The Nervous System Final Exam Quizgecko (PDF)

**[The Nervous System]** [Functions] 1. **Sensory** -- Detect changes in environment. 2. **Integration** -- Processing and decision making. 3. **Motor** -- Telling the body what to do in response. [Systems of the Nervous Systems] 1. Central Nervous System a. Brain b. Spinal Cor...

**[The Nervous System]** [Functions] 1. **Sensory** -- Detect changes in environment. 2. **Integration** -- Processing and decision making. 3. **Motor** -- Telling the body what to do in response. [Systems of the Nervous Systems] 1. Central Nervous System a. Brain b. Spinal Cord 2. Peripheral Nervous System c. Cranial Nerves and Branches d. Spinal Nerves and Branches e. Ganglia: Cluster of Neuron Bodies f. Sensory Receptors g. Enteric Nervous System [Functional Organization of the Nervous System] 1. Skin sensory receptors detect change in external environment. 2. Sends sensory neurons through PNS to CNS. 3. CNS stores, anaylzes and makes decision; sends down somatic motor neurons. 4. Somatic Motor Neurons go down from CNS to PNS through nerves towards musculoskeletal region and perform decision Sympathetic and Parasympathetic Divisions 1. Visceral sensory receptors detect change in environment. (Blood Pressure, Glucose levels, etc) 2. Send visceral sensory neurons through afferent pathways to CNS. 3. CNS stores, analyzes information and makes decision; sends down autonomic motor neurons down efferent pathways. 4. Visceral smooth muscles or cardiac muscle receives neuron signal and performs decision. Enteric Nervous System 1. Enteric sensory receptors detect change in GI tract environment. 2. ENS sends enteric motor neurons to the smooth muscle to perform decision made. 3. CNS can override ENS decisions [Neuron Structure] Dendrites: Tree-shaped extensions that receive electrical nerve impulses and send towards cell body. Cell Body: Axon: Tail-shaped structure that sends electrical nerve impulses away from Cell body. Myelin Sheath: Fatty tissue that surrounds axon; increase speed of electrical nerve impulse of axon. [Non-Nervous Cells in CNS] Astrocytes: - Star shaped cell - Found between blood vessels and neuron - Regulates what substances come into contact with neuron - Removes waste products - Serves as glue Oligodendrocytes: - Round, bulbous with cytoplasmic extensions - Creates myelin sheath Microglial Cells - Destroys viruses and bacteria from CNS Ependymal Cells - Cuboid, epithelial tissue - Lines specific cavities of [Non-Nervous Cells in PNS] Satellite Cells - Flat - Surrounds PNS Cell body within a Ganglion. - Remove waste products Schwann Cell - Flat - Covers axon of neuron with myelin [Multiple Sclerosis] - Immune cells attack Myelin Sheath of axon - Myelin sheath becomes hardened plaque - Progressive loss of motor functions to breakdown of Nervous System functions. - No cure only medication to slow down process. **[The Brain]** 3 Main Structures of the Brain - Forebrain - Midbrain - Hindbrain Structures of the Forebrain 1. Cerebrum a. White Matter: Neuron Cell Bodies b. Gray Matter: Axons of Neurons 2. Dark Gray Matter c. Thalamus d. Hypothalamus e. Basal Nuclei [Functions of the Forebrain] Thalamus: Passes sensory information to the Cerebrum from the Brain and the Spinal Cord. Hypothalamus: Regulates Autonomic Nervous system (involuntary motor signals) and Endocrine System. Basal Nuclei: - Sends involuntary motor signals to the Cerebrum from the brain and spinal cord. - Sends sensory signals to the Brain and spinal cord from the Cortex and Dark Gray Matter. Should I know composition of Basal Nuclei? [Lobes of the Brain] Frontal Lobe -- Front Parietal -- Top (near back) Occipital -- Back Temporal -- Side Insula -- Beneath lobes [Forebrain Tracts] Commissural Tract: Communication connection of the Right and Left hemisphere. Projection Tract: - A Longitudinal Tract: Goes along the hemisphere Arcuate Tract: Goes along a single lobe [Midbrain and Hindbrain Functions] Midbrain: - Auditory and visual reflexes - Eye movement Hindbrain - Pons: Regulates breathing - Medulla Oblongata: Regulates breathing, heart rate and blood pressure. - Cerebellum: coordinates motor actions - Has a Vermis: **[Meninges and Ventricles]** Dura Mater: - "tough mother" - Outermost, toughest layer Arachnoid Mater: - "spider mother" Subarachnoid Space - Space between arachnoid mater and pia mater filled with Cerebral spinal fluid (CSF) Pia Mater - " " - Innermost layer Dural Fold: Venous Sinus: Occurs when Fissure: **[Cranial Nerves]** Pneumonic Oh Oh Oh To Touch And Feel Very Good Fabric A(s) H Some Say Money Matters But My Big Brother Says Big Brain Matters More **Respiratory System Overview Part 1 ** - **Purpose**: - Deliver atmospheric oxygen to tissues. - Remove byproducts of respiration, primarily carbon dioxide. - **Components**: - **Upper Respiratory System**: - Nasal cavity, oral cavity, pharynx (throat), upper part of larynx (above vocal folds). - **Lower Respiratory System**: - Lower part of larynx (below vocal folds), trachea, bronchi, bronchioles, lungs. **Nasal Cavity** - **Function**: One of two entry points for inhaled air (other is the oral cavity). - **Anatomy**: - Divided into two halves by the **nasal septum**. - **Bones involved**: - **Vomer**: Central posterior bone. - **Ethmoid**: Upper bone contributing to septum and conchae. - **Maxilla and Nasal Bones**: Form upper nasal cavity structure. - External nose made of cartilage. - **Nasal Conchae**: - Three projections of bone per side: - **Superior Nasal Concha** (not visible in provided images). - **Middle Nasal Concha**. - **Inferior Nasal Concha** (independent bone). - Function: - Create grooves (spaces) beneath them called **nasal meatuses**. - Increase surface area of the nasal cavity. - **Nasal Meatuses**: - Spaces beneath conchae. - Purpose: - Facilitate warming, humidifying, and filtering of air. - Trap foreign particles. - **Mucous Membrane**: - Lines the nasal cavity and conchae. - Traps foreign particles (e.g., insects, dust, viruses). - Ensures particles are sneezed, blown out, or swallowed safely into the digestive system. - Protects the lungs from harmful particles or pathogens. - Warms and humidifies incoming air to prevent irritation in the pharynx and lower structures. - **Cold Air**: - Running or exercising in cold temperatures can bypass proper humidification, causing throat discomfort. **Air Flow and Filtration** - Air swirls around the conchae due to their shape. - This swirling: - Enhances filtration of foreign particles. - Optimizes warming and humidifying. - Ensures air quality before reaching lower respiratory structures. **Olfactory Receptors** - Located in the **nasal meatuses**. - Bind to particles carrying scents. - Connected to **cranial nerve I (olfactory nerve)**. - Transmit signals to the brain for smell