BIOS 255
(EDAPT WEEK 2)
Anatomy & Physiology III course with a lab
,Gross and Microscopic Anatomy of the Heart
Introduction
The heart represents the central organ that we associate with
the cardiovascular system. This organ is associated with two distinct sets
of blood vessels—pulmonary and systemic. Before delving into
these circulatory systems, you must first learn about the gross anatomical
features of this four-chambered hydraulic pump.
The Position of the Heart in the
Thoracic Cavity
In the first week of the course, we learned about the properties of blood
including its development, function, and appearances. We are going to
shift our focus this week to the mechanisms of pumping the blood
conducted by the heart.
The heart is in the mediastinum of the thoracic cavity surrounded by loose
connective tissue known as the pericardium. The majority of the heart
rests to the left side of the sternum, pointing into the left lung between
ribs 2 and 5. If you feel (palpate) the left side of the chest, you should be
able to feel rhythmic contractions.
If we were to observe the heart, we would see that it comes to a rounded
point. This structure is known as the apex and it rests just above the
diaphragm.
,Pericardium
As mentioned, the heart is surrounded by a connective tissue serous
membrane known as the pericardium. Peri refers to "around" and cardio
refers to "heart." Outside the serous pericardium a thicker connective
tissue layer can be found that is called the fibrous pericardium.
Previously you learned that serous membranes would have two sides.
The side that faces the heart is known as the visceral pericardium.
Visceral refers to organs or organ-side. The side that faces away from the
heart is known as the parietal pericardium. Parietal refers to the side of a
structure or facing away. We have seen the word parietal when referring
to the parietal bone and parietal lobe, both of which are located on the
sides of the skull and brain, respectively.
Between the parietal and visceral layers of serous membranes is typically
a volume of serous fluid. The pericardial fluid that resides within the
pericardium acts to reduce friction as the heart beats.
, Layers of the Heart Wall
Moving deeper in the heart, there are 3 distinct layers: the epicardium, the
myocardium, and finally, the innermost layer, the endocardium.
The epicardium is the outer-most layer that consists of the visceral
pericardium and is made of the mesothelium, adipose tissue, and elastic
fibers. This layer functions in the production of pericardial fluid and
reduction of friction against the surrounding tissues.
The myocardium is the thick middle layer that consists of the cardiac
muscle. This layer functions in pumping blood throughout the body to
deliver nutrients and oxygen.
The endocardium is the inner-most layer of the heart. It consists of an
epithelial layer and an underlying basement membrane and is similar to
the endothelium of blood vessels. This layer functions in providing a
smooth surface for blood movement, protection of the valves, and
regulating contractility.
(EDAPT WEEK 2)
Anatomy & Physiology III course with a lab
,Gross and Microscopic Anatomy of the Heart
Introduction
The heart represents the central organ that we associate with
the cardiovascular system. This organ is associated with two distinct sets
of blood vessels—pulmonary and systemic. Before delving into
these circulatory systems, you must first learn about the gross anatomical
features of this four-chambered hydraulic pump.
The Position of the Heart in the
Thoracic Cavity
In the first week of the course, we learned about the properties of blood
including its development, function, and appearances. We are going to
shift our focus this week to the mechanisms of pumping the blood
conducted by the heart.
The heart is in the mediastinum of the thoracic cavity surrounded by loose
connective tissue known as the pericardium. The majority of the heart
rests to the left side of the sternum, pointing into the left lung between
ribs 2 and 5. If you feel (palpate) the left side of the chest, you should be
able to feel rhythmic contractions.
If we were to observe the heart, we would see that it comes to a rounded
point. This structure is known as the apex and it rests just above the
diaphragm.
,Pericardium
As mentioned, the heart is surrounded by a connective tissue serous
membrane known as the pericardium. Peri refers to "around" and cardio
refers to "heart." Outside the serous pericardium a thicker connective
tissue layer can be found that is called the fibrous pericardium.
Previously you learned that serous membranes would have two sides.
The side that faces the heart is known as the visceral pericardium.
Visceral refers to organs or organ-side. The side that faces away from the
heart is known as the parietal pericardium. Parietal refers to the side of a
structure or facing away. We have seen the word parietal when referring
to the parietal bone and parietal lobe, both of which are located on the
sides of the skull and brain, respectively.
Between the parietal and visceral layers of serous membranes is typically
a volume of serous fluid. The pericardial fluid that resides within the
pericardium acts to reduce friction as the heart beats.
, Layers of the Heart Wall
Moving deeper in the heart, there are 3 distinct layers: the epicardium, the
myocardium, and finally, the innermost layer, the endocardium.
The epicardium is the outer-most layer that consists of the visceral
pericardium and is made of the mesothelium, adipose tissue, and elastic
fibers. This layer functions in the production of pericardial fluid and
reduction of friction against the surrounding tissues.
The myocardium is the thick middle layer that consists of the cardiac
muscle. This layer functions in pumping blood throughout the body to
deliver nutrients and oxygen.
The endocardium is the inner-most layer of the heart. It consists of an
epithelial layer and an underlying basement membrane and is similar to
the endothelium of blood vessels. This layer functions in providing a
smooth surface for blood movement, protection of the valves, and
regulating contractility.
