Human Body Cavities & Regions Exam Review PDF

Final Exam Overview Organization of the Human Body Describe the major body cavities and explain what organ(s) fit within each cavity Two Main Types of Body Cavities 1. Ventral Cavity: Located on the front (anterior) side of the body Thoracic Cavity: Above the diaphragm. Contains: The heart, lu...

Final Exam Overview Organization of the Human Body Describe the major body cavities and explain what organ(s) fit within each cavity Two Main Types of Body Cavities 1. Ventral Cavity: Located on the front (anterior) side of the body Thoracic Cavity: Above the diaphragm. Contains: The heart, lungs, esophagus, trachea, and large blood vessels (e.g., aorta, superior vena cava). Subdivisions: The thoracic cavity itself can be divided further: - Pleural cavities (2): Each one surrounds a lung. - Pericardial cavity: Surrounds the heart. - Mediastinum: The central region between the lungs that contains the heart, great blood vessels, trachea, esophagus, and other structures. 2. Abdominopelvic Cavity: ○ Location: Below the diaphragm, extending down into the pelvis. ○ Contains: The organs involved in digestion, excretion, and reproduction, including the stomach, liver, intestines, kidneys, bladder, and reproductive organs. ○ Subdivisions: The abdominopelvic cavity is often divided into two parts: Abdominal cavity: Houses digestive organs like the stomach, intestines, liver, and pancreas. Pelvic cavity: Contains the bladder, reproductive organs, and rectum. 2. Dorsal Cavity: Located on the back (posterior) side of the body, the dorsal cavity primarily protects the nervous system. It is divided into two sub-cavities: Cranial Cavity: Within the skull. Contains: The brain. The cranial cavity is encased in the bony structure of the skull and is filled with cerebrospinal fluid to protect and cushion the brain. Spinal (Vertebral) Cavity: Within the vertebral column (spine). Contains: The spinal cord. The spinal cavity is a bony canal formed by the vertebrae and houses the spinal cord, which transmits signals between the brain and the rest of the body. Summary of Body Cavities and Major Organs: Cranial Cavity: Brain Spinal Cavity: Spinal cord Thoracic Cavity: Heart, lungs, esophagus, trachea, major blood vessels Abdominal Cavity: Stomach, liver, spleen, intestines, pancreas, kidneys Pelvic Cavity: Bladder, reproductive organs, rectum Describe the four abdominal quadrants and the nine body regions 9 ABDOMINOPELVIC REGIONS 1. Umbilical 2. Epigastric 3. Hypogastric 4. Right and left iliac or inguinal 5. Right and left lumbar 6. Right and left hypochondriac ABDOMINOPELVIC QUADRANTS Right upper, Left upper, Right lower, Left lower RUQ: liver, galbladder, duodenum, right kidney and adrenal gland, hepatic flexure of colon LUQ: stomach, spleen, left lobe of liver, body of pancreas, left kidney and adrenal gland, splenic flexure of colon, parts of transverse and descending colon RLQ: cecum, appendix, ascending colon, right ovary and fallopian tube, right ureter LLQ: descending colon and sigmoid colon, left ovary and fallopian tube, left ureter ANATOMICAL DIRECTIONS 1. Superior (Cranial): Toward the head or upper part of the body (e.g., the head is superior to the neck). 2. Inferior (Caudal): Away from the head, or toward the lower part of the body (e.g., the feet are inferior to the knees). 3. Anterior (Ventral): Toward the front of the body (e.g., the chest is anterior to the spine). 4. Posterior (Dorsal): Toward the back of the body (e.g., the spine is posterior to the heart). 5. Medial: Toward or at the midline of the body (e.g., the nose is medial to the eyes). 6. Lateral: Away from the midline, toward the sides of the body (e.g., the ears are lateral to the eyes). 7. Proximal: Closer to the point of attachment or the origin of a structure (e.g., the elbow is proximal to the wrist). 8. Distal: Farther from the point of attachment or the origin of a structure (e.g., the fingers are distal to the shoulder). 9. Superficial (External): Toward or at the body surface (e.g., the skin is superficial to the muscles). 10. Deep (Internal): Away from the body surface; more internal (e.g., the lungs are deep to the ribcage). BODY PLANES AND SECTIONS Frontal/Coronal - divides the body into anterior and posterior parts Transverse/ horizontal (cross section) - divides body into superior and inferior parts Sagittal and medial - divides body into right and left parts Identify the basic differences between passive transport and active transport. 1. Energy Requirement Passive Transport: No energy (ATP) is required. Movement occurs naturally due to the concentration gradient, from areas of higher concentration to lower concentration. Active Transport: Energy (ATP) is required to move substances across the membrane, as molecules are transported against their concentration gradient (from areas of lower concentration to higher concentration). 2. Movement Direction Relative to Concentration Gradient Passive Transport: Molecules move down their concentration gradient (from high concentration to low concentration), which is a spontaneous process. Active Transport: Molecules move against their concentration gradient (from low concentration to high concentration), which is an energetically unfavorable process requiring energy input. 3. Types of Transport Passive Transport: Includes processes such as: ○ Diffusion: Movement of small or nonpolar molecules (e.g., oxygen, carbon dioxide) through the lipid bilayer. ○ Facilitated Diffusion: Movement of larger or polar molecules (e.g., glucose, ions) via membrane proteins (channels or carriers), but still down the concentration gradient. ○ Osmosis: The diffusion of water molecules across a selectively permeable membrane. Active Transport: Includes processes such as: ○ Primary Active Transport: Direct use of energy (usually ATP) to transport molecules via a pump (e.g., the sodium-potassium pump that moves Na⁺ out of the cell and K⁺ into the cell). ○ Secondary Active Transport: Indirect use of energy. The movement of one molecule down its gradient powers the transport of another molecule against its gradient (e.g., symport and antiport systems like the sodium-glucose co-transporter). 4. Transport Proteins Passive Transport: Often involves channel proteins or carrier proteins that allow molecules to passively flow through the membrane in the direction of the gradient. Active Transport: Involves pumps or transporters that require energy to move molecules in the opposite direction of the gradient. 5. Speed of Process Passive Transport: Generally a faster process since it relies on the natural movement of molecules along their concentration gradient. Active Transport: Tends to be slower because it requires energy input to move substances against their gradient. 6. Examples Passive Transport: ○ Oxygen and carbon dioxide entering and exiting cells by simple diffusion. ○ Glucose entering cells via facilitated diffusion using a glucose transporter. ○ Water moving across membranes through osmosis. Active Transport: ○ Sodium-potassium pump (Na⁺/K⁺ pump): Pumps sodium out of the cell and potassium into the cell, maintaining important ion gradients. ○ Proton pump in the stomach lining, which helps produce gastric acid. ○ Calcium pump: Actively transports calcium ions out of the cell or into the endoplasmic reticulum. Summary of Key Differences: Feature Passive Transport Active Transport Energy No energy required Requires energy (ATP) Requirement Movement Down concentration gradient (high to Against concentration gradient (low to Direction low) high) Types of Transport Diffusion, Facilitated diffusion, Primary and Secondary active transport Osmosis Transport Proteins Channel or carrier proteins Pumps or transporters Speed Generally faster Generally slower Comparison of Isotonic, Hypotonic, and Hypertonic Solutions These terms describe the relative concentrations of solutes in solutions, and they specifically refer to how the concentration of solutes in a solution compares to that inside a cell. The movement of water across the cell membrane (osmosis) depends on the type of solution, and this can affect the size and shape of cells. 