Understanding Human Organ Systems Through Cellular Level

3D Rendering Of The Brain. undefined. [Virtual Presenter] Understanding Human Organ Systems Through Cellular Level Exploring the Cellular Basis of Human Physiology Belinda Silvar Rodriguez February 19 2024.

[Audio] Introduction to Organ Systems Importance of cellular biology in understanding organ systems Provides the foundation for comprehending how individual cells work together to form tissues organ and complex organ systems. Organs are composed of specialized cells that work together to perform specific functions. Review the 10 Organ Systems. Importance of Cellular Biology in Understanding Physiology [break]% We will be reviewing about the basic human anatomy and systems in the human body. In terms of various systems each of which is responsible for specific functions. Importance of cellular biology in understanding organ systems Cellular structures and function Cell communication Cellular specialization Disease mechanisms Development and regeneration What is the Organ Systems? A group of related organs that work together to perform specific functions. Each system has a role in maintaining the overall health and functioning of the body. Easy way to remember all 10 Organ Systems: nicer DRUMS Nervous system Integumentary system Cardiovascular system Endocrine system Reproductive system Digestive system Respiratory system Urinary system Muscular system Skeletal system Some organs may be involved in the function of more than one organ system. Importance of Cellular Biology in Understanding Physiology Cellular structure and function Cellular communication Cellular metabolism Cellular adaptation and homeostasis Disease mechanism.

[Audio] Nervous System Three Unique Cell Types: Neurons Glial cells choroid plexus cells “Choroid plexuses participate in neurohumoral brain modulation and neuroimmune interactions thereby contributing greatly in maintaining brain homeostasis” (Strazielle & Ghersi‐Egea 2000). Unique Tissues: Brain tissue Spinal cord tissue Nerve tissue Functions and Interactions: Facilitates communication regulates bodily functions interacts with muscular and endocrine systems Nervous System Composed of three components: brain spinal cord and nervous. Regulates body functions provides for sensation movement automatic functions and higher mental functions via nerve impulses. *What makes these cell types unique? Neurons – ”conducting” cell that transmits impulse structural unit of the NS. Has three basic parts: cell body (soma) one or more dendrites and a single axon. Communicate with neighboring neurons facilitating information processing and transmission in the NS. Neurons cannot be replaced if destroyed as they do not go through mitosis. Glial cells – (astrocytes oligodendrocytes ependymal cells & microglia) also known as neuroglia. Means “nerve glue.” do not conduct nerve impulses ; support nourish and protect the neurons. Help complete the neurons function in communication. Are capable of mitosis. Work with neurons to maintain homeostasis . -astrocytes – star shaped cells that regulate the concentrations of ions neurotransmitters and other substances. Participate in formation and maintenance of blood brain barrier contribute to synaptic function and plasticity. oligodendrocytes – fatty substance that wraps axons which facilitates rapid conductions of electrical impulses. Form myelin sheaths around multiple axons (C-N-S--) in P-N-S they myelinate individual axons. microglia – immune surveillance and defense against pathogens. Also synaptic pruning neurogenesis and neuroinflammation. Choroid plexus cells – involved In numerous exchange processes that either supply the brain with nutrient and hormones or clear deleterious compounds and metabolites from the brain. Produce C-S-F that surrounds brain and spinal cord. *How do these cell types function together to form unique tissue? All 3 cells form the nervous tissue. Glial protects the neurons while choroid plexus and neurons regulate C-S-F productions and composition which in turn regulates the extracellular environment. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Brain Tissue – main organ of the CNS. It is the center of processing sensory info coordinating motor responses regulating emotions cognition and memory Spinal cord tissue – located within the spinal canal. Has bundles of nerve fibers (sensory&motor neurons) relay center for transmitting signals between brain and PNS. Nerve tissue – found throughout the body part of PNS. Transmits information to C-N-S that transmit to muscles and glands ”communication network” *How do these tissues function together to form the system? Enables organisms to interact with environment regulate bodily functions and coordinate complex behaviors and cognitive processes. All NS functions such as sensory motor and cognitive are essential for survival adaptation and maintaining homeostasis in changing environments. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Nervous & Endocrine: communicate and coordinate through network of interconnected structures and signaling molecules. Together they regulate and coordinate metabolism growth reproduction stress response and immune function. Ex) regulating blood glucose blood glucose rise after meal cells in pancreas (betacells) increase/release insulin(hormone) (vice versa). NS modulates insulin/glucagon secretion  to changing metabolic demands and stressors. Nervous & Muscular: connected through motor neurons that innervate skeletal muscles. Transmit signals to initiate muscle contraction (voluntary movements and reflexive responses to stimuli). Muscular produces movement while NS controls and coordinates movement. Ex) Reflex Arcs.

