exam 2 : anatomy & physiology II : ott-reeves

tunics of blood vessels : tunica interna (tunica intima)

lines the inside of the vessel and is exposed to the blood.

- consists of an endothelium of simple squamous connective tissue, lined by a subendothelial layer of areolar connective tissue.

- endothelium.

- subendothelial layer of connective tissue and basal lamina.

- internal elastic lamina.

tunics of blood vessels : tunica media is the

middle layer and is usually the thickest.

- consists of smooth muscle, collagen, and elastic tissue.

- strengthens the vessels, prevents blood pressure from rupturing them, and regulates the diameter of a blood vessel.

tunics of blood vessels : tunica externa (tunica adventitia) is the

outermost layer.

- consists of loose connective tissue that often merges with that of neighboring blood vessels, nerves, or other organs.

tunics of blood vessels : tunica externa (tunica adventitia) anchors the

vessel to adjacent tissue and provides passage for small nerves, lymphatic vessels, and smaller blood vessels that supply the tissues of the larger ones.

tunics of blood vessels : arteries

tunica interna : smooth & stretchy.

- endothelium. (simple squamous epithelium)

- basement membrane.

- internal elastic lamina.

tunica media : vasomotion.

- smooth muscle.

- elastic fibers.

tunica externa : (collagen fibers for support, protection, and anchor)

- loose connective tissue.

- vasoactive chemicals.

- vasa vasorum.

tunics of blood vessels : tunica externa : vasa vasorum are a

group of small blood vessels.

- located on the outside surface of the tunica externa.

tunics of blood vessels : veins have

thinner walls, but the lumen is larger.

- tunica interna : smooth & stretchy.

- endothelium. (simple squamous epithelium)

- basement membrane.

- internal elastic lamina.

- tunica media : (vasomotion)

- fewer smooth muscles & elastic fibers.

- tunica externa : (collagen fibers for support, protection, & anchor)

- loose connective tissue.

- vasoactive chemicals. (& vasa vasorum)

tunics of blood vessels : veins often

collapse easier than arteries when not filled with blood.

arteries : conducting arteries (elastic or large) are the

biggest, thickest, near the heart, and are elastic.

- expand during systole.

- recoil during diastole.

- regulates BP.

- examples : aorta, common carotid, subclavian, pulmonary trunk, and common iliac arteries.

arteries : distributing arteries (muscular or medium) are the

medium small branches that are most abundant.

- distribute blood to specific organs.

- examples : brachial, femoral, renal, and splenic arteries.

arteries : resistance arteries are the

smallest and lead to capillary beds.

- controls amount of blood to organs.

- thick tunica media.

- examples : arterioles. (distribute blood flow into capillary beds.

arteries : arterioles are a

small artery that empties into a metarteriole or capillary.

arteries : metarterioles link

arterioles to capillaries.

veins : post capillary venules are the

smallest, thin, and even more porous than capillaries.

- exchanges fluid with surrounding tissues.

veins : muscular venules have

1-2 layers of smooth muscle.

- receive blood from the postcapillary venules.

veins : medium veins are a

one-way venous valves and internal elastic lamina.

- tunica externa is relatively thick.

- examples : radial and ulnar veins of the forearm and the small and great saphenous veins of the leg.

veins : venous sinus have

very thin walls, large lumens, and no smooth muscle.

- collect blood from the brain.

- not capable of vasoconstriction.

- examples : coronary sinus of the heart and the dural sinuses of the brain.

veins : large veins are the

largest and thickest with some smooth muscle in all three tunics.

- examples : venae cavae, pulmonary veins, internal jugular veins, and renal veins.

arteries have a

circular lumen.

- transport blood AWAY from the heart.

veins have a

folded lumen, less muscular and elastic tissue, collapse when empty, and keep a steady blood flow.

- RETURN blood back toward the heart.

capillaries have

no smooth muscle, endothelium, and basal lamina.

- surround body cells and tissues to deliver and absorb oxygen, nutrients, and other substances.

- connect branches of arteries to branches of veins.

anastomosis allows for

blood to bypass capillaries and flow directly into another vessel.

anastomosis : arteriovenous anastomosis is

between an artery and vein.

anastomosis : venous anastomosis is

between two veins.

anastomosis : arterial anastomosis is

between two arteries.

portal system is a type of

circulation pathway where two capillary networks are found.

- arrives through an arteriole & flows into the first capillary network.

- then enters a vessel that leads to the second capillary network.

- only after the blood has passed the second capillary network does it enter the venules.

the portal system circulation is found in the

liver, kidneys, and hypothalamus.

capillaries are the

smallest blood vessels.

- thin tunica intima : endothelium is one cell thick, and they have pericytes. (cells present at intervals along the walls of capillaries)

capillaries : continuous capillaries are

least leaky and most common.

- loosely connected by intercellular clefts and closely held together by tight junctions.

- narrow range of substances can cross.

