7. Cardiovascular system Flashcards
What does the cardiovascular system consist of?
4-chambered heart, blood and blood vessels
What does the vasculature consist of? (aka what are the 3 types of blood vessels?)
Thick walled arteries, one-way valve thin veins, capillaries w/ greatest surface area and cross sect area –> slow vel
Pulmonary circulation vs systemic circulation
The first pump: when right side of heart takes deoxygenated blood to lungs via pulmonary arteries vs The second pump: when left side of heart takes oxygenated blood from lungs via pulmonary veins
Why do arterioles have greatest amount of resistance?
They’re highly muscular and can contract/dilate to regulate bp
What are venae cavae?
Large veins carrying deoxygenated blood to heart. There are 2: inferior for blood from lower body, superior for blood from head, arms and upper body
Describe the blood flow between heart and body
right atrium –> right ventricle via triscuspid valve –> pulmonary artery via pulmonary trunk/valve –> lungs –> pulmonary veins –> left atrium –> left ventricle via bicuspid/mitral valve –> aorta via aortic valve –> arteries –> arterioles –> capillaries –> venules –> veins –> venae cavae –> right atrium
Describe pathway of electrical conduction in heart
Electrical signal starts in SA node = small collection of cells in wall of right atrium –> depolarization from SA node causes 2 atria to contract simultaneously –> signal reaches AV node = in junction b/w atria and ventricles –> signal travels to bundles of His = located in interventricular septum –> signal moves to Purkinje fibers to be distributed thru ventricular muscle
What causes atrial systole (contraction)?
inc in atrial pressure that forces a little more blood in ventricles; this additional volume of blood => atrial kick
Why is signal delayed at AV node? Action potentials w/ slower depolarization are found in which nodes?
To wait for ventricles to be filled with blood completely before they can contract. AV node and SA node
What are ventricular muscles cells connected by?
Intercalated discs which contain many gap junctions that directly connect cytoplasm of adjacent cells for cell to cell communication
Systole vs diastole
Ventricular contraction and AV valves close –> blood = pumped out of ventricles vs ventricles relax and semilunar valves close –> blood moves from atria to ventricles
What is cardiac output?
Total blood vol pumped out in a minute; product of HR (beats per min) and stroke vol (SV, vol of blood pumped per beat)
What is the hepatic portal system?
When blood leaves capillary beds of gut thru hepatic portal vein before reaching capillary beds in liver
What is hypophyseal portal system?
When blood leaves capillary beds of hypothalamus thru capillary beds in anterior pituitary to allow for paracrine secretion of releasing hormones
What is renal portal system?
When blood leaves glomerulus thru efferent arteriole before surrounding the nephron in a capillary network called vasa recta
How is blood pressure measured mathematically in circulation?
deltaP = CO x TPR (CO = cardiac output, TPR = total peripheral (vascular) resistance)
Longer blood vessel —> more resistance, larger cross sectional area of blood vessel —> less resistance; Capillaries have greatest total cross sectional area —> lowest blood vel (to allow time for gas and nutrient exchange)
Continuous vs fenestrated vs sinusoidal capillaries
No pores vs small pores vs big leaky pores
Which blood vessel has highest and lowest bp?
Highest in aorta, lowest in venae cavae. Generally, arteries have high bp and low vol (that’s why blood spurts out when you cut an artery) and veins have low bp and high vol (Sometimes venous system has more blood than arterial system b/c Veins lack smooth muscle wall —> thin wall —> easily stretches)
Hydrostatic vs oncotic pressure
Pressure of fluid within blood vessel, pushes fluid out of arteriole end of capillary; low hydrostatic pressure means blood is moving thru capillary vs “sucking” pressure that draws water towards solutes, draws fluid out back to venule end of capillary
Vagus nerve is impt for which nervous system?
Parasympathetic nervous system. It slows down HR
Quick summary functions of SA node, AV node, bundles of His and Purkinje fibers
SA node - responsible for autoregulation of heart contractions (so w/o SA node, heart can still contract but irregularly) and for atrial contractions; AV node initiates ventricular contraction, bundles of His carries signal, and Purkinje fibers allow synchronized contraction of diff regions of ventricular wall (so basically, AV node + bundle of His + Purkinje fibers = responsible for ventricular contractions)
Alpha vs beta 1 vs beta 2 adrenergic receptors
all stimulated by nor/epi => agonists, all part of SNS, all beta receptors responsible for smooth muscle relaxation; located in arteries, cause vasoconstriction –> inc bp and blood flow to heart vs located in heart, cause inc HR & inc strength of contractions vs located in bronchioles and arteries of skel muscle; cause vasodilation in skel muscle to receive inc blood flow started from alpha and beta 1 receptor, dilate bronchioles –> let more air in
Slowest blood vel vs fastest blood vel occur in which blood vessels?
Capillaries b/c they have higher cross sect area than arteries (they also have greatest surface area) –> allow time for gas and nutrient exchange vs aorta
If there is dec blood flow, what will heart do?
dec blood flow –> low O2 –> heart will contract harder to compensate