[Audio] Integumentary System Three Unique Cell Types: Keratinocytes Melanocytes Dendritic cells “Melanocytes (and melanin) also function early during human development; they play critical roles during embryonic development as can be seen in individuals with oculocutaneous albinism type 1 (O-C-A-1-).” (Płonka and others 2009) Unique Tissues: Epidermis Dermis Hypodermis “Much of the body’s water supply is stored within the dermis.” (Layers of the Skin | seer Training n.d.). “functions as both an insulator conserving the body's heat and as a shock-absorber protecting the inner organs. It also stores fat as an energy reserve for the body. The blood vessels nerves lymph vessels and hair follicles also cross through this layer.” (Layers of the Skin | seer Training n.d.). Functions and Interactions: Protects against pathogens regulates temperature interacts with nervous and Circulatory systems Integumentary System includes hair nails and skin. Protect from the external environment produce vitamin D retain water and regulate body temperature. *What makes these cell types unique? Keratinocytes – located above the basal layer “produce keratin a tough protective protein that makes up the majority of the structure of the skin hair and nails” (Layers of the Skin | seer Training n.d.). Form multiple layers in the epidermis. Outermost layer consisting of dead keratinocytes that shed and are replaced by the new cells from lower layers. Primary functions is to form a protective barrier against environmental factors pathogens and UV radiation. Melanocytes – Produce melanin pigment responsible for skin coloration and protects skin from sun damage Dendritic cells – Part of skin’s immune system detect and capture antigens (bacteria viruses and allergens). Maintain skin health. *How do these cell types function together to form unique tissue? All three cell types create a complex and dynamic tissue structure that is essential for the skin’s health integrity and function. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Epidermis – located in the outermost layer of the skin protects the body from the environment thickness of the epidermis varies in different types of skin Did you know skin is “only .05 millimeters thick on the eyelids and is 1.5 millimeters thick on the palms and the soles of the feet. ” Has 5 sublayers that work together to continually rebuild the surface of the skin (basal cell layer squamous cell layer stratum granulosum the Stratum Lucidum and Stratum Corneum). Dermis – located beneath the epidermis thickest of the three layers make 90% of the thickness of the skin. Hypodermis – also known as subcutaneous layer. Located in the innermost layer of the skin. Consists of a network of fat and collagen cells. *How do these tissues function together to form the system? Form a cohesive system that protects the body regulates temperature maintain hydration and facilitate sensory perception. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Integumentary and nervous: linked through sensory receptors in the skin (stimuli – touch pressure temperature and pain). Receptors are sent to NS allowing sensory perception and response. NS interprets sensory info. Recevied from the skin which then prompts a motor response. Ex) pain sensation – when a hot stove is touched. Sensory receptors (nociceptors) transmit pain signals promoting reflexive withdrawal responses. Helps avoid potential harmful stimuli and maintain tissue integrity Integumentary and cardiovascular – linked through blood vessels that supply oxygen nutrients and hormones to the skin. Regulating temp wound heling and immune responses. Ex) Nutrient & Oxygen Deliver Blood vessels in the skin supply oxygen and nutrients to the epidermis dermis and hair follicles supporting cellular metabolism growth and repair. Oxygen and nutrients are delivered to skin cells via diffusion from capillaries.

