Muscle Physiology PDF

MUSCLE PHYSIOLOGY Part 1 – Skeletal Muscle Nicole A M Herbert, PhD [email protected] Learning Objectives At the end of the lecture, students should be able to: Understand the basic components of skeletal muscle, the muscle fiber, and...

MUSCLE PHYSIOLOGY Part 1 – Skeletal Muscle Nicole A M Herbert, PhD [email protected] Learning Objectives At the end of the lecture, students should be able to: Understand the basic components of skeletal muscle, the muscle fiber, and the myofibril. Give examples of muscle functions. Understand the organization of the skeletal muscle. Describe the types of muscles and muscle fibers. Describe the physiological events of muscle contraction. Types of Muscles Skeletal (40% of the body) Voluntary muscle; controlled consciously Striated muscle, multinucleate Attached to the skeleton Locomotion, posture, body temperature. Smooth (10% of the body) Involuntary muscle; controlled unconsciously Non-striated muscle, one nucleus per cell In the walls of blood vessels and internal organs Respiration, digestion, blood circulation. Cardiac Controls itself with help from nervous and endocrine systems Striated muscle, one nucleus per cell Only in the heart Blood circulation Muscle Properties MUSCLES HAVE FOUR SPECIFIC PROPERTIES THAT ENABLE THEM TO PERFORM THEIR FUNCTIONS EFFECTIVELY. Contractility - The ability to contract or shorten, allowing muscles to generate tension. Extensibility - Is the property of muscles that allows them to be stretched or lengthened beyond their resting length. Elasticity - The ability to return to its original shape after being stretched or contracted. Excitability - The capacity to receive and respond to stimuli (from the motor neuron, neurotransmitters, hormone, etc). Key Points General Characteristics of a Muscle Fiber There are three types of muscle: skeletal, smooth, and cardiac Muscle contraction is essential for a wide range of physiological functions including locomotion, respiration, blood and lymph circulation Muscle fibers have four specific properties: Contractility, Excitability, Extensibility, and Elasticity Skeletal Muscle Primary function is to enable movement of the body – Attached to the bones of the skeleton viatendons – Skeletal muscles work in coordination with the skeletal system to produce voluntary movements, such as walking, running, and lifting objects. – Most segments have one or more muscles on both sides either to increase or decrease its angle. – Is stimulated by a motor neurone – Under voluntary (conscious) control  Skeletal Muscle Structure EPIMYSIUM – A fascia (thin sheath) of fibrous Tendon connective tissue that surrounds the entire muscle. Bone FASCICLE - A small bundle or cluster of muscle fibers Epymysium (Surrounds the PERIMYSIUM - Connective tissue extensions muscle/muscle belly) from the epimysium that surround each fascicle. ENDOMYSIUM - Connective tissue extensions from the perimysium that surround the muscle Perimysium fibers and are attached to the sarcolemma. (Surrounds the fascicle) MYOFIBRILS - Each muscle fiber contains several hundred to several thousands myofibrils. Each myofibril is composed by a linear series of repeating sarcomeres Fascicle (Bundle of muscle fibers) MYOFILAMENTS - Are responsible for muscle contraction. Composed of thin and thick Endomysium filaments. (Surrounds the Muscle Myofibril fiber) (Muscle cell) Myofilaments (Thin and thick filaments)  Skeletal Muscle Structure EPIMYSIUM – A fascia (thin sheath) of fibrous connective tissue that surrounds the entire muscle. Tendon FASCICLE - A small bundle or cluster of muscle fibers Bone PERIMYSIUM - Connective tissue extensions Epymysium from the epimysium that surround each fascicle. (Surrounds the muscle/muscle belly) ENDOMYSIUM - Connective tissue extensions from the perimysium that surround the muscle Perimysium fibers and are attached to the sarcolemma. (Surrounds the fascicle) MYOFIBRILS - Each muscle fiber contains several hundred to several thousands myofibrils. Each myofibril is composed by a linear series of repeating sarcomeres Fascicle (Bundle of muscle fibers) MYOFILAMENTS - Are responsible for muscle Endomysium contraction. Composed of thin and thick (Surrounds the Muscle Myofibril fiber) (Muscle cell) filaments. Myofilaments (Thin and thick filaments) SARCOLEMMA – It is a thin cell membrane enclosing a skeletal muscle fiber (cell) – A special feature of the sarcolemma is that it invaginates into the sarcoplasm of the muscle cell, forming membranous T-tubules. – FUNCTION: to carry depolarization from action potentials to interior of fiber Level of Organization in Skeletal Muscle MUSCLE FIBERS Bundle of myofibril – elongated shape Contain the basic contractile unit (sarcomere) SARCOMERE – Contain the myofilaments, basic contractile unit of striated muscle fibers (Found between Z LINES or Z discs) – Their arrangement gives the striation pattern. Myofilaments Myofilaments are responsible for muscle contraction Thin filament Actin, Troponin complex, Tropomyosin Thick filament Myosin (two heads) Myosin (60%), Actin and Tropomyosin – Muscle Proteins Arrangement of Filaments in a Sarcomere Arrangement of Filaments in a Sarcomere A Myosin Filament (Thick Filament) Myosin heads Heavy Chain Light Chain Weymouth Actin binding site ATP binding site Myosin tail Flexible hinge Are composed of multiple MYOSIN molecules – Myosin molecule contains a TAIL of intertwined helices and 2 globular HEADS that can bind both ATP and ACTIN Functions as an ATPase enzyme – uses ATP as an energy source for contraction – Approximately 500 myosin heads of a thick myosin filament form cross-bridges that interact with actin to shorten the sarcomere An Actin Filament (Thin Filament) Troponin C I Troponin T Are composed of ACTIN, TROPOMYOSIN, and TROPONIN COMPLEX – 2 helical strands of actin protein (contains myosin binding sites) All intertwined together as a large helical complex – 2 helical strands of tropomyosin protein – Troponin is a complex of three globular protein subunits (C, I and T) TnC – Calcium-binding subunit (no calcium, no contraction!) TnI – Inhibitory subunit TnT – Tropomyosin binding subunit Organelles of the Muscle Cell (Fiber) MITOCHONDRIA – Power plant of a cell (generates ATP) – Provides myofibrils with large amounts of energy allowing muscle contraction – Slow-Twitch fibers (Type 1 – Red, aerobic) have more numbers of mitochondria slowtwiton namemore mitochondriabecause theyrequiremoreATP Organelles of the Muscle Cell (Fiber) SARCOPLASMIC RETICULUM – Is a specialized endoplasmic reticulum – Very important for muscle contraction – Regulates calcium storage, release and reuptake – Bigger in fast contracting fibers (white) Organelles of the Muscle Cell (Fiber) T-TUBULES – Tubules arranged transversely to the myofibril – Periodic invaginations of the sarcolemma in muscle cell – Allows rapid transfer action potentials to the interior of the fiber. – Presence of voltage sensitive receptor (dihydropyridine receptor in tubule) attached physically to the ryanodine receptor voltage gated in the sarcoplasmic reticulum. Key Points The Muscle Fiber The skeletal muscle is surrounded by several layers of connective tissue (epimysium, perimysium, and endomysium) that provide strength and stability to the muscle and prevent it from ripping while contracting. A muscle fiber is enclosed by a plasma membrane called the sarcolemma. The sarcoplasmic reticulum (SR) is a specialized organelle responsible for storing, releasing, and reuptake of calcium ion. T-tubules allow for rapid transmission of the action potential into the cell and play an important role in regulating cellular calcium concentration. Muscle cells are multinucleate Key Points The Myofibril Myofibrils are made up of sarcomeres, the smallest functional units of a muscle. A sarcomere is composed of filaments of two proteins, myosin and actin, which are responsible for muscle contraction. Myosin is a thick filament with a globular head at one end. An actin filament is composed of actin, tropomyosin, and troponin. It is attached to a Z