A&P Exam PDF

Learning Objectives: 1. Divisions of Peripheral Nervous System (PNS): ◦Functional Divisions: ▪ Somatic Sensory (skeletal muscles, skin, joints) ▪...

Learning Objectives: 1. Divisions of Peripheral Nervous System (PNS): ◦Functional Divisions: ▪ Somatic Sensory (skeletal muscles, skin, joints) ▪ Visceral Sensory (internal organs) ▪ Special Sensory (smell, taste, vision, hearing, balance) ▪ Somatic Motor (skeletal muscle) ▪ Autonomic Motor (internal organs): includes Parasympathetic (rest/ digest), Sympathetic ( ght/ ight), Enteric (gastrointestinal system) ◦ Anatomical Divisions: ▪ Cranial Nerves (12 pairs, Roman numerals) ▪ Spinal Nerves (31 pairs, named by vertebral region) 2. White and Gray Matter Organization: ◦ Brain: ▪ Gray Matter: Outer layers (cerebral and cerebellar cortex) and inner areas (basal nuclei, thalamus) ▪ White Matter: Myelinated axons forming tracts (association, projection, commissures) ▪ Primary Motor Cortex: Controls body movement; located in the frontal lobe. ▪ Somatosensory Cortex: Receives sensory input; located posterior to the motor cortex. ▪ Both cortices feature body maps (homunculi) for sensory and motor functions. 3. Spinal Cord White and Gray Matter: ◦ Gray Matter: ▪ Dorsal horns (sensory nuclei) ▪ Ventral horns (motor nuclei) ▪ Lateral horns (visceral motor, only in thoracic and lumbar regions) ◦ White Matter: Axon columns (anterior, posterior, lateral) forming tracts for sensory and motor communication. 4. Spinal Re exes: ◦ Patellar Re ex: Involves stretch receptors in muscle spindles, afferent neuron activation, and motor neuron response. ◦ Withdrawal Re ex: Activated by pain, involves ipsilateral (same side) contraction of exor muscles and inhibition of extensor muscles. ◦ Crossed-Extensor Re ex: Opposite-side response to maintain balance during withdrawal re ex. Learning Objectives: fl fl fl fl fl fi fl fl  1. Divisions of the Motor Nervous System: ◦ Autonomic Nervous System (ANS): ▪ Controls viscera (smooth muscle, cardiac muscle, glands). ▪ Comprises two main divisions: ▪ Parasympathetic Nervous System (PNS): "Rest and Digest" (decreases cardiac output, stores energy). ▪ Sympathetic Nervous System (SNS): "Fight or Flight" (increases cardiac output, mobilizes energy). ◦ Both divisions are continuously active to maintain homeostasis. 2. Neural Pathways: ◦ The ANS uses a two-neuron chain: ▪ Preganglionic neuron (cell bodies in the CNS). ▪ Postganglionic neuron (cell bodies in peripheral ganglia). ◦ The PNS has long preganglionic and short postganglionic neurons. ◦ The SNS has short preganglionic and long postganglionic neurons. 3. Adrenergic and Cholinergic Receptors: ◦ Adrenergic Receptors: Bind norepinephrine/epinephrine (Alpha and Beta subtypes). ◦ Cholinergic Receptors: Bind acetylcholine (Nicotinic and Muscarinic subtypes). ◦ Nicotinic receptors are ion channels (ionotropic), while muscarinic and adrenergic receptors use second messenger systems (metabotropic, GPCRs). 4. Sympathetic vs. Parasympathetic Neurotransmitters: ◦ Parasympathetic: ▪ Preganglionic and postganglionic neurons both release acetylcholine (ACh). ▪ Nicotinic receptors (preganglionic), muscarinic receptors (postganglionic). ◦ Sympathetic: ▪ Preganglionic neurons release ACh (nicotinic receptors). ▪ Postganglionic neurons release norepinephrine (adrenergic receptors). 5. Adrenal Medulla's Role in Sympathetic Response: ◦ The adrenal medulla releases epinephrine (EPI) into the bloodstream in response to sympathetic activation, amplifying the body's ght or ight response. 