Nervous, Circulatory, Respiratory, and Digestive Systems

STRUCTURE OF THE NERVOUS SYSTEM

• Gaps on Myelin Sheath: The gaps on the myelin sheath are called nodes.

• Action Potentials: When an action potential is triggered by a signal stronger than the threshold, the action potential retains the same strength as the threshold.

• Motor Neurons: A person lacking motor neurons would be unable to perform functions such as swinging a hammer.

• Axon Function: An axon carries nerve impulses away from the cell body to other neurons or muscles.

• Myelin Sheath Role: The myelin sheath insulates the axon, allowing for the action potential to jump from node to node, thereby increasing the speed of the impulse.

• Central vs. Peripheral Nervous System:

  • Central Nervous System (CNS): Composed of the brain (100 billion neurons) and spinal cord (extending to the lower back).

  • Peripheral Nervous System (PNS): Comprised of bundles of neurons that distribute to all body parts, transmitting information to and from the CNS.

DIGESTION

• Chemical Digestion Example: Amylase in saliva breaks down food (and not chewing or churning).

• Neurons: Specialized cells that receive and transmit impulses. Neurons are crucial for relaying sensations of pleasure and pain.

• Respiratory System Function: Its main role is to provide oxygen to the body and to remove carbon dioxide.

• Malfunctioning Neurotransmitter Effect: A malfunction could mean impulses can't cross the gap between neurons.

• Importance of Proteins: Essential because the body can only produce 12 out of 20 necessary amino acids.

SENSORY SYSTEM

• Taste Receptors: Taste buds on the human tongue are sensory receptors for taste.

• Hearing Mechanics: The middle ear, including the malleus, receives vibrations from the eardrum.

• Pain Receptors: Present in all body tissues except the brain.

• Pupil Reaction to Light: When light is introduced in a dark room, the pupil constricts to limit light entry.

CIRCULATORY SYSTEM

• Arterial Structure: Fibrin is not a part of artery structure.

• Blood Clot Formation: Platelets produce fibrin to form blood clots.

• Oxygen Diffusion: Diffuses from the lungs into the capillaries due to lower concentration in capillaries.

• Blood Flow Dynamics: Oxygenated blood returns from the lungs to the left atrium, initiating the second circulatory loop.

• Heart Pacemaker: A group of cells controlling heart contractions are known as the pacemaker.

• Blood Components:

  • Plasma: Transports nutrients and waste.

  • Red Blood Cells: Carry oxygen.

  • White Blood Cells: Fight disease.

  • Platelets: Aid in clot formation.

RESPIRATORY SYSTEM

• Inhalation Process: Caused by the contraction of rib and diaphragm muscles.

• Alveoli Function: Thin-walled air sacs crucial for gas exchange; maximize diffusion due to their large surface area and moisture lining.

• Path of Air: Air enters through the mouth/nose, travels through the pharynx to the trachea, then branches into bronchi/bronchioles before reaching alveoli for gas exchange.

• Efficient Gas Exchange:

  • Large Surface Area: About 300 million alveoli provide extensive space for gas exchange.

  • Thin Walls: Alveoli walls are one cell thick, minimizing diffusion distance.

  • Capillary Network: Dense capillaries surround each alveolus for quick gas transport.

EXCRETORY SYSTEM

• Kidney Function: Nephrons are the functional units of the kidneys that filter waste and maintain blood pH.

• Nitrogenous Waste: Urea is the primary waste product resulting from kidney filtration.

• Kidney Inflammation: Nephritis is an inflammation of the glomeruli, affecting kidney function.

• Reabsorption Process: In the kidneys, water and useful substances like glucose are reabsorbed from the renal tubules into surrounding capillaries.

INTEGRATION OF SYSTEMS

• Circulatory System Function: Transports oxygen and vital materials throughout the body.

• Normal Blood Pressure: A healthy adult's normal blood pressure averages around 113/77.

• Excretory System's Role in Homeostasis: Maintains body balance by excreting ammonia and regulating potassium levels.

• Blood Vessel Composition: Capillaries possess walls that are only one cell thick.

• Respiration Types: External respiration involves the exchange of pollutants like carbon monoxide.

DIGESTIVE SYSTEM

• Order of Digestion: The sequence of food processing in the digestive tract involves: mouth → esophagus → stomach → small intestine → large intestine → anus.

• Nutrient Absorption: The small intestine is critical for nutrient absorption, with amylase initiating digestion in the saliva.

• Mechanical vs. Chemical Digestion: Mechanical digestion breaks down food into smaller particles, increasing surface area for enzymes to act during chemical digestion.

• MyPlate Guide: Illustrates the five food groups necessary for a balanced diet and promotes healthy eating habits.