve