Unit 4_Animal Body Systems Notes

Biological Levels of Organization and Homeostasis

• Hierarchy of Complexity: Living organisms are organized into levels from the smallest, most basic unit to the most complex system.

  • Cells: The most basic unit of structure and function in living things. Cells are specialized to perform specific tasks (e.g., muscle cell, skin cell, neuron, cardiac cell).

  • Tissue: A group of similar cells working together to perform a specific function (e.g., muscle tissue, epithelial tissue, connective tissue, dermis).

  • Organs: A group of different tissues working together to perform a specific task (e.g., heart, liver, stomach, lungs, brain).

  • Organ System: A group of organs that carry out a specific job in the body (e.g., Digestive System, Nervous System, Excretory System).

  • Organism: The highest level of organization, representing the complete individual living body.

• Repair and Mitosis: When an organism is injured, the repair begins at the most basic level: the cells. If cells are destroyed, it signals the process of Mitosis to begin, which repairs and replaces those cells to eventually restore tissue and organ function.

• Homeostasis: The process by which different body systems work together to maintain a constant, functional internal environment.

Microorganisms and Human Health

• Helpful Bacteria: The majority of bacteria humans encounter are helpful or neutral.

  • The human digestive system contains billions of beneficial bacteria.

  • Functions: They aid in digestion and nutrient absorption, synthesize vitamins, and limit the growth of harmful bacteria and excess yeast (fungi).

  • Homeostasis: These bacteria help maintain balance. If killed off by antibiotics, the body is thrown off balance.

  • Probiotics/Supplements: These are bacteria added to food (like yogurt) or taken as supplements to improve or restore digestive bacteria.

• Harmful Bacteria: Only a small amount of bacteria cause harm to humans (e.g., Salmonella, E. coli, Strep throat, Sepsis, Tuberculosis).

  • Symptoms: Nausea, vomiting, bloating, loss of appetite, tissue damage, and the release of toxins.

  • Body Responses to Infection:

    • Increased white blood cell count.

    • Increased body temperature (fever) intended to kill bacterial cells.

    • Swollen lymph nodes (e.g., sore throat) as pathogens are filtered from body fluids.

  • Antibiotics: Used to treat bacterial infections. They are often developed from studying organisms like fungi that produce toxins to kill bacteria.

  • Side Effects: Antibiotics kill ALL bacteria in the digestive tract (both good and bad), which can lead to stomach cramps and yeast overgrowth (such as Candida).

Integumentary System

• Primary Components:

  • Cells: Skin cells, hair cells, nail cells.

  • Tissues: Epithelial (Epidermis) and Connective (Dermis).

  • Organs: Skin, hair, and nails.

• Functions:

  • Protection: Acts as a barrier against infection and injury (working with the immune system). Protects against harmful UV radiation and water loss (critical for burn victims). Hair protects openings like the nose and eyes from dust.

  • Regulation: Sweat glands produce sweat to cool the body (working with the excretory system). Hair provides warmth in cool temperatures.

  • Vitamin Production: The skin produces Vitamin D.

• Buzz Words: Hair, Skin, or Nails.

Immune and Lymphatic Systems

• Primary Components:

  • Cells: White blood cells (leukocytes, macrophages), Lymphocytes (B and T cells).

  • Tissues: Bone marrow, lymphoid tissue.

  • Organs: Thymus, liver, spleen, appendix, lymph nodes, and skin.

• Functions:

  • Disease Protection: Works with the integumentary system (skin is the first line of defense). Produces white blood cells that enter the circulatory system to attack bacteria and viruses.

  • Filtration: Lymph nodes act as filters to trap microorganisms; swelling indicates active lymph nodes fighting infection.

  • Fluid Homeostasis: Maintains fluid levels by returning excess fluids to the bloodstream.

  • Nutrient Absorption: Absorbs fats from the digestive tract into the bloodstream.

• Buzz Words: White blood cells, lymph nodes, illness, spleen, liver, thymus, appendix.

Circulatory (Cardiovascular) System

• Primary Components:

  • Cells: Red blood cells, white blood cells, platelets (cell fragments).

  • Tissues: Muscular tissue (heart), connective tissue, epithelial tissue.

  • Organs: Heart, arteries, veins, capillaries, and lungs.

• Functions:

  • Transportation:

    • Delivers oxygen via red blood cells and removes $CO_2$ (working with the Respiratory System).

    • Delivers nutrients and removes wastes (working with Digestive and Excretory systems).

    • Transports hormones (working with the Endocrine System).

    • Transports white blood cells (working with the Immune/Lymphatic system).

  • Regulation: Controls body temperature by dilating blood vessels to release heat.