1. Isotonic Solution: An isotonic solution has the same concentration of solutes as the inside of the cell. Effect on Cells: In an isotonic solution, there is no net movement of water into or out of the cell. The water molecules move in and out of the cell at the same rate, so the cell maintains its normal shape and size. 2. Hypotonic Solution: A hypotonic solution has a lower concentration of solutes compared to the inside of the cell. Effect on Cells: Water moves into the cell because the concentration of solutes is higher inside the cell than outside, so water moves to balance the concentration. If too much water enters, the cell may swell and even burst (lyse) if the osmotic pressure becomes too great. Examples: Distilled water (very low solute concentration). 3. Hypertonic Solution: A hypertonic solution has a higher concentration of solutes compared to the inside of the cell. Effect on Cells: Water moves out of the cell into the surrounding solution, as the solute concentration is higher outside the cell than inside. As water leaves the cell, it may shrink (crenate in animal cells) or become dehydrated. This process is known as plasmolysis in plant cells. Hypertonic solutions used to treat certain medical conditions, such as reducing swelling or increasing blood pressure. Summary Table Solution Solute Effect on Cells Water Movement Examples Type Concentration Isotonic Equal to inside No change in cell No net movement 0.9% NaCl, of cell shape; cell remains of water into or out normal saline, normal of the cell Ringer's solution Hypotonic Lower than Cell swells and may Water enters the Distilled water, inside of cell burst (lysis) cell 0.45% NaCl Hypertonic Higher than Cell shrinks Water leaves the 3% NaCl, inside of cell (crenation or cell hypertonic IV plasmolysis in solutions plants) Key Differences: Isotonic Solution: Equal solute concentration inside and outside the cell, causing no net water movement. Hypotonic Solution: Lower solute concentration outside the cell, causing water to move into the cell, potentially causing swelling or bursting. Hypertonic Solution: Higher solute concentration outside the cell, causing water to move out of the cell, leading to cell shrinkage or dehydration. Nervous System (all three Units) How a Nerve Impulse is Generated and Conducted A nerve impulse, or action potential, is the electrical signal that travels along a neuron (nerve cell). This process allows messages to be sent quickly through the nervous system. Here's how it works: 1. Resting Membrane Potential When a neuron is not firing (resting), there is a difference in the number of ions (charged particles) inside and outside the cell. This difference creates a resting membrane potential of about -70 mV (millivolts), meaning the inside of the neuron is negatively charged compared to the outside. Sodium (Na⁺) ions are more concentrated outside the neuron, and potassium (K⁺) ions are more concentrated inside. 2. Stimulus and Threshold A stimulus (like a signal from another neuron or a physical touch) can cause a change in the neuron’s membrane. If the stimulus is strong enough, it will cause a small depolarization (a shift in charge), making the inside of the cell less negative. If this change reaches a certain level, called the threshold (about -55 mV), it triggers an action potential (nerve impulse). 3. Depolarization (Action Potential) When the neuron reaches the threshold, sodium (Na⁺) channels open, and sodium ions rush into the cell. As Na⁺ enters the neuron, the inside of the cell becomes positive (around +30 mV), and the cell experiences depolarization. This is the firing of the nerve, the actual action potential. 4. Repolarization After the cell becomes positive, the sodium channels close and potassium (K⁺) channels open. Potassium ions move out of the neuron, which makes the inside of the cell negative again. This is called repolarization and brings the cell back to its resting state. 5. Refractory Period After an action potential, the neuron has a refractory period where it cannot fire another impulse immediately. This is because the channels need to reset to their original state (sodium outside, potassium inside) before the neuron can fire again. 6. Conduction of the Impulse The action potential travels along the axon (the long, threadlike part of the neuron). As sodium ions rush in at one part of the axon, they cause the next part to become depolarized, creating a wave-like effect that moves the impulse down the length of the axon. If the axon is myelinated (covered with a fatty layer), the impulse can jump from one gap in the myelin (called Nodes of Ranvier) to the next, which speeds up the transmission of the nerve signal. This is called saltatory conduction. 7. Transmission to the Next Neuron or Muscle When the action potential reaches the axon terminals, it triggers the release of neurotransmitters (chemical messengers) into the synapse (the gap between two neurons). These neurotransmitters bind to receptors on the next neuron (or muscle cell), which can trigger another action potential or cause a muscle to contract. Summary of Steps: 1. Resting potential: The neuron is at rest, with a negative charge inside. 2. Stimulus: A signal causes the neuron to depolarize. 3. Depolarization: Sodium ions rush in, making the inside positive. 4. Repolarization: Potassium ions flow out, restoring the negative charge. 5. Refractory period: The neuron resets before it can fire again. 6. Conduction: The impulse travels down the axon, often jumping across gaps (in myelinated neurons). 7. Synaptic transmission: Neurotransmitters pass the signal to the next cell. Key Terms: Action potential: The electrical signal that travels along a neuron. Resting membrane potential: The charge difference when the neuron is at rest. Depolarization: When the inside of the neuron becomes more positive. Repolarization: When the inside of the neuron becomes negative again. Refractory period: The period during which the neuron cannot fire another action potential. Neurotransmitters: Chemicals that transmit signals between neurons. Why It’s Important: The nerve impulse is how the nervous system communicates, allowing your brain to send signals to muscles (for movement), organs (for regulation), and other parts of your body. Without nerve impulses, we wouldn’t be able to move, think, or respond to our environment. Identify the protective coverings of the brain and spinal cord The brain and spinal cord are protected by several layers of membranes and fluid. These protective coverings ensure that the delicate neural tissue is shielded from mechanical injury, infection, and harmful substances. Here’s a breakdown of the protective coverings: 1. Meninges The meninges are three layers of connective tissue membranes that surround and protect the brain and spinal cord. These layers are: a. Dura Mater Location: The outermost layer, closest to the skull and vertebral column. Structure: It is tough, thick, and durable, acting like a protective shield. Function: The dura mater provides mechanical protection and helps hold the brain and spinal cord in place within the skull and vertebral canal. It also contains blood vessels that supply the brain. Special Feature: In some areas, the dura mater forms dural sinuses (large veins) that collect blood from the brain. b. Arachnoid Mater Location: The middle layer, lying beneath the dura mater and above the pia mater. Structure: The arachnoid mater is a thin, web-like membrane. It gets its name because it resembles a spider's web (arachnoid means "spider-like"). Function: This layer acts as a cushion for the brain, providing a space for the cerebrospinal fluid (CSF) to circulate. Special Feature: Between the arachnoid mater and the pia mater is a space called the subarachnoid space, which is filled with cerebrospinal fluid (CSF) that helps protect and nourish the brain and spinal cord. c. Pia Mater Location: The innermost layer, directly in contact with the surface of the brain and spinal cord. Structure: The pia mater is a very thin, delicate membrane that follows the contours (gyri and sulci) of the brain and spinal cord. Function: It provides a layer of protection and nourishment to the underlying neural tissue. Blood vessels that supply the brain and spinal cord are also found in this layer. 2. Cerebrospinal Fluid (CSF) Location: CSF is found in the subarachnoid space (between the arachnoid and pia mater) and in the ventricles of the brain. Structure: CSF is a clear, colorless liquid that is produced by the choroid plexus in the ventricles of the brain. Function: CSF acts as a shock absorber (cushioning the brain and spinal cord from mechanical damage), nourishing the brain and spinal cord, and removing waste products from the central nervous system (CNS). It also maintains chemical stability in the brain. 