[Audio] Cardiovascular System Three Unique Cell Types: Cardiomyocytes Endothelial cells cardiac fibroblasts. “Endothelial Cells also communicate with adjacent cardiomyocytes by producing paracrine factors that play essential roles in cardiovascular homeostasis including modulation of cardiomyocytes contractility growth and survival” (Lim et al. 2015). Cardiac Fibroblast “produce extracellular matrix scaffold of the heart and are thought to constitute more than half of all heart cells.” (Doll S and others 2017) Unique Tissues: Heart tissue Valvular tissue Blood tissue Functions and Interactions: Circulates oxygen and nutrients removes waste interacts with respiratory and digestive systems Cardiovascular system – includes heart and blood vessels. Roles include pumping and delivering oxygen poor blood to the lungs and oxygen rich blood to the tissues removes waste from the tissues transports cells nutrients and other substances. *What makes these cell types unique? Cardiomyocytes – provide 30% of the total cell # but account to over 70% of the total cardiac mass due to large volume. Generate the force needed to pump blood throughout body. Branched cells single nucleus abundant mitochondria (connected by intercalated discs) Endothelial cells – form the interior lining of the heart blood vessels and cardiac valves secret vascoactive substances such as nitric oxide (N-O---) and endothelin. Cardiac fibroblasts – are mesenchymal cells provide structural support and maintain the extracellular matrix. Distributed throughout the myocardium and interact with CM and EC. The key function of FBs is to produce constituents of the ECM. *How do these cell types function together to form unique tissue? CMs ECs and CF form cardiac muscle tissue or myocardium. CM forms the muscle fibers that make up the myocardium (enables heart to contract/pump blood effectively). EC lines blood vessels in heart facilitating nutrient and oxygen delivery to CMs Regulates coronary blood flow to changes in metabolic demand and oxygen levels. CF synthesize and organize E-M-C proteins. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Heart Tissue – in the walls of the heart. Responsible for contraction and relaxation of heart chambers. Valvular tissue – heart valves regulates blood flow in heart chambers prevents backflow. In the AV valves and semilunar valves. Blood Tissue circulates within blood vessels and heart. Travels to and from various tissues and organs. transports oxygen nutrients hormones and waste products throughout the body facilitates gas exchange immune responses and homeostasis. *How do these tissues function together to form the system? They collaborate to ensure efficient blood circulation oxygen delivery nutrient exchange and waste removal throughout the body. Important in maintaining tissue viability. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Cardiovascular & Respiratory – linked through the exchanges of gases (O2 and C-O-2--) between lungs and blood vessels. Ex of how they work together is oxygen transport. Cardiovascular & Digestive – linked through the blood vessels that supply O2 and nutrients to the gastrointestinal tract and absorb digested nutrients into bloodstream. Ex of how they work together waste removal..

[Audio] Endocrine System Three Unique Cell Types: alpha beta and delta cells Unique Tissues: Pituitary glands Pancreas Thyroid tissue Functions and Interactions: Regulates hormones maintains homeostasis interacts with cardiovascular and digestive systems Endocrine composed of lots of glands (pineal pituitary thyroid thymus gland and adrenal glands pancreas hypothalamus ovaries and testes. Endocrine system regulates body functions regulate functions of muscles glands and other tissues through secretion of hormones. *What makes these cell types unique? The body automatically tries to stabilize the raise of blood sugars levels Alpha cells – alpha is activated with blood sugars drop hormone glucagon is produced Beta cells – release insulin when blood sugars rise in order to aid cells absorb glucose. Delta cells – produces somatostatin which acts as a counterbalance to insulin and glucagon. Helps maintain blood sugars within range. *How do these cell types function together to form unique tissue? Alpha beta and delta cells allow regulation of blood sugar levels by the secretion of different hormones. The cells are scattered throughout the pancreas. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Pituitary gland – located at the base of brain – in the sella turcica. Two lobes (anterior and posterior pituitary). Regulates the endocrine system. Pancreas – located behind the stomach. Has both exocrine and endocrine functions. Has dual role in digestive and endocrine system regulating energy metabolism and blood glucose levels. Thyroid –located in the neck. Sets the body’s pace as it produces a hormone that can affect metabolism. *How do these tissues function together to form the system? The pituitary gland releases growth hormone (stimulates growth & cell reproduction) in tissues it stimulates thyroid gland which produces T3 and T4. thyroid hormones can also increase oxygen consumption in cells promoting energy production and heat generation. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Endocrine & cardiovascular – linked through the circulation of hormones via the bloodstream. Work together to regulate cardiovascular function maintain blood volume and pressure ensure adequate perfusion of tissues w/O2 & nutrients. An ex is regulation of blood pressure. Endocrine & digestive – communicate through the secretion of hormones by endocrine cells located within the gastrointestinal tract and endocrine glands (pancreas). Regulate nutrient metabolism energy balance and GI function. Example is the regulation of blood glucose levels..

