Copy of Exam 2 Review Sheet PDF

Please write your answers in blue. SI-reviewed answers will be in green. Review Sheet 1 (5-2 Part 1) 1. Describe the centrality of homeostasis in physiology. Define homeostasis. Many physiological variables must be kept within well defined narrow limits enforced by physiolo...

Please write your answers in blue. SI-reviewed answers will be in green. Review Sheet 1 (5-2 Part 1) 1. Describe the centrality of homeostasis in physiology. Define homeostasis. Many physiological variables must be kept within well defined narrow limits enforced by physiological control systems Why is homeostasis necessary? Homeostasis is essential for the survival and proper functioning of organisms. All disease is caused by failure of homeostasis. Is homeostasis relevant to a few physiological variables or many? Homeostasis is relevant to many physiological variables. In general, regulation of homeostasis is enforced and maintained by two different control systems. Regulation of homeostasis is maintained by the Nervous System and Endocrine System What are those two systems? Compare and contrast the way these two control systems deliver messages to the target tissue and organs they control. Nervous System Endocrine System Works with Receptors and Controllers Effectors, Glands, and Hormones Speed Receives and responds to stimuli Receives and responds to stimuli FASTER SLOWER (fastest in milliseconds) (fastest in seconds) Delivery Use neurons (electrical signal Use hormones (chemicals that method released from axon, to synapse, pass the bloodstream to target to dendrite) destination Organs Brain, spinal cord Pituitary gland, Pancreas, controlled Please write your answers in blue. SI-reviewed answers will be in green. Who was the scientist or physician that coined the term homeostasis and when did he propose the concept of “homeostasis”? Walter Cannon, M.D. first coined the term “Homeostasis” (1926) This was built off from Claude Bernard who coined the term “Internal milieu” (1849) 2. List major examples of variables that are homeostatically regulated. Know the examples of physiological variables mentioned in class including all the important electrolytes. Physiological variables Average normal values pH of blood 7.35 - 7.45 or 7.00 - 7.50 Body temperature 98.6℉ or 37℃ Blood glucose 70 to 99 mg/dL Blood oxygen levels 95-100% Blood carbon dioxide levels 23-29 mmol/L Blood pressure Systolic pressure of 120 and diastolic pressure of 80 (120/80 mmHg) What happens when these variables get out of range to the extent discussed in class? The organism loses homeostasis and is more susceptible to diseases? 3. Know examples of important electrolytes and the specific charge for each. What are electrolytes in general? What is an equivalent phrase for the term “electrolytes”? Electrolytes are substances that conduct electricity when dissolved in water? Is the equivalent phrase “ions”? Know the specific electrolytes listed, their names, symbols and charges. Important Electrolyte Symbol + Ion Charges Calcium Ca2+ +2 Sodium Na+ +1 Chloride Cl− −1 Please write your answers in blue. SI-reviewed answers will be in green. Potassium K+ +1 Phosphate PO43− −3 Bicarbonate HCO3− −1 Magnesium Mg2+ +2 Sulfate SO42− −2 Hydronium or Hydrogen? H3O+ or H+ +1 Are all electrolytes charged atoms of elements? If not, name exceptions. In general, are electrolytes regulated to the same concentration intracellularly compared to the interstitial fluid? NOT all electrolytes are charged atoms of elements. Some can be polyatomic ions. Polyatomic ions include: PO43−, HCO3−, SO42− Electrolytes are NOT regulated to the same concentration intracellularly compared to the interstitial fluid. Electrolytes are famously homeostatically regulated both inside and outside the cell-often at radically different levels. For example, Potassium (K+) is located inside the cell while Sodium (Na+) is located outside the cell membrane. 4. Describe the phrase “negative feedback and its component parts (signal, receptor(s), controller and effector(s). Define the set-point of a homeostatically regulated variable. It is the desired ideal level of a variable that is set by the brain. It's the target value that the body's regulatory mechanisms strive to maintain. By convention, what is the character (positive or negative) of any deviation from this setpoint? Any deviation from the setpoint is always considered POSITIVE Example: Please write your answers in blue. SI-reviewed answers will be in green. Why is negative feedback called negative feedback? Negative feedback is called negative feedback because the components of negative feedback work to diminish (negatively affect) the deviation (the signal, which is always positive) of the variable back toward the set point value. It pushes things in the opposite direction of where things are going. Deviations are always “positive” so the body corrects it by going “negative” Generally, for a homeostatically regulated variable, what is the signal and what is the signal’s relationship to the variable? The three main components of a feedback cycle