disk. Elements of muscle contraction – Action Potential Rapid change in voltage across a membrane. Based on ratio of ions – intra and extracellular Caused by inflow of Na+ (high extracellular conc) and outflow of K+ (high intracellular conc), causing change in voltage and increase in action potential Muscle Contraction (Sliding Filaments Model) neuron Jafina offilament doesn'tchange length in itiIne The Sliding Filament Model Proposed in the early 1950s. Two British biologists, Hugh Huxley and Andrew Huxley. The theory proposes that a muscle shortens or lengthens because thick and thin filaments slide over each other without changing length. Professor Hugh E. Huxley (Feb 25th 1924 – July 25th 2013) SLIDING FILAMENT MODEL OF MUSCLE CONTRACTION Before muscle contraction begins Myosin heads bind with ATP (low energy configuration) The ATPase activity immediatly cleaves the ATP in ADP and Pi Cleavage products are kept bound to the head Head becomes energized in a “cocked position” Ca2+ Troponin C Troponin T SLIDING FILAMENT MODEL OF MUSCLE CONTRACTION When calcium ions bind the troponin-tropomyosin complex, active sites of the actin filaments are uncovered Myosin heads bind to these sites The cross bridge is formed The phosphate ion and ADP are released SLIDING FILAMENT MODEL OF MUSCLE CONTRACTION The cross bridge causes a conformational change in the head Myosin heads bend toward the center of the sarcomere, causing the actin to slide toward the M line – POWER STROKE The energy that activates comes from the stored ADP Another ATP molecule will take place causing detachment of the myosin head from the actin filament to begin a new cycle Key Points Muscle Fiber Action Muscle action is initiated by a nerve impulse. If the cell receives the right stimulus, an action potential occurs which releases stored Ca2+ ions. Ca2+ ions bind with troponin, which lifts the tropomyosin molecules off the active sites on the actin filament. These open sites allow the myosin heads to bind to them. Energy for muscle action is provided when the myosin head binds to ATP. ATPase on the myosin head splits the ATP into a usable energy source. Key Points Muscle Fiber Action Once myosin binds with actin, the myosin head tilts and pulls the actin filament so they slide across each other. Muscle action ends when calcium is pumped out of the sarcoplasm to the sarcoplasmic reticulum for storage. Muscle Physiology Videos Structure of Skeletal Muscle | Skeletal Muscle Bands | Muscle Tissue | Nerve Muscle Physiology -YouTube Muscle Contraction Part 3 The Cross Bridge Cycle - YouTube  Types of Muscle Fibers – Skeletal muscles contain both Type I and Type II fibers. Type I (Red) slowtwitch – Type I fibers have high aerobic endurance and are suited to low-intensity endurance activities. Uses more oxygen – myoglobin protein Type II (White) fasttwitch – Type II fibers are better for anaerobic or explosive activities. » Type IIa » Type IIb 4923124 not TYPE I MUSCLE FIBERS Type I - Oxidative Fiber High aerobic capacity and fatigue resistance cannotgettiredduetohigh ofATP Rich in mitochondria (high ATP) Slow contractile speed (110 ms) = Slow Twitch Plentiful in muscles where the main function is slow prolonged activity (back muscles) 10–180 fibers per motor neuron Type IIa Muscle Fibers Type IIa – Are mixed oxidative-glycolytic fiber Moderate aerobic (oxidative) capacity and fatigue resistance High anaerobic (glycolytic) capacity Fast contractile speed (50 ms) = Fast Twitch Highly developed sarcoplasmic reticulum 300–800 fibers per motor neuron Type IIb Muscle Fibers FTb (Type IIb) – Glycolytic Fiber Low aerobic (oxidative) capacity and fatigue resistance High anaerobic (glycolytic) capacity and motor unit strength Fast contractile speed (50 ms) Highly developed sarcoplasmic reticulum (rapid Ca2+ release) 300–800 fibers per motor neuron Functional Classification of Muscles Agonists — muscle responsible for the movement Antagonists — oppose the agonists to prevent overstretching of them Synergists — assist the agonists and sometimes fine-tune the direction of movement Muscle Action During Elbow Flexion Satellite Cell Function Satellite cells are a type of stem cell located in skeletal muscles. Are involved in muscle growth and repair. Are normally in a dormant state but become activated when a muscle is injured and multiply to form new muscle fibers or myofibers. Mechano Growth Factor (MGF) in mechanically overloaded muscles Inflammatory cytokines (Interleukin 6 (IL-6) and Tumor Necrosis Factor alpha (TNF- ). Myostatin Function muscle remise Its primary function is to regulate muscle growth and development by inhibiting the proliferation and differentiation of muscle cells. Produced and secreted by skeletal muscle cells. Myostatin has been the subject of intense research in the field of muscle biology and has been identified as a potential therapeutic target for conditions associated with muscle wasting, such as muscular dystrophy and sarcopenia.  MUSCLE PHYSIOLOGY Part 2 – Smooth and Cardiac Muscle Dr. Nicole A M Herbert [email protected] Learning Objectives At the end of the lecture, students should be able to: – Describe the 2 types of smooth muscle. – Understand the physical structure of smooth and cardiac muscle. – Describe the function of the intercalated disks in the cardiac muscle. Smooth Muscle SMOOTH MUSCLE OF EACH ORGAN IS DISTINCTIVE: Different physical dimensions to adjust to the organs they are in; Organization into bundles or sheets to enable coordinated contractions for functions like digestion and blood flow regulation. Response to different stimuli, including neural, hormonal and local factors (O2, CO2, H2). Receives nerve signals from the autonomic nervous system (Sympathetic (fight and flight) and Parasympathetic nervous (relaxation) system). Smooth muscle has various functions depending on the organ it is in, including peristaltic contraction, regulation of blood flow, and control of airway diameter Types of Smooth Muscle Can be generally divided into – Single-unit (visceral) smooth muscle – Multi-unit smooth muscle e.g. Walls of stomach e.g. Lungs and ciliary and bladder muscle of eye  Types of Smooth Muscle SINGLE-UNIT SMOOTH MUSCLE – Also called visceral, syncytial or unitary smooth muscle – Fibers are arranged in sheets or bundles Cell membranes are connected to each other The force generated in one muscle fiber can be transmitted to the next (myogenic) Contract together as a single unit  Types of Smooth Muscle SINGLE-UNIT SMOOTH MUSCLE – Cell membranes are joined by many gap junctions Ions can flow freely from one muscle cell to the next Fibers contract together – Locations Gastrointestinal tract, bile ducts, ureters, uterus, and many blood vessels  Types of Smooth Muscle MULTI-UNIT SMOOTH MUSCLE – Discrete, separate smooth muscle fibers – Each muscle fiber contracts independently – Innervated by a single nerve ending (neurogenic) – Locations Ciliary muscles of the eyes Iris muscle of the eyes Base of hair follicles Smaller airways to lungs Walls of large blood vessels  Particularities of Smooth Muscle Iissiised S.Ties Fusiform/spindle shape otzdiskf.name Smooth muscle has only one nucleous at the cell’s center. No striations Smooth muscle does not contain myofibrils or sarcomere, but it contains thick and thin filaments, and contract via a sliding filament mechanism.  