6. Neurotransmitter Removal: ◦ Acetylcholine: Broken down by acetylcholinesterase in the synaptic cleft. ◦ Norepinephrine: Reuptake by presynaptic neurons and enzymatic breakdown by monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT) in the liver Learning Objectives: 1. Microanatomy of the Skin: fi fl  ◦ Epidermis (outer layer): Avascular, strati ed squamous epithelium with 4-5 layers. ▪ Layers of the Epidermis: 1. Stratum Basale: Deepest layer, contains stem cells, melanocytes, and Merkel cells. 2. Stratum Spinosum: Contains keratinocytes, Langerhans cells (immune function). 3. Stratum Granulosum: Cells accumulate keratin and glycolipids. 4. Stratum Lucidum: Found only in thick skin (e.g., palms, soles). 5. Stratum Corneum: Outermost layer, dead keratinocytes forming a protective barrier. ◦ Dermis: Below the epidermis, contains blood vessels and sensory receptors. ▪ Papillary Layer: Loose areolar tissue with Meissner’s corpuscles. ▪ Reticular Layer: Dense connective tissue, contains mechanoreceptors and thermoreceptors. ◦ Hypodermis (subcutaneous layer): Contains adipose tissue, anchors skin to muscle. 2. Functions of the Integumentary System: ◦ Protection, temperature regulation, vitamin D synthesis, waste excretion, sensation, and immune defense. 3. Appendages of the Skin: ◦ Sweat Glands: ▪ Eccrine (merocrine) glands: Widely distributed, release watery secretion for thermoregulation. ▪ Apocrine glands: Located in axillary and genital regions, secrete lipid- rich uid. ◦ Sebaceous Glands: Secrete oily sebum, provide lubrication and waterproo ng. ◦ Hair/Hair Follicles: Dead keratinized cells. Growth regulated by hormones (e.g., androgens). ◦ Nails: Keratinized cells; function for protection and as tools. 4. Skin Pigmentation: ◦ Melanin: Produced by melanocytes, provides UV protection. ◦ Carotene: Yellow-orange pigment. ◦ Hemoglobin: Oxygenated (red) or deoxygenated (purple/blue) pigment in blood. 5. Skin Conditions and Cancers: ◦ Skin color changes: erythema, cyanosis, jaundice, pallor, bronzing. ◦ Skin cancers: ▪ Basal Cell Carcinoma: Most common and least lethal. ▪ Squamous Cell Carcinoma: More aggressive. ▪ Malignant Melanoma: Most aggressive, early detection is key (ABCDE rule). 6. Thermoregulation: fl fi fi  ◦ Sympathetic nervous system regulates blood ow and sweat gland activity. ◦ Vasodilation/vasoconstriction of blood vessels and increased eccrine sweat gland activity help regulate body temperature Learning Objectives: Function of Bone: 1. Support, Movement & Protection: ◦ Provides body shape, supports weight, and protects organs like the lungs. ◦ Facilitates movement. 2. Metabolic Functions: ◦ Hematopoiesis: Blood cell formation in red bone marrow. ◦ Storage: Calcium salts and lipids (yellow bone marrow). Bone Tissue (Osseous Tissue): Components: ◦ Mineral Salts (2/3): Hydroxyapatite, mainly calcium phosphate, gives hardness and resistance to compression. ◦ Collagen Fibers (1/3): Provides strength and exibility. Bone Cells: ◦ Osteoprogenitor Cells: Stem cells that produce osteoblasts. ◦ Osteoblasts: Cells that build the bone matrix (ECM). ◦ Osteoclasts: Cells that break down bone matrix. ◦ Osteocytes: Mature bone cells in lacunae, maintaining bone tissue. Types of Bone: 1. Compact Bone (Cortical Bone): ◦ Dense, located beneath the periosteum, and provides strength and protection. ◦ Contains osteons (Haversian systems), with lamellae surrounding Haversian canals. 