Visceral system Flashcards
Cardiovascular System
Major structural components of the CVD system:
- Blood vessels
Arteries: carry blood away from the heart (mostly oxygenated blood)
Capillaries: Supply blood cells with nutrients and oxygen and take waste products away
Veins: Return blood to the heart (most deoxygenated blood)
- Heart: a muscular organ that pumps blood through blood vessels
- Blood: Is a fluid connective tissue that is transported in the CV system
The heart
The heart functions as a dual pump system: A muscular wall called the septum separates the left and the right sides of the heart
- The right heart deals with oxygen: poor blood and is low-pressure system (pulmonary circuit)
- The left heart deals with oxygen-rich blood and is high-pressure system (systemic circuit)
Location and orientation within the thorax
- First sized, cone-shaped organ
- Located left of the body midline; posterior to the sternum in the mediastinum
- Obliquely oriented, apex is inferior
- The right side is located more posteriorly
- The heart is located within the mediastinum
Mediastinum: is a space between the sternum, the vertebral column, the lungs and the diaphragm
Structure of the heart
Pericardium: Triple-layered sac that encloses the heart
- Fibrous pericardium: Outer, strong layer of dense connective tissue. Attached to the diaphragm inferiorly and vessels of the heart superiorly
Serous pericardium: 2 layers
- parietal layer= outer
- Visceral layer (epicardium)- directly covers the heart
- Pericardial cavity: between the 2 layers and contain fluid film to reduce friction
Layers of the heart wall: 3 layers
- Epicardium: Consists of visceral serous pericardium
- Myocardium: Cardiac muscle tissue, contractile layer
- Endocardium: Deep to myocardium, sheet of simple squamous epithelium on a thin layer connective tissue (lines chambers and valves)
Myocardium
- Small branched cells: 25 cm wide: 120 cm long
- contains myofibrils and sarcomeres (striated)
- Cardiac cells are interconnected at junctions called intercalated discs
- Spontaneously contracts- without neural input
- Innervated by autonomic nervous system
Internal heart anatomy
Atria are separated from each other by interatrial septa: and ventricles by interventricular septa.
Within the septa is the fibrous skeleton of the heart which has these functions:
- Anchors heart valves by forming supportive rings
- Provides a rigid framework for the attachment of cardiac muscle tissue in atria and ventricles
- Electrical insulation between atria and ventricles: ensures that muscle impulses are timed properly
Papillary muscles
Papillary muscles and chordae tendineae present the values from being pushed to the atria
- Papillary muscles are relaxed and chordae tendineae slack when bicuspid and tricuspid valve are open
- Papillary muscles are contracted and chordae tendineae taut when bicuspid and tricuspid valves are open
Right atrium
- Receives deoxygenated blood from systemic circulation via 3 blood vessels
- Conveys blood into the right ventricle through the tricuspid valve
- Contains the SA and AV nodes
- Important internal feature: fossa ovalis
- Receives deoxygenated blood from systemic circulation via 3 blood vessels
- Conveys blood into the right ventricle through the tricuspid valve
- Contains the SA and AV nodes
- Important internal feature: fossa ovalis
- Receives deoxygenated blood from the right atrium and pumps it into the pulmonary circuit through the pulmonary
- Trunk via the pulmonary semilunar valve
- Important internal features: trabecular carneae line the walls of both ventricles
Left atrium and ventricle
- Receives oxygenated blood from pulmonary circulation via 4 pulmonary veins (2 left and 2 right)
- Separated from the left ventricle by bicuspid (mitral valve)
- Important internal features: auricle contains pectinate muscles
V - Forms the apex of the heart
- Pumps blood into the systemic circuit through the aortic semilunar valve into the aorta
Flow is uni-directional
Pulmonary circuit
- Pumps blood from the right side of the heart through pulmonary vessels, to the lungs and back to the left side of the heart
Systemic circuit
- Pumps blood from the left side of the heart through systemic vessels in peripheral tissues and back to the right side of the heart
Heart blood supply
- The heart has 3 major sulci (grooves) that separate the 4 chambers and major coronary blood vessels occupy these sulci
- Atrioventricular and interventricular grooves contain adipose tissue and coronary blood vessels
- Fat depot in epicardium surrounds and cushions coronary blood vessels
- Increased epicardial adipose tissue is, however, viewed as a cardiac risk marker
Coronary arteries of the heart
- Coronary arteries originate from the base of the aorta
- Coronary arteries supply oxygen and nutrients to the heart muscles and coronary veins drain the blood
Coronary veins
- The coronary sinus is the biggest cardiac vein which ultimately collects the blood from all cardiac veins and drains the blood into the right atrium
- Coronary sinus, great and small cardiac veins are located in the coronary groove
- Middle cardiac vein is located in posterior interventricular groove
- Great cardiac vein primarily drains the left heart, the small cardiac vein drains the right heart and the middle cardiac vein drains the interventricular septum
Atrial Fibrillation
- Irregular and rapid heart beat caused by extra electrical impulses disrupting SA node activity
- Result in chaotic atrial contractions at faster rate than ventricles
- Diagnosis: ECG
- Treatments: ECG, catheter ablation, pacemaker
Hepatic portal system
The hepatic portal system is a network of veins that carries venous blood from the gastrointestinal tract and spleen to the liver before it returns to the inferior vena cava and the heart.
The liver receives 2 blood supplies:
-The hepatic portal veins contain oxygen-poor but nutrient-rich blood, drains only unpaired organs
- The hepatic artery proper contains oxygen rich blood
Veins of the lower limb
Deep veins
- Medial plantar veins drain into posterior tibial veins
- Fibula veins drain into the posterior tibial veins
- Tibial veins merge to form the popliteal veins which becomes the femoral vein and then the external iliac vein
- External and internal iliac veins unite into the common iliac vein
- The common iliac veins merge to form the inferior vena cava
Superficial veins
- Dorsal venous arch drains into and great saphenous veins and small saphenous vein
- Great saphenous drains into femoral vein
- Small saphenous drains into popliteal
Boyle’s law
The pressure of a gas decrease if the volume of the container increase and vice versa.
Inhalation: increasing volume of the thoracic cavity decreases intrapulmonary pressure relative to the atmospheric pressure and air flows into the lungs
During inhalation,
- The lungs expand
- The pressure in the lung’s decreases
- Air flows towards the lower pressure in the lungs
Exhalation= Volume of the thoracic cavity decreases, pressure rises relative to outside atmospheric pressure air is forced out of the lungs
During an exhalation
- Lung volume decreases
- Pressures within the lungs increases
- Air flows from the higher pressure in the lungs to the outside
Disorders of the Respiratory system
Bronchial asthma= allergic inflammatory response causes bronchoconstriction
Cystic fibrosis: Accumulation of mucous, clogs the respiratory system and causes bacterial infection
Chronic bronchitis: Inhaled irritants lead to excess mucous, inflammation and fibrosis- impairing ventilation and gas exchange
Emphysema Permanent enlargement of alveoli due to inc. lysosomes destroying alveolar walls; lungs become less elastic
