Chapter 20 - The Heart - PART 1 Flashcards
Does the heart ever rest?
no
Blood flows through a network of blood vessels that extend between the ___ and ____ ____
between the heart and peripheral tissues
What is a pulmonary circuit?
The blood vessels that carry blood to and from the gas exchange surfaces of the lungs
what is a systemic circuit?
transports blood to and from the rest of the body
Each circuit begins and ends where?
at the heart
Blood returning to the heart from the systemic circuit must complete the ——– before returning to the systemic circuit
(blood travels through circuits in ____)
must complete the pulmonary circuit
(blood travels through circuits in SEQUENCE)
Arteries could also be called….
efferent vessels
veins could also be called….
afferent vessels
efferent vessels carry blood…
away from the heart
afferent vessels carry blood….
towards the heart
(they return blood to the heart)
What are microscopic, thin-walled vessels?
capillaries
What do capillaries interconnect?
the smallest arteries and the smallest veins
capillaries could also be called…..
exchange vessels
Why could capillaries also be called exchange vessels?
because their thin walls permit the exchange of nutrients, dissolved gasses, and waste products between the blood and surrounding tissues
Each day the heart pumps about _____ liters of blood
8000
Is the heart a relatively large or small organ?
small - roughly the size of a clenched fist
Is the heart a relatively large or small organ?
small - roughly the size of a clenched fist
How many muscular chambers does the heart have?
4
List the 4 muscular chambers of the heart
right atrium
right ventricle
left atrium
left ventricle
Explain the function of the right atrium
the right atrium RECEIVES blood from the SYSTEMIC CIRCUIT and passes it to the RIGHT VENTRICLE
The right ventricle receives blood from —– and pumps blood into the—–
the right ventricle receives blood from the RIGHT ATRIUM and pumps blood into the PULMONARY CIRCUIT
The left atrium collects blood from —— and empties it into ——-
the left atrium collects blood from the PULMONARY CIRCUIT and empties it into the LEFT VENTRICLE
The left ventricle receives blood from —– and pumps it into——
the left ventricle receives blood from the LEFT ATRIUM and pumps it into the SYSTEMIC CIRCULATION
When the heart beats fast - which contracts first: the atria or the ventricles?
the atria contract first
the two ventricles contract ____(when?) and eject equal volumes of blood into—-
AT THE SAME TIME and eject equal volumes of blood into the PULMONARY AND SYSTEMIC CIRCUITS
The heart is located near the ____ chest wall
anterior chest wall
the heart is directly posterior to the ____
sternum
the great veins and arteries are connected to the _____ end of the heart at its base
superior
the inferior, pointed tip of the heart is called the….
apex
what is the medastinum?
the region between the 2 pleural cavities
The heart sits in the _____ portion of the mediastinum
anterior
what are the “great vessels”?
the largest veins and arteries
besides the heart, what else does the mediastinum contain?
the great vessels, the thymus, esophagus, and trachea
the ___ atrium and ____ ventricle dominate the picture in an anterior view of the heart
the right atrium and right ventricle
what surrounds the heart?
the pericardial sac
what is another name for the pericardial sac?
the fibrous pericardium
the pericardial sac consists of…
a dense network of collagen fibers
the pericardial sac stabilizes the positions of which 2 structures?
the heart and associated vessels within the mediastinum
the lining of the pericardial cavity is called the….
pericardium
Where on the heart are the great vessels attached?
at the base of the heart
The pericardium is lined by a….
delicate serous membrane that can be divided into 2 parts:
-visceral pericardium
-parietal pericardiu
the visceral pericardium could also be called the…
epicardium
the visceral pericardium covers and adheres closely to the ____ surface of the heart
outer
the parietal pericardium lines the ___ surface of the ______
lines the inner surface of the tough pericardial sac surrounding the heart
the small space between the parietal and visceral surfaces is called the…
pericardial cavity
the pericardial cavity normally contains….
pericardial fluid
pericardial fluid is secreted by…
the pericardial membranes
what is the purpose of the pericardial fluid?
it acts as a lubricant, reducing friction between opposing surfaces as the heart beats
what is pericarditis?
when pathogens infect the pericardium producing inflammation.
The inflamed pericardial surfaces rub against each other, making a scratching sound that can be heard with a stethoscope
pericarditis could also result in what other condition?
cardiac tamponade
what is cardiac tamponade?
pericarditis results in increased production of pericardial fluid. Fluid collects in the pericardial cavity, restricting the movement of the heart
besides pericarditis, what else could cause cardiac tamponade?
traumatic injuries that produce bleeding into the paricardial cavity
what can you say about the walls of the 2 atria of the heart?
the walls of the atria are very thin and highly expandable
when not filled with blood, what happens to the atrium?
it deflates and becomes a lumpy, wrinkled flap
the heart wall has _____ distinct layers
three
what are the 3 layers of the heart wall?
the epicardium, myocardium, and the endocardium
What does the epicardium consist of?
exposed mesothelium and an underlying layer of loose areolar connective tissue
what does the epicardium cover?
the outer surface of the heart
“the epicardium is the ___ pericardium that covers the outer surface of the heart”
visceral
what is the myocardium?
the muscular wall of the heart
what layer of the heart wall forms the atria and ventricles?
the myocardium
the myocardium is composed of….
centric layers of cardiac muscle tissue, blood vessels, and nerves
the endocardium covers….
the inner surfaces of the heart including those of the heart valves
the endocardium is composed of….
endothelium (simple squamous epithelium) and connective tissue
cardiac muscle cells are interconnected by….
intercalated discs
What is going on at an intercalated disc?
the interlocking membranes of adjacent cells are held together by desmosomes and linked by gap junctions
what is the purpose of intercalated discs?
they transfer the force of contraction from cell to cell and spread action potentials
name 4 differences between cardiac muscle cells and skeletal muscle fibers
- Small size
- A single, centrally located nucleus
- Branching interconnections between cells
- The presence of intercalated discs
The right atrium communicates with the….
right ventricle
The left atrium communicates with the….
left ventricle
The atria are separated by what structure?
the interatrial septum
what does septum mean?
wall
The ventricles are separated by what structure?
the interventricular septum
Each septum is a ____ partition
muscular
What does the “AV” stand for in AV valves?