3. Bone (Skull and Vertebral Column) Skull (Cranium): The brain is housed within the skull, a rigid bone structure that protects it from external physical damage. Vertebral Column (Spine): The spinal cord is protected by the vertebral column, a bony structure made up of vertebrae. The vertebrae encase the spinal cord, protecting it from external trauma. Summary of Protective Coverings: Layer Location Description Dura Mater Outermost layer Tough, protective outer membrane. Arachnoid Mater Middle layer Web-like structure; contains cerebrospinal fluid (CSF). Pia Mater Innermost layer Thin, delicate membrane that covers the surface of the brain and spinal cord. Cerebrospinal Between arachnoid and Fluid that cushions, nourishes, and removes waste Fluid pia mater from the brain and spinal cord. Bone (Skull & Skull and vertebral Bony structures that provide physical protection for Spine) column the brain and spinal cord. Functions of the Protective Layers: Physical Protection: The skull and vertebral column provide a strong, bony shield against physical trauma. Shock Absorption: The cerebrospinal fluid (CSF) and meninges help cushion the brain and spinal cord from sudden movements and impacts. Chemical and Nutritional Support: The pia mater and CSF help provide nutrients and remove waste products to keep the neural tissue healthy. Infection Defense: The meninges and the blood-brain barrier (a selective barrier formed by cells in the blood vessels of the brain) help prevent harmful substances and pathogens from entering the brain. These protective layers work together to ensure that the brain and spinal cord are safeguarded from damage, infection, and environmental changes Formation, Circulation, and Functions of Cerebrospinal Fluid (CSF) Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds and cushions the brain and spinal cord. It plays a vital role in protecting the central nervous system (CNS), maintaining its chemical environment, and supporting its function. Here’s a breakdown of how CSF is formed, circulates, and functions: 1. Formation of Cerebrospinal Fluid How CSF is Made: CSF is a clear fluid that is made inside the ventricles of the brain. These ventricles are small spaces inside the brain. The main place where CSF is produced is called the choroid plexus. Choroid Plexus: The choroid plexus is made up of tiny blood vessels that are surrounded by special cells. These cells filter the blood to make CSF. It's like how a coffee filter works, where it lets good stuff through and keeps out the bad stuff. What the Choroid Plexus Does: It removes waste and extra ions (like sodium and potassium) from the blood and adds nutrients, like glucose (a type of sugar), which the brain needs to function properly. How Much CSF is Made: CSF is made at a rate of about 500 milliliters (mL) per day, but only about 150 mL is present in the brain and spinal cord at one time. This means CSF is always being made, used, and replaced to keep things balanced. 2. Circulation of Cerebrospinal Fluid Once formed, CSF flows through a specific pathway that ensures it bathes the brain and spinal cord, providing both mechanical protection and nutritional support. 1. Ventricles: CSF is made in the brain's lateral ventricles, then flows to the third ventricle, and from there to the fourth ventricle. 2. Subarachnoid Space: From the fourth ventricle, CSF moves into the space around the brain and spinal cord, where it cushions and protects them. 3. Spinal Cord: CSF continues around the spinal cord, helping to nourish it. 4. Arachnoid Granulations: As CSF flows, it is absorbed by small projections in the brain (arachnoid granulations) into veins. 5. Reabsorption: This process keeps CSF levels steady and prevents fluid buildup, which could cause problems like hydrocephalus. 3. Functions of Cerebrospinal Fluid CSF is crucial for maintaining a healthy environment for the brain and spinal cord, and it performs several key functions Protection and Cushioning: CSF acts like a shock absorber for the brain and spinal cord. It helps protect them from sudden impacts or movements by floating the brain in a protective cushion of fluid. Nutritional Support: CSF transports vital nutrients, like glucose and oxygen, to the brain and spinal cord. It also helps remove waste products, keeping the brain functioning properly. Chemical Balance: CSF helps maintain the right balance of chemicals (like sodium, potassium, and chloride) in the brain. This balance is crucial for the brain cells (neurons) to communicate and work efficiently. Buoyancy: The brain is heavy, but the CSF allows it to "float," reducing its weight and preventing pressure on the skull that could cause damage. Waste Removal: CSF helps remove waste products from the brain, carrying them to the blood so they can be filtered out by the kidneys. Summary of Key Points Process Description Formation CSF is produced by the choroid plexus in the brain's ventricles. Circulation CSF flows through the ventricles, subarachnoid space, and around the spinal cord, before being reabsorbed into the blood. Functions 1. Cushioning: Acts as a shock absorber for the brain. 2. Nutrient transport: Supplies nutrients to the brain and removes waste. 3. Chemical stability: Maintains the proper ionic environment for neurons. 4. Buoyancy: Supports the brain, reducing its weight. Conclusion - Cerebrospinal fluid is essential for maintaining the health and functionality of the brain and spinal cord. - Its formation, circulation, and various protective functions ensure that the nervous system remains safe from physical damage, well-nourished, and able to perform at its best. - Without CSF, the brain and spinal cord would be far more vulnerable to injury and stress, and the chemical balance necessary for proper neural function could easily be disrupted. Describe the major parts of the brain on the basis of location, structure, and function 1. Cerebrum Location: The largest part of the brain, occupying the uppermost region. Structure: Divided into two hemispheres (left and right) and four lobes (frontal, parietal, temporal, occipital). The outer layer is called the cerebral cortex, characterized by its gyri (folds) and sulci (grooves). Function: Responsible for higher cognitive functions, including reasoning, problem-solving, emotions, memory, and voluntary motor control. Each lobe has specialized functions: Frontal Lobe: Decision-making, planning, and motor control. Parietal Lobe: Sensory processing, spatial orientation. Temporal Lobe: Auditory processing, language comprehension, and memory. Occipital Lobe: Visual processing. 2. Cerebellum Location: Located posteriorly (toward the back) and inferiorly (below) to the cerebrum. Structure: Composed of two hemispheres and a highly folded surface (folia) that increases its surface area. It contains a core of white matter surrounded by gray matter. Function: Coordinates voluntary movements, maintains balance and posture, and ensures smooth execution of motor tasks. It integrates sensory information for fine motor control. 3. Brainstem Location: Located at the base of the brain, connecting the cerebrum to the spinal cord. Structure: Composed of three main parts: ○ Midbrain: Uppermost part, involved in vision and hearing. ○ Pons: Middle part, acting as a bridge between different brain regions. ○ Medulla Oblongata: Lowest part, continuous with the spinal cord. Function: Controls vital autonomic functions necessary for survival, such as heart rate, breathing, and blood pressure. It also regulates sleep and arousal. Additional Brain Structures 4. Limbic System Location: Deep within the cerebrum, surrounding the thalamus. Structure: Includes structures such as the hippocampus (involved in memory) and the amygdala (involved in emotion). Function: Plays a key role in emotion regulation, memory formation, and motivation. 5. Thalamus Location: Located above the brainstem and below the cerebral cortex. Structure: A large, egg-shaped mass of gray matter. Function: Acts as the main relay station for sensory information (except smell) to the cerebral cortex and plays a role in consciousness and alertness. 