perception. **Pharynx** - **Three Sections**: - **Nasopharynx**: Posterior to nasal cavity. - **Oropharynx**: Posterior to oral cavity. - **Laryngopharynx**: Posterior to the larynx. - Divides into: - **Esophagus** (digestive system). - **Larynx** (respiratory system). - **Shared Space**: - Air and food share the pharynx, creating a transition point for both systems. - Smooth muscle lining facilitates this dual-purpose function. **Oral Cavity** - **Structure**: - Located inferior to the nasal cavity. - **Divided by the Palate**: - **Hard Palate** (anterior): Formed by maxilla and palatine bones. - **Soft Palate** (posterior): Smooth muscle; includes uvula. - **Tongue**: Large, muscular organ filling most of the oral cavity. - **Functions**: - **Soft Palate**: Elevates during swallowing to block the nasopharynx, preventing food or drink from entering the nasal cavity. **Tonsils** - Part of the lymphatic system. - Help detect and fight infections. - Types: - **Pharyngeal Tonsils** (nasopharynx). - **Palatine Tonsils** (oropharynx; prone to infection, sometimes removed if chronically inflamed). - **Lingual Tonsils** (base of tongue). - Role: - Protect incoming air and food from harmful particles. **Epiglottis** - Cartilage structure in the larynx. - Function: - Covers the laryngeal opening during swallowing to direct food into the esophagus. - Prevents choking by keeping food out of the respiratory tract. **Auditory Tube (Eustachian Tube/Pharyngotympanic Tube)** - **Location**: Connects the nasopharynx to the middle ear. - **Function**: - Equalizes air pressure on the eardrum (e.g., during altitude changes like flying). - Default state is closed; opens during chewing, swallowing, or yawning. - Movements of the oral cavity assist in tube opening. - **Symptoms of Pressure Changes**: - Feeling of fullness or pressure in the ear. - Relief achieved by opening the auditory tube. **Paranasal Sinuses** - **Anatomy**: - Air-filled spaces in bones: frontal, ethmoid, sphenoid, maxilla. - Connected to the nasal cavity via small openings. - **Functions**: - Humidify and warm inhaled air. - Decrease the weight of the skull. - Assist in maintaining intracranial pressure. - **Clinical Note**: - Sinus infections lead to excess mucus, causing pressure and headaches. **Protective Mechanisms** 1. **Mucous Membranes**: - Trap foreign particles. - Warm and humidify air. 2. **Nasal Conchae and Meatuses**: - Increase filtration efficiency. - Enhance air quality. 3. **Soft Palate**: - Prevents food from entering the nasal cavity. 4. **Epiglottis**: - Directs food to the esophagus. - Keeps respiratory pathways clear. 5. **Auditory Tube**: - Prevents damage to the eardrum during rapid pressure changes. **Practical Examples** - Cold weather: - Rapid breathing causes inadequate warming and humidification. - Results in throat irritation and pain. - Swallowing: - Soft palate and epiglottis ensure food enters the digestive tract, not respiratory pathways. - Flying or altitude changes: - Opening the auditory tube helps equalize ear pressure. **Respiratory System Part 2 -- The Larynx** **Overview** - **Larynx Location**: - Found at the point where the respiratory and digestive systems split. - **Air Pathway**: - Air moves from the larynx to the trachea, eventually reaching the lungs. - Air exits the lungs via the larynx and moves through the nasal or oral cavity. - **Food Pathway**: - Food or liquid moves into the esophagus, bypassing the larynx. - Functions: - Respiratory passage. - Sound production (voice box). **Anatomy** 1. **General Structure**: - Covered in a **mucous membrane** in real-life anatomy, which is often omitted in diagrams for clarity. - Composed mainly of **cartilage** and **ligamentous membranes**, with minimal bone. - **Hyoid Bone**: - U-shaped (horseshoe-shaped). - Only bony component, located at the top of the larynx. 2. **Main Cartilages**: - **Thyroid Cartilage**: - Largest cartilage of the larynx. - Consists of two large plates joined anteriorly at the **laryngeal prominence (Adam's apple)**. - **Gender Differences**: - Larger and angled forward in males, making the Adam's apple more pronounced. - Present in females but less visible. - **Open posteriorly** (not a complete ring). - Connected to the hyoid bone via a ligamentous membrane. - **Cricoid Cartilage**: - Located inferior to the thyroid cartilage. - Forms a **complete ring**: - Narrow anteriorly. - Broad posteriorly. - **Epiglottis**: - Fan-shaped cartilage. - Covers the larynx during swallowing, preventing food entry into the respiratory tract. - Attached to the **interior surface of the thyroid cartilage** via a ligament. 3. **Paired Cartilages**: - **Arytenoid Cartilages**: - Pyramid-shaped. - Located on top of the cricoid cartilage. - Form **cricoarytenoid joints**, allowing movement. - Key landmarks: - **Vocal Process**: Point of attachment for vocal ligaments. - **Muscular Process**: Attachment site for small muscles controlling movement. - **Cuneiform and Corniculate Cartilages**: - Minor cartilages providing structural support. - Not emphasized in detail. **Joints and Ligaments** 1. **Cricothyroid Joint**: - Found between the cricoid and thyroid cartilages. - Allows **tilting** of the thyroid cartilage: - Forward tilt: Stretches vocal ligaments → increases pitch. - Backward tilt: Relaxes vocal ligaments → lowers pitch. 2. **Cricothyroid Membrane**: - Connects cricoid cartilage to thyroid cartilage. - Forms the foundation of the vocal folds (with vocal ligaments and mucous membrane). 3. **Vocal Ligaments**: - Attach from the arytenoid cartilages to the thyroid cartilage. - Core structure of the **vocal folds**. 4. **Vocal Folds**: - Composed of vocal ligaments, cricothyroid membrane, and mucous membrane. - Appear as "theater curtains" when covered with mucous membrane. - States: - **Abduction** (open): For breathing. - **Adduction** (closed): For sound production or preventing food entry. - **Glottis**: - Space between vocal folds. - Open during breathing, closed during swallowing or sound production. **Functions of the Larynx** 1. **Respiratory Protection**: - **Epiglottis**: - Drops during swallowing to cover the laryngeal opening, preventing food entry. - **Vocal Folds**: - Adduct during swallowing to provide a secondary barrier. 2. **Sound Production**: - Produced by the vibration of the **vocal folds** when air is forced through them. - Pitch modulation: - **Higher pitch**: - Faster vibration. - Smaller space between vocal folds. - Stretched vocal ligaments (via cricothyroid joint). - **Lower pitch**: - Slower vibration. - Larger space between vocal folds. - Relaxed vocal ligaments. - **Sex Differences**: - Males: - Larger larynx. - Longer vocal ligaments. - Deeper voices. 