[Audio] Reproductive System (male) Two Unique Cell Types: Spermatocytes Sertoli cells Unique Tissues: Tunica and Erectile Tissue Functions and Interactions: Reproduction hormone production interacts with endocrine and urinary systems Reproductive system male reproductive system (ductus deferens prostate gland testes & penis). Roles are to produce and transport sperm secretes hormones and sexual function. Female reproductive system (mammary glands uterine tubes ovaries uterus & vagina). Roles are producing and transporting eggs (oocytes) site of fetal development nourishment childbirth and lactation also secretes hormones and involved in sexual function *What makes these cell types unique? Sertoli cells – associated with developing germ cells in seminiferous tubule. Support nourish and regulate the process of spermatogenesis. Takes 74 days for sperm to develop. Spermatocytes– diploid cells-have 46 chromosomes go through meiosis I and meiosis II before becoming mature sperm cells. *How do these cell types function together to form unique tissue? Support nourish and regulate the process of spermatogenesis. Takes 74 days for sperm to develop. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Tunica – tough fibrous layer of tissue that covers each testicle Erectile tissue – spongy distensible blood spaces that extends through the shaft of penis. When nitric oxide is released production of cGMP (cyclic guanosine monophosphate) causing smooth muscle of arterial walls to relax and the erectile tissue to fill with blood. *How do these tissues function together to form the system? Located in the penis. Function together during sexual arousal and as sexual stimulation intensifies sperm is ejaculated. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Reproductive & Endocrine – connected by the release of hormones (hypothalamus pituitary gland ovaries & testes) that regulate reproductive processes sexual development and fertility. Endo controls production maturation and release of gametes which influences puberty menstruation ovulation sperm production. Example is puberty and sexual development. Reproductive & Urinary – share anatomical structures and work together in the elimination of waste products fluid balance maintenance and regulation of electrolyte concentrations. Both use urinary bladder and urethra. Example is pregnancy and fluid balance..

[Audio] Digestive System Three Unique Cell Types: Enterocytes Goblet cells Paneth cells Unique Tissues: Intestinal tissue Gastric tissue Pancreatic tissue Functions and Interactions: Digests and absorbs nutrients eliminates waste interacts with respiratory and integumentary systems “Digestion describes the process by which complex dietary substances are converted into simple forms that can be absorbed by the body. Protein digestion starts in stomach and finishes in the intestine.” (Kong S and others 2018) Digestive consists of the mouth salivary glands esophagus liver stomach gallbladder pancreas and large/small intestine. Roles are to digest food absorb nutrients into the blood remove food waste maintain fluid electrolyte and acid base balance. *What makes these cell types unique? Enterocytes – Enterocytes are primarily responsible for the absorption of nutrients (from) secrete digestive enzymes mucus and electrolytes (into) form a physical barrier that regulates the movement (between) Goblet cells – higher concentration in the stomach and intestines. Produce and secrete mucus which lubricates the surface of the digestive tract in order to protect it from abrasion makes it easier to move food and prevents bacterial adhesion. Paneth cells – secretes mucus into the intestinal crypts. *How do these cell types function together to form unique tissue? All found in the epithelial lining of the small intestine. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Intestinal tissue – located in the lining of the small and large intestine. Breaks down complex molecules into simpler forms. Gastric tissue – located in the stomach lining. Contains hydrochloric acid that activates pepsinogen into pepsin. Pancreatic tissue – located in the pancreas. Creates enzymes that aid bile from liver to further break down food. *How do these tissues function together to form the system? The tissues work together from the moment food enters the mouth. When chewing occurs food is mixed with saliva which contains salivary amylase. This initiates digestion of carbohydrates. It then goes down esophagus to stomach were gastric juices break down the food further. digested food enters small intestine where pancreatic enzymes and bile from liver break down nutrients. Intestinal tissues then absorb digested nutrients vitamins & minerals to bloodstream to distribute to body cells. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Digestive & Respiratory – interconnected through the shared roles in gas exchange and pH regulation. Respiratory provides O2 needed for cellular respiration while DS breaks down nutrients to produce energy (A-T-P--) and metabolic substrates. An example is cellular respiration. Digestive & integumentary – interact in nutrient absorption and waste elimination. An example is Vitamin D synthesis..