  • Protection: Platelets facilitate blood clotting to stop bleeding.

• Buzz Words: Blood, red blood cells, delivery, heart, arteries, veins, lungs.

Respiratory System

• Primary Components:

  • Cells: Lung cells.

  • Tissues: Epithelial tissue.

  • Organs: Nose, lungs, trachea, pharynx, larynx.

• Functions:

  • Gas Exchange: Provides oxygen for cellular respiration and removes excess $CO_2$. It is considered part of the excretory system because it rids the body of $CO_2$ waste. It works closely with the Circulatory System for gas transport.

  • Protection: Nose hairs (integumentary interaction) filter particles. Sneezing, coughing, and mucus production expelled foreign matter.

  • Sound Production: Exhaled air moves over vocal cords in the throat; sound depends on the tension and length of the cords.

• Buzz Words: Lungs, breathing, talking, sneezing, coughing, trachea, nose.

Nervous System

• Primary Components:

  • Cells: Nerve cells (neurons) and brain cells. Neurons transmit electrical impulses.

  • Tissues: Nervous tissue.

  • Organs: Brain, spinal cord, nerves.

• Functions:

  • Coordination: Sends electrical impulses to respond to internal and external changes.

  • Voluntary/Learned Response: Processed by the brain (e.g., walking, texting).

  • Reflex Response: Immediate reaction without conscious thought (e.g., reacting to pain, breathing, digestion).

• Buzz Words: Brain, neurons, impulses, response, spinal cord.

Skeletal and Muscular Systems

• Skeletal System:

  • Structure: Consists of $206$ individual bones. Includes osteocytes and osteoblasts (cells), and connective tissues like ligaments (bone to bone), tendons (muscle to bone), and cartilage (cushioning).

  • Functions: Supports the body, protects organs (e.g., rib cage), allows movement, stores minerals (calcium), and produces blood cells in the bone marrow.

• Muscular System:

  • Structure: Approximately $600$ muscles making up about $40\%$ of body weight.

  • Cell Types: Myocytes (skeletal, smooth, and cardiac). These contain actin and myosin filaments that slide to create contractions.

  • Functions: Produces movement (voluntary and involuntary), helps circulate blood (heart contractions), moves food through the digestive system, and controls waste release in the excretory system.

Endocrine and Reproductive Systems

• Endocrine System:

  • Hormones: Chemical messengers traveling via the bloodstream. Examples: Melatonin (sleep), Serotonin (happiness), Testosterone/Estrogen (development), Adrenaline (fear), Insulin (pancreas), Erythropoietin (kidney).

  • Organs: Hypothalamus, pituitary gland, thyroid, pancreas, kidney, adrenal gland.

  • Function: Controls growth, development, metabolism, emotions, and blood pressure.

• Reproductive System:

  • Gametes: Sperm (male) and Egg (female).

  • Organs: Female (ovaries, uterus, vagina, mammary glands); Male (testes, scrotum, prostate, penis).

  • Interactions during Birth: Stretch receptors (nervous) signal the brain; the endocrine system releases Oxytocin; muscles (muscular) contract to push the baby ($9$ month gestation) through the birth canal.

Digestive and Excretory Systems

• Digestive System:

  • Digestion Types: Chemical (utilizing enzymes) and Mechanical (chewing/muscle contractions).

  • Function: Breaks down food, absorbs nutrients, and eliminates solid waste (poop).

  • Enzymes as Catalysts: Proteins that speed up chemical reactions and reduce activation energy. They break down a substrate (food molecule) into products.

• Excretory (Urinary) System:

  • Function: Eliminates liquid (urine, sweat) and gaseous ($CO_2$) waste.

  • Organs: Kidneys (filter blood), large intestine, liver, skin (sweat glands), bladder, and lungs ($CO_2$).

Practice Scenarios and System Interactions

• Sneeze Response: Involves the Integumentary (nasal lining), Nervous (electrical signal to brain), Muscular (lung contraction/eye closure), and Respiratory (expelling air) systems.

• Waste Removal: The Nervous system sends signals to the Excretory system (kidneys/bladder) to filter blood and remove waste.

• Thermoregulation: The Nervous system controls the Circulatory system (dilating blood vessels) and the Excretory/Integumentary systems (sweat glands) to release heat.

• Injury Repair: Systems like the Circulatory (transporting platelets), Immune (white blood cells), and Integumentary (repairing epithelial tissue) work together.

• Order of Complexity Example: Lung Cell ($1$) → Lung Tissue ($2$) → Lung ($3$) → Respiratory System ($4$).

• Urination: Nerves (Nervous) signal the brain, and the individual uses muscles (Muscular) to release urine from the bladder (Excretory).