Particularities of Smooth Muscle Smooth muscle does not have the same striated arrangement of actin and myosin filaments The actin filaments are attached to dense bodies, which are analogous to the Z-discs in striated muscle sarcomeres. Some bodies are attached to cell membrane Some bodies are dispersed inside the cell Myosin filaments are inserted among the actin filaments. No troponin Contraction different and is more intense than in skeletal muscle  Particularities of Smooth Muscle Myosin filaments have side-polar cross-bridges – They are arranged so that the bridges on one side bend in one direction and those on the other side bend in the opposite direction – This configuration allows the myosin to pull an actin filament simultaneously in opposite directions no int peas am Particularities of Smooth Muscle Myosin filaments have side-polar cross-bridges – Smooth muscle can contract as much as 80% of their length Skeletal muscle only 30% n rg Particularities of Smooth Muscle Low frequency of cross-bridge cycles – Low energy to maintain the contraction - 1/10 to 1/300 of the energy necessary to contract skeletal muscle (fatigue resistant – low ATP) – Once smooth muscle initiates the contraction, a low energy is needed to keep the tonic contraction for hours. – Some smooth muscle has a tonic contracting (resting tone), that can last for hours or days. E.g. arteries  Particularities of Smooth Muscle Sarcoplasmic reticulum is not well developed – It is not the major source of Ca2+ for smooth muscle contraction – extra cellular fluid is! Not present in all smooth muscle fibers – Lies near the cell membrane in some larger smooth muscle cells – Small invaginations of the cell membrane, called CAVEOLAE, that make contact with the surface of SR. Rudimentary T-Tubule. Is believed to excite calcium release from the SR. – The more extensive the SR in the smooth muscle fiber, the more rapidly it contracts (Ca2+)  Smooth Muscle Contraction Smooth muscle uses calmodulin as a calcium-binding protein to regulate the contraction process iinstead of troponin. 1. Calcium-bound calmodulin, resulting in its activation. 2. Activated calmodulin then activates an enzyme called myosin light chain kinase (MLCK). MLCK phosphorylates a specific region of myosin. dependenton 3. Phosphorylated myosin binds to actin, forming a cross-bridge between myosin and actin allowing the muscle cell to contract. 4. When the ion calcium concentration is reduced, myosin phosphatase removes the phosphate from the myosin light chain, causing muscle relaxation actslikeadisk stractualintegrity Key Points General Characteristics of Smooth Muscle Smooth muscle can be divided into two types: 1) Multi- unit smooth muscle; 2) Single-unit smooth muscle. Dense bodies are small, dense structures found within the cytoplasm of smooth muscle cells. They serve as anchoring points for actin filaments. These dense bodies are functionally analogous to the Z-discs found in skeletal muscle. The arrangement of actin, myosin, and dense bodies in smooth muscle allows for the coordinated contraction and relaxation of the muscle. Key Points General Characteristics of Smooth Muscle Smooth muscle contracts involuntarily without conscious control. It is found in the walls of various organs and structures throughout the body, such as blood vessels, the digestive system, respiratory system, and reproductive system. Smooth muscle performs essential functions, such as regulating blood pressure, propelling food through the digestive tract, and facilitating the movement of air in the lungs. Compared to skeletal muscle, smooth muscle exhibits slower contraction and relaxation times. The slower kinetics of smooth muscle contraction and relaxation are important for sustained contractions, such as maintaining muscle tone in blood vessels or in the uterus. Cardiac Muscle Cardiac muscle cells are called cardiomyocytes or cardiocytes. These cells make up the myocardium, the muscle layer of the heart. The myocardium contracts to pump blood throughout the body, supplying organs and tissue with oxygen and nutrients.  Cardiac Muscle The structure of cardiac muscle share some similarities with skeletal muscle – Fibers are striated – Myofibrils are made up from actin and myosin filaments Similar organization of the sarcomere – Contains a less developed Sarcoplasmic Reticulum – T-tubules (also release Calcium ions)  Cardiac Muscle But cardiac muscle also differs from skeletal muscle in several ways – Contraction is involuntary (controlled via autonomic nervous system) – Fibers are shorter and branched – Usually uninucleated – Interconnected by intercalated disks – Generates their own action potential (pacemaker fibers) Cardiac Muscle THE CARDIAC ACTION POTENTIAL IS NOT INITIATED BY NERVOUS ACTIVITY. – It is generated by a group of specialized cells known as pacemaker cells. – These cells have automatic action potential generation capability. – Are found in the sinoatrial node in the right atrium. – They produce roughly 60–100 action potentials every minute.  Cardiac Muscle Function is L Cardiac muscle is a FUNCTIONAL SYNCYTIUM – Greek: Syn = together + Kytos = cell – Do not fuse into a single multinucleated fiber during embryonic development like skeletal muscle does (morphological syncytium) – Cardiac myocytes branch or bifurcate during development and bind to other myocytes – Fibers remain separated as distinct cells with their respective sarcolemma Electrically connected to each other through intercalated disks  Cardiac Muscle The INTERCALATED DISK is a dark, dense cross-band found in the end of each myocardial cell – Continuous with the sarcolemma (wave-like contraction) – Contain important cell-cell junctions GAP JUNCTIONS – Allow rapid diffusion of ions (passive) – Action potential travel easily – =electrical coupling (passive movement) DESMOSOME – Provide mechanical strength and stability » Adhesive intercellular junctions » Tissue integrity pdisc Key Points General Characteristics of a Cardiac Muscle Cardiac muscle is a specialized type of muscle found in the heart. It consists of elongated cells called cardiomyocytes, which are striated due to the organized arrangement of actin and myosin filaments. Cardiac muscle contracts involuntarily, but the contraction is controlled via ANS. Intercalated discs are unique structures found between adjacent cardiac muscle cells. They contain specialized cell-to-cell junctions called desmosomes and gap junctions. Key Points General Characteristics of a Cardiac Muscle Desmosomes provide mechanical strength and stability, allowing for the transmission of force during contraction. Gap junctions permit the passage of ions between cells, enabling electrical coupling. Structural & Functional Biology Skin & Integumentary System Sarah Hooper, DVM, MS, PhD E-mail: [email protected] 1  If you can't fly, then RUN. If you can't run, then WALK. If you can't walk, then CRAWL. But whatever you do, YOU HAVE TO KEEP MOVING. Martin Luther King, Jr. – Civil Rights Activist and Pastor 2 Learning Objectives: List the functions of the skin in mammals Explain the mechanisms that help the skin protect the animal Explain the components of the skin Cells layers of the epidermis and relevant cells types Keratin synthesis Function and synthesis of melanin Nerve endings in the skin Hairs and feathers Thermoregulation through the skin Glands of the skin The hoof 3  The Skin and the Integumentary System Skin: Largest sensory organ in the body Covers the body thereby protecting cells and tissues Very important for communication in animals Piloerection in localized parts of the skin functions as visual signals From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 4  The Skin and the Integumentary System The skin helps animals recognize the structure of surfaces, their composition and temperature. In humans, the skin is an essential component of our affective behavior. 