- found in skin, most nervous and connective tissue, and muscle tissue.

capillaries : fenestrated capillaries are

moderately leaky.

- receive nutrients and hormones.

- allow large volumes of fluid and large molecules to cross.

- found in kidneys, endocrine glands, and small intestine.

capillaries : sinusoid capillaries are the

leakiest.

- large intercellular clefts.

- allow large molecules such as proteins, erythrocytes, and leukocytes.

- found in Liver, lymphoid organs, bone marrow, and spleen.

blood supply is expressed in terms of

flow and perfusion.

blood flow is the

amount of blood flowing through an organ, tissue, or blood vessel in a given time. (mL/min)

perfusion is the

flow per given volume or mass of tissue in a given time. (mL/min/g)

- example : femur greater flow but lower perfusion than the ovary.

relationship between flow rate and blood pressure : flow rate (between two points) is

directly proportional to the pressure difference.

relationship between flow rate and resistance : flow rate is

inversely proportional to resistance.

flow =

change in pressure / resistance.

- the greater the pressure difference between the two points, the greater the flow.

- the greater the resistance, the less flow.

blood pressure (BP) is expressed by

mL/min.

pulse pressure (PP) is the

difference between systolic and diastolic pressure.

- PP = systolic pressure - diastolic pressure.

mean arterial pressure (MAP) is the

average pressure during the cardiac cycle.

- (DP + PP / 3) = MAP

- DP : diastolic blood pressure.

resistance is the

amount of friction the blood experiences as it travels through the blood vessels.

factors that determine resistance : peripheral resistance (resistance to flow)

- blood viscosity.

- vessel length.

- vessel radius.

- cardiac output.

- blood volume : controlled by kidneys.

factors that determine resistance : blood viscosity (thickness)

- RBC count and albumin elevate viscosity.

- anemia and hypoproteinemia decrease viscosity. (faster flow)

- polycythemia dehydration increases viscosity. (slower flow)

factors that determine resistance : vessel length

the farther liquid travels through a tube, the more cumulative friction it encounters.

- pressure and flow decline with distance.

primary factor that changes resistance is the

diameter of the blood vessel because it is the most variable under normal physiological conditions.

vasomotion is a

physiological process thought to aid blood flow through tissues by reducing resistance.

purposes of vasomotion

a generalized raising or lowering of blood pressure throughout the body, and selectively modifying the perfusion of a particular organ and rerouting blood from one region of the body to another.

- this process may become more important when metabolic demand increases such as during exercise.

vasodilation is when the

muscle relaxes, increases lumen diameter.

- lowers the total peripheral resistance, increases urine production, and ultimately decreases blood pressure.

vasoconstriction is when the

muscle contracts, decreases lumen diameter.

- adjusts resistance in blood vessels, and subsequently adjusts blood pressure and blood flow.

arteries have more pulsatile nature due to

rhythmic movement of blood during each heartbeat.

veins have less

pulsatile nature and maintain blood flow through distensibility of vessels wall.

veins without the pulsatile mechanism, the blood would

stop at each pulse, the pulsatile nature is critical to make a smooth flow of blood at the capillary level.

veins without the compliance of pulsatile nature

blood flow would stop or slow during diastole and the central nervous system (CNS) wouldn't be able to tolerate that.

autoregulation is the ability of

tissues to regulate their own blood supply.

metabolic theory of autoregulation happens when

tissue is inadequately perfused, wastes accumulate, stimulating vasodilation which increases perfusion.

- bloodstream delivers oxygen and removes metabolites.

neural controls of vessel diameter :

has sympathetic control over blood vessels.

neural controls of vessel diameter : baroreceptors monitor

blood pressure, glossopharyngeal nerve, and baroreflex.

neural controls of vessel diameter : automatic, negative feedback response to

change in blood pressure.

- baroreflexes govern short-term regulation of BP.

- adjustments for rapid changes in posture.

- not helpful in correcting chronic hypertension.

- after 2 days or less they adjust their set point.

hormonal controls of vessel diameter is when

hormones influence blood pressure through vasoactive means or by regulating water balance.

hormonal controls of vessel diameter : hormones : angiotensin II

raises BP.

- vasoconstrictor.

- Na+ and water retention by the kidneys.

hormonal controls of vessel diameter : hormones : aldosterone

raises BP.

- promotes Na+ and water retention by the kidneys.

hormonal controls of vessel diameter : hormones : ADH

raises BP.

- promotes water retention.

hormonal controls of vessel diameter : hormones : atrial natriuretic peptide

lowers BP.

- increases urinary sodium excretion.

- reduces blood volume and promotes vasodilation.

hormonal controls of vessel diameter : hormones : epinephrine and norepinephrine

most blood vessels.

- bind to a-adrenergic receptors : vasoconstriction.

- in cardiac muscle blood vessels.

- bind to b-adrenergic receptors : vasodilation.

how does the body shift the flow of blood from one organ to another?

thru coordinated vasomotion.