3. **Movements of the Arytenoid Cartilages**: - Controlled by muscles attached to the muscular processes. - **Adduction**: - Closes vocal folds for sound production or to protect the airway. - **Abduction**: - Opens vocal folds for breathing. **Key Terminology** - **Laryngeal Prominence (Adam's Apple)**: - Visible anterior projection of the thyroid cartilage. - **Glottis**: - Space between the vocal folds. - Open or closed depending on the state of the vocal folds. - **Vocal Ligament**: - Core structure of the vocal folds. **Visual Orientation** 1. **Anterior View**: - Shows thyroid and cricoid cartilages. - Epiglottis visible at the top. 2. **Posterior View**: - Highlights arytenoid cartilages and their positioning on the cricoid cartilage. 3. **Superior View**: - Air's perspective entering the larynx. - Shows open/closed glottis and vocal fold positioning. **Additional Insights** 1. **Hyoid Bone**: - Facilitates movement and anchoring of laryngeal structures. 2. **Mucous Membrane**: - Adds elasticity and functional smoothness to the vocal folds. 3. **Laryngeal Variability**: - Opera singers modulate pitch through precise control of vocal fold tension and vibration speed. **Summary** - The larynx plays a dual role in respiratory protection and sound production. - Its cartilage structures, ligaments, and joints allow for complex movements essential for voice modulation and airway management. - Understanding the anatomy and functions of the larynx provides insight into both physiological processes and clinical implications. **Respiratory System Part 3 -- The Trachea and Lungs** **Overview** - **Transition to Lower Respiratory System**: - **Cutoff**: Everything below the **vocal folds** in the larynx is classified as the lower respiratory system. - Begins with the **trachea**. **Trachea** 1. **Structure**: - A solid, hollow tube supported by **cartilaginous rings**. - Rings are connected by **ligamentous membranes**. - Located inferior to the larynx and anterior to the esophagus. 2. **Bifurcation**: - Occurs at the **sternal angle** (junction of the **manubrium** and the body of the **sternum**). - At the **Carina** (split point), the trachea divides into: - **Right primary bronchus**. - **Left primary bronchus**. **Primary Bronchi** 1. **Right Main Bronchus**: - Shorter and points more vertically downward. - More likely to receive foreign bodies (e.g., pathogens) due to the straighter pathway. 2. **Left Main Bronchus**: - Longer and more horizontal to accommodate the heart's position. **Bronchial Tree** 1. **Branching**: - **Primary Bronchi**: - Enter the lungs. - **Lobar (Secondary) Bronchi**: - Right lung: 3 lobar bronchi (one per lobe). - Left lung: 2 lobar bronchi (one per lobe). - **Segmental (Tertiary) Bronchi**: - Further subdivide within each lobe. - **Bronchioles**: - Smaller airways. - **Terminal Bronchioles**: - Final bronchioles before reaching the respiratory zone. - **Respiratory Bronchioles**: - Lead to **alveoli**, where gas exchange occurs. 2. **Clinical Note**: - Know the lobar bronchi divisions (3 in right lung, 2 in left). - No need to memorize smaller subdivisions. **Alveoli** 1. **Structure**: - Resemble clusters of grapes. - Very thin-walled sacs. - Surrounded by **capillaries**. 2. **Function**: - Site of gas exchange. - **Pulmonary arteries**: - Bring deoxygenated blood to alveoli. - High in carbon dioxide, low in oxygen. - **Pulmonary veins**: - Carry oxygenated blood away from alveoli. - High in oxygen, low in carbon dioxide. **Lungs** 1. **Overview**: - **Right Lung**: - Larger, with three lobes: - **Superior Lobe**. - **Middle Lobe**. - **Inferior Lobe**. - Divided by: - **Oblique Fissure**: Separates superior/middle from inferior lobes. - **Horizontal Fissure**: Separates superior from middle lobe. - **Left Lung**: - Smaller, with two lobes: - **Superior Lobe**. - **Inferior Lobe**. - Divided by: - **Oblique Fissure**: Separates the two lobes. - Includes **cardiac impression** to accommodate the heart. **Pleural Membranes** 1. **Structure**: - **Parietal Pleura**: Outer layer, lines the thoracic cavity. - **Visceral Pleura**: Inner layer, directly covers the lungs. - **Pleural Cavity**: - Space between the two layers. - Allows for lung expansion during breathing. - Contains **serous fluid** to reduce friction during movement. 2. **Function**: - Enables smooth lung expansion and contraction. **Lung Root and Hilum** 1. **Root of the Lung**: - Collection of structures entering/exiting the lung: - **Main or lobar bronchi**. - **Pulmonary arteries**. - **Pulmonary veins**. 2. **Hilum**: - The specific area on the lung where the root structures pass through. **Clinical Notes** 1. **Lung Size Differences**: - Right lung is larger due to the heart occupying space on the left. - Left lung has a smaller capacity. 2. **Foreign Bodies**: - Right lung is more prone to foreign body entry due to the straighter pathway of the right main bronchus. 3. **Gas Exchange**: - Occurs efficiently at the alveoli due to their thin walls and proximity to capillaries. **Key Definitions** - **Carina**: Point of tracheal bifurcation into the primary bronchi. - **Lobar Bronchi**: Bronchi serving each lobe of the lung (3 in right lung, 2 in left lung). - **Pleural Cavity**: Space between parietal and visceral pleura, filled with serous fluid. - **Root of the Lung**: Collective structures entering/exiting the lung. - **Hilum**: The physical area on the lung where the root is located. **Lung Surface Markings** - **Lateral Surface**: - Faces outward toward ribs. - Smooth. - **Medial Surface**: - Faces inward toward the heart. - Includes cardiac impression and other markings from nearby vessels. **Summary** - The trachea and lungs form the lower respiratory system, beginning below the vocal folds. - Air flows through a branching structure: trachea → primary bronchi → lobar bronchi → segmental bronchi → bronchioles → alveoli. - The lungs are protected by pleural membranes, which allow for smooth respiratory movement. - Gas exchange occurs at the alveoli, facilitated by the proximity of capillaries. - The right lung is larger and has three lobes; the left lung is smaller with two lobes, accommodating the heart. **Overview** - The male reproductive system involves the production of sperm and testosterone (male sex hormone) and the delivery of sperm to the female reproductive system. - Components include the testes, epididymis, ductus deferens, accessory glands (prostate, seminal vesicles, bulbourethral glands), and penis. **Sagittal Section Overview** - **Posterior structures**: - Rectum: End of the large intestine, leading to the anus. - Sacrum: Bone posterior to the rectum. - **Anterior structures**: - **Urinary bladder**: Stores urine; located anterior to the rectum. - **Pubic symphysis**: Cartilage connecting the pelvic bones; anterior to the bladder. - **Reproductive-specific structures**: - **Testes**: Male gonads for sperm and testosterone production. - **Epididymis**: Coiled structure where sperm mature. - **Ductus deferens**: Transports sperm from the epididymis. - **Seminal vesicles**: Secretes fluid that nourishes sperm. - **Prostate gland**: Adds fluids to sperm to form ejaculate. - **Penis**: - **Root**: Internal portion attached to the body. - **Body**: External portion of the penis. **Testes and Scrotum** 1. **Testes**: - **Primary functions**: - **Sperm production**: Occurs in seminiferous tubules. - **Testosterone secretion**: Acts locally and systemically. - **Endocrine function**: Classified as accessory endocrine glands because testosterone affects other systems. - Structure: - Protected by a **double-layered sac** and smooth muscle. - Enclosed within the **scrotum**. 