5 Functions of Skin Protect against loss of water, electrolytes, Protection of the body against mechanical and and other constituents chemical injury by 3 mechanisms oftheskin Physical structure of skin Turnover (shedding) of superficial cells Hair and keratinized surface and hair helps regulate number of microorganisms and debris on skin Secretory products surface Antibacterial and antifungal properties Normal bacterial flora (aka skin microbiome) Prevents invasion by pathogenic bacteria by occupying microbial niches and producing compounds that inhibit the growth of other microorganisms 6 Functions of Skin Protection of the body against mechanical and chemical injury Limitation of loss of water from the body Immunologic barrier Thermoregulation Sensory information provision (pressure, temperature, pain) Transmission of emotional and chemical signals Fat storage Synthesis of 7-dehydrocholesterol, which is converted to vitamin D3 by ultraviolet light 7  Our two case studies – Ollie and Azzy 8 From: https://www.animaldermatologyclinic.com.au/case-studies  Skin structure: Use the weblink on the previous slide and the figure on the right to help you fill in the blanks: Three main components of the skin: The __________, epidermis the outermost layer of skin, a multilayered epithelium The ________, dermis an underlying layer of vascularized connective tissue subcutis or hypodermis also known as the The __________________, subcutaneous layer. ------------------------------------------------------------------- Accessory structures, such as hair, 9 feathers, and glands From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“  The Skin and the Integumentary System The epidermis The epidermis is made up of four cell layers: Stratum corneum (layers of keratinized, dead cells still connected by desmosomes) ____________ Stratum granulosum (flattening of cells, high keratin content) ________________ Stratum spinosum (cells joined by _______________ Desmosomes providing mechanical strength) Desmosomes = prominent cell-to-cell junctions ____________ Stratum basale (stem cells) https://ohiostate.pressbooks.pub/vethisto/chapter/7-structure-of-the-epidermis/ 10  The Skin and the Integumentary System Haired skin (“thin skin”). Thorax, dog Hairless skin (“thick skin”). Pawpad, dog Stratum corneum Stratum corneum 12 From: Zachary. „Pathologic Basis of Veterinary Disease“  The Skin and the Integumentary System The four cells of the epidermis are……. (Hint: https://www.ncbi.nlm.nih.gov/books/NBK470464/) Keratinocytes (the most predominant ones) Melanocytes Langerhans’ cells Merkel’s cells 1) Keratinocytes: Produce keratin, the major structural protein in the epidermis Contribute to the formation of the epidermal water barrier Makes up majority of the structure of the skin, hair, and nails 14  The Skin and the Integumentary System Keratin synthesis and the formation of the epidermal water barrier I Cell division occurs in the stratum basale (basal layer). These cells synthesize tonofilaments (intermediate keratin filaments). Cells are pushed into the stratum spinosum As it enters tonofilaments synthesis continues and the cell begins to produce: keratohyalin granules that contain proteins (aid in aggregation of keratin filaments), helps convert granular cells to cornified cells (keratinization) and glycolipids-containing lamellar bodies 15 Physiologic Variants https://www.ncbi.nlm.nih.gov/books/NBK470464/) From: Ross & Pawlina „Histology: A Text and Atlas“  The Skin and the Integumentary System Keratin synthesis and the formation of the epidermal water barrier Cells are pushed into the stratum granulosum and continue to stratum corneum. Lamellar bodies are discharged by exocytosis into the spaces between stratum granulosum and stratum corneum Lamellar bodies + lipid envelope -> epidermal water barrier The epidermal water barrier prevents entry of fluids and microorganisms as well as fluid loss from the body 16 From: Ross & Pawlina „Histology: A Text and Atlas“  The Skin and the Integumentary System 2) Melanocytes: Melanocyte precursor cells originate in the neural crest Melanocytes are in close association with a number of keratinocytes in the epidermis Normally located in stratum basale are easily recognized by the presence of melanin granules inside “dendritic” processes From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 17  The Skin and the Integumentary System Melanin protects the skin against nonionizing UV 2) Melanocytes: irradiation Synthesis starts in premelanosomes from the amino acid tyrosine As more melanin is produced, melanosomes become more visible at the tip of the dendritic process being then transferred to neighboring keratinocytes (pigment donation) Ando, H., Niki, Y., Ito, M., Akiyama, K., Matsui, M. S., Yarosh, D. B., & Ichihashi, M. (2012). Melanosomes are transferred from melanocytes to keratinocytes through the processes of packaging, release, uptake, and dispersion. Journal of Investigative Dermatology, 132(4), 1222-1229. From: Ross & Pawlina „Histology: A Text and Atlas“ 18  The Skin and the Integumentary System Melanocytes: Light skin vs dark skin melanin degradation Lysosomal activity degradation of melanin is faster in individuals with light skin than in individuals with dark skin and melanosomes are distributed only in stratum basale) Two forms of melanin pigments (genetically determined): Eumelanin -> brownish black Pheomelanin -> reddish yellow Exposure to UV light accelerates the rate of melanin production as a way to protect From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ the skin 19  The Skin and the Integumentary System 3) Langerhans’ cell: dendetriccell 4) Merkel’s cells: torean Can be seen in the stratum spinosum Modified epidermal cells found in stratum First line defenders, play a role in antigen basale presentation Most abundant in skin where sensor perception Aka dendritic cells are antigen-presenting is acute, such as fingertips cells Merkel’s cells are associated with a terminal disk of an afferent myelinated nerve fiber (Merkel’s corpuscle -> mechanoreceptor) From: Ross & Pawlina „Histology: A Text and Atlas“ 20 Case Study it Navigate to: https://www.animaldermatologyclinic.com.au/case- studies/ollie/atopic What test/procedures were done? i.iamisnsea it i i If the last procedure listed was performed incorrectly through all skin layers, list these 3 main layers in order of most superficial to deepest. epidermis superior Epidermis deep If a superficial skin scrape was performed, what are the 4 cell layers of the epidermis that could be affected? im feridermis FYI information on skin scrapes: https://todaysveterinarypractice.com/dermatology/der matology-diagnostics-skin-scrapes-hair-plucks/ 21 Case Study Navigate to: https://www.animaldermatologyclinic.com.au/case- studies/ollie/atopic What are the 4 main cells in the epidermis? keratinocytes Melanocytes Langerhanscells Marketscells What is something you should be aware of when giving the treatment when thinking about the 3 mechanisms that help protect Ollie? Shiina L.isuagtf.Ised 3mechanisms skinstructure physical 22  The Skin and the Integumentary System The dermis Strong and flexible connective tissue composed by cells and collagen fibers Cells of the dermis: ____________ Fibroblasts (primary cells) Macrophages Leukocytes Mast cells Tissue derived from the epidermis extend into the dermis and gives rise to sweat glands, sebaceous glands, and the papillae that form hair and feathers https://www.ncbi.nlm.nih.gov/books/NBK535346/ Contributed by Wikimedia Commons, USGOV (Public Domain) 23 The Skin and the Integumentary System 24  The Skin and the Integumentary System Other nerve endings in the skin Hairless skin Haired skin Dermis Meissner Merkel Pacini Hair folicle sensor Ruffini Hypodermis From: Schmidt, Lang, Heckmann „Physiology of Humans“ In hairless skin only; Only in haired skin; touchreceptors mechanoreceptors (tactile hairs) Deep pressure Respond to Tactile hairs in the receptors for mechanical whiskers of a cat mechanical and displacement of vibratory pressure adjacent collagen fibers From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 25  The Skin and the Integumentary System Hairs Hair follicles are formed by invaginations of the epidermis into the dermis After a skin injury, cells in stratum basale are capable of forming new hair follicles At the deep end, each follicle is expanded into a hair root or hair bulb that surrounds a portion of dermis, the hair papilla From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ The matrix region of the hair bulb produces new daughter cells that are pushed towards the surface 26 https://www.proteinatlas.org/learn/dictionary/normal/skin  The Skin and the Integumentary System The hair shaft consists of keratinized epithelial cells that are pushed from the hair root outwards the root canal Cuticle: single layer of dead, scale-like keratinocytes Cortex: several layers of dead keratinocytes containing hard