are signal, receptor, controller, and effector The Signal is the change in the variable. What quality must a receptor have to be a good receptor? The Receptor is the information receiver about a single variable What is the relationship of the receptor to the controller? The Controller is the brains of the operation and receives information from the Receptor. Is the controller “the brains of the operation”? If so, how so (hint: memory, decision-making and command and control). Yes. The controller sends out signals to the brain to start negative feedback (bring something back to the set points) Define, in general, what the effector(s) component(s) is are. The effector is the “muscle of the operation” and brings the variable back to the set point How is the effector “the muscle of the operation”. The effector response to the signal given by the control center Please write your answers in blue. SI-reviewed answers will be in green. If the controller is embedded within the nervous system, what is the nature of the communication it sends forth to the effectors? 2 nuclei in hypothalamus nerve impulse to sweat glands, to smooth muscle, 2 nuclei produce hormones to release into blood stream If the controller is embedded within the endocrine system, what is the nature of the communication it sends forth to the effectors? It is a hormone How and why is negative feedback ideal for regulating homeostasis? Effectors stop their response once the variable has returned to its set point. What are the two major control systems of the body, and which is tuned for regulation within milliseconds? How does this compare with the speed of regulation associated with the other control system? The two major control systems in the body are the Nervous System and Endocrine System. Nervous System is tuned for regulation within milliseconds Endocrine System is tuned for regulation within seconds 5. Describe all the components of negative feedback regulation of body temperature I went over this in class in granular detail. Be able to describe in this detail. What the variable is and its associated signal, the nature of the receptors and how they communicate with the controller, what the controller is and where it resides, and finally all effectors involved and how they work to either cool the body down if appropriate or warm it up (or at the very least, keep it from losing heat) if appropriate. Receptors in the skin (called thermoreceptors) monitor body temp. If body temp rises, the receptors send a message to the control center, the hypothalamus. Control center compares the value against the set point. If a response is necessary the control center will stimulate the effectors to produce their response. The sweat glands will secrete sweat. Once the value of the variable has returned to the set point, the effectors no longer receive information from the control center. Secretion of sweat stops. Please write your answers in blue. SI-reviewed answers will be in green. Regarding the signal, how does it change once the controller decides to act? Signal begins to weaken when the deviation from set point becomes smaller How and when does the controller know when to stop activating the appropriate effector? When the value of the variable has returned to the set point and the controller stops receiving signals. In describing the above you should understand in general what a “nucleus” or nuclei is in the context of neuroanatomy and understand its significance in the context of the function of the hypothalamus. You should also be familiar with how the body’s heating and cooling system is analogous to the heating and cooling system that regulates room temperature inside a classroom. The hypothalamus is a nucleus which is the control Body’s heating and cooling system analogy to AC system When outside is hot, then AC starts working more to cool down building (Negative feedback) When outside is cold, then AC starts working more to heat up building (Negative feedback) The AC Control room can withstand heat, but it won’t immediately work more if the temperature is a bit hotter than the original room temperature A receptor in room works as a receiver that measures very accurately the value of the variable. This receptor is made using a thermometer. Its function is to identify temp. This receptor is also connected to the control room. A brain receives information (temperature) as memory. Brain takes information from receptors in the brain and makes signals. That controller is the thermostat. 