2. **Scrotum**: - External sac that holds the testes. - Maintains the optimal temperature (\~2--3°C cooler than body temperature) for sperm development. - Contains **smooth muscle**: - Contracts to pull the testes closer in cold conditions. - Relaxes in warm conditions or during physical activity. **Sperm Development Pathway** 1. **Seminiferous Tubules**: - Initial site of sperm production. 2. **Straight Tubules**: - Collect sperm from seminiferous tubules. 3. **Rete Testes**: - Network of interconnecting tubules. 4. **Efferent Ducts**: - Transport sperm to the epididymis. 5. **Epididymis**: - **Head, body, and tail regions**. - Sperm mature and gain motility over 2--3 months. 6. **Ductus Deferens (Vas Deferens)**: - Carries sperm to the ejaculatory duct during ejaculation. **Spermatic Cord** - Contains: - **Ductus deferens**. - Nerves, arteries, veins, and lymphatic vessels. - Travels through the scrotum into the abdominal cavity. - Provides structural and vascular support to the testes. **Pathway to Ejaculation** 1. **Ductus Deferens**: - Travels over the bladder to the posterior side. - Expands at the **ampulla** to connect with the seminal vesicles. 2. **Seminal Vesicles**: - Produce fluid rich in fructose to nourish sperm. - Fluid combines with sperm in the **ejaculatory duct**. 3. **Ejaculatory Duct**: - Formed by the ductus deferens and seminal vesicles. - Passes through the **prostate gland**. 4. **Prostate Gland**: - Adds enzymes and nutrients to sperm. - Produces fluid that contributes to ejaculate volume. 5. **Bulbourethral (Cowper's) Glands**: - Located at the membranous urethra. - Secrete pre-ejaculatory fluid to: - Lubricate the urethra. - Neutralize traces of urine. 6. **Urethra**: - Common pathway for sperm and urine. - Sections: - **Prostatic urethra**: Within the prostate. - **Membranous urethra**: Short segment near the pelvic floor. - **Spongy (Penile) urethra**: Runs through the penis to the external urethral opening. **Penis** 1. **Internal Structures**: - **Root**: Internal portion attached to: - **Bulb**: Connects to pelvic floor muscles. - **Crura (plural)**: Lateral extensions attached to pubic bones. 2. **External Structures**: - **Body**: Composed of erectile tissue: - **Corpus Spongiosum**: - Surrounds the urethra. - Forms the **glans penis** at the tip. - **Corpora Cavernosa** (paired): - Responsible for erection. 3. **Erection**: - Triggered by the **sympathetic nervous system**. - Blood fills erectile tissues (corpora cavernosa and corpus spongiosum), causing rigidity and enlargement. **Key Terminology** - **Ejaculate**: Mixture of sperm and fluids from accessory glands. - **Sympathetic Nervous System**: Controls erection and ejaculation. - **Prostatic Urethra**: Intersection of reproductive and urinary systems in males. **Summary** - The male reproductive system is specialized for sperm production, maturation, and delivery. - Testes and scrotum regulate temperature and protect developing sperm. - Sperm mature in the epididymis and travel through the ductus deferens, where fluids are added by the seminal vesicles, prostate gland, and bulbourethral glands. - The penis facilitates the delivery of sperm to the female reproductive system. **Female Reproductive System** **Sagittal View Overview** 1. **Orientation**: - **Pubic Symphysis**: Anterior-most cartilage joint. - **Urinary Bladder**: - Smaller in females compared to males. - Shorter **urethra** increases the likelihood of urinary tract infections (UTIs). - Opens at the **external urethral orifice**. - **Uterus**: - Located posterior to the bladder. - Supports fetal development if fertilization occurs. - Opens into the **cervix** (lower, narrow section) and then the **vagina**. - **Ovaries**: - Lateral to the uterus. - Produce ova (eggs) and female sex hormones (estrogen and progesterone). - Connected to the uterus by the **uterine (fallopian) tubes**. - **Rectum and Anus**: Posterior structures. **Detailed Anatomy of the Uterus** 1. **Major Regions**: - **Fundus**: Dome-shaped uppermost region. - **Body**: Main central part. - **Cervix**: Inferior, narrow part opening into the vagina. - Connects the uterus to the external environment through the **vaginal canal**. 2. **Wall Structure**: - Composed of **smooth muscle** to facilitate contractions during childbirth. 3. **Associated Ligaments**: - **Ovarian Ligament**: Connects the ovaries to the uterus. - **Suspensory Ligament**: Connects ovaries to the pelvic wall; contains ovarian blood vessels and nerves. - **Broad Ligament**: - Sheet of **parietal peritoneum** covering the uterus, uterine tubes, and ovaries. - Attaches to the posterior abdominal wall, providing support. **Ovaries and Uterine Tubes** 1. **Ovaries**: - Female gonads; homologous to male testes. - Produce **oocytes** (eggs) and female sex hormones (**estrogen** and **progesterone**). 2. **Uterine Tubes (Fallopian Tubes)**: - Function: - Capture the oocyte released from the ovary during ovulation. - Site of **fertilization** (usually in the ampulla of the tube). - Transport fertilized ovum to the uterus. - Structures: - **Fimbriae**: Finger-like projections that catch the ovum. - **Infundibulum**: Funnel-shaped opening near the ovary. - Tube sections lead toward the uterus. **External Genitalia (Vulva)** 1. **Labia**: - **Labia Minora**: - Thin skin folds bordering the **vestibule**. - Homologous to the skin of the penis. - **Labia Majora**: - Later to labia minora - Thicker external folds of skin and connective tissue. - Homologous to the male scrotum. 2. **Mons Pubis**: (anterior to vestibule)  - Fatty tissue anterior to the vulva. - Provides protection for the area. 3. **Structures within the Vestibule**: - **Clitoris**: - Erectile tissue; homologous to the male penis. - Becomes engorged with blood during sexual stimulation. - **External Urethral Orifice**: - Opening of the urinary tract. - **Vaginal Orifice**: - Opening of the vagina. - May be covered by a thin membrane called the **hymen** at birth, which typically breaks during the first sexual experience. **Perineum** 1. **Definition**: - Diamond-shaped area on the pelvic floor containing openings for the urinary, digestive, and reproductive systems. - Divided into: - **Urogenital Triangle**: Contains external genitalia and reproductive openings. - **Anal Triangle**: Contains the anus and external anal sphincter. 