Cell and Disease



Understanding cell components
Organelles — contained in the cytoplasm and surrounded by cell membrane
Nucleus — responsible for cellular reproduction and division and stores DNA (genetic material)

Other cell components:
– adenosine triphosphate
– ribosomes and endoplasmic reticulum
– Golgi apparatus
– lysosomes.



Stages of cell reproduction
• Stage 1 — mitosis
• Stage 2 — cytokinesis

Stages of cell division
Prophase—chromosomes coil and shorten, the nuclear membrane dissolves, and chromatids connect to a centromere.
Metaphase—centromeres divide, pulling the chromosomes apart, and align in the spindle.
Anaphase—centromeres separate and pull new replicated chromosomes to the opposite sides of the cell; 46 chromosomes on each side of the cell.
Telophase—final phase; new membrane forms around 46 chromosomes through cytokinesis producing two identical new cells.

Types of cell injury
Toxic injury—endogenous (metabolic errors, gross malformations, hypersensitivity reactions), exogenous (alcohol, lead, carbon monoxide, drugs).
Infectious injury—viruses, protozoa, bacteria.
Physical injury—thermal (electrical, radiation), mechanical (trauma, surgery).
Deficit injury—lack of basic requirement.

Maintaining homeostasis
• Medulla, pituitary gland, reticular formation are regulators.
• Two types of feedback mechanisms maintain homeostasis:
– negative mechanism senses change and returns it to normal
– positive mechanism exaggerates change.

Differentiating disease and illness

Disease
• Occurs when homeostasis isn’t maintained.
• Influenced by genetic factors, unhealthy behaviors, personality type, and perception of the disease.
• Manifests in various ways depending on patient’s environment.

Illness
• Occurs when a person is no longer in a state of “normal” health.
• Enables a person’s body to adapt to the disease.

Causes of disease
Intrinsic—hereditary traits, age, gender
Extrinsic—infectious agents or behaviors, such as:
– inactivity
– smoking
– using drugs.
Stressors, such as:
– physiologic
– psychologic.

How diseases develop

Signs and symptoms
• Increase or decrease in metabolism or cell division
• Hypofunction such as constipation
• Hyperfunction such as increased mucus production
• Increased mechanical function such as a seizure.

Stages of disease
• Exposure or injury
• Latent or incubation period
• Prodromal period
• Acute phase
• Remission
• Convalescence
• Recovery

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