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Lecture 1- levels of organizations, feedback loops, Radiology, Sonograms

Levels of Organization of the Human Body

  • Levels (as listed on the slide):

    • Chemical components – Hydrogen, oxygen atoms and water

    • A cell is the smallest independently functioning unit of a living organism. Includes cell membrane, cytoplasm and organelles

    • A tissue is a group of many similar cells (though sometimes composed of a few related types) that work together to perform a specific function.

      • Skeletal muscles are voluntary, controlled by your brain impulses.

      • Smooth muscles are involuntary, controlled automatically

    • An organ is an anatomically distinct structure of the body composed of two or more tissue types. Each organ performs one or more specific physiological functions.

    • An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body.

Organ Systems of the Human Body

  • 1. Integumentary System

    • Skin and layers of skin, includes hair, nails, and glands which protect inside layers from outside environments

  • 2. Skeletal System

  • 3. Muscular System

  • 4. Nervous System

  • 5. Endocrine System

  • 6. Cardiovascular System

  • 7. Lymphatic System

  • 8. Respiratory System

  • 9. Digestive System

  1. Urinary System

  1. Reproductive System

Metabolism

  • Basic function of metabolism: to consume energy and molecules from food, convert some into fuel for movement, sustain body functions, and build/maintain body structures.

  • Two types of reactions: anabolism and catabolism

  • Anabolic reactions: building reactions into bigger compounds, requires energy.

    • Recovery, new growth

      • Example: Tissue injury

  • Catabolic reactions: break materials down into smaller compounds, release energy.

    • Example: Digestion

  • Metabolism includes both anabolic and catabolic reactions

  • ATP (adenosine triphosphate) is the chemical compound used by every cell to store and release energy

Homeostasis

  • Homeostasis: the state of steady internal conditions maintained by living things.

  • Set point - Normal range.

    • Example: Body temperature; normal set point at 37C (which equals 98.6F).

  • Negative feedback loop: When deviation is detected form set point, the body activates mechanisms to counteract the change and restore balance

  • Negative feedback loop maintains homeostasis with three parts:

    • Sensor (receptor): monitors deviations from the set point

    • Control: compares deviations to the set point; if deviations are too high, it activates the effector

    • Effector: helps return the body system to its set point

  • Body temperature regulation

    • Body temp exceeds 37C

    • Sensor: Nerve cells in skin and brain

    • Control: temp regulatory center in brain

    • Effector: sweat glands throughout body

  • Risk of developing seizures when there’s high temperature: when the brain is unable to regulate the temperature, especially in infants, this can lead to an overload in the brain, causing a seizure.

  • Positive Feedback Loop:A positive feedback loop results in a rapid change in the body’s status.

  • No continuous stimulus

  • Example: Childbirth

  • Stimulus - first contractions of labor push the baby towards the cervix

  • Sensors - stretch-sensitive nerve cells in the cervix, that monitor the degree of stretching

  • Effectors - nerve cells send signals to the brain causing the pituitary gland to release the hormone Oxytocin into the blood

  • Right after the child is born, Oxytocin is no longer secreted, because there is no longer a stimulus, therefore a positive feedback loop.

another example: blood clotting, lactation

Medical Imaging (Non-surgical Methods to Study the Living Body)

  • X-ray

    • High energy electromagnetic radiation with a short wavelength capable of penetrating solids and ionizing gases

    • Soft tissues appear gray; bones appear white

    • Good for visualizing teeth and bones

    • Drawback/risk: Radiation damage

  • Computed Tomography (CT)

    • Uses computers to analyze several cross-sectional X-rays to reveal minute details about structures

  • Magnetic Resonance Imaging (MRI)

    • Patient is exposed to magnetic fields and radio waves; the resulting radio signals are analyzed

    • Cancer cells may have a different signal pattern than normal tissue

    • Drawbacks: High cost, noise, and discomfort to the patient during imaging

  • Positron Emission Tomography (PET)

    • Uses radiopharmaceuticals that emit short-lived radiation

    • Advantage: studies physiologic activity (e.g., blood flow)

  • Ultrasonography

    • Uses high-frequency sound waves to generate an echo signal interpreted as real-time images of anatomy and physiology

    • Drawbacks: Cannot penetrate bone or gas