Digestive and Cardiac System Functions: Stomach, Liver, Heart

Digestive System: Definition and Function

Definition: Set of organs that are responsible for carrying out digestion; this is for transforming food into simple substances that pass into the blood and eliminate undigested remains. Function: Provide nutrients to cells by digesting food.

Stomach

Muscular organ 'J'-shaped, located in the abdominal cavity beneath the diaphragm. It dilates when filled with food. On its internal wall there are gastric glands which secrete gastric acid and mucus. The mucus stops the gastric acid from attacking the stomach's own walls.

Pancreas: Exocrine and Endocrine

Exocrine: It secretes pancreatic juice into the small intestine (duodenum) through the ampulla of Vater. It contains enzymes capable of digesting molecules present in food. Endocrine: Secretion of hormones into the blood. Example: Insulin, which regulates the transport of glucose into the cell.

Liver: Key Functions

• Produces bile (helps in the digestion of lipids).
• Glucose storage: stores glucose as glycogen.
• Reservoir of blood.
• Elimination of toxic substances from the blood (e.g., alcohol).
• Recycling of red blood cells: non-useful parts are excreted as bile pigments.

Bile and Gallbladder

The liver secretes bile. It is stored in the gallbladder (a small sac) and is poured into the duodenum through the ampulla of Vater. Bile lacks digestive enzymes. It contains bile salts that facilitate the emulsion (breakdown) of fats so digestive juices can digest them.

Heart: Structure and Layers

Pericardium: Outermost layer. A double-walled sac that encloses the heart. Myocardium: Middle layer. Thick layer of contractile muscle tissue whose contractions propel the blood. Endocardium: Innermost layer. Connective tissue that lines the inner cavities of the heart and makes up the valves.

Cardiac Parameters: Blood Pressure

Blood pressure: It is the pressure exerted by blood on the walls of the blood vessels. This pressure is stronger during systole, when it is provoked by heart contraction, and lower when it is provoked by expanded arteries during diastole. Normal adult blood pressure is less than 140 systolic and less than 80 diastolic, although these values are relative.

Blood Pressure: Systolic and Diastolic

Systolic blood pressure (top): This is the maximum blood pressure in the cardiovascular system. It is coincident with ventricular systole. Diastolic blood pressure (bottom): This is the minimum blood pressure in the artery. It is coincident with ventricular diastole.