6. Hypothalamus Location: Located below the thalamus, forming the floor of the third ventricle. Structure: Small but crucial, consisting of various nuclei that perform different functions. Function: Regulates homeostasis, including temperature, hunger, thirst, and circadian rhythms. It also controls the pituitary gland, influencing hormonal balance. Describe the functional areas of the cerebral cortex Cerebral cortex: The intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information-processing center. Motor cortex: An area at the rear of the frontal lobes that controls voluntary movements Sensory cortex: Area at the front of the parietal lobes that registers and processes body touch and movement sensations Skeletal Joints Identify the classifications of joints based on function 1. Fibrous Joints Description: These joints consist of dense connective tissue that holds bones tightly together and are generally immovable or have very little movement. Function: Synarthrotic joints – they permit essentially no movement. Types of Fibrous Joints: Sutures: ○ Location: Found only in the skull. ○ Function: Immovable, as the bones are fused together. These joints protect the brain. ○ Adult Development: In adulthood, sutures become completely fused. Syndesmoses: ○ Description: A type of fibrous joint where fibrous ligaments connect the bones. ○ Example: The distal end of the radioulnar joint, where the radius and ulna are connected but can still move slightly. Gomphoses: ○ Description: A fibrous joint found only between teeth and the jaw. ○ Function: Holds teeth in place in the sockets of the jawbone (mandible). 2. Cartilaginous Joints Description: These joints are connected by hyaline cartilage or fibrocartilage and allow for limited movement. Function: Amphiarthrotic joints – they are slightly movable. Types of Cartilaginous Joints: Synchondroses: ○ Description: A joint where hyaline cartilage connects the bones. ○ Example: The first sternocostal joint, where the first rib connects to the manubrium of the sternum. Most synchondroses are temporary and occur in childhood. ○ Function: These joints are typically temporary and help in bone growth during childhood. Symphysis: ○ Description: A joint where a disk of fibrocartilage connects two bones. ○ Example: The pubic symphysis (between the pubic bones) or the intervertebral discs (between the vertebrae). ○ Function: Allows slight movement, typically for shock absorption. 3. Synovial Joints Description: These are freely movable joints, meaning they allow a large range of movement. Function: Diarthrotic joints – they are freely movable and are the most common type of joint in the body. Components of Synovial Joints:  Joint Capsule: A fibrous sac that surrounds the joint and provides stability. Synovial Membrane: The lining inside the joint capsule that secretes synovial fluid, which lubricates the joint. Articular Cartilage: Hyaline cartilage that covers the ends of bones in synovial joints, reducing friction. Joint Cavity: The space between two bones, filled with synovial fluid for lubrication. Meniscus: A piece of cartilage found in some synovial joints (e.g., knee) that helps with shock absorption. Ligament: Strong fibrous tissue that connects bones to other bones, providing stability to the joint. Bursa: A fluid-filled sac that reduces friction between parts of the joint. Types of Synovial Joints (Based on Movement) 1. Uniaxial Joints (Movement in One Plane) ○ Hinge Joint: Moves like a door hinge, in one direction (back and forth). Example: Elbow joint. ○ Pivot Joint: Allows rotational movement around a single axis. Example: First and second vertebrae (allows head rotation). 2. Biaxial Joints (Movement in Two Planes) ○ Saddle Joint: Allows movement in two directions at right angles to each other. Example: Base of the thumb. ○ Condyloid Joint: Allows movement in two planes, like an oval-shaped ball fitting into a concave surface. Example: Wrist joint (between the radius and the carpal bones). 3. Multiaxial Joints (Movement in Three or More Planes) ○ Ball and Socket Joint: The rounded head of one bone fits into a cup-like socket of another bone, allowing movement in all directions. Example: Shoulder joint and Hip joint. ○ Gliding Joint: Allows bones to slide past each other, often with limited movement. Example: Carpal bones (in the wrist), tarsals (in the foot), and intervertebral joints (between the vertebrae). Summary of Joints Based on Function: Type of Joint Movement Example Function Fibrous Joints No movement Skull sutures, gomphoses Synarthrotic, provides (teeth) stability Cartilaginous Limited Pubic symphysis, Amphiarthrotic, slightly Joints movement intervertebral discs movable Synovial Joints Freely movable Elbow, shoulder, knee, hip Diarthrotic, allows full movement Describe the structure of a typical synovial joint A synovial joint is the most common and freely movable type of joint in the body. The structure of a synovial joint is designed to allow a wide range of motion while also providing stability. Here are the main parts that make up the structure of a typical synovial joint: 1. Articular Cartilage Location: Covers the ends of the bones in the joint. Function: This smooth hyaline cartilage reduces friction and acts as a cushion, preventing the bones from rubbing against each other during movement. 2. Joint Capsule Location: Surrounds the entire joint. Function: This fibrous capsule encloses the joint, providing structural support and holding the bones together. It helps maintain the joint's stability while allowing for movement. Parts: - Outer Fibrous Capsule: Made of tough connective tissue, it provides strength to the joint. - Inner Synovial Membrane: Lines the inner surface of the capsule and produces synovial fluid. 3. Synovial Fluid Location: Found within the joint cavity, between the articular cartilage and inside the joint capsule. Function: This lubricating fluid reduces friction between the moving parts of the joint and nourishes the articular cartilage, keeping it healthy. It also absorbs shock during movement. 4. Joint Cavity Location: The small space between the two bones in the joint. Function: The cavity is filled with synovial fluid and acts as a space that allows for smooth movement between the bones. 5. Ligaments Location: Surround the joint and connect bone to bone. Function: Ligaments provide stability and prevent excessive movement that could damage the joint. They help hold the bones in place and keep the joint from moving too far in any one direction. 6. Bursa Location: Fluid-filled sacs that are located outside the joint, often near tendons or ligaments that pass over bones. Function: Bursae reduce friction and cushion pressure points between the bone and tendons or muscles, helping the joint move smoothly. 7. Meniscus (in Some Joints) Location: Found in some synovial joints, such as the knee. Function: These are cartilage discs that help absorb shock, stabilize the joint, and provide a better fit between the bones of the joint. 8. Tendons (Not a direct part of the joint, but related) Location: Tendons connect muscles to bones around the joint. Function: Tendons help in moving the bones when the muscles contract, enabling joint movement. Summary of the Structure of a Synovial Joint: Structure Description Function Articular Smooth cartilage covering bone ends Reduces friction, absorbs shock Cartilage Joint Capsule Tough outer fibrous tissue that Holds bones together, provides stability encloses the joint Synovial Fluid Lubricating fluid in the joint cavity Reduces friction, nourishes cartilage Joint Cavity Space between the bones Allows smooth movement, filled with synovial fluid Ligaments Connect bone to bone outside the Provides stability, limits excessive joint movement Bursa Fluid-filled sac near the joint Reduces friction, cushions pressure points Meniscus Cartilage disc in some joints (e.g., Absorbs shock, stabilizes the joint knee) Tendons Connect muscles to bones Enable movement by transmitting muscle force to bones How the Parts Work Together: Articular cartilage cushions the bones so they don’t rub together. The joint capsule holds everything in place and contains the synovial fluid that lubricates the joint. Ligaments keep the bones stable and prevent dislocation, while tendons help move the bones when muscles contract. Bursae reduce friction around the joint, and the meniscus (in some joints) helps with shock absorption and joint stability. This structure allows synovial joints to be highly mobile while still maintaining stability and protection for the bones and tissues involved. Cardiovascular System Describe the location and structure and function of the heart Location: The heart is located in the thoracic cavity, slightly to the left side of the chest, between the lungs. Its base is near the vertebral column, and its apex points towards the left hip. Structure: The heart has four chambers: 2 atria (upper chambers), which receive blood. 