[Audio] Respiratory System Three Unique Cell Types: Ciliated cells lymphocyte cells B&T cells Unique Tissues: Lymphoid tissue mucosa tissue and ciliated pseudo-stratified epithelium tissue Functions and Interactions: The cells and tissues work together to filter the air we breath protecting attacking and destroying invading bacteria; interacts with cardiovascular and urinary systems “The nasal cavity functions to humidify warm filter and act as a conduit for inspired air as well as protect the respiratory tract through the use of the mucociliary system. The nasal cavity also houses the receptors responsible for olfaction.” (Sobiesk 2023) Respiratory System – nasal cavity pharynx larynx trachea and lungs. Roles are to deliver oxygen to the blood remove carbon dioxide from the body maintains the acid base balance of the blood. *What makes these cell types unique? Ciliated cells – they act as odor receptors which are led by nerves to the brain where impulses generated by the odor receptors are interpreted as smell. Lymphocyte cells – circulate the blood. protect against invasion of inhaled foreign antigens. Primary defense. Two types of lymphocytes (B&T cells) B&T Cells – B cells produce antibody molecules that latch on and destroy invading viruses or bacteria. T cells produce cytokines which are biological substances that help activate other parts of the immune system. *How do these cell types function together to form unique tissue? They all work together in protecting attacking and destroying the invading bacteria viruses and toxins. While the cilia sweep mucus out of the respiratory tract. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Lymphoid tissue – located in the tonsils; and are part of the immune system Mucosa Tissue – lines body canals and multiple organs (digestive respiratory & reproductive). The body carries more than 200 times more mucosa than skin largest protective barrier. Ciliated pseudo-stratified epithelium tissue – has tiny hairs (cilia) project out of it and move back and forth to sweep mucus out of the respiratory tract. Located in the nasal cavity *How do these tissues function together to form the system? The cells and tissues work together to filter the air we breath as small particles and germs are trapped in the nasal cavity by the mucus while the cilia work to sweep the mucus out of the nasal passageways. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Respiratory & Cardiovascular –linked through the exchanges of gases (O2 and C-O-2--) between lungs and tissues. Done through pulmonary circulation where blood vessels supply deoxygenated blood to the lungs for oxygenation and return it to the heart to distribute to the body. Example is regulation of blood pH controlling levels of C-O-2 and bicarbonate ions H-C-O-3 in bloodstream. homeostasis is maintained by the external respiration of gases oxygen and carbon dioxide between air and the blood. Transport of gases to and from the lungs and the tissues. Internal respiration the exchange of gases between the blood and tissue fluid. Respiratory & Urinary – connected by maintaining acid-base balance and regulate electrolyte levels in the body. Example is fluid and electrolyte balance..

[Audio] Stylized Human Kidney And Urinary System Urinary System Two Unique Cell Types: Podocytes Microvilli Unique Tissues: inner mucosa (mucous membrane) smooth muscle layer and outer fibrous coat Functions and Interactions: Filters blood regulates electrolyte balance interacts with cardiovascular and endocrine systems Urinary System (Excretory System) – kidneys ureters urinary bladder and urethra. Roles are removing metabolic waste from the blood maintaining fluid electrolyte and acid base balance and stimulate blood cell production. *What makes these cell types unique? Podocytes – cling to the capillary walls of the glomerulus and leave pores that allow easy passage of small molecules. Called glomerular filtration which produces a filtrate of the blood. Microvilli – tightly packed and form a brush border which increases the surface area for the tubular reabsorption of filtrate components. Each cell has many mitochondria which helps supply energy for active transport of molecules from lumen to the peritubular capillary network. *How do these cell types function together to form unique tissue? They play a part in the anatomy of a nephron and aid in creating urine for disposal. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Inner mucosa – consist of transitional epithelium goes with that in the ureters. Has numerous folds when bladder is empty. Smooth muscle layer Allows bladder to expand/stretch as it fills. Outer fibrous coat – supporting layer of fibrous connective tissue *How do these tissues function together to form the system? All tissues work together in the ureter (tubes that carry urine from the kidneys to the bladder). *How does it work with two other systems to maintain homeostasis/life? How are they linked? Urinary & Cardiovascular – interconnected through blood vessels located in the renal arteries and veins that supply and drain the kidneys. Cardiovascular role is to deliver blood to the kidneys where filtration occurs. An example is filtration and reabsorption. Urinary & Endocrine – both communicate and coordinate activities through hormonal signaling. Endo produces and releases hormones that influence renal function fluid balance and electrolyte levels. Example is Antidiuretic hormone regulation. Urinary systems assists homeostasis through the excretion of urea (produced by liver) and other nitrogenous wastes maintenance of water-salt balance and maintenance of blood pH..

