Organs

• Human blood is red and always red, but the shade of red can vary based on how much oxygen is in the blood.
• Veins and arteries are often drawn in diagrams as blue or red to show whether they have lower or higher concentrations of oxygen, but that’s just how they are used in most diagrams.
• Human blood maintains a certain pH, temperature, and osmotic pressure for homeostasis.
• Human blood transports things like hormones, nutrients, and gases.
• Human blood is made up of different components including plasma, the liquid portion, and cellular components which include red blood cells, white blood cells, and platelets.
• Red blood cells have an iron-containing protein called hemoglobin, which is where the red coloring of blood comes from.
• Human heart anatomy observes the heart divided into two distinct and separated partitions: a deoxygenated, or low-oxygen partition, and an oxygenated partition.
• Arteries generally carry blood “away” from the heart.
• Veins generally carry blood “to” the heart.
• Capillaries are small blood vessels and it is at the capillary level where oxygen is delivered to organs and tissues and where carbon dioxide will also be picked up to travel back to the lungs.
• The right side of the heart pumps deoxygenated blood and the left side pumps oxygenated blood.
• The heart contains 4 chambers: the right atrium and right ventricle and the left atrium and left ventricle.
• Atria have thinner walls than the thicker walled ventricles.
• The heart also contains valves which we’ll see when we get to tracing the pathway of blood.
• The valves are one-way structures that help separate the chambers and prevent backflow of blood.
• Blood travels through the heart pathway from a human toe, entering the right atrium, then through the tricuspid valve into the right ventricle, then through the pulmonary valve to the pulmonary artery, and finally to the lungs where red blood cells take on oxygen and release carbon dioxide, becoming oxygenated blood.
• The oxygenated blood returns to the heart through a pulmonary vein to the left atrium, then through the mitral valve (bicuspid valve) into the left ventricle, then through the aortic valve and out a major artery known as the aorta.
• The heart needs its own blood supply to deliver oxygen and glucose, which it can receive through coronary arteries that branch off the aorta and deliver blood into capillaries.
• Capillaries deliver oxygen and glucose to the heart.
• Coronary veins take the deoxygenated blood to the right atrium where the blood will eventually travel the pathway to become oxygenated.
• The heart beats over 100,000 times per day, with every beat coordinated and blood directed where it should go.
• The complexity of the cardiac cycle, which is the coordinated sequence of the heart’s contractions and relaxations, isn’t something this short video can go into; hopefully a separate video on that soon.
• There are many conditions in which the heart doesn’t function correctly, and some heart conditions change the pathway flow of blood.
• An atrial septal defect is an example of a heart condition that changes the pathway flow of blood, as it is an opening in the muscular wall that separates the right and left side of the heart, allowing oxygen-rich blood to mix with oxygen-poor blood.
• Depending on the size of an atrial septal defect, it can cause future problems such as an abnormal heartbeat, stroke, or potentially heart failure in severe cases.
• Some medications may help the symptoms of an atrial septal defect or surgery can be an option.
• There continues to be more advancements for treating cardiovascular conditions.
• If you have interest in the field of cardiology, take a look at the suggested further reading links in the video details.
• The muscular system consists of muscles, which can be identified under the skin like biceps or triceps, but muscles are so much more than that.
• Muscle tissue is made up of muscle fibers, which are muscle cells with a structure that aids in their function.
• Cardiac Muscle tissue is found in the heart, has branched and striated fibers, one nucleus, and intercalated discs involved in helping the tissue contract in an organized, wave-like pattern.
• Smooth Muscle tissue is smooth, has one nucleus, is spindle-shaped, and can be found in the digestive system, arteries and veins, the bladder, and the eyes changing the iris size.
• Skeletal muscle tissue attaches to bone or skin and is involved with voluntary control, meaning it can be consciously controlled.
• Skeletal muscle fibers are striped, or striated, long cylinders that are multinucleated.
• Muscle tissue can stretch or extend, has elasticity, and can retract back to its starting length.
• Muscle tissue has the ability to be stimulated and their membranes can have electrical changes and send action potentials.
• Muscle tissue has the ability to contract, or contractility.
• Many skeletal muscles are named by their location or their shape, and some have Latin or Greek root words in them.
• The part of a skeletal muscle that attaches to the bone that will be moved is called the insertion, and the part that attaches to a fixed part of the bone is called the origin.
• The main muscle doing the work in a single action is called the agonist, and antagonists are muscles that can do the opposite action which is helpful for keeping position.