2. **Borders**: - Anterior: Pubic symphysis. - Lateral: Ischial tuberosities. - Posterior: Coccyx. 3. **Internal Structures**: - **Bulb of the Vestibule**: - Erectile tissue lateral to the vaginal opening. - Homologous to the **bulb of the penis** and **corpus spongiosum**. - **Greater Vestibular Glands**: - Located posterior and lateral to the vestibule. - Homologous to **bulbourethral glands** in males. - Secrete lubricating fluid to cleanse and protect the vagina. **Mammary Glands** 1. **Anatomy**: - Located lateral to the sternum, extending from ribs 2 to 6. - Composed of: - **Adipose Tissue** (yellow): Fat tissue. - **Lactiferous Glands**: Glandular tissue that produces milk. - **Lactiferous Ducts**: Transport milk to the nipple. 2. **Function**: - Stimulated by hormones during pregnancy and breastfeeding. - Milk ejection is triggered by hormonal signals during infant suckling. 3. **Areola**: - Darkened pigmented area surrounding the nipple. - Contains sweat and oil glands to protect the sensitive tissue during breastfeeding. **Key Homologies Between Male and Female Structures** - **Testes** ↔ **Ovaries**: Produce germ cells (sperm vs. oocytes) and sex hormones. - **Penis** ↔ **Clitoris**: Erectile tissue. - **Scrotum** ↔ **Labia Majora**: Protective external folds. - **Bulbourethral Glands** ↔ **Greater Vestibular Glands**: Secrete lubricating fluids. - **Corpus Spongiosum** ↔ **Bulb of the Vestibule**: Erectile tissue near the reproductive opening. **Summary** - The female reproductive system supports ovum production, fertilization, fetal development, and childbirth. - External genitalia provide protection and facilitate reproduction, while internal structures, like the uterus and ovaries, play critical roles in these processes. - The mammary glands provide nourishment to the newborn during breastfeeding. **Purpose of the Urinary System** - **Primary Function**: - **Filtration of blood** to remove waste products and excess substances. - Produces and expels **urine** to eliminate these substances. - **Key Organs**: - **Kidneys**: Main site of filtration. - **Ureters**: Transport urine to the bladder. - **Bladder**: Stores urine. - **Urethra**: Expels urine from the body. **Kidneys** 1. **Location**: - **Retroperitoneal**: Positioned at the back of the abdomen. - **Right Kidney**: - Lower than the left due to the **liver** sitting above it. - Less rib protection compared to the left. - **Left Kidney**: - More protection from the bottom ribs. 2. **Protection**: - Surrounded by a **fibrous capsule**. - Encased in a layer of **peri-renal fat** for cushioning. 3. **Blood Supply**: - **Renal Arteries**: Branch from the abdominal aorta. - **Renal Veins**: Drain directly into the inferior vena cava. 4. **Urine Formation and Transport**: - Urine exits through the **ureters**, which connect to the bladder. 5. **Adrenal Glands**: - Located on top of each kidney. - **Endocrine glands**: Produce hormones that affect functions throughout the body. **Internal Kidney Structure** 1. **Hilum**: - Medial area where the **renal artery**, **renal vein**, and **ureter** enter/exit. 2. **Renal Sinus**: - Yellow, fatty region inside the kidney that holds calyces, renal pelvis, and vessels. 3. **Functional Region (Cortex and Medulla)**: - **Blood Filtration**: 1. Filters blood to remove waste while returning necessary components. - Waste destined for urine travels through the following pathway: 2. **Renal Pyramids** (functional structures). 3. **Minor Calyces** (8--15 per kidney). 4. **Major Calyces** (2--3 per kidney). 5. **Renal Pelvis**: Connects to the **ureter**. **Ureters** - **Structure**: - Long tubes that transport urine from the kidneys to the bladder. - Enter the bladder at the posterior. **Urinary Bladder** 1. **Location**: - Positioned in the pelvic cavity. - In females: - Uterus sits on top of the bladder. - In males: - No uterus, so the bladder has more space. 2. **Function**: - **Storage**: - Holds urine until expulsion. - Expands due to its elastic smooth muscle walls (**detrusor muscle**). 3. **Internal Structure**: - Smooth muscle in the walls allows contraction to push urine out. - Urine exits via the **urethra**. 4. **Sphincters**: - **Internal Urethral Sphincter**: - Located at the bladder's base. - **Involuntary control** (smooth muscle). - **External Urethral Sphincter**: - Located lower along the urethra. - **Voluntary control** (skeletal muscle). - Allows for conscious control over urination. **Urethra** 1. **Differences by Sex**: - **Female Urethra**: - Shorter (\~4 cm). - Increases susceptibility to **urinary tract infections (UTIs)** due to the shorter pathway for bacteria. - **Male Urethra**: - Longer (\~20 cm), passes through the penis. - Differences will be detailed in reproductive system videos. 2. **Function**: - Transports urine from the bladder to the external environment. **Clinical Note** 1. **UTIs in Females**: - Shorter urethra increases risk of infection. - Commonly caused by bacteria traveling from the urethral opening to the bladder or higher. 2. **Protection for Kidneys**: - Fibrous capsule and peri-renal fat provide significant cushioning. - Rib protection is asymmetrical (left kidney more protected than the right). **Summary** - The urinary system\'s main task is to filter blood and remove waste products as urine. - **Kidneys** are the central organs, performing blood filtration and urine production. - Urine travels via **ureters** to the **bladder** for storage, then through the **urethra** for excretion. - Differences between male and female urinary anatomy have clinical implications, particularly regarding UTIs in females. - The system is supported by structural and functional components such as the **renal fat**, **capsules**, and specialized **muscles** in the bladder and urethra. **Urinary System Part 2 (Kidney Focus)** **Overview of the Urinary System** - **Primary Function**: - **Filtration and purification** of blood. - Excretion of unwanted substances as **urine**. - **Main Components**: - **Kidneys**: The site of blood filtration. - **Ureters**: Transport urine from kidneys to the bladder. - **Bladder**: Stores urine. - **Urethra**: Pathway for urine excretion. **Kidney Anatomy** 1. **External Anatomy**: - **Renal Cortex**: - Light-colored, outermost layer. - Covered by a **fibrous capsule** for protection. - **Renal Medulla**: - Inner, darker region containing **renal pyramids**. - **Renal Columns**: Extensions of cortex tissue between pyramids. - **Renal Papilla**: - The tip of each pyramid where urine collects before exiting into minor calyces. 