Understanding Heart, Lungs, Puberty, Immunity, and Prevention
Heart Anatomy and Physiology
The heart, a muscular organ, is located below the sternum and between the lungs. Its bottom part is in contact with the diaphragm. It is composed of two atria and two ventricles. The heart also has four valves: the tricuspid valve, pulmonary valve, mitral valve, and aortic valve.
The heart’s physiology involves two circulations. The large systemic circulation is the movement of blood that leaves the heart and supplies the body. The small pulmonary circulation is the movement of blood from the heart to the lungs to be oxygenated and then back to the heart to be pumped throughout the body. The heart’s contraction is controlled by action potentials (polarization and repolarization) initiated by the sinoatrial node.
Lung Anatomy and Physiology
The right lung is divided into three lobes: top, middle, and bottom. The left lung is divided into two lobes: top and bottom. Both lungs are covered by pleural membranes. The respiratory system is divided into the upper respiratory system (mouth, nasal cavities, pharynx, and larynx) and the lower respiratory system (trachea, bronchi, and lungs). The lower respiratory system is located in the chest cavity, surrounded by the ribs, vertebral column, and diaphragm.
Lung physiology involves the flow of air during respiration, which is driven by a pressure gradient. This pressure gradient is created by the thoracic muscles (diaphragm and intercostals) that contract, moving the diaphragm and ribs, altering the pressure within the lungs, and facilitating the movement of air in and out. The lungs also contain surfactant, which prevents the alveoli from collapsing by equalizing pressure between larger and smaller alveoli.
Puberty and the Tanner Scale
Changes during puberty are primarily caused by the hypothalamic-pituitary-gonadal axis. The hypothalamus produces GnRH, which controls the secretion of LH and FSH by the pituitary gland. FSH increases the size of the testicles and seminiferous tubules in males. Hormonal changes are related to LH, FSH, and steroid sex hormone concentrations. In girls, breast development is due to estrogen, while androgen action comes from the adrenal glands.
Tanner Scale
The Tanner Scale describes the stages of pubertal development:
Females
- Stage 1: Elevation of the mammary papillae.
- Stage 2: Appearance of the breast bud and enlargement of the areola.
- Stage 3: Enlargement of the breast and areola, with no separation of their contours.
- Stage 4: Projection of the areola and papilla to form a secondary mound above the level of the breast.
- Stage 5: Adult stage, with projection of the papilla only, due to recession of the areola to the general contour of the breast.
Pubic Hair (Females)
- Stage 1: No pubic hair.
- Stage 2: Sparse, lightly pigmented, straight, mainly along the labia.
- Stage 3: Darker, coarser, curlier hair spreading sparsely over the pubic area.
- Stages 4 & 5: Adult-like in type and quantity.
Males
- Stage 1: Pre-teen.
- Stage 2: Enlargement of the testicles and scrotum; scrotum skin reddens and changes in texture.
- Stage 3: Initial growth of pubic hair.
- Stage 4: Growth and development of the glans penis.
- Stage 5: Adult stage.
Pubic Hair (Males)
- Stages 1 & 2: Hair at the base of the penis.
- Stage 3: Darker, coarser, curlier hair.
- Stages 4 & 5: Adult-like in type and quantity.
Immunity
Vaccination: The use of live, attenuated, or dead microorganisms, or microbial substances, for preventive, curative, or palliative purposes.
Humoral Immunity
Mediated by molecules in the blood and mucous secretions, primarily antibodies produced by B cells. This is the main defense mechanism against extracellular organisms.
Cell-Mediated Immunity
A T lymphocyte-mediated mechanism that defends against intracellular microorganisms such as viruses and certain bacteria. It promotes the destruction of microorganisms through phagocytes or the destruction of infected cells to eradicate the infection.
Passive Immunity
Occurs when antibodies are transferred rapidly to confer resistance without an expected immunological response. Example: maternal-fetal transfer.
Active Immunity
Induced by exposure to a natural or artificial antigen (vaccine).
Prevention and Health Promotion
Prevention: Interventions aimed at preventing the emergence of specific diseases, reducing their incidence and prevalence, controlling their transmission, and reducing specific degenerative injuries or other health issues.
Health Promotion: Strategies to improve overall health and well-being. These transformations address the underlying conditions of work and life that contribute to health problems, requiring an intersectional approach (community empowerment to improve quality of life and health).