Atrioventricular valves
The atrioventricular valves are made up of…
folds of fibrous connective tissue
Where do the AV valves extend into?
the openings between the atria and ventricles
What is the FUNCTION of the AV valves?
They permit blood flow only in one direction: from the atria to the ventricles
The right atrium receives blood from the ____ circuit through the two great ____:
the right atrium receives blood from the SYSTEMIC circuit through the two great VEINS:
-superior vena cava
-inferior vena cava
The SUPERIOR vena cava opens into the ___and ____ portion of the right atrium
posterior and superior portion of the right atrium
The superior vena cava delivers blood to the right atrium from which body parts?
the superior vena cava delivers blood TO the right atrium from the head, neck, upper limbs, and chest
The INFERIOR vena cava opens into the ____ and ____ portions of the right atrium
inferior posterior
The INFERIOR vena cava carries blood to the right atrium from which body parts?
the rest of the trunk, the viscera (internal organs in the main cavities of the body), and the lower limbs
The cardiac veins drain the ____ and return blood to the ____ ____
the cardiac veins drain the MYOCARDIUM and return blood to the CORONARY SINUS
What is the coronary sinus?
a large, thin-walled vein that opens into the right atrium inferior to the connection with the superior vena cava
What is the foramen ovale?
an oval opening that connects the 2 atria of the fetal heart. Present from the 5th week of embryonic development until birth
What is the FUNCTION of the foramen ovale?
-before birth
-at birth
before birth, the foramen ovale permits blood to flow from the right atrium to the left atrium while the lungs are developing.
at birth, the foramen ovale closes and permanently sealed off within 3 months of delivery
What happens if the foramen ovale is not closed after birth?
cardiovascular problems may result (discussed in ch 21)
When the foramen ovale is permanently closed off within 3 months after delivery, what remains in its former place in the adult heart?
the FOSSA OVALIS
(a small, shallow depression)
which is smooth:
a.) the posterior wall of the right atrium and interatrial septum
b.) The anterior atrial wall and the inner surface of the auricle
the posterior wall of the right atrium and the interatrial septum are smooth
The anterior atrial wall and the inner surface of the auricle are NOT smooth. What do they contain?
they contain prominent muscular ridges called pectinate muscles
Blood travels from the —– into the right ventricle
right atrium
Blood travels from the right atrium into the right ventricle through a broad opening bordered by 3 fibrous “flasps” called…
cusps
What prevents the backflow of blood into the right atrium from the right ventricle?
The right AV valve closes when the right ventricle contracts
What anchors the free adges of the cusps (“flaps”)? What purpose does it serve?
the chordae tendinae. This prevents the cusps from becoming like swinging doors that permit blood flow in both directions
Contractions of the papillary muscles pull on….
the chordae tendineae (which tugs on the heart valves)
Blood flowing from the right ventricle passes through the ____ valve into the ____ trunk
through the pulmonary valve and into the pulmonary trunk
What is the start of the pulmonary circuit?
the pulmonary trunk
Once in the pulmonary trunk, where does blood flow next?
into the left pulmonary arteries and the right pulmonary arteries
The left and right pulmonary arteries branch repeatedly in the______ before supplying the _____, where gas exchange occurs
branch repeatedly in the LUNGS before supplying the CAPILLARIES, where gas exchange occurs
From the respiratory capillaries, where does blood collect?
blood collects into small veins that unite to form the 4 PULMONARY VEINS
The posterior wall of the left atrium receives blood from where?
from 2 left and 2 right pulmonary veins
Like the right atrium, the left atrium has a _____
auricle
the left AV valve could also be called the ___ valve
bicuspid valve
The left AV valve guards the entrance to the ___ ___
left ventricle
the left AV valve contains how many cusps? how can you remember this?
2 cusps.
The left av valve is also called the BICUSPID valve
Besides left AV and bicuspid, what is another name for this valve?
the mitral valve
The left AV valve permits blood flow from the ___ to the _____ but prevents backflow when the ____ contracts
the left AV valve permits blood flow from the LEFT ATRIUM into the LEFT VENTRICLE but prevents backflow when the LEFT VENTRICLE contracts
Do the 2 ventricles hold and pump equal amounts of blood?
yes
which is larger and why? the left or right ventricle?
the left ventricle is much larger because it has very thick, muscular walls that enable it to push blood through the large systemic circuit
The right ventricle only needs to pump blood to and from where?
the lungs
Blood leaves the left ventricle through the….
aortic valve
Blood leaves the left ventricle through the AORTIC VALVE and goes into the __ ___
ascending aorta
What prevents backflow into the left ventricle?
the aortic valve
from the ascending aorta, blood flows through the ____ and into the ____
from the ascending aorta, blood flows through the AORTIC ARCH and into the DESCENDING AORTA