2. **Internal Structures**: - **Hilum**: - Entry and exit site for: - **Renal Artery**: Delivers blood to the kidney. - **Renal Vein**: Drains filtered blood. - **Ureter**: Transports urine to the bladder. - **Renal Sinus**: - Central cavity housing: - **Minor Calyces** (8--15): Collect urine from renal papillae. - **Major Calyces** (2--3): Formed by merging minor calyces. - **Renal Pelvis**: Collects urine before it enters the ureter. **Filtration and Urine Formation** - **Functional Unit**: **Nephron**. - Each kidney contains \~2.5 million nephrons. - Responsible for filtering blood and forming urine. 1. **Blood Flow into the Nephron**: - **Afferent Arteriole**: - Brings blood into the nephron. - Branches from the **renal artery**. - **Glomerulus**: - A network of capillaries within **Bowman's (glomerular) capsule**. - Filters small molecules (e.g., water, ions, metabolites) into the capsule. - **Efferent Arteriole**: - Carries blood away after filtration. - Branches into **peritubular capillaries** that surround the nephron. 2. **Pathway of Filtrate**: - **Bowman's Capsule**: - Initial site where filtrate (fluid from blood) collects. - **Proximal Convoluted Tubule (PCT)**: - Site of **most reabsorption** (water, ions, glucose, amino acids). - **Nephron Loop (Loop of Henle)**: - **Descending Limb**: Reabsorbs water. - **Ascending Limb**: Reabsorbs ions (e.g., Na+, Cl−). - **Distal Convoluted Tubule (DCT)**: - Fine-tunes the reabsorption and secretion processes. - **Collecting Duct**: - Collects final filtrate (now urine). - Urine exits the nephron and flows through the renal pyramid towards the **renal papilla**. 3. **Final Pathway of Urine**: - From collecting duct → Minor Calyx → Major Calyx → Renal Pelvis → Ureter → Bladder. **Blood Regulation by the Kidney** - **Reabsorption**: - Restores useful substances (water, ions, glucose) to the blood. - Occurs at various nephron segments (e.g., PCT, nephron loop). - **Secretion**: - Removes unwanted substances (e.g., H+, K+, toxins) from the blood into the nephron. - **Key Structures**: - **Peritubular Capillaries**: - Surround the nephron for reabsorption and secretion. - Transition into veins that merge into the **renal vein**. - **Renal Vein**: - Carries filtered, balanced blood back to the **inferior vena cava**. **Nephron Function Details** 1. **Filtration**: - Occurs in the **glomerulus**. - Filters small molecules like water, electrolytes, and waste products into Bowman's capsule. - Larger molecules (e.g., red blood cells, proteins) remain in the blood. 2. **Processing of Filtrate**: - **Proximal Convoluted Tubule**: - Reabsorbs \~65--70% of water and solutes. - **Nephron Loop**: - Descending limb: Water reabsorption via osmosis. - Ascending limb: Active transport of ions. - **Distal Convoluted Tubule**: - Adjusts ion concentrations. - **Collecting Duct**: - Final adjustment of urine composition. - Directed by hormones (e.g., ADH for water reabsorption). **Key Notes on Blood and Urine Flow** 1. **Blood Pathway**: - Renal Artery → Afferent Arteriole → Glomerulus → Efferent Arteriole → Peritubular Capillaries → Renal Vein → Inferior Vena Cava. 2. **Filtrate and Urine Pathway**: - Bowman's Capsule → Proximal Tubule → Nephron Loop → Distal Tubule → Collecting Duct → Renal Papilla → Minor Calyx → Major Calyx → Renal Pelvis → Ureter → Bladder. **Important Terminology** - **Filtrate**: Initial fluid extracted from blood in the nephron. - **Urine**: Final waste product leaving the nephron. - **Peritubular Capillaries**: Blood vessels surrounding the nephron for reabsorption. - **Minor/Major Calyx**: Structures collecting urine from pyramids. - **Renal Papilla**: Tip of the pyramid, entry to the minor calyx. **Summary** - The kidney constantly filters blood to maintain homeostasis. - Nephrons perform the core functions of filtration, reabsorption, and secretion. - Blood flow ensures nutrient exchange and waste removal. - Urine formation is a detailed process balancing body needs with waste excretion. Processed blood exits via the **renal vein**, while urine is excreted through the ureter. **Digestive System Part 1 -- The Oral Cavity** **Overview of the Digestive System** 1. **Path of Food (Gastrointestinal/Alimentary Tract)**: - Starts in the **oral cavity**. - Moves to the **pharynx**, then the **esophagus**. - Passes through the **diaphragm** to the **stomach**. - Proceeds to the **small intestine**: - **Duodenum** (C-shaped, first part). - **Jejunum** (middle, squiggly section). - **Ileum** (last section, empties into the large intestine). - Enters the **large intestine (colon)**: - Starts at the **cecum** (appendix located here). - Travels up, across, and down. - Ends in the **rectum** and **anus** (undigested material is excreted). 2. **Accessory Digestive Organs**: - Food doesn't pass through these organs. - Contribute to digestion via chemical secretions. - Examples: **Salivary glands**, **liver**, **pancreas**, **gallbladder**. **Teeth** 1. **Primary (Deciduous) Teeth**: - Also called **milk teeth** or **baby teeth**. - Total: **20 teeth** (10 upper, 10 lower). - Types: - **4 incisors** (front teeth). - **2 canines** (one on each side). - **4 molars** (two on each side). - Timeline: Present in children under \~6 years old; replaced by permanent teeth. 2. **Permanent (Adult) Teeth**: - Total: **32 teeth** (16 upper, 16 lower). - Types: - **4 incisors** (same as primary). - **2 canines** (same as primary). - **4 premolars** (new addition, also called bicuspids). - **6 molars** (includes 2 new sets and the **third molars/wisdom teeth**). - Wisdom teeth: - Appear around age 20 (or earlier). - Often removed due to space or hygiene issues. - Evolutionary purpose: Grinding vegetation in early human diets. **Salivary Glands** 1. **Types**: - **Parotid Glands**: - Location: Anterior and inferior to the ear. - Duct pierces cheek muscles to enter the oral cavity. - **Submandibular Glands**: - Location: Floor of the mouth, beneath the mandible. - Ducts open under the tongue near the frenulum. - **Sublingual Glands**: - Location: Beneath the tongue. - Contains multiple ducts opening in the floor of the mouth. 2. **Functions**: - Produce **saliva**: - Mainly water-based. - Contains **digestive enzymes** for chemical breakdown of food. - Initiates **chemical digestion** in the oral cavity. - Saliva aids in swallowing and food lubrication. 