2. Spongy Bone (Cancellous Bone): ◦ Less dense and more porous, found inside bones, housing bone marrow and blood vessels. Microanatomy of Bones: Compact Bone: Organized into osteons with lamellae and Haversian canals. Spongy Bone: Trabeculae with osteocytes in lamellae, and bone marrow in spaces. Bone Marrow: fl fl  Red Marrow: Involved in blood cell synthesis, found in spongy bone. Yellow Marrow: Stores lipids, found in the cavity of long bones in adults. Bone Growth and Development: Periosteum: Outer layer covering compact bone, containing osteoprogenitor cells. Endosteum: Lines the trabeculae and Haversian canals, also containing bone cells. Structure of Long Bones: Diaphysis: The shaft, consisting of compact bone surrounding the medullary cavity. Epiphysis: Ends of the bone with spongy bone inside and compact bone outside, covered by articular cartilage. Learning Objective Key De nitions: Appositional Growth: Growth from the outside (increases width). Interstitial Growth: Growth from the inside (increases length). Longitudinal Growth: Length increase in bones. Bone Resorption: Breakdown of bone. Bone Deposition: Formation of bone. Ossi cation: Formation of bone tissue. Bone Remodeling: Reorganization of existing bone. Bone Modeling: Formation of the bony skeleton during embryonic development. Learning Objective 1: Bone Modeling and Ossi cation Bone Modeling: ◦ Occurs during embryonic development starting in Week 8. ◦ Hyaline cartilage model forms the skeleton before bones develop. Endochondral Ossi cation: ◦ Formation of bone from a hyaline cartilage model. ◦ Occurs in bones below the skull (except the clavicles). ◦ Involves primary ossi cation in the diaphysis (midsection) during fetal development, followed by secondary ossi cation in the epiphysis (ends of the bone) from birth through puberty. Intramembranous Ossi cation: ◦ Formation of bones directly from brous membranes, especially in the skull and clavicles. ◦ Begins around 8 weeks of gestation and completes by about 2 years of life. Learning Objective 2: Growth at Epiphyseal Plate fi fi fi fi fi fi fi fi  Elongation at Growth Plate (Interstitial Growth): ◦ Resting Zone: Non-proliferative chondroblasts. ◦ Zone of Proliferation: Mitosis of chondroblasts. ◦ Zone of Hypertrophy: Chondrocytes enlarge, and the matrix expands. ◦ Zone of Calci cation: Matrix calci es, and chondrocytes die. Growth in Width (Appositional Growth): ◦ Osteoblasts deposit new bone at the periosteum. ◦ Osteoclasts resorb bone at the endosteum. Learning Objective 3: Bone Remodeling and Regulation Bone Remodeling: ◦ Continuous replacement of old bone with new bone. ◦ Spongy bone is replaced every 3-4 years, while compact bone is replaced every 10 years. ◦ Involves osteoblasts (bone deposition) and osteoclasts (bone resorption). Regulation of Remodeling: ◦ Mechanical Forces: Bone responds to stress (Wolf’s Law: bone grows in response to demand). ◦ Calcium Homeostasis: Controlled by Parathyroid Hormone (PTH), which increases calcium resorption from bones when blood calcium levels are low. Factors In uencing Bone Growth: Vitamins: ◦ Vitamin C: Required for collagen synthesis. ◦ Vitamin D: Aids calcium absorption. Hormones: ◦ Growth Hormone: Stimulates bone growth. ◦ Thyroid Hormones: Promote osteoblast and chondrocyte activity. ◦ Sex Hormones: Stimulate bone growth and closure of the growth plates during puberty. Fractures and Repair: Types of Fractures: Closed (internal), open (through the skin), transverse, spiral, etc. Fracture Repair: 1. Hematoma Formation: Blood clot at the fracture site. 2. Soft Callus Formation: Formation of a cartilaginous callus. 3. Hard Callus Formation: Osteoblasts replace cartilage with bone. 4. Bone Remodeling: Replacement of woven bone with mature, organized bone. fl fi fi