2Q_Sabrina_Science

Muscle Function

• Muscles play a crucial role in posture and stability by providing support and allowing for controlled movement.
• Muscles involved in respiration include the diaphragm, intercostal muscles, and abdominal muscles.
• Muscle contractions generate heat as a byproduct of metabolic processes, contributing to the body's overall temperature regulation.
• Muscle contraction is triggered by a signal from the brain conveyed through nerves. This signal stimulates the release of calcium ions, which initiate a chain reaction leading to the sliding of muscle fibers and contraction.
• The heart, a specialized muscle, propels blood throughout the body through rhythmic contractions.
• Voluntary muscles, also known as skeletal muscles, are under conscious control, allowing for deliberate movements.
• Cardiac muscle, found only in the heart, is responsible for pumping blood throughout the body. It's involuntary, meaning it contracts without conscious effort.
• Involuntary muscles, such as smooth muscle, are responsible for functions like digestion, blood vessel constriction, and eye pupil dilation. These muscles operate without conscious control.
• Isometric contraction occurs when a muscle generates tension without changing its length, often seen in activities like holding a heavy object.
• Antagonistic pairs of muscles work together to produce movement. When one muscle contracts, the other relaxes, allowing for smooth and coordinated motion. For instance, the biceps and triceps muscles in the arm work antagonistically to flex and extend the elbow.

Skeletal System

• Long bones, characterized by a length greater than their width, serve as levers for movement, allowing for efficient force generation.
• The primary function of the skull is to protect the brain, a vital organ, from injury.
• The shoulder girdle, connecting the upper limbs to the axial skeleton, is composed of the clavicle (collarbone) and scapula (shoulder blade). The clavicle provides stability and acts as a strut, while the scapula provides a point of attachment for muscles that rotate and move the arm.
• The ribcage serves multiple functions, including protecting vital organs like the heart and lungs, facilitating breathing, and supporting the skeletal structure of the chest.
• The arm consists of three bones: the humerus (upper arm), radius (thumb side), and ulna (pinky finger side). These bones work together to allow for a wide range of arm movements.
• The human hand consists of several types of bones crucial for dexterity and grasping: carpals (wrist), metacarpals (palm), and phalanges (fingers).
• Ribs play a vital role in protecting the heart and lungs. They also contribute to breathing by expanding and contracting the chest cavity.
• The upper limb's support structure is composed of the humerus (upper arm bone), radius and ulna (forearm bones), carpals (wrist bones), metacarpals (hand bones), and phalanges (finger bones). Each bone plays a unique role in providing strength, stability, and flexibility to the upper limb.
• The spine serves multiple functions, including providing structural support for the body, protecting the spinal cord, allowing for flexibility and movement, and providing a point of attachment for muscles and ligaments.
• The pelvis, located at the base of the spine, serves as the foundation for the lower limbs, supporting the weight of the upper body and providing a point of attachment for muscles involved in walking, running, and other movements.

Digestive System

• The mouth is the first part of the digestive system where food enters.
• The stomach is responsible for mixing food with enzymes and acids, breaking it down into a liquid form called chyme.
• The esophagus, a muscular tube, carries food from the mouth to the stomach via peristaltic contractions.
• The small intestine plays a crucial role in absorbing nutrients from digested food. It contains villi, tiny finger-like projections that increase its surface area for efficient absorption.
• The digestive process involves breaking down food into smaller components, such as carbohydrates, proteins, and fats, to allow for easier absorption and usage by the body.
• The primary function of the small intestine is to absorb nutrients from digested food and transfer them into the bloodstream.
• The large intestine does not absorb nutrients. Its primary functions include absorbing water from undigested food, forming stool, and absorbing electrolytes.
• The rectum is the final segment of the large intestine where stool is stored before elimination.
• The anus is the opening at the end of the digestive tract through which waste is eliminated from the body.
• The digestive system interacts with other body systems, such as the circulatory system for the transport of nutrients and the nervous system for controlling digestion.

Circulatory System

• The circulatory system is composed of the heart, blood vessels (arteries, veins, and capillaries), and blood itself.
• To calculate your pulse rate, count the number of heartbeats in a minute.
• The heart's primary function in the circulatory system is to pump blood throughout the body, delivering oxygen and nutrients to tissues and removing waste products.
• During exercise, your heartbeat increases to deliver more oxygen and nutrients to working muscles.
• The right atrium of the heart receives deoxygenated blood from the body.
• Red blood cells, a critical component of blood, carry oxygen from the lungs to the tissues.
• White blood cells, also known as leukocytes, play a crucial role in fighting diseases by engulfing and destroying pathogens.
• Arteries are characterized by thick elastic walls capable of carrying oxygenated blood under high pressure away from the heart. Veins, on the other hand, have thinner walls and carry deoxygenated blood back to the heart.
• Blood components are separated for testing through a process called centrifugation, where blood is spun at high speeds, causing its components to separate based on density.
• Capillaries, the thinnest blood vessels, allow for the exchange of substances between blood and tissues due to their thin walls.

Respiratory System

• The trachea, or windpipe, is a long tube that carries air from the larynx to the bronchi.
• The epiglottis, a flap of cartilage, prevents food from entering the trachea during swallowing.
• Gas exchange, the transfer of oxygen from the lungs to the blood and carbon dioxide from the blood to the lungs, primarily occurs in the alveoli, tiny air sacs in the lungs.
• The oral cavity, or mouth, plays a role in respiration by providing an alternative pathway for airflow, especially during strenuous activities.
• The pharynx, commonly called the throat, connects the nasal cavity and mouth to the trachea. It's essential for breathing and swallowing.
• The diaphragm, a dome-shaped muscle below the lungs, is responsible for controlling breathing by contracting and relaxing. When the diaphragm contracts, it flattens, increasing chest cavity volume and allowing air to enter the lungs.
• Inspiration, the phase of breathing where air is drawn into the lungs, is triggered by contraction of the diaphragm and intercostal muscles, which expand the chest cavity.
• The nasal cavity, lined with hairs and mucus, warms, filters, and moistens incoming air, protecting the lungs from harmful substances.
• The trachea, through its branching structure, carries air down into the bronchi, leading to the lungs for gas exchange.
• The alveoli, tiny air sacs within the lungs, are the primary sites of gas exchange in the respiratory system. Oxygen passes from the alveoli into the bloodstream, while carbon dioxide moves from the blood into the alveoli to be exhaled.

Digestive System

• The esophagus is a long tube that carries food from the mouth to the stomach.
• The mouth is where the digestive process begins, with chewing and saliva breaking down food.
• The stomach is where food is mixed with enzymes and acids to break it down into smaller pieces.
• The small intestine produces juices that aid in transforming food into nutrients.
• The small intestine separates nutrients from waste.

Circulatory System

• The circulatory system's main function is to transport blood throughout the body.
• Veins carry deoxygenated blood to the heart.
• The heart pumps blood to the organs and tissues of the body.
• Arteries carry oxygenated blood away from the heart to the tissues.