Levels of Organization in Human Body

Levels of Organization in the Human Body

• Humans are complex organisms with hierarchical levels of organization.
• Atomic level: Atoms of elements make up living matter.
• Molecular level: Molecules form from bonded atoms.
• Cellular level: Cells are the basic units of life.
• Tissue level: Tissues comprise similar cells working together.

Human Cells

• Cells are the simplest living units capable of nutrition, relationship, and reproduction.
• Human cells are eukaryotic and heterotrophic.
• Eukaryotic cells have a nucleus containing genetic material.
• Heterotrophic cells obtain nutrients from outside sources.

Organelles in Human Cells

• Ribosomes: Non-membrane structures building proteins.
• Mitochondria: Oval organelles for cellular respiration (energy production).
• Endoplasmic Reticulum (ER): Membranous network (rough ER and smooth ER).
• Golgi Apparatus: Flattened sacs (cisternae) for processing and packaging.
• Vesicles: Small sacs for storage, transport, and digestion.

Cell Differentiation and Disease

• Cells are programmed for growth, division, and death.
• Cancer: Uncontrolled cell multiplication forming tumors.
• Benign tumors: Grow slowly, remain localized.
• Malignant tumors (cancer): Invade surrounding tissues, metastasize.
• Cancer causes are numerous (e.g., environment, radiation, heredity).
• Prevention and early detection are crucial.
• Common cancer risk factors include environment, radiation, obesity, infections, tobacco use, sunlight, alcohol, age, poor diet, and heredity.

Muscle Tissue Types

• Muscle tissue: Elongated cells (myocytes) with contractile proteins.
• Skeletal muscle: Striated, cylindrical cells with multiple nuclei, voluntary, attached to bones.
• Cardiac muscle: Striated, branched cells with one or two nuclei, involuntary, forms heart walls.
• Smooth muscle: Elongated cells with single nuclei, involuntary, surrounds internal organs (digestive system, blood vessels, bladder).

Epithelial Tissue

• Epithelial tissue: Cells packed tightly in layers, linings and glands.

Nervous Tissue

• Nervous tissue: Transmits nerve signals.
• Composed of neurons and glial cells.
• Microglia: Protect against infections, clear damaged cells.
• Oligodendrocyte: Forms myelin sheath around neuron extensions.
• Neuron: Specialized, non-dividing cell.
• Astrocyte: Provides nutrients to neurons.

Connective Tissue Types

• Connective tissue: Supports, connects other tissues.
• Loose connective tissue: Fills spaces between organs and structures.
• Adipose tissue: Stores fat, protects, insulates, energy reserve.
• Blood tissue: Fluid matrix (plasma), transports substances.
• Cartilaginous tissue: Supports and cushions.
• Bone tissue: Mineralized, solid matrix for support.

The Function of Nutrition

• Nutrition involves taking in substances and converting them to matter and energy.
• Systems involved in nutrition include respiratory, urinary, and digestive systems.

Health, Illness, and Determinants

• Health: State of complete physical, mental, and social well-being.
• Social health: Related to social conditions.
• Physical health: Biological functioning influenced by factors.
• Mental health: Well-being to handle daily stressors.
• Health determining factors: Biological considerations, lifestyle behaviors, environmental impacts, and health systems.

Disease

• Disease: Alteration of body structure/function causing health loss.
• Pathology: Study of disease.
• Etiology: Study of disease causes.
• Symptoms: Subjective experiences (e.g., pain, nausea).
• Signs: Objective observations (e.g., fever, rash).
• Types of diseases: Non-infectious, infectious (origin).
• Types of diseases: Acute, chronic (duration).

Non-Infectious Disease Types

• Genetic diseases: Caused by genetic mutations.
• Tumor/Neoplastic diseases: Abnormal cell growth, cancer.
• Immune diseases: Impaired immune response (allergies, celiac).
• Mental disorders: Alterations in thoughts/emotions.
• Degenerative diseases: Progressive tissue/organ damage (Alzheimer's).
• Nutritional/behavioral diseases: Malnutrition, anorexia, bulimia.
• Other non-infectious disease types: Accidents, environmental exposures.

Pathogenic Agents

• Prions: Abnormal proteins causing neurological damage.
• Viruses: Non-living entities requiring host cells to reproduce.
• Bacteria: Unicellular, prokaryotic organisms.
• Fungi: Eukaryotic organisms, some causing skin infections.
• Parasites: Protozoa and worms causing parasitic diseases.

Reservoir and Source of Infection

• Reservoir: Natural habitat of the pathogen.
• Source of Infection: Place/organism from which pathogen moves to host.

Host

• Host: Organism that harbors another organism (e.g., parasite/virus/bacteria).

Endemic, Epidemic, Pandemic

• Endemic: Regularly present disease in a specific area.
• Epidemic: Spread of disease affecting many people.
• Pandemic: Epidemic that spreads internationally.

Immunity

• Immunity: Body's defense system against pathogens.
• Innate immunity: Primary and secondary barriers.
• Acquired immunity: Learned and improves over time, has memory.