2 ventricles (lower chambers), which pump blood out of the heart. The heart is made of three layers: ○ Endocardium (inner lining), ○ Myocardium (muscular middle layer), ○ Epicardium (outer layer, also called visceral pericardium). The heart is separated into right and left halves by the septum. Function: The heart pumps oxygenated blood to the body (systemic circulation) and deoxygenated blood to the lungs (pulmonary circulation). Explain how blood travels through the heart Right Atrium → receives deoxygenated blood from the body via the superior and inferior vena cava. Tricuspid Valve → blood flows from the right atrium into the right ventricle. Right Ventricle → pumps deoxygenated blood through the pulmonary valve to the pulmonary trunk. Pulmonary Arteries → carry the blood to the lungs, where it is oxygenated. Left Atrium → receives oxygenated blood from the lungs via the pulmonary veins. Mitral Valve (Bicuspid Valve) → blood flows from the left atrium into the left ventricle. Left Ventricle → pumps oxygenated blood through the aortic valve into the ascending aorta, which distributes it throughout the body. Discuss the role and operation of the coronary arteries and veins. Coronary Arteries: These arteries branch off the ascending aorta and supply oxygen-rich blood to the heart muscle (myocardium). There are left and right coronary arteries. Coronary Veins: These veins collect deoxygenated blood from the heart muscle and return it to the right atrium via the coronary sinus. Describe how each heartbeat is initiated - The heartbeat is initiated by electrical impulses starting at the SA node (Sinoatrial node), also known as the pacemaker of the heart. - The impulse spreads through the atria, causing atrial contraction (atrial systole). - The impulse then travels to the AV node (Atrioventricular node), down the Bundle of His, through the bundle branches, and reaches the Purkinje fibers, stimulating ventricular contraction (ventricular systole). Describe the phases of the cardiac cycle 1. Atrial Systole: The atria contract and push blood into the ventricles. 2. Ventricular Systole: The ventricles contract, forcing blood out of the heart through the semilunar valves (pulmonary and aortic valves). 3. Relaxation Phase (Diastole): Both atria and ventricles relax and fill with blood in preparation for the next cycle. The S1 sound occurs when the AV valves (tricuspid and mitral) close. The S2 sound occurs when the semilunar valves (pulmonary and aortic) close. Compare systemic circulation with pulmonary circulation Systemic Circulation: Carries oxygenated blood from the left ventricle to the rest of the body (through the aorta and its branches) and returns deoxygenated blood to the right atrium (via the superior and inferior vena cava). Pulmonary Circulation: Carries deoxygenated blood from the right ventricle to the lungs (via the pulmonary arteries) for oxygenation and returns oxygenated blood to the left atrium (via the pulmonary veins). List the major components of plasma and describe their function Plasma: The liquid component of blood that makes up about 55% of total blood volume. It consists of: Water (90%): Helps transport nutrients and maintain blood pressure. Plasma Proteins: ○ Albumin: Maintains blood osmotic pressure and volume. ○ Immunoglobulins (Antibodies): Help fight infections. ○ Fibrinogen: Involved in blood clotting. Other solutes: Nutrients, hormones, gases (oxygen, carbon dioxide), and waste products (urea, etc.). Describe the blood cells according to general characteristics and functions Red Blood Cells (Erythrocytes): Carry oxygen from the lungs to body cells and return carbon dioxide to the lungs for exhalation. They contain hemoglobin, which binds oxygen. White Blood Cells (Leukocytes): Defend the body against infection and disease. ○ Neutrophils: Engulf bacteria. ○ Eosinophils: Combat parasitic worms and allergic reactions. ○ Basophils: Involved in inflammatory responses. ○ Lymphocytes: B-cells produce antibodies; T-cells attack infected cells. Platelets (Thrombocytes): Involved in blood clotting. They help form a platelet plug at the site of injury and activate clotting factors. 9. Blood Vessels: Arteries: Carry blood away from the heart. Have thick walls with three layers: ○ Tunica Intima: Innermost layer, smooth to reduce friction. ○ Tunica Media: Middle layer of muscle, allows for expansion and contraction.  ○ Tunica Adventitia: Outer layer, connective tissue. Veins: Carry blood back to the heart. They have thinner walls than arteries and contain valves to prevent backflow. Capillaries: Thin-walled vessels where nutrient and gas exchange occurs. Connect arterioles to venules. 10. Blood Pressure and Related Concepts: Blood Pressure: The force exerted by blood on the walls of blood vessels. It is measured as systolic (when the heart contracts) and diastolic (when the heart relaxes). Cardiac Output: The amount of blood the heart pumps per minute (heart rate × stroke volume). Vascular Resistance: The resistance to blood flow caused by friction between blood and vessel walls. 11. Summary of the Circulatory Pathway: 1. Arteries → Carry oxygenated blood (except pulmonary arteries). 2. Arterioles → Smaller branches of arteries leading to capillaries. 3. Capillaries → Where exchange of gases, nutrients, and wastes occurs. 4. Venules → Small veins that collect blood from capillaries. 5. Veins → Carry deoxygenated blood (except pulmonary veins) back to the heart. Key Terms: Systole: Contraction phase of the heart. Diastole: Relaxation phase of the heart. Cardiac Output: Amount of blood pumped by the heart in one minute. Blood Pressure: The pressure exerted by blood against the vessel walls The Digestive System/Nutrition and Metabolism Describe the major digestive organs based on location, structure, and function Mouth Location: Oral cavity. Structure: The mouth contains teeth, the tongue, and salivary glands. Function: The mouth is the entry point for food. It is involved in mechanical digestion (chewing) and chemical digestion (via enzymes in saliva like amylase). The tongue helps in mixing food and forming a bolus for swallowing. Pharynx Location: The throat, connecting the mouth to the esophagus. Structure: It is divided into three sections: nasopharynx, oropharynx, and laryngopharynx. Function: The pharynx serves as a passageway for food and air. The pharyngeal muscles facilitate the swallowing of food. Esophagus Location: A muscular tube that connects the pharynx to the stomach.  Structure: A long, muscular tube lined with mucous membranes. Function: The esophagus conducts food from the mouth to the stomach through peristaltic waves. The esophageal sphincters control food entry and prevent reflux. Stomach Location: Located in the upper left quadrant of the abdomen. Structure: A J-shaped organ with four main regions: fundus, body, pylorus, and an inner mucosa layer with gastric glands. Function: The stomach mechanically and chemically digests food. It secretes gastric juices (acid and enzymes) that break down proteins and mix food into chyme. The pyloric sphincter regulates food passage to the small intestine. Small Intestine Location: Central and lower part of the abdomen. Structure: Composed of three parts: duodenum, jejunum, and ileum. It has a large surface area due to villi and microvilli. Function: The small intestine is the primary site of digestion and absorption. Enzymes from the pancreas and bile from the liver aid in digestion, while nutrients are absorbed through the villi into the bloodstream. Large Intestine (Colon) Location: Surrounding the small intestine, it extends from the ileum to the anus. Structure: Composed of the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum. Function: The large intestine absorbs water, electrolytes, and certain vitamins. It forms and stores feces for elimination. Rectum and Anus Location: At the end of the large intestine. Structure: The rectum stores feces, and the anus has sphincter muscles controlling the release of waste. Function: The rectum temporarily stores feces, while the anus controls defecation. Accessory Organs of Digestion Salivary Glands: Secrete saliva to aid in chewing and chemical digestion. Liver: Produces bile, which emulsifies fats for digestion. Gallbladder: Stores and concentrates bile from the liver. Pancreas: Secretes digestive enzymes and bicarbonate into the duodenum to aid digestion and neutralize stomach acid. Describe the absorption of nutrients, ions, and water Nutrients: Carbohydrates: Digested by enzymes like amylase into simpler sugars (glucose) and absorbed in the small intestine.  