[Audio] Muscular System Three Unique Cell Types: Sarcolemma sarcoplasmic reticulum myofibril Unique Tissues: Skeletal muscle tissue Smooth muscle tissue Cardiac muscle tissue Functions and Interactions: Facilitates movement maintains posture interacts with skeletal and nervous systems human Muscle people musculoskeletal Disorder cardiac Muscle human Musculoskeletal System skeletal Muscle Humanity Muscular system Xray human Anatomy Muscular System – skeletal muscles. Roles are producing movement control body openings and generate heat. *What makes these cell types unique? Sarcolemma – plasma membrane of muscle fiber – forms T Tubules sarcoplasmic reticulum – also known as endoplasmic reticulum. Does not fuse with T-tubules when expanded. When expanded SR are calcium (Ca2 plus ) storage sites Myofibril – encased by sarcolemma. Contracts the muscle fibers. *How do these cell types function together to form unique tissue? All cells work in conjunction to send the signal when there is a skeletal muscle contraction. *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Skeletal muscle tissue – striated cell with multiple nuclei occurs in mscles attached to skeleton voluntary movement Smooth muscle tissue – spindle shaped cells with a single nucleus no striations involuntary movements of substances in lumens of body. Found in blood vessel walls and walls of the digestive tract Cardiac muscle tissue – branching striated cells with single nucleus pumping of blood involuntary. In the wall of the heart *How do these tissues function together to form the system? All tissues are involved with movement. Either movement of the entire organism or movement of materials within the organism. *How does it work with two other systems to maintain homeostasis/life? How are they linked? Muscular & Skeletal enable movement. Muscles attached to bones (tendons). Bones are pulled when muscle contracts (movement in joints). Muscle contraction provides heat to warm the body; bones play a role in C-A-2 plus balance. Nervous & Muscular: connected through motor neurons that innervate skeletal muscles. Transmit signals to initiate muscle contraction (voluntary movements and reflexive responses to stimuli). Muscular produces movement while NS controls and coordinates movement. Ex) Reflex Arcs.

[Audio] Skeletal System Three Unique Cell Types: Osteoblasts Osteocytes Osteoclasts formation maintenance and remodeling of bone tissue – bone metabolism. Unique Tissues: Bone tissue Cartilage Ligaments Functions and Interactions: Provides structural support facilitates movement interacts with Endocrine Cardiovascular Muscular and Digestive systems Skeletal system consist of bones and joints. They support the the body protect internal organs provide leverage for movement produce blood cells and store calcium salts Bone is constantly being remolded in a dynamic process. *What makes these cell types unique? Osteoblasts – responsible for bone formation bone-forming cell. Synthesize and deposit organic matrix of bone tissue. They become osteocytes when trapped within the mineralized matrix. Osteoclasts – responsible for resorption bone-resorbing cells. Osteoclast is linked with osteoblast. They degrade the organic matter matrix of bone secreting enzymes which is important in maintaining homeostasis. Osteocytes – osteoblasts entrapped within lacunae. Communicate with neighboring neighboring cells and the blood supply The three cells are involved in the formation maintenance and remodeling of bone tissue known as bone metabolism. “Osteoblasts secrete two proteins rankl and O-P-G which are responsible for the communication between osteoclasts and their precursors. These two molecules have antagonistic effects on bone mass; while rankl induce bone resorption O-P-G blocks it. Leptin can act through the hypothalamus blocking osteoblast activity or it can act directly on osteoblast receptors enhancing osteoblast function. “(Caetano-Lopes J. Canhao H. & Fonseca J E 2007) *How do these cell types function together to form unique tissue? Together these three types of cells maintain a balance between bone formation resorption and ensuring the structural integrity and metabolic functions of bone tissue. The cells Osteoblasts osteocytes and osteoclasts allows bone tissue to adapt to mechanical stresses repair damage and regulate calcium and phosphate levels in the body. However “any imbalance between the processes of bone formation and bone resorption is linked to various inflammatory bone diseases.” (Yang & Liu 2021) *What makes these tissues unique? Where are these tissues found(in what organ within the system)? Bone tissue – hard and rigid matrix composed of collagen fibers & calcium phosphate crystals contains osteocytes allows nutrient and waste exchange participates in mineral homeostasis. Cartilage – flexible matrix composed of collagen fibers proteoglycans and chondrocyte cells no nerve supply so relies on diffusion for nutrient and repair. Ligaments – Dense bands of fibrous connective tissue made of collagen fibers and some elastic fibers can withstand tension stabilize joints limiting excessive movement and connects bones to other bones. All part of connective tissue *How do these tissues function together to form the system? Bone tissue is the structure for Skeletal System (S-S---) that supports/protects soft tissues/organs. Cartilage is a shock absorber reduces friction between bones (joints). Ligaments reinforce stability (joints) connecting bones preventing dislocations and injuries. How does it work with two other systems to maintain homeostasis/life? How are they linked? Muscular and Skeletal enable movement. Muscles attached to bones (tendons). Bones are pulled when muscle contracts (movement in joints) Endocrine and skeletal Skeletal and Endocrine regulate calcium levels in body. Calcium important for bone health and involved in muscle contraction nerve transmission and blood clothing. Endocrine through glands (thyroid and parathryroid). Endo secretes hormone: PTH -release of calcium from bones to blood when levels are low. calcitonin – calcium deposition in bones when levels are high.