keratin Medulla: dead loosely keratinized cells Piloerector muscle (aka arrector pili m.): a smooth muscle associated to hair bulb and anchored to the outer layer of the dermis (sympathetic innervated) Hair follicules have cycles of activity ________(growth) ________(regression) catagen _________(resting) telogen __________(shedding) antigen exogen From: Ross & Pawlina „Histology: A Text and Atlas“ 27  The Skin and the Integumentary System Feather Types Flight feathers Cover feathers (down feathers) The vane is the flat part of the feather It consists of barbs that are at angles of about 45 ° The hooklets, which are present only on the barbules on one side of the barb, hook onto the From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ smooth barbule from the adjacent barb The barbules of down feathers lack hooklets The barbules of down feathers lack hooklets Feathers from the same feather follicle can have different pigmentation RUSVM student: Joe Richichi 28  The Skin and the Integumentary System Thermoregulation Heat transport to the skin. Heat passes through layers with good insulation properties, the subcutaneous adipose tissue and fur or plumage. Mechanisms of heat exchange -> From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 29  The Skin and the Integumentary System Glands of the skin Sebaceous glands Sweat glands Mammary glands Virtual histology slides of skin and glands: From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ http://medcell.med.yale.edu/histology/skin_lab.php#vm-slides 30  The Skin and the Integumentary System Sebaceous glands Duct opens into A hair follicle (most common) Pore on the skin surface Composition: detached, degraded epithelial cells as well as lipids and proteins Functions: lubrication of the skin, provides water impermeability, and inhibition of bacterial growth Stimulated by testosterone m and There are no sebaceous glands associated with feathers. Uropygial glands in waterfowl produces a secretion that impregnate the From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ feathers of the bird 31  The Skin and the Integumentary System Sweat glands Eccrine glands: o Very common in primates o Open in pores at the skin surface o Ionic composition is similar to the plasma. In the duct, Na+ and Cl- are reabsorbed o Degree of reabsorption depends on the secretion rate Apocrine glands: o Very common in domestic animals o Open into hair follicle o Odoriferous secretion composed of fatty shiny acids and proteins From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 32  The Skin and the Integumentary System Mammary gland Glands + teats = The udder From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ Nutrients and water required for milk production Alveoli (acini): milk-producing units diffuse from blood capillaries and enter into the Lobuli: clusters of alveoli epithelial cells Lobi: clusters of lobuli Myoepithelial cells are involved in milk ejection 33  The Skin and the Integumentary System Cornified epidermal structures Hooves, claws, and horns in mammals Claws in reptiles and birds Beaks in turtles and birds I t Shells and scales in reptiles Scales in fish Hooves Horny hoof wall is formed by keratinization of the cells in the coronary band. Recently produced horn is pushed downward as new horn is being formed At the coronary band the dermis of the skin is continuous with the dermis of the hoof. From: Sjaastad, Sand, Hove „Physiology of Domestic Animals“ 34 Clinical Case Study Navigate to: https://www.animaldermatologyclinic.com.au/c ase-studies/azzy-equine In equine eosinophilic granuloma, eosinophils and macrophages are the primarily inflammatory cells. They are found in what skin layer and cell layer if they stimulate the maturation of Langerhans cells and dendritic cells? skinlayer epidermis celllayer stratnusspinosum What is a concern if corticosteroids are used when thinking about the hoof? (Hint look up condition in Merck Vet Manual) distalphalanxsinkslaminess 35 Clinical Case Study Gross and histological images available at: https://www.vet.upenn.edu/research/academic -departments/clinical-studies-new-bolton- center/centers-laboratories/laminitis-lab-photo- gallery 36 Thank you 37  Vet Prep Structural and Functional Biology Meninges Dr. Melissa Kehl Courtesy of Dr. Melania Crisan  Learning Objectives Describe where the spinal cord ends in dog. Describe membranes around CNS (central nervous system), spaces they create and the contents of these spaces. Describe production of CSF, its function and its circulation. Describe access points to the epidural and subarachnoid spaces, why these places are preferred, and structures to avoid.  OVERVIEW central nervous system (1) brain (2) spinal cord spinderves oranges peripheral nervous system (3) peripheral nerves The peripheral nervous system is divided into (4) sensory or afferent system to cns (5) motor or efferent system awaycus SAME The brain and spinal cord are contained within a continuous space provided by the cranial cavity of the skull and the vertebral canal.  epaxiahus.ie 1. spinal cord inside canal vertebral ÉÉ 2. dorsal root within vertebrates 4. ventral root 5. spinal nerve Rib 6. dorsal branch of spinal n. 7. ventral branch of spinal n. S 8. body of vertebra out p 10. epaxial muscles thora ran Transection of the vertebral column TVA 5TH Ed. Dyce, Sack and Wensing  Spinal cord and cauda equina Dog Spinal cord ends atlas around axis lumbosacral junction. The spinal nerves after L7 travel caudally within the vertebral canal. They exit when they 00 reach their corresponding vertebrae. This cluster of spinal nerves is known as cauda equina because it looks like a horse tail. FYI Cauda equina syndrome (CES) is caused by compression of the nerve roots passing from the lower back toward the tail at the level of the lumbosacral junction. Lumbosacral stenosis is most commonly caused by degenerative changes to the intervertebral disc, arthritis of the joints, and abnormal proliferation of the ligaments. Dogs with abnormal shape to their last lumbar or sacral vertebrae and German Shepherd dogs are predisposed to developing lumbosacral stenosis. Neoplasia (cancer) and infection at the level of the lumbosacral disc (discospondylitis) may also cause signs of CES. What are the symptoms of cauda equina syndrome? The most common neurologic sign associated with cauda equina syndrome is pain in the lower back. Signs of pain may include decreased willingness to jump up and climb up stairs, low tail carriage or reduced tail wagging, difficulty posturing to defecate, and whimpering/crying if the lower back is touched. In some cases, dogs will have a weakness or lameness in one or both hind limbs—this occurs secondary to compression of the nerve root that supplies the sciatic nerve as it exits at the lumbosacral joint. Severe compression of the nerve roots can lead to fecal and urinary incontinence, which is irreversible in most cases. How is it diagnosed? The first step in diagnosing cauda equina syndrome is through a neurologic examination. The doctor will observe the dog’s gait for any lameness and/or stiffness. A physical examination will include palpation over the spine to determine the site where the dog is most painful. Manipulation of the hips and tail will elicit pain response in most dogs suffering this syndrome. The doctor will also test reflexes, proprioception (foot placement), and anal tone. Radiographs are taken for abnormal shape of the lumbosacral joint, spinal arthritis at the lumbosacral joint, infection of the disc space, or tumors. How is it treated? Dogs that are exhibiting mild pain and have never had an episode of back pain before are usually treated with strict rest and pain medications. In cases where the dog is not responding to conservative medical therapy or exhibiting neurologic symptoms, surgical intervention is necessary. The procedure is called a dorsal laminectomy and involves removing the “roof” of the spinal canal to release the entrapped nerve roots and remove the associated ruptured intervertebral disc, if present. What is the post-operative prognosis? Prognosis is very good in dogs with mild neurologic signs (i.e. pain only, mild weakness). Dogs with severe nerve root compression and subsequent urinary or fecal incontinence have a very poor prognosis, and the majority of dogs never become continent again—even with surgery. Many dogs with lumbosacral disease have other back problems (i.e. chronic intervertebral disc disease) and hip or other orthopedic disease, which can affect their recovery after surgery. Recovery is also slower in overweight dogs, and obese patients must be put on a strict diet to reduce their weight.  