Proteins: Digested by pepsin in the stomach and trypsin in the small intestine into amino acids, which are absorbed in the jejunum. Fats: Emulsified by bile and digested by pancreatic lipase into fatty acids and monoglycerides, absorbed through the villi of the small intestine. Vitamins: Fat-soluble vitamins (A, D, E, K) are absorbed with fats, while water-soluble vitamins (B and C) are absorbed directly into the bloodstream. Ions: Electrolytes like sodium, potassium, calcium, and magnesium are absorbed in the small intestine and colon through active transport mechanisms and ion channels. Water: Most water absorption occurs in the small intestine, with additional water absorbed in the large intestine. Water is reabsorbed to prevent dehydration, and any unabsorbed water forms part of the stool. Digestion Process 1. Mechanical Digestion: ○ Mouth: Teeth break food into smaller pieces (chewing). ○ Stomach: Churning and mixing food into chyme. ○ Small Intestine: Segmentation and peristalsis further break down food and mix digestive enzymes. 2. Chemical Digestion: ○ Saliva: Contains amylase, which begins carbohydrate digestion. ○ Gastric Juices: Pepsinogen is activated into pepsin in the acidic stomach environment to break down proteins. ○ Pancreatic Enzymes: Amylase, lipase, and proteases (trypsin, chymotrypsin) break down carbohydrates, fats, and proteins in the small intestine. Peristalsis Definition: Peristalsis is the involuntary, wave-like muscle contractions that propel food through the digestive tract. Location: Occurs in the esophagus, stomach, small intestine, and large intestine. The Role of the Large Intestine in Absorption The large intestine is primarily responsible for water absorption, along with some vitamins like vitamin K and B vitamins produced by gut bacteria. Electrolyte absorption also occurs, contributing to fluid balance in the body. The large intestine has no villi but instead has a smooth surface, and its primary role is to reabsorb water and electrolytes and store feces. The Structure and Function of Accessory Organs: 1. Salivary Glands ○ Structure: Major glands include the parotid, submandibular, and sublingual glands.  ○ Function: Produce saliva, which contains enzymes like amylase to begin the digestion of carbohydrates and also aids in swallowing. 2. Liver ○ Structure: The largest internal organ, located under the diaphragm. ○ Function: Produces bile, which emulsifies fats in the duodenum. Also processes nutrients from digestion and detoxifies harmful substances. 3. Gallbladder ○ Structure: A small, pear-shaped organ located under the liver. ○ Function: Stores and concentrates bile produced by the liver, releasing it into the small intestine to aid fat digestion. 4. Pancreas ○ Structure: Located behind the stomach, it has both endocrine and exocrine functions. ○ Function: Produces digestive enzymes like amylase (carbohydrates), lipase (fats), and proteases (proteins) and secretes them into the duodenum. It also produces bicarbonate to neutralize stomach acid. Summary of Nutrient Absorption: Small intestine: The majority of digestion and nutrient absorption occurs in the jejunum, where nutrients like sugars, amino acids, and fatty acids are absorbed. Villi: These microscopic finger-like projections increase surface area for absorption, with each villus containing lacteals (for fat absorption) and capillaries (for nutrient absorption into the blood). Large intestine: Primarily absorbs water, electrolytes, and produces some vitamins through bacterial fermentation. No villi are present in the large intestine. The Endocrine System State the difference between the nervous and endocrine systems The nervous system uses electrical signals (action potentials) to transmit information rapidly through neurons, resulting in fast, short-term effects on the body. The endocrine system uses hormones (chemical messengers) that are released into the bloodstream to communicate with target cells. This system typically has slower, longer-lasting effects than the nervous system. Define target cells and describe the role of hormone receptor Target cells are specific cells that have receptors for a particular hormone. Hormone receptors are proteins located either in the plasma membrane or within the target cell. They bind to specific hormones and initiate a response within the cell. Hormones only affect cells that have the appropriate receptors, like a "lock and key" model. Identify how lipid soluble and non-lipid soluble hormones interact with cells Lipid-soluble hormones (such as steroid hormones) can pass through the lipid bilayer of the cell membrane. Once inside the cell, they bind to intracellular receptors and directly affect the DNA in the nucleus, altering gene expression. Non-lipid-soluble hormones (such as protein hormones) cannot pass through the cell membrane. They bind to receptors on the surface of the cell membrane, activating a secondary messenger (like cAMP) inside the cell to initiate a response. Describe the role of the hypothalamus in the secretion of hormones The hypothalamus is a region of the brain that plays a crucial role in regulating the endocrine system. It produces releasing and inhibiting hormones that control the secretion of hormones from the pituitary gland. For example, the hypothalamus releases thyrotropin-releasing hormone (TRH) to stimulate the release of TSH from the anterior pituitary. Name and describe the functions of the hormones secreted from the pituitary gland Anterior pituitary hormones: Growth hormone (GH): Stimulates growth in skeletal muscle and long bones, primarily during childhood. Prolactin: Promotes milk production in females. Thyroid-stimulating hormone (TSH): Stimulates the thyroid to release T3 and T4, which regulate metabolism. Adrenocorticotropic hormone (ACTH): Stimulates the adrenal cortex to release cortisol and other steroid hormones. Follicle-stimulating hormone (FSH): Stimulates the development of eggs in females and sperm in males. Luteinizing hormone (LH): Triggers ovulation in females and stimulates testosterone production in males. Urinary System Functions of the Kidneys: 1. Regulation of Extracellular Fluid (ECF): Maintains fluid balance and overall volume. 2. Regulation of Ion Concentrations: Controls levels of key ions like sodium, potassium, and calcium. 3. Regulation of pH: Helps maintain acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate. 4. Excretion of Wastes: Filters out metabolic waste products like urea, uric acid, and creatinine. 5. Production of Hormones: ○ Erythropoietin: Stimulates red blood cell production in response to low oxygen levels. ○ Calcitriol (active Vitamin D): Regulates calcium absorption from the intestines. ○ Renin: Helps regulate blood pressure via the RAAS (Renin-Angiotensin-Aldosterone System). External and Internal Anatomy of the Kidneys: Kidneys: Located in the lower back, with the left kidney positioned higher than the right due to the liver’s position.  Renal Fascia: Fibrous connective tissue surrounding the kidney, securing it to surrounding structures. Kidney Adipose Capsule: Fatty cushion protecting the kidney from physical trauma. Renal Capsule: Tough outer covering protecting the kidney. Adrenal Gland: Positioned atop each kidney, secretes hormones like adrenaline during stress. Internal Structure: 1. Hilus: Area where blood vessels and nerves enter and exit the kidney. 2. Renal Cortex: Outer layer of the kidney containing the nephrons. 3. Renal Medulla: Inner region of the kidney, where renal pyramids are located. 4. Renal Pyramids: Triangular tissue areas in the medulla that drain urine into the renal pelvis. 5. Renal Pelvis: Central cavity where urine from the renal pyramids collects. 6. Renal Artery: Carries blood from the aorta to the kidneys. 7. Renal Vein: Carries filtered blood from the kidneys back to the heart. Nephron Structure and Function: Nephron: The functional unit of the kidney. Each kidney contains around 1 million nephrons. ○ Bowman’s Capsule: Cup-shaped structure that surrounds the glomerulus and filters blood. ○ Proximal Convoluted Tubule (PCT): Reabsorbs nutrients, water, and ions from the filtrate. ○ Loop of Henle: Conserves water and reduces urine volume. ○ Distal Convoluted Tubule (DCT): Involved in selective reabsorption and secretion, particularly regulating sodium, water, and potassium. ○ Collecting Duct: Carries urine toward the renal pelvis, where it is collected for excretion. Peritubular Capillaries: Small blood vessels that surround the renal tubules and allow for reabsorption and secretion. Hormonal Regulation of Nephron Functions: 1. Renin-Angiotensin-Aldosterone System (RAAS): ○ Renin is secreted by juxtaglomerular cells when blood pressure drops. ○ Angiotensin I is converted to Angiotensin II in the lungs, a vasoconstrictor that increases blood pressure. ○ Angiotensin II stimulates the release of Aldosterone from the adrenal glands, promoting sodium and water reabsorption in the distal tubule, raising blood volume and blood pressure. 