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Examen

BIOL 252 Exam 3 questions and answers 100% correct

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BIOL 252 Exam 3 questions and answers 100% correct

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BIOL 252 Exam 3 questions and answers
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3 Major parts of the cardiovascular system - blood
- heart
- blood vessels


blood carries important "stuff" through the body
• stuff = amino acids, glucose, vitamins, oxygen, CO2, etc.


Composition of the Blood - 55% plasma → fluids, proteins, nutrients
- 45% formed elements


formed elements • red blood cells (erythrocytes)
• white blood cells (leukocytes)
• platelets (thrombocytes)


Plasma - water (90% of plasma)
- proteins
- ions and nutrients

,plasma proteins • carriers (e.g., albumin) to shuttle molecules that are not
soluble because they're lipophilic (e.g., hormones)
through the circulation
• keep water in the bloodstream (contribute to
osmotic pressure)
• role in clotting (fibrinogen, clotting factors)



plasma ions and nutrients • ions involved in osmotic pressure
• hormones, amino acid, glucose, etc.


erythrocytes (RBCs) 99% of formed elements
• 45% of whole blood
• transport of gases
-- mainly transport O2 to the tissues (reversible binding to
load and unload)
-- assist in transport of CO2 to the lungs
• biconcave shape, no nucleus and lack some organelles
-- more sacs so that more oxygen can be carried



leukocytes (WBCs) • 1% of whole blood
• defense and immune systems
• use the blood for transport BUT not there to serve the
blood
-- can leave the blood and migrate through connective tissues
to serve the tissues
• much larger and far fewer than erythrocytes
• have a nucleus and organelles; can be
subdivided into different groups

platelets blood clotting


Hemoglobin major component of RBCs; pigment protein composed of four
globin polypeptides each bound to a heme group bearing an
atom of iron which can bind to one oxygen molecule
- each hemoglobin can transport four molecules of oxygen
(one per four globin polypeptide bound to a heme
group)
- oxygenated heme = red color
- reversibly binds with oxygen
- carrying 20% of the CO2 molecules back to the heart

Hematopoiesis blood cell formation


where are red and white blood cells in the red bone marrow
and platelets synthesized?


from what are red and white blood cells and stem cells
platelets synthesized?


how long do RBCs live for? 120 days


erythropoietin hormone hormone produced in the kidney's that promotes RBC
synthesis

,triggers of RBC synthesis include... • decreased oxygen levels
• increased demand for oxygen


Blood Clotting - Platelets are the first compounds to form a temporary
plug that helps seal breaks in blood vessels
- through a complex chain of activations, clotting factors
from the plasma convert the plasma protein fibrinogen
into fibrin
- a fibrin net traps blood cells, platelets, and fluid until
tissue recovery occurs

heart pumps or pushes blood through the body


3 layers in the heart wall • epicardium
• myocardium
• endocardium




epicardium (aka visceral pericardium) a serous membrane of the external
heart surface consisting mainly a simple squamous epithelium
overlying a thin layer of areolar tissue
- may also include thick layer of adipose in some places
- largest branches of the coronary blood vessels travel
through this layer


myocardium middle layer of the heart composed of cardiac muscle
- thickest layer of the heart wall
- performs the work of the heart
- muscle organized into bundles that spiral around the heart
→ myocardial vortex


what kind of motion do the muscles of a twisting or wringing motion due to the myocardial
the heart exhibit when the ventricles vortex (spiraling bundles of muscle) that enhances the
contract and why? ejection of blood


endocardium membrane lining the interior chambers of the heart made of a
simple squamous epithelium overlying a thin areolar tissue
layer
- does NOT include any adipose tissue
- covers the valve surfaces
- continuous with the endothelium of the blood vessels


fibrous skeleton of the heart a framework of collagenous and elastic fibers


especially concentrated in
• the walls between the heart chambers
• fibrous rings around the valves
• in sheets of tissue that interconnect these rings

, multiple functions of fibrous skeleton of the provide structural support for the heart especially around the
heart valves and the openings of the great vessels


anchors the cardiomyocytes and gives them something to pull
against


serves as electrical insulation between the atria and the
ventricles so the atria cannot stimulate the ventricles directly
• important in timing and coordination of
electrical/contractile activity


elastic recoil of the fibrous skeleton may aid in refilling the
heart with blood after each beat



two superior chambers of the heart receiving chambers for blood returning to the heart by way of
the great veins
- right atria
- left atria




auricle an earlike flap on each atrium that slightly increases its volume


blood vessels routes blood travels


walls of arteries and veins are composed of tunics
3 layers • tunic interna/intima
• tunica media
• tunica externa


tunic interna/intima innermost layer of the vessels made of simple
squamous epithelium called the endothelium overlying a
basement membrane and a sparse layer of loose
connective tissue; continuous with the endocardium
of the heart

tunica media usually the thickest


Arteries efferent vessels; carry blood away from the heart
- resistance vessels with relatively strong, resilient
tissue structure
- more muscular than veins, retain round shape even
when empty


3 classes of arteries by size • conducting (elastic/large) arteries
• distributing (muscular/medium) arteries
• resistance (small) arteries

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Subido en
18 de agosto de 2026
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