Meninges 1 The brain and spinal cord are surrounded by 3 continuous membranes of connective tissue called meninges. 1. DURA MATER Dura mater – is the outer and thickest layer. In the vertebral canal, the dura is separated from the periosteum of the bony canal. Inside the cranial cavity, the dura and the periosteum are fused. 2. ARACHNOID trabeculae The arachnoid is attached to the dura and sends delicate trabeculae to the pia. These trabeculae have blood vessels that course on the surface of the pia. 3. PIA MATER Innermost meningeal layer. Intimately follows the brain’s gyri and sulci (bumps and grooves). Pia is the region of some CSF production. Note: A 4th membrane which is not a meninx is the periosteum lining the vertebral canal and skull.  Meninges SPINAL CORD SKULL spider Epidural space jÉÑ bÉuÉboneandduramater vertebra havespace whilebrainskilldoesn'thavethatspace https://www.marvistavet.com/meningioma.pml  Vertebral Canal Dorsal view of the opened vertebral canal. The dura mater has been dissected and is reflected. Spinal Cord Dura Dorsal Root of a Spinal Nerve (covered by Mater pia mater) TVA 5TH Ed. Dyce, Sack and Wensing.  Membrane spaces in Vertebral Canal Epidural space Only present Spinous around spinal cord Red line = periosteuminside areplaced wheredrugs Process Blue line = dura mater Yellowline Yellow line= =arachnoid arachnoid Subdural space Green line = pia mater (potential space only) arch Not normally present tryS Subarachnoid Space Contains CNS wheretotakesampleout Vertebral Body  Membrane spaces in Cranium In skull, dura mater is fused to periosteum - hence no epidural space in skull Red line = periosteum Blue line = dura mater Yellow Yellow line line = arachnoid = arachnoid Green line = pia mater Olfactory nerve (surrounded by meninges) Clinical: Possible route for meningitis! Nose to brain II cerebar connection. I  Ese wy L CSF (Cerebral Spinal Fluid) Function Shock absorption: the CSF encasing the brain absorbs the shock so that it does not smack against the skull. Nutrition: CSF supplies the central nervous system with essential nutrients, such as glucose, proteins, lipids, and electrolytes. Intracranial pressure: A steady flow of CSF keeps the pressure around the brain stable. Too much CSF, possibly due to a traumatic brain injury or brain tumor, raises intracranial pressure. Waste removal: CSF washes through the subarachnoid space, cleaning up toxins and waste products Temperature: CSF circulation keeps the temperature of your brain and spine stable. Immune Function: CSF contains numerous immune cells that monitor the central nervous system for foreign agents that could damage vital organs.  CerebroSpinal Fluid Clear colorless CSF is formed from the blood plasma by ultrafiltration through the “blood– cerebrospinal fluid barrier” at the choroid plexuses. Gross visual examination: Normal CSF is clear, colorless, and odorless. It has the consistency of water. Cloudy indicates infection and/or inflammation. https://slideplayer.com/slide/12078519/  Red line = periosteum CSF Sampling Sites Blue line = dura mater Yellow line = arachnoid arachnoid Cerebellum Green line = pia mater fluid Sacrum skull Cerebellomedullary cistern Sacral cistern (also called lumbar cistern) CSF Sampling Sites https://vcahospitals.com/know-your-pet/cerebrospinal-fluid-collection-and-examination  CSF Sampling Sites - Equine CSF collection from the atlantooccipital space requires general anesthesia. The atlantooccipital space is located just caudal to the poll, sedation on the dorsal midline, at the level of the wings of the atlas. The lumbosacral space is usually accessed in the awake, standing patient; this avoids the risk of recovery from general anesthesia. However, the lumbosacral space is technically more difficult to enter, and patients may display violent reactions to pain from the procedure. Sedation is needed. https://veteriankey.com/equine-clinical-procedures/  Epidural Anesthesia Used in obstetrics to numb the pudendal nerve to prevent excessive straining. Be especially careful not to pierce the cauda equina (way too many nerves). Avoid hitting the venous sinus (blood vessels within vertebral canal). Should not inject into CSF (brain connection). Avoid femoral, obturator and sciatic nerves.  Epidural Anesthesia http://www.tsvs.net/ www.vcahospitals.com 1. In the dog, the spinal cord ends around what region of the vertebral canal? A)Cervical B)Thoracic C)Lumbar D)Caudal/coccygeal E)Occipital  2. Which of the meninges is labelled by a star? (4 choices) A)Pia mater B)Dura mater C)Arachnoid D)Periosteum o brain 3. Which of the following is NOT a function of the Cerebrospinal Fluid (CSF)? A) Temperature B) Nutrition C) Waste removal D) Immune function E) Blood flow Practice Question Answers: 1.C 2.A 3.E  Vet Prep Structural and Functional Biology Dr. Melissa Kehl Thoracic Limb Joints Courtesy of Dr. Terri Clark  Learning Objectives: Describe the bones that make up the shoulder, elbow and carpus. Describe the important boney prominences / structures that make up these joints. Utilize scientific terminology necessary to describe these joints movements and directional terms. Give examples of muscles which cause action at these joints; as well as their individual origin and insertions. Species differences in this lecture are NOT required knowledge at this point; however, they will be important in the future. Species difference provided in this lecture are only to encourage critical thinking. Shoulder or Glenohumeral or Scapulohumeral Joint tanners scapua humans laps  Medial view Lateral view SCAPULA spine intra c supra supra ip sina.acant acr.si Left scapula of the dog. 2 - spine; 3 - supraspinous fossa; 4 - infraspinous fossa; 6 - supraglenoid tubercle; 7 - acromion; 12 - glenoid cavity iseanono.niaseascmoi.vn strong.my see c avity t.p.fgien.io  DOG HUMERUS reactions arec arec resiserie Left humerus 1 - Greater tubercle lateral 2 – head de 3 - lesser tubercle medial of 4 - teres major tuberosity medial 5 - deltoid tuberosity Catoid 8 - medial epicondyle 9 – condyle 10 - lateral epicondyle a no Caudal view I Cranial view crackview and.ie contrias  Bones of the Shoulder Joint are esford Head of the humerus me spine Synovial- ball and socket joint s L cromion glenoid.it Glenoid cavity of the scapula  Shoulder joint AKA Glenohumeral joint AKA Scapulohumeral joint “Glenoid”  Greek “Socket” 1 Scapula 5 humerus 6 joint capsule Shoulder Extension  Lateral View Left front Supraspinatus cranial Origin: Supraspinous Fossa Insertion: Greater Tubercle of Humerus Action: Extension of the shoulder Shoulder Flexion  Medial View fresent Left front Teres Major Origin: Caudal border of scapula Insertion: Teres Major Tuberosity Action: Shoulder Flexion cranial caudal Elbow or Humeroradioulnar Joint  Elbow joint 3 joints: humeroradial, humeroulnar and proximal radioulnar. Elbow joint of the dog 5 - Distal humerus 11 - lateral collateral ligament 13 – radius 14 - ulna 15 - joint capsule; 19 - biceps brachii 21 - medial collateral ligament. Lateral view Medial view ha ha  cranial view Radius Medial epicondyle condyle Ulna cranial view lateral view  ulna radius Dog ammar 1 olecranon 2 anconeal process 3 trochlear notch 6 lateral styloid process, ulna 8 medial styloid process, radius 9. Condyle of humerus craniolateral cranial caudal cranial Extension of the elbow  Lateral View Left front limb Triceps Brachii Origin: Caudal border of scapula and proximal humerus Insertion: Olecranon of Ulna Action: Extension of the elbow flex the shoulder Flexion of the Elbow  Biceps Brachii Origin: Supraglenoid tubercle of scapula Insertion: Radial and Ulnar Tuberosity (cranial, medial) Action: Flex the elbow Extend the shoulder Cranial View Medial View Supination Pronation  Supinator Origin: Lateral Epicondyle of humerus Cranial view Insertion: Cranial radius Action: Supinate antebrachium (turn inward) Pronator teres Origin: Medial Epicondyle of humerus Insertion: Cranial radius Action: Pronate the antebrachium (turn outward) Carpal Joint  Carpal Joints Antebrachiocarpal joint between the distal radius / ulna and the carpal bones. Middle carpal joint between the two rows of carpal bones Carpometacarpal joint between the distal row of carpal bones and the metacarpals.  