2. Aldosterone: Acts on the DCT to reabsorb sodium and water, increasing blood pressure. 3. Antidiuretic Hormone (ADH): Released by the posterior pituitary, increases water reabsorption in the collecting ducts, conserving water and increasing blood volume. 4. Parathyroid Hormone: Promotes the reabsorption of calcium and excretion of phosphate in the kidneys.  5. Atrial Natriuretic Factor: Opposes RAAS by promoting sodium and water excretion, reducing blood volume and pressure. Urine Formation Processes: 1. Glomerular Filtration: ○ The first step in urine formation, where blood is filtered in the glomerulus. ○ Filtered substances: Water, glucose, electrolytes, small proteins, nutrients, and waste products. ○ Non-filtered: Blood cells and plasma proteins. 2. Tubular Reabsorption: ○ 99% of the filtered fluid is reabsorbed back into the bloodstream. ○ Occurs primarily in the PCT, Loop of Henle, and DCT. ○ Key processes: Osmosis, Active Transport, and Diffusion. 3. Tubular Secretion: ○ The secretion of substances like hydrogen ions, potassium, and wastes into the filtrate, primarily in the DCT. 4. Creatinine Clearance Test: Measures the kidney's ability to clear creatinine from the blood and serves as an indicator of kidney function. Normal Characteristics of Urine: Components: Sodium, potassium, urea, uric acid, creatinine, ammonia, bicarbonate. Should not be present: Glucose, red blood cells (RBC), white blood cells (WBC), protein, bile. Normal Volume: 800 to 2,000 mL per day, with a minimum of 500 mL/day (or 30 mL/hour) to maintain kidney function. Structure and Function of the Urinary Tract: 1. Ureters: Tubes that transport urine from the kidneys to the urinary bladder. 2. Bladder: Stores urine until it is ready to be excreted. ○ Trigone: Triangular area in the bladder formed by the entry points of the ureters and the exit point of the urethra. It is smooth and lacks rugae. 3. Urethra: The tube through which urine is expelled from the body. 4. Prostate (in males): Surrounds the neck of the bladder, releasing prostatic fluid. Micturition (Urination) Process: 1. Bladder fills with urine, triggering stretch receptors. 2. Signal sent to the brain, creating the sensation of fullness. 3. Voluntary control: The external urethral sphincter is relaxed when the individual decides to urinate. 4. Involuntary control: The detrusor muscle of the bladder contracts to expel urine through the urethra. Acute Renal Failure: Definition: A sudden loss of kidney function, often due to a blockage, toxins, or a sudden loss of blood flow to the kidneys. It results in the kidneys' inability to filter waste properly, leading to a buildup of waste products in the blood. Dialysis: 1. Hemodialysis: Blood is filtered outside the body through a semi-permeable membrane, removing waste and excess fluids by diffusion and ultrafiltration. 2. Peritoneal Dialysis: Uses the peritoneal lining of the abdominal cavity as a filter to remove waste and excess fluid from the blood. Major Functions of the Lymphatic and Immune Systems: 1. Fluid Balance: ○ The lymphatic system collects excess interstitial fluid that is not returned to the blood capillaries and returns it to the circulatory system. 2. Protection from Infection: ○ Lymphocytes (T cells and B cells) attack and destroy foreign pathogens. ○ Lymphoid tissues filter out pathogens and toxins. 3. Fat Absorption: ○ Some fats (too large to enter blood vessels) are absorbed into the lymphatic system through lymphatic capillaries, specifically from the digestive tract. Organization of Lymphatic Vessels and Circulation of Lymph: Lymph: Clear, straw-colored fluid composed of water, electrolytes, proteins, wastes, and interstitial fluid. Lymphatic Capillaries: Small, thin-walled vessels with large pores, allowing interstitial fluid to enter. They transport lymph toward the heart. Lymphatic Vessels: Larger vessels formed by the merging of lymphatic capillaries, which have one-way valves to ensure unidirectional flow of lymph. Lymphatic Ducts: ○ Right Lymphatic Duct: Drains lymph from the right upper arm, right side of the head, and thorax. It empties into the right subclavian vein. ○ Thoracic Duct: Drains lymph from the left upper body, digestive organs, and lower body. It empties into the left subclavian vein. Lymph Transport: ○ Lymph moves due to the contraction of skeletal muscles, breathing movements, and smooth muscle contraction in lymphatic vessels. ○ Valves in lymphatic vessels ensure the one-way flow of lymph. Formation of Lymph: Formation Process: Lymph is formed from interstitial fluid that leaks out of blood capillaries and is collected by lymphatic capillaries. Movement: The fluid moves toward the heart, propelled by muscle contractions, breathing, and smooth muscle action in the lymphatic vessels. Structure and Functions of Lymphatic Organs and Tissue: 1. Lymph Nodes: ○ Function: Filter lymph, removing pathogens and foreign particles. Serve as sites for activation of T and B lymphocytes. ○ Structure: Bean-shaped with an outer cortex (B cells) and an inner medulla (T cells). ○ Key Locations: 1. Axillary Nodes: Under the arms. 2. Inguinal Nodes: In the groin area. 3. Cervical Nodes: In the neck area. 2. Tonsils: ○ Location: Form a ring around the entrance to the pharynx. ○ Types: 1. Palatine Tonsils: Largest, often infected. 2. Lingual Tonsils: Located at the base of the tongue. 3. Pharyngeal Tonsils (Adenoids): Located in the nasopharynx, often enlarged and infected in children. 3. Thymus: ○ Location: Above the heart. ○ Function: Matures T lymphocytes (T cells). ○ Characteristics: Shrinks after puberty. 4. Spleen: ○ Function: Filters blood, removes old or damaged red blood cells, and stores platelets. It also contains leukocytes that help fight infections. ○ Location: In the upper left abdomen. 5. Peyer's Patches: ○ Location: Found in the walls of the small intestine. ○ Function: Monitor and destroy harmful bacteria in the intestines. Types of Nonspecific Resistance to Disease: 1. Physical Barriers: ○ Skin: First line of defense. ○ Mucous Membranes: Trap pathogens. 2. Inflammatory Response: ○ When tissues are injured, inflammation occurs to promote healing and mobilize immune cells to the site. 3. Phagocytosis:  ○ Cells such as macrophages and neutrophils engulf and digest pathogens. ○ 4. Fever: ○ An elevated body temperature can inhibit pathogen growth and enhance immune responses. 5. Antimicrobial Proteins: ○ Interferons: Protect cells from viral infections. ○ Complement System: Proteins that enhance the ability of antibodies to clear pathogens. Antigen and Antibody: Antigen: A foreign substance (usually a protein or polysaccharide) that triggers an immune response. It can be a pathogen, toxin, or foreign molecule. Antibody (Immunoglobulin): A protein produced by B cells that specifically binds to and neutralizes antigens. They are crucial in the immune response to infections. Cell-Mediated vs. Antibody-Mediated Immunity: 1. Cell-Mediated Immunity: ○ Involves T cells: These cells directly attack and destroy infected cells or cancer cells. ○ Types of T cells: Helper T cells: Activate other immune cells, including B cells and cytotoxic T cells. Cytotoxic T cells: Directly kill infected or cancerous cells. ○ Example: Response to viral infections or intracellular pathogens. 2. Antibody-Mediated Immunity (Humoral Immunity): ○ Involves B cells: These cells produce antibodies that target and neutralize pathogens or toxins. ○ Antibodies: Bind to specific antigens, marking them for destruction or neutralization. ○ Example: Response to bacterial infections or toxins. Types of Immunity and How They Are Acquired: 1. Innate Immunity: ○ Present from birth and provides the first line of defense against pathogens. ○ Nonspecific: Does not target specific pathogens but provides broad protection (e.g., skin, inflammation, phagocytosis). 