- constriction of precapillary sphincters & capillary blood vessels in tissues where blood flow is discouraged, & dilation in tissues where blood flow is promoted.

- the parasympathetic & sympathetic nervous systems are constantly redirecting blood to different organs.

the body shifting the flow of blood from one organ to another is a

simple physical concept where fluid will travel to the area of lowest pressure.

mechanisms of capillary exchange : diffusion is the

most important mechanism of exchange.

- glucose and oxygen being more concentrated in the systemic blood than in the tissue fluid diffuses out of the blood.

- carbon dioxide and other wastes being more concentrated in the tissue fluid, diffuse into the blood.

mechanisms of capillary exchange : transcytosis is a process in which

endothelial cells pick up material on one side of the plasma membrane by pinocytosis or receptor-mediated endocytosis, which then transport the vesicles across the cell, and discharge the material on the other side by exocytosis.

mechanisms of capillary exchange : filtration and reabsorption is when

fluid filters out of the arterial end of a capillary and osmotically reenters it at the venous end.

- the fluid then delivers materials to the cells and rinses away their metabolic wastes.

mechanisms of capillary exchange : filtration and reabsorption : hydrostatic pressure is the

physical force exerted by a liquid against a surface such as a capillary wall.

- these forces are opposed by colloid osmotic pressure. (due to proteins)

capillary filtration is

favored by hydrostatic pressure.

capillary reabsorption is

favored by colloid osmotic pressure.

edema is the

accumulation of excess fluid in a tissue.

causes of edema :

- increased capillary filtration.

- reduced capillary reabsorption.

- obstructed lymphatic drainage.

edema is dangerous because : tissue necrosis

impaired O2 delivery and waste removal.

edema is dangerous because : pulmonary edema

risk of suffocation.

edema is dangerous because : cerebral edema

headaches, nausea, seizures, and coma.

edema is dangerous because : severe edema or circulatory shock

decreased blood circulation and blood pressure.

mechanisms to return blood from veins to heart : pressure gradient is the

most important.

- one-way valves in the veins make it easier for blood to return from veins to the heart.

- makes sure that the blood flows in one direction, toward the heart.

mechanisms to return blood from veins to heart : skeletal muscle pump is a

muscle contraction.

- blood is pushed back to the heart by the skeletal muscles in the limbs contracting.

- veins are compressed when the muscles contract, forcing blood toward the heart.

mechanisms to return blood from veins to heart : respiratory pump is the

breathing-related pressure changes aid in returning blood to the heart.

- when breathing, the diaphragm contracts and expands, changing the pressure inside the chest cavity.

mechanisms to return blood from veins to heart : venous tone is the

walls of the veins include smooth muscle that my contract or relax in response to nervous system impulses.

- the smooth muscle contracts, reducing the vein's width and boosting venous tone, which helps to push blood into the heart.

mechanisms to return blood from veins to heart : gravity helps

blood that is moving downward from the head and upper body return to the heart.

circulatory shock is an

inadequate blood flow throughout the body, to the extent that the body tissues are damaged.

circulatory shock : physiological perspective : syndrome in which

tissues are hypoperfused to the extent that blood flow is inadequate to maintain metabolic demands.

circulatory shock : clinical perspective

manifests when organ hypoperfusion alters mental status, cool clammy extremities, decreased blood pressure, decreased pulse rate, and oliguria. (less urine output)

stages of circulatory shock : compensated shock is the phase of

shock in which the body is still able to compensate for absolute or relative fluid loss.

- patient can maintain blood pressure and brain perfusion.

- symptoms : restlessness, agitation, thirst, delayed capillary refill, and narrowing pulse pressure.

stages of circulatory shock : decompensated shock is the phase where the

body's compensatory mechanisms are unable to maintain adequate perfusion to the brain and other organs.

- cardiac output is failing.

stages of circulatory shock : decompensated shock : symptoms are

increased vasoconstriction, confusion, disorientation, tachycardia, tachypnea, cyanosis, labored and irregular breathing, and decrease in body temperature.

stages of circulatory shock : irreversible shock is the

terminal phase of shock and once the patient progresses into this phase it is at the point of no return.

- is a rapid deterioration of the cardiovascular system and the patient's compensatory mechanisms have failed.

stages of circulatory shock : irreversible shock : symptoms are

severe decrease in cardiac output, blood pressure, and tissue perfusion.

perfusion in the brain is maintained and achieved by

supporting the mean arterial pressure (MAP) and decreasing the intracranial pressure by the mechanism of fluid resuscitation and direct acting of vasoconstrictors.

- also maintained by dilation and constriction of arteries that are controlled by CO2 levels.

how does low hydrostatic pressure in the pulmonary circuit affect the fluid dynamics of the capillaries there and prevent pulmonary edema?

failure in the left ventricle causes pressure to back up in the lungs causing pulmonary edema.

- low hydrostatic pressure meaning low fluid in tissues prevents pulmonary edema.