[Audio] Summary The human body is a marvel of hierarchical organization from the microscopic level of individual cells to the macroscopic level of organs and organ systems. Molecular Level  Cellular Level  Tissue Level Organ Level Organ  System Level  Organism Level Understanding the importance of cellular biology in organ systems: cellular biology provides the fundamental knowledge needed to understand how individual cells contribute to the structure function and regulation of organ systems in the human body. By studying cells at the molecular and cellular levels researchers and healthcare professionals can gain insights into the complexities of organ systems and develop strategies to maintain health and treat diseases effectively. Each system plays a vital role in maintaining homeostasis and ensuring the body functions properly. Collaboration between these system Understanding the importance of cellular biology in Physiology: cellular biology provides the fundamental knowledge and insights necessary to understand the complex physiological processes that govern the functioning of living organisms. By studying cells and their interactions we can gain a deeper understanding of health disease and the mechanisms that regulate life processes at the cellular and molecular levels. “proteins are the driving forces of the cellular machinery and they are involved in the control of virtually all physiologic events.” (Doll S and others 2017).

[Audio] References Caetano-Lopes J. Canhao H. & Fonseca J E (2007). Osteoblasts and bone formation. Acta reumatológica portuguesa 32(2) 103-110. Doll S Dreßen M Geyer PE Itzhak DN Braun C Doppler SA Meier F Deutsch MA Lahm H Lange R Krane M Mann M Region and cell-type resolved quantitative proteomic map of the human heart. Nat Commun. 2017 Nov 13;8(1):1469. doi: 10.1038/s41467-017-0-1-7-4-7-2. PMID: 29133944; PMCID: PMC5684139. Kong S Zhang YH Zhang W Regulation of Intestinal Epithelial Cells Properties and Functions by Amino Acids. Biomed Res Int. 2018 May 9;2018:2819154. doi: 10.1155/2018/2819154. PMID: 29854738; PMCID: PMC5966675. Layers of the Skin | seer Training. (n.d.). cancer Lim S L Lam C S Segers V F Brutsaert D L & De Keulenaer G W (2015). Cardiac endothelium-myocyte interaction: Clinical opportunities for new heart failure therapies regardless of ejection fraction. European Heart Journal 36(31) 2050–2060. Mader Sylvia S. and Michael Windelspecht. Human Biology. McGraw Hill Education 2023. Plonka P M Passeron T. Brenner M. Tobin D J Shibahara S. Thomas A. ... & Schallreuter K U (2009). What are melanocytes really doing all day long…?. Experimental dermatology 18(9) 799-819. Strazielle N. & Ghersi‐Egea J (2000). Choroid plexus in the central nervous system: biology and physiopathology. Journal of Neuropathology and Experimental Neurology 59(7) 561–574. Sobiesk J L (2023 July 24). Anatomy head and neck nasal cavity. StatPearls NCBI Bookshelf. Yang N. & Liu Y (2021). The role of the immune microenvironment in bone regeneration. International Journal of Medical Sciences 18(16) 3697–3707. doi.