Anatomy and Physiology of Key Human Body Systems

Biology19 Nov 20255.29 KB

The Digestive System: Anatomy and Function

The digestive tract processes food through several key structures:

Mouth: Contains the teeth and tongue.
Salivary Glands: Parotid, Sublingual, and Submaxillary glands.
Pharynx: Connects the nasal and oral cavities to the larynx and esophagus.
Esophagus: Muscular tube leading to the stomach.
Stomach: Features the cardiac valve and the pyloric valve. It contains gastric glands that produce gastric juice and hydrochloric acid.
Small Intestine: Composed of the duodenum, jejunum, and ileum. It contains intestinal glands that produce intestinal juice.
Large Intestine: Includes the cecum, colon, and rectum, ending at the anus.

Digestion is the transformation process food undergoes in the digestive tube. It consists of two main processes:

Mechanical Digestion: Physical processes like grinding (chewing) and motion (peristalsis).
Chemical Digestion: Digestive enzymes found in digestive juices chemically break down macromolecules, transforming them into smaller molecules that can be absorbed in the intestine into the blood as nutrients.

Location of Mechanical Digestion:

The respiratory system facilitates gas exchange and is divided into upper and lower tracts.

Nostrils (Nasal Cavity): Lined with red and yellow pituitary mucosa.
- The red mucosa warms the inhaled air using blood vessels (maintaining temperature near 36°C).
- The yellow mucosa is responsible for the sense of smell.
Larynx: Contains the vocal cords.
Epiglottis: A protective valve.
Trachea: Windpipe.
Lungs: Supported by the diaphragm.
Bronchi and Bronchioles: Passageways leading to the alveoli.
Pulmonary Alveoli: Tiny sacs where gas exchange (oxygen and carbon dioxide) occurs.

The excretory system is responsible for the elimination of waste substances resulting from cellular metabolism.

Lungs: Excrete carbon dioxide (CO₂) through the airways.
Liver: Excretes remnants of carbohydrate metabolism, lipids, blood cell debris, and hemoglobin, including substances from medications. Bile aids in the digestion of fats and is excreted through the digestive tract, along with the feces.
Skin (Sweat Glands): Excretes sweat, maintaining the body's thermal balance. Sweat is primarily water and urea, which comes from broken-down proteins.

The urinary system includes the kidneys, ureters, bladder, and urethra.

Kidneys: Two bean-shaped organs located on both sides of the spine. They form urine.
- Interior Structure: The outermost part is the Cortex, which has a granular appearance. Below this is the Medulla, divided into pyramidal areas and calyces (cup-shaped structures).
- Blood enters and leaves the kidney through its concave part via the renal artery and vein.
Ureters: Two fine tubes that collect urine produced in each kidney.
Bladder: Collects urine continuously delivered by the ureters. It is extensible and can contain a variable amount of urine. When full, it contracts, creating the need to urinate.
Urethra: The canal that carries urine from the bladder to the outside.

Transport of Substances: Transports nutrients and dissolved solids in the plasma.
Transport of Respiratory Gases: Oxygen (O₂) is transported by hemoglobin. If the amount of O₂ in the plasma is high, hemoglobin combines with it to form bright red oxyhemoglobin.
Distribution of Body Heat: Helps regulate temperature.
Defense: White blood cells (leukocytes) defend the body against infections.
Hemorrhage Control: Platelets assist in blood clotting.