Flexion of the carpus A = antebrachial carpal joint; B= middle carpal joint; C = carpometacarpal joint Flexor carpi ulnaris Origin: Medial epicondyle of the humerus and olecranon Insertion: Accessory carpal bone Action: Flex the Carpus Caudal View Left front  Extension Carpal Extension Carpal Hyperextension  Extensor carpi radialis Origin: Lateral epicondyle of the humerus Extensor carpi radialis Insertion: Metacarpal bones II and III Action: Dorsolateral Extend the Carpus View Left front  Vet Prep Structural and Functional Biology Pelvic Dr. Melissa Kehl Limb Joints Courtesy of Dr. Terri Clark  Learning Goals Describe the actions of muscles on the pelvic limb joints (flexion and extension) according to the location of the muscles relative to the joints. Describe the bones and parts of the bones that form the coxofemoral joint. Describe the bones, parts of the bones, and individual joints that form the stifle joint. Name and identify the ligaments and structures associated with the coxofemoral and stifle joints and describe their functions. Joints of the Pelvic Limb Sacroiliac jt. Coxofemoral (hip) joint Stifle joint Tarsus Metatarso- phalangeal jts. Proximal and distal interphalangeal jts.  Pelvis caudal view  Coxofemoral Joint Lateral view Ilium Head of the femur (ball) and acetabulum (socket) synovial joint Ischium Primary movements are flexion and Acetabulum extension Pubis Also allows for abduction, adduction, and circumduction Head of femur Lateral view Left femur, cranial view  Flexion and Extension Example Quadriceps femoris m. 4 heads (only 2 heads shown) Origin of rectus femoris : Ilium Origin of vastus lateralis: Proximal femur Insertion of both: Tibial tuberosity Tibial tuberosity Lateral view Actions of both together: Flex the hip Extend the stifle  partolfeg caudal Extension and Flexion Example Tuber ischii Semitendinosus m. A hamstring muscle Origin: Pelvis (tuber ischii) Insertion: Proximal, caudal tibia calcaneus Calcaneus (a tarsal bone) Actions: Extend the hip Flex the stifle Lateral views Extend the hock Radiograph of normal canine coxofemoral joints Femur Ventrodorsal view  Joint capsule – fibrous Coxofemoral Joint outer layer and synovial inner membrane that secretes synovial fluid for lubrication Ligament of the head of the femur - courses from the acetabulum to the head of the femur Ventral view Lateral view FYI Coxofemoral luxation (dislocation) Ventrodorsal view Stifle Joint Complex condylar synovial joint Stifle Joint Movements are limited to flexion and extension Joints: Femorotibial Femoropatellar Proximal tibiofibular Several ligaments associated with the stifle Caudolateral view Cranial view  Menisci and associated ligaments Two C-shaped fibrocartilage discs – medial and lateral menisci Located between the condyles of the femur and the condyles of the tibia Dorsal view  Patellar ligament Tendon of quadriceps femoris m. Patella pa Patellar ligament Lateral view Ligament between the patella and the tibial tuberosity  Collateral ligaments of the stifle Located on the lateral and medial sides of the stifle – extra-articular Help stabilize the stifle Lateral collateral ligament Courses from the femur to the fibula and tibia Limits medial motion of the tibia Medial collateral ligament Courses from the femur to the tibia Limits lateral motion of the tibia  Cruciate ligaments Stifle of a cat intra synovial Course between the femur and tibia Intra-articular Named for where they attach to the tibia Cranial cruciate ligament Attaches to the tibia cranially Lateral view Prevents the tibia from sliding cranially Caudal cruciate ligament Attaches to the tibia caudally Prevents caudal movement of the tibia Cranial view FYI Cranial cruciate ligament rupture causesa drawl ofthestifle Normal cruciate ligaments (left stifle) Normal caudal cruciate on the right, torn cranial cruciate on the left  FYI Cranial cruciate ligament rupture Diagnosis Cranial drawer test Tibial compression test MRI Arthroscopy  Vet Prep Structural and Functional Biology Dr. Melissa Kehl Axial Skeleton Courtesy of Dr. Terri Clark  Learning Goals Describe the vertebral formula for the dog. Describe the features of a typical vertebra. Describe the difference between vertebral foramen, vertebral canal, and the intervertebral foramen. Describe the distinguishing features of vertebrae in each region of the body. Describe the joints and ligaments associated with the vertebrae. Describe the articulation of ribs with vertebrae. Define axial muscles and explain the difference between epaxial and hypaxial muscles including their general location and function.  Skull and mandibles Axial skeleton Vertebrae Ribs Vertebral formula for the dog: Sternum C7 T13 L7 S3 Ca 20-23 Hyoid apparatus FYI ONLY T gene mutation of C189G T box transcription factor T gene This mutation has been studied in these breeds: Australian Shepherd, Austrian Pinscher, Brittany Spaniel, Jack Russell Terrier, Karelian Bear Dog, Schipperke, Spanish Water Dog, Swedish Vallhund, and the Pembroke Welsh Corgi Always heterozygous – homozygous expected to be fatal  Features of a typical vertebra C7, Caudal view Vertebral body Intervertebral discs are located between adjacent bodies Vertebral arch Articular process Consists of pedicles (walls) and laminae (roof) Vertebral foramen - surrounded by arch and dorsal surface of body where p cord Processes (Dorsal) spinous process Transverse processes – bilateral Articular processes – cranial and caudal pairs  Vertebral canal and intervertebral foramen Vertebral canal Intervertebral foramen Formed by the vertebral foramen Houses spinal cord Intervertebral foramen between Located laterally between adjacent vertebrae Spinal nerves and blood vessels course through Intervertebral foramen Vertebral canal Lateral view, thoracolumbar region  Cervical vertebrae C1 and C2 are NOT typical vertebrae! Atlas, dorsal view C1 (Atlas) Large transverse processes, referred to as wings No spinous process C2 (Axis) Prominent spinous process Dens articulates with atlas Axis, left lateral view C1 and C2 craniolateral view Hants atlas Joints associated with the Atlas Atlanto-occipital joint Between occipital condyles of skull and the atlas (C1) Allows extension and flexion only (nodding “yes” joint) Atlantoaxial joint Between the atlas (C1) and the axis (C2) Rotary movement along the long axis (“no” joint) www.reddit.com  Ligaments associated with the atlas and axis Several ligaments stabilize the atlas and axis. Transverse ligament of the atlas - holds dens against the atlas  Vertebral a. Cervical vertebrae C3-C6 C5, Craniolateral view More typical Short spinous processes Transverse foramen present in transverse processes of C1- C6 for vertebral artery, vein, nerve in systemotherthan c not C7 No transverse foramen Has a costal fovea for articulation with the 1st rib C7, Caudal view  Lateral radiograph of cervical vertebrae Dog FYI  Thoracic vertebrae Long spinous processes Short transverse processes due to articulation with ribs Costal foveae on bodies and transverse processes for articulation with ribs T6, craniolateral view  Ribs and Sternum 13 pairs of ribs in the dog 8 sternebrae in the dog Costochondral junction Junctionwhereribs thecartilage meet Costal Cartilage FYI Flat Chested Kitten Syndrome Kittens with flat chests have a thoracic deformity and is characterized by sharp angulation at the costo-chondral junction causing marked dorso-ventral (top to bottom) flattening of the rib cage.  