3. **Gland Classification**: - **Exocrine glands**: - Contain ducts that transport secretions to the oral cavity. - **Endocrine glands** (for comparison): - Release substances (e.g., hormones) directly into the bloodstream. **Oral Cavity and Mechanical Breakdown** 1. **Role of Teeth**: - Crush food into smaller pieces for easier swallowing. - Increase surface area for enzymes to act upon food. 2. **Role of the Tongue**: - **Functions**: - Positions food for chewing. - Moves food to teeth for thorough breakdown. - Aids in speech and pronunciation. - **Structure**: - Attached to the floor of the mouth by the **frenulum**. - Tip is highly mobile for manipulation of food. - **Surface**: - Covered in small bumps called **papillae**. - **Types of Papillae**: - Assist in food breakdown and cleaning teeth (e.g., removing food stuck in molars). - Some contain **taste buds**, which detect food chemicals. **Digestive Processes in the Oral Cavity** 1. **Mechanical Digestion**: - Food is crushed by teeth and manipulated by the tongue. - Prepares food for chemical digestion and easier swallowing. 2. **Chemical Digestion**: - Begins with **digestive enzymes** in saliva. - Salivary enzymes start breaking down chemical bonds in food. 3. **Importance of Digestion in Oral Cavity**: - Reduces food to smaller particles for easier swallowing. - Ensures proper preparation for absorption in the small intestine. **Key Histological Features** 1. **Salivary Glands**: - Contain epithelial cells that produce: - Mucus. - Digestive enzymes. - Branching ducts transport saliva to the oral cavity. 2. **Duct Openings**: - **Parotid ducts**: Open inside the cheek. - **Submandibular ducts**: Open under the tongue near the frenulum. - **Sublingual ducts**: Multiple openings under the tongue. **Key Definitions** - **Alimentary Tract**: Path of food from oral cavity to anus. - **Papillae**: Small bumps on the tongue; some aid in digestion, others contain taste buds. - **Frenulum**: Connective tissue anchoring the tongue to the floor of the mouth. - **Exocrine Glands**: Glands with ducts to deliver secretions to specific locations. **Clinical and Evolutionary Notes** 1. **Wisdom Teeth**: - No longer necessary for most diets. - Commonly removed to prevent dental crowding or decay. 2. **Role of Papillae**: - Specific papillae types help remove food stuck in teeth (e.g., molars). 3. **Caveman Diet**: - Evolutionary need for additional molars to grind fibrous foods like vegetation. **Summary** - The oral cavity is the starting point of digestion, involving both mechanical (teeth, tongue) and chemical (saliva) processes. - Salivary glands play a critical role in initiating digestion by releasing enzymes. - Teeth evolve from 20 primary teeth in children to 32 permanent teeth in adults, with additional molars (wisdom teeth). - The tongue is multifunctional, aiding in food manipulation, digestion, and speech. - Papillae on the tongue are specialized for various functions, including taste and cleaning. **Digestive System Part 2 -- The Gastrointestinal Tract Beyond the Oral Cavity** **Overview** - Continues the journey of food from the **oral cavity** through the gastrointestinal (GI) tract. - Focuses on the **pharynx**, **esophagus**, **stomach**, **small intestine**, and **large intestine**. **Pharynx** 1. **Regions**: - **Oropharynx**: Receives food from the oral cavity. - **Laryngopharynx**: Transition point where: - The **epiglottis** drops to block entry into the larynx, directing food into the esophagus. 2. **Function**: - Facilitates the movement of food while preventing it from entering the respiratory tract. **Esophagus** 1. **Structure**: - A smooth muscle tube with two layers of muscle: - **Circular muscles**: Surround the esophagus, contract behind the food (bolus). - **Longitudinal muscles**: Run along the length, contract in a wave-like motion to push the bolus downward. - These coordinated movements are called **peristalsis**. 2. **Lower Esophageal Sphincter**: - Also called the **cardiac sphincter** (near the heart). - **Function**: - Opens to allow the bolus to enter the stomach. - Closes to prevent stomach contents from regurgitating into the esophagus. **Stomach** 1. **Regions**: - **Cardia**: Entry point of food from the esophagus. - **Fundus**: Uppermost region. - **Body**: Largest region, where most breakdown occurs. - **Pyloric Antrum**: Narrowing section leading to the pyloric canal. - **Pyloric Canal**: Leads to the pyloric sphincter and small intestine. - **Curvatures**: - **Lesser Curvature**: Superior, concave side. - **Greater Curvature**: Inferior, convex side. 2. **Functions**: - **Mechanical Breakdown**: - Three layers of smooth muscle fibers (in different directions) crush and slosh the bolus. - **Chemical Breakdown**: - **Rugae** (internal folds): Contain **gastric pits** with various cells producing substances for digestion. 3. **Gastric Pit Cells**: - **Surface Mucous Cells and Mucous Neck Cells**: - Secrete mucus to lubricate and protect the stomach lining. - **Parietal Cells**: - Produce **hydrochloric acid (HCl)**: Lowers pH for protein digestion. - Produce **intrinsic factor**: Essential for vitamin B12 absorption. - **Chief and G Cells**: - Secrete digestive enzymes for breaking down food. 4. **Clinical Notes**: - **Heartburn**: - Occurs when stomach acid enters the esophagus due to improper sphincter closure. - **Gastroesophageal Reflux Disease (GERD)**: - Chronic acid reflux causing damage to the esophagus. 5. **Transition to Small Intestine**: - Food, now a semi-liquid **chyme**, exits the stomach through the **pyloric sphincter** into the **duodenum**. **Small Intestine** 1. **Structure**: - **Duodenum**: - First, C-shaped segment. - Less than 1 foot long. - **Jejunum**: - Second segment. - \~3 feet long. - **Ileum**: - Final segment. - \~6 feet long. 2. **Functions**: - **Absorption of Nutrients**: - Nutrients broken down into molecular components. - Absorbed into the bloodstream via diffusion. - **Maximizing Surface Area**: - **Villi**: Small finger-like projections on the intestinal walls. - **Microvilli**: Even smaller projections on the villi. - Increases surface area for nutrient absorption. - **Blood Supply**: - Nutrient-rich blood flows to the **liver** for detoxification before entering general circulation. **Large Intestine** 1. **Structure**: - Begins at the **cecum** (receives material from the ileum via the ileocecal sphincter). - Includes: - **Ascending Colon**: Travels up the right side of the abdomen. - **Right Colic (Hepatic) Flexure**: Sharp turn near the liver. - **Transverse Colon**: Crosses the abdomen. - **Left Colic (Splenic) Flexure**: Sharp turn near the spleen. - **Descending Colon**: Travels down the left side of the abdomen. - **Sigmoid Colon**: S-shaped curve leading to the rectum. - Ends at the **rectum** and **anal canal**. 2. **Functions**: - Absorbs **water** and **vitamins**. - Compacts undigested material and waste products into feces. 