2. Acquired Immunity: ○ Develops after exposure to specific pathogens. ○ Active Immunity: Natural: Exposure to pathogens triggers an immune response (e.g., infection). Artificial: Immunization (vaccination) stimulates the immune system to produce antibodies without causing disease. ○ Passive Immunity:  Natural: Antibodies passed from mother to fetus through the placenta or via breast milk. Artificial: Transfer of antibodies (e.g., from an immune person or animal serum). Summary: The lymphatic system plays a crucial role in fluid balance, fat absorption, and protection against infection. Lymph is the fluid circulated by the lymphatic vessels, and the flow is aided by skeletal muscle, breathing, and smooth muscle contraction. Lymphatic organs (lymph nodes, spleen, thymus, tonsils) are essential for filtering pathogens and activating immune responses. The immune system defends the body through nonspecific resistance mechanisms (e.g., inflammation, phagocytosis) and specific immunity, which involves cell-mediated immunity (T cells) and antibody-mediated immunity (B cells). Immunity can be acquired actively (through infection or vaccination) or passively (through antibodies from another person or organism). Parts of the Male Reproductive System: 1. Testes (Testicles): ○ Location: Located in the scrotum. ○ Structure: Oval-shaped organs. ○ Function: Produce sperm (spermatogenesis) and testosterone (male sex hormone). 2. Epididymis: ○ Location: Coiled tube on the surface of each testis. ○ Structure: Composed of tightly coiled ducts. ○ Function: Sperm maturation and storage. 3. Vas Deferens: ○ Location: Tubes that carry sperm from the epididymis to the urethra. ○ Structure: Smooth muscle tube. ○ Function: Transports sperm during ejaculation. 4. Seminal Vesicles: ○ Location: Near the junction of the vas deferens and the urethra. ○ Structure: Glands that secrete fluid. ○ Function: Produce a thick fluid that is part of semen. 5. Prostate Gland: ○ Location: Surrounds the urethra just below the bladder. ○ Structure: Walnut-sized gland. ○ Function: Secretes a milky fluid that is part of semen. 6. Bulbourethral Glands (Cowper's Glands): ○ Location: Near the base of the penis. ○ Structure: Small glands. ○ Function: Secrete a lubricating mucus before ejaculation. 7. Penis:  ○ Location: External organ. ○ Structure: Composed of erectile tissue. ○ Function: Delivers sperm into the female reproductive tract. Parts of the Female Reproductive System: 1. Ovaries: ○ Location: Located in the pelvic cavity, one on each side of the uterus. ○ Structure: Oval-shaped glands. ○ Function: Produce eggs (ova) and hormones (estrogen and progesterone). 2. Fallopian Tubes (Oviducts): ○ Location: Extend from the ovaries to the uterus. ○ Structure: Tubes with fimbriae that capture the egg. ○ Function: Carry the egg from the ovary to the uterus; site of fertilization. 3. Uterus: ○ Location: Located in the pelvis, above the vagina. ○ Structure: Hollow, muscular organ. ○ Function: Houses and nourishes the developing fetus. 4. Vagina: ○ Location: Canal leading from the uterus to the outside of the body. ○ Structure: Muscular tube. ○ Function: Receives the penis during intercourse; passageway for menstruation and childbirth. 5. Cervix: ○ Location: Lower part of the uterus. ○ Structure: Narrow, muscular opening. ○ Function: Allows passage of menstrual blood, sperm, and facilitates childbirth. Oogenesis: Definition: The process of egg (ova) formation. Phases: 1. During fetal development: Oogonia (germ cells) undergo mitosis, forming primary oocytes that are arrested in prophase I of meiosis. 2. At puberty: One oocyte per menstrual cycle resumes meiosis, completing the first division to form a secondary oocyte. 3. Fertilization: The secondary oocyte completes meiosis and becomes a mature ovum. Hormonal Regulation of the Female Reproductive Cycle: 1. FSH (Follicle-Stimulating Hormone): ○ Stimulates the growth of ovarian follicles and egg maturation. 2. LH (Luteinizing Hormone): ○ Triggers ovulation (release of the mature egg from the follicle). 3. Estrogen:  ○ Secreted by developing follicles; promotes endometrial thickening for pregnancy. 4. Progesterone: ○ Secreted by the corpus luteum; stabilizes the endometrial lining for pregnancy. 5. Negative Feedback: ○ High levels of estrogen and progesterone inhibit the release of FSH and LH to prevent multiple eggs from maturing. Phases of the Female Reproductive Cycle: 1. Menstrual Phase (Days 1-5): ○ Shedding of the endometrial lining (menstruation). 2. Follicular Phase (Days 1-14): ○ Follicles in the ovaries mature, and estrogen levels rise. ○ Leads to ovulation at the end of the phase. 3. Ovulation (Day 14): ○ Release of a mature egg from the ovary triggered by a surge in LH. 4. Luteal Phase (Days 15-28): ○ The ruptured follicle becomes the corpus luteum, which secretes progesterone to prepare the uterus for a potential pregnancy. The Menstrual Cycle (Overview) Length of Cycle: Usually 28 days, but can range from 21 to 35 days. Main Phases: 1. Menstrual Phase 2. Proliferative Phase 3. Secretory Phase Key Hormones Involved: 1. FSH (Follicle-Stimulating Hormone) ○ Stimulates the growth of ovarian follicles (eggs). 2. LH (Luteinizing Hormone) ○ Triggers ovulation (release of the mature egg). 3. Estrogen ○ Secreted by developing follicles. ○ Stimulates the thickening of the uterine lining (endometrium). 4. Progesterone ○ Secreted by the corpus luteum (leftover follicle after ovulation). ○ Maintains and stabilizes the uterine lining for pregnancy. Menstrual Cycle Phases: 1. Menstrual Phase (Day 1-5) ○ What happens:  Shedding of the uterine lining → menstruation (period). ○ Hormones: Low levels of estrogen and progesterone signal the shedding of the endometrial lining. 2. Proliferative Phase (Day 6-14) ○ What happens: The uterine lining thickens again in preparation for a possible pregnancy. Eggs in the ovaries start to mature. ○ Hormones: FSH stimulates follicle growth in the ovaries. Estrogen levels rise as follicles develop, causing the endometrium to thicken. 3. Secretory Phase (Day 15-28) ○ What happens: After ovulation, the empty follicle turns into the corpus luteum. Progesterone from the corpus luteum helps maintain the thickened uterine lining. ○ Hormones: Progesterone stabilizes the endometrium for potential implantation of a fertilized egg. If pregnancy doesn’t occur, the corpus luteum breaks down, progesterone drops, and the endometrial lining starts to shed, leading to the next menstrual phase. Negative Feedback Loop (Preventing Multiple Eggs): When estrogen and progesterone levels rise (after ovulation), they send signals to the brain to reduce the release of FSH and LH. ○ This prevents the ovaries from releasing more eggs. ○ Prevents multiple eggs from maturing at the same time. Quick Recap of the Phases: 1. Menstrual Phase (Days 1-5): ○ Bleeding occurs (shedding of the uterine lining). ○ Hormones (estrogen and progesterone) are low. 2. Proliferative Phase (Days 6-14): ○ The uterine lining thickens (preparing for pregnancy). ○ FSH helps eggs grow; estrogen helps build the uterine lining. 3. Secretory Phase (Days 15-28): ○ Progesterone maintains the uterine lining. ○ If no pregnancy, progesterone drops and the cycle starts over. Summary of Key Points: FSH = Egg growth. LH = Triggers ovulation.  Estrogen = Thickens the uterine lining. Progesterone = Keeps the uterine lining stable for pregnancy. The cycle is controlled by a balance of these hormones, and if no pregnancy occurs, the cycle restarts with menstruation! Inheritance and Genetics: 1. Genotype: ○ An organism's genetic makeup (the combination of alleles it carries). ○ Internally coded, inheritable information 2. Phenotype: ○ An organism's physical appearance resulting from the genotype. ○ The way that genotype is expressed in the body ○ Outward expression of our internal genetic code 3. Homozygous: ○ An organism with two identical alleles for a trait (e.g., AA or aa, BB or bb). 4. Heterozygous: ○ An organism with two different alleles for a trait (e.g., Aa, Bb). 5. Dominant Gene: ○ A gene that is expressed in the phenotype even when only one copy is present (e.g., A,in Aa, B in Bb). 6. Recessive Gene: ○ A gene that is only expressed in the phenotype when two copies are present (e.g., aa, bb). 7. Sex-Linked Inheritance: ○ Traits carried on the sex chromosomes, often affecting males more than females. ○ Examples: Hemophilia, Duchenne muscular dystrophy, color blindness, Fragile X syndrome. 8. Gene Therapy: ○ A treatment that involves inserting working copies of a gene into the cells of a person with a genetic disorder to correct the disorder.