Tubercle of rib Rib articulation T4 T5 Head of rib The head of the rib articulates with the body of the corresponding thoracic vertebrae. Transverse process For ALL ribs, the head of the rib Body articulates with the body of the same number. For ribs 1-10, the head of the rib ALSO articulates with the body of the vertebrae cranial to it. ai The tubercles of the ribs articulate with the transverse processes of the corresponding vertebrae for ALL Rib 5 ribs.  Lumbar vertebrae Large bodies Large transverse processes Prominent spinous processes T13 Extra processes for muscle Sacrum attachment  Sacrum Fused S1, S2, S3 vertebrae Ventral view Articulates with ilium Fused transverse processes Sacral foramen for nerves instead of intervertebral foramina Dorsal view (3, 3’) dyingIsdtogether Cranial view 2. Articular surface 3. Ventral (3’ dorsal) sacral foramina 4. Spinous process 6. Vertebral canal 7. Body  Caudal/coccygeal vertebrae First few caudal vertebrae look like typical vertebrae and then they become more rod-shaped Hemal arch located on Ca4-Ca6 - Protects tail vessels Ca5  Intervertebral disc  Located between vertebral bodies (except at C1-C2 and in the sacrum)  Two parts: 1. Anulus fibrosus Outer circumferential collagenous fibers Thicker ventrally 2. Nucleus pulposus Inner gelatinous core  Shock absorber, spreads the load evenly between bones FYI Intervertebral Disc Disease acute chronic Is cord me _ spinal  Vertebral ligaments Supraspinous ligament Courses dorsally along the spinous processes of T1 – Ca3 vertebrae Nuchal ligament Cranial extension of the supraspinous ligament Courses between the spinous processes of the axis (C2) and T1 in the dog (more extensive in large animals!) Not present in the cat or pig Nuchal ligament Supraspinous ligament smashiTames See you in week 5! Preheat Dr. Cristian Martonos 1 Previous lecturer: Dr. Cristian Dezdrobitu “The right half of the brain controls the left half of the body. This means that only left handed people are in their right mind.” https://www.pinterest.com/pin/565483296946963803/ !!! ‘’Pathways of nerve impulses are crossed pathways — meaning that the Left side of the brain controls the RIGHT side of the body, and the Right side of the brain controls the LEFT side of the 2 body’’ !!!  3 https://www.slideshare.net/wyllhy/the-nervous-system-slide-show 4 Role: controls and coordinates all essential functions of the body in the smooth functioning of the different parts of our body without the nervous system we wouldn't be able to think, feel, move or survive the most important function of the nervous system is to integrate and respond to the environment 5 ‘’The detection of environmental changes, their subsequent integration and interpretation, and finally, the production of a behavioral response are the function of the nervous system, incomparably the most complicated of the body systems.’’ DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 6 Function: SENSORY sensory receptors used to monitor changes both inside and outside of the body gathered informations : Sensory input 7 Function: INTEGRATIVE process and interprets the sensory input and takes decisions about what should be done - INTEGRATION MOTOR NS sends informations to the effectors (muscle, glands, internal organs) 8  DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 A simplified receptor: effector neural circuit. 1. Skin receptor; 2, afferent or sensory neuron; 3, synapses on interneuron; 4, interneuron; 5, efferent or motor 9 neuron; 6, striated muscle (effector). 10 DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 cervicaln erves sacralnerves 11  Brain and spinal cord act like the integrating and command center of the nervous system. Role: to interpret incoming sensory information and issue instructions based on past experience and current conditions 12 Outside the CNS Carries impulses from the sensory receptors to the CNS and from the CNS to effectors Cranial nerves: to and from the brain Spinal nerves: to and from the spinal cord 13 Divided functionally in: afferent division (also termed the sensory component, conducts impulses toward the spinal cord and brain) efferent division (or motor component of the peripheral nervous system conveys impulses away 14from the brain and spinal cord) Afferent and Efferent subdivided into the SOMATIC and VISCERAL systems 15 Somatic system is concerned with both sensory and motor functions that determine the relationship of the organism to the outside world they include detection of stimuli in the skin in the tissues of the limbs and trunk 16 behavioral actions such as locomotion Somatic system is sometimes referred to as the voluntary system, because there is a greater conscious awareness and greater voluntary control of somatic functions than of the visceral functions 17 Visceral system concerned with sensory and motor functions that relate to the internal viscera. E.g: the regulation of the blood pressure and heart rate, the control of glandular activity and digestive processes the motor component of the visceral peripheral nervous system is also referred to as18the autonomic nervous system  Autonomic nervous system: Sympathetic Parasympathetic Most organs receive innervation from both components. The sympathetic and parasympathetic components are often described as having antagonistic actions on each organ, although “balancing” might better describe their cooperative role. Visceral efferent fibers of the sympathetic division leave the central nervous system via the spinal nerves in the thoracolumbar regions of the spinal cord; those of the parasympathetic division are found in a small group of cranial nerves (III, VII, IX, X) and in spinal nerves in the sacral region of the spinal cord. Many visceral efferent fibers travel to their target organ by joining with19other nerves so that they obtain a very widespread peripheral distribution. Somatic Nervous System Autonomic Nervous System Regulates the voluntary movement Regulates the involuntary movement of the body of the body Regulates movements of the body Regulates bodily functions such as via the skeletal muscles, along with respiratory rate, heart rate, urination, sensory stimuli related to vision, smell, digestion, sexual arousal, pupillary taste, pain, noise, touch, and response temperature Made up of the afferent nerves Made up of a complex network of (sensory nerves) and efferent nerves motor neurons, which control glands, (motor nerves) that stimulate skeletal cardiac muscles, and smooth muscle movement muscles Divisions include the sympathetic Divisions include the spinal nerves and the parasympathetic nervous 20 and the cranial nerves system  21 https://www.slideshare.net/wyllhy/the-nervous-system-slide-show  DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 Neurons (nerve cells) are the basic elements of the nervous system. 22  Thin branching extensions of the cell body that conduct nerve impulses toward the cell body Courtesy of Drs Ray Wilhite, Dan Hillmann and Joe Rowe https://www.slideshare.net/itutor/nervous-system-22589837 A single branch (in most neurons) which conducts nerve 23 impulses away from the cell body. spinalnervesaremixednerve have ftp.mf Pffrasympanetic CROSS SECTION OF SPINAL 24 CORD  DYCE, SACK AND WENSING’S TEXTBOOK OF VETERINARY ANATOMY, FIFTH EDITION ISBN: 9780323442640 Dorsal view of the spinal cord and the vertebral pedicles of the horse. The spinal cord is shorter than the vertebral canal (ascensus medullae spinalis). (B) Enlargement of the caudal part. 1, Atlas; 2, ilium; 3, sacrum; 4, cervical intumescence; 5, lumbar 25 intumescence; 6, cauda equina.  NERVES Based on the direction of the nerve impulse, there are: Sensory (afferent) nerves Motor (efferent) nerves Mixed nerves = sensory + motor (somatic and/or autonomic) 26 Based on the site of emergence, there are: Spinal nerves (emerge from the spinal cord) Cranial nerves (emerge from the brain) NOTE! A