3. **Appendix**: - Located at the **cecum**. - Immune function: Recognizes bacteria and signals the immune system. - Often removed if inflamed (**appendicitis**). **Rectum and Anal Canal** 1. **Structure**: - **Rectum**: Connects sigmoid colon to the anal canal. - **Anal Canal**: - Final 1--1.5 inches of the GI tract. - Ends at the **anus** (external opening). 2. **Control Mechanisms**: - **Internal Anal Sphincter**: - Involuntary smooth muscle. - Opens automatically when feces arrive. - **External Anal Sphincter**: - Voluntary skeletal muscle. - Allows conscious control over defecation. **Key Definitions** - **Bolus**: Semi-chewed food that moves through the GI tract. - **Peristalsis**: Wave-like muscle contractions that propel food. - **Chyme**: Semi-liquid food mass produced in the stomach. - **Villi/Microvilli**: Structures in the small intestine that maximize nutrient absorption. - **Rugae**: Folds in the stomach lining containing gastric pits. - **Ileocecal Sphincter**: Controls passage from small to large intestine. - **Appendix**: Immune-related organ at the cecum, not essential for survival. **Clinical Notes** 1. **Heartburn/GERD**: - Caused by stomach acid entering the esophagus. 2. **Appendicitis**: - Inflammation of the appendix, requiring removal. 3. **Vitamin B12 Absorption**: - Dependent on intrinsic factor produced by parietal cells. **Summary** - Food travels through the GI tract undergoing mechanical and chemical breakdown. - Key digestive organs and processes: - Esophagus: Peristalsis moves bolus to stomach. - Stomach: Chyme formation via muscular and chemical digestion. - Small Intestine: Absorbs nutrients with a highly specialized surface area. - Large Intestine: Absorbs water, forms feces, and hosts immune functions. - Rectum and anal canal regulate defecation with involuntary and voluntary controls. **Digestive System Part 3 -- Accessory Digestive Organs** **Overview** - **Accessory Digestive Organs**: - Aid in digestion but food doesn't pass through them. - Include **salivary glands** (discussed earlier), **liver**, **gallbladder**, and **pancreas**. - **Spleen**: Not part of digestion but located near digestive organs. **Liver** 1. **Location**: - Just below the **diaphragm**, mostly on the right side. - Sits anterior to the stomach and near the gallbladder. - Divided into **four lobes**: - **Right lobe** (largest). - **Left lobe**. - **Caudate lobe** (posterior, near inferior vena cava). - **Quadrate lobe** (posterior, near gallbladder). 2. **Functions**: - **Produces bile**: - Key for **fat digestion**. - Emulsifies fats, breaking them into smaller droplets for enzyme action. - **Detoxifies blood**: - Removes toxins and metabolic waste. - Other metabolic roles (not discussed in detail). 3. **Bile Pathway**: - Bile exits the liver via: - **Right hepatic duct** (from right lobe). - **Left hepatic duct** (from left lobe). - These ducts merge to form the **common hepatic duct**. - Bile then takes one of two routes: - **To the duodenum** via the **common bile duct** (if needed immediately for fat digestion). - **To the gallbladder** via the **cystic duct** (for storage if not immediately needed). **Gallbladder** 1. **Location**: - Small, sac-like organ tucked beneath the liver. - Visible as a green structure in anatomical illustrations. 2. **Function**: - **Stores bile** produced by the liver. - Releases bile into the **common bile duct** when fatty food enters the duodenum. - Works in conjunction with the enteric nervous system: - Signals from neurons trigger bile release into the small intestine. 3. **Bile Release**: - If bile is stored in the gallbladder, it exits via the **cystic duct**. - Joins the **common bile duct** to reach the duodenum. **Pancreas** 1. **Location**: - Lies behind the stomach. - Divided into: - **Head**: Fits into the C-shape of the duodenum. - **Body**: Central portion. - **Tail**: Narrow end near the spleen. 2. **Functions**: - **Exocrine Function**: - Produces digestive enzymes that break down carbohydrates, proteins, and fats. - Enzymes travel via the **pancreatic duct** to the duodenum. - Includes a secondary duct for backup secretion. - **Endocrine Function**: - Produces metabolic hormones (e.g., insulin, glucagon) released directly into the bloodstream. 3. **Bicarbonate Secretion**: - Neutralizes acidic chyme from the stomach. - Ensures a suitable environment for enzymes in the duodenum. **Peritoneum and Mesentery** 1. **Peritoneum**: - Membrane lining the abdominal cavity and covering many internal organs. - **Parietal Peritoneum**: - Lines the walls of the abdominal cavity. - **Visceral Peritoneum**: - Covers the surface of abdominal organs. - **Peritoneal Cavity**: - Space between parietal and visceral layers. - Filled with a small amount of fluid to reduce friction. 2. **Mesentery**: - Formed where visceral and parietal peritoneum meet. - **Functions**: - Supports and anchors intestines. - Contains blood vessels, lymphatics, and fat for protection and nourishment. - **Structure**: - Double layer of peritoneum. - Visible as membranous coverings around the intestines. 3. **Omentum**: - Specialized type of mesentery. - **Greater Omentum**: - Large, fatty apron hanging over the abdominal organs. - Attached to the greater curvature of the stomach and transverse colon. - Contains fat for protection and insulation. - **Protective Function**: - Moves to envelop areas of pathology (e.g., tumors) to shield the rest of the abdomen. - **Lesser Omentum**: - Connects the lesser curvature of the stomach to the liver. **Spleen** 1. **Location**: - Behind the stomach, near the **left colic (splenic) flexure** of the large intestine. 2. **Role**: - Not part of digestion. - Functions in the immune system, filtering blood and managing red blood cells. **Accessory Organ Summary** **Organ** **Primary Function** ----------------- ----------------------------------------------------------------- **Liver** Produces bile, detoxifies blood. **Gallbladder** Stores bile, releases it when fatty food enters the duodenum. **Pancreas** Produces digestive enzymes (exocrine) and hormones (endocrine). **Spleen** Immune system function, not related to digestion. **Clinical Notes** 1. **Gallstones**: - Hardened deposits in the gallbladder that can block bile flow. 2. **Pancreatitis**: - Inflammation of the pancreas, affecting enzyme secretion. 3. **Omentum in Surgery**: - Greater omentum's mobility and protective nature often observed in cadaver dissections, especially in cases of abdominal pathologies. **Summary** - Accessory organs play vital roles in digestion despite not being part of the GI tract. - The **liver**, **gallbladder**, and **pancreas** work closely to digest and process nutrients. - The **peritoneum** and **mesentery** support and protect abdominal organs, with the **greater omentum** providing additional protection and adaptability. - Understanding these structures is key to grasping the complexities of the digestive system and its accessory components