6. Describe, in general, the role of a flexible setpoint using homeostatic regulation of both blood pressure and homeostatic regulation of body temperature as examples. Please write your answers in blue. SI-reviewed answers will be in green. Homeostatically, regulated set-points are not always set in stone, nor should they be. Describe why the blood pressure setpoint elevates from resting levels to significantly higher levels during exercise. When we are exercising, we get hot and sweaty, our bodies need more oxygen, heart rate increases, respiration rate increases, more muscle contractions, temperature increases. This causes the set point for Blood Pressure to increase and allow more blood flow. This is mandatory since a higher blood pressure will burn more ATP, allow more oxygen intake, and nutrient intake. Why is this necessary? If the blood pressure setpoint remained fixed at resting levels during exercise, the body would be unable to meet the increased metabolic demands of the muscles when exercising. By allowing the blood pressure setpoint to elevate, the body can ensure that the muscles receive the necessary oxygen and nutrients to maintain optimal function. Are and should setpoints that change, reversible back to their original value? If so, explain the importance of this. Yes, setpoints that change must be able to return to their original value. Also using the exercise example, When resting, your energy demands go down, so its commensurate for blood pressure to go down as well. This allows the body to recover and conserve energy. Also explain how homeostatic regulation of body temperature, at least in the beginning stages of a bacterial and viral infection, can involve a change temporary change in Please write your answers in blue. SI-reviewed answers will be in green. set-point and why this is beneficial as long as the elevation of body temperature does not stay too high for too long before being adjusted back to normal. When we are sick, our bodies change the set points of our body temperature and increase to shock bacteria. Then the temperature goes down to allow the immune system to attack bacteria. During initial bacterial or viral infection, the initial immune response of white blood cells (WBC) will fight the pathogens. While fighting, WBC will secrete a hormone called PYROGENS which will enter the bloodstream and send signals to the hypothalamus to make the body hot. (Pyrogen means “bring the fire”). This is done by increasing the set point for body temperature. This leads to fever. Pathogens are sensitive to temperature, so an increase can reduce their virality. Once pathogens are dead, WBC stops secreting pyrogens, leading the hypothalamus to go back to the original set point. Hypothalamus then orders to sweat more to bring the temperature back down. However, a prolonged elevation of body temperature can be harmful. High fevers can lead to dehydration and organ damage, as the body is not suited to constantly be at high temperatures. Review Sheet 2 (5-2 Part 2) 1. Describe positive feedback in relation to negative feedback. How does positive feedback differ from negative feedback, in terms of how the controller affects the signal? The response to the original stimulus results in the deviation from the set point becoming even greater. (Positive = to increase) In class, I went over a positive feedback mechanism that governs the physiology of labor contractions that drive giving birth. Know the details of this to the extent discussed in class. Variable: rate of contraction, Signal: strength/intensity of contractions Please write your answers in blue. SI-reviewed answers will be in green. What type of molecule is oxytocin? Answer the question from a macromolecular standpoint and from a physiological standpoint (Hint: Oxytocin is a type of macromolecule (what type) that functions in the endocrine system). Oxytocin is released by the Pituitary gland. It’s production is ordered by the brain itself (not endocrine function). Oxytocin is 10 amino acids long protein What is a hormone in general? Chemical messengers that travel in the bloodstream to tissues and organs Is Oxytocin a peptide hormone? Explain. Yes, oxytocin is a peptide hormone as it is secreted to the bloodstream to the target tissue (uterus smooth muscle tissue) to create contraction from stimulus of cervix pushing. Your answer should contain the following words or phrases: endocrine gland, secretion, blood, target tissue (what is it?), receptor, change in target cell physiology (how does the physiology change?). ? Specifically, how does oxytocin fulfill the general characteristics of a hormone? Oxytocin is released into the bloodstream and into the target tissue to create contractions. For this positive feedback, can you name the receptor(s), the controller, the effector and the signal as well as the variable? Stretch of the uterus receptors signal control center, contractions trigger release of oxytocin by hypothalamus, contractions of the uterus increase (effector) Interestingly, the receptor function and the effector function are in the same organ….can you explain? The receptor and effector are both the uterus Please write your answers in blue. SI-reviewed answers will be in green. What stops the positive feedback from spiraling out of control beyond its own usefulness, both in this specific case of maternal labor and for positive feedback regulation in general? Positive feedback stops when the original stimulus is removed. Ex, contractions stop when the fetus is pushed out of the uterus. What is the general pattern of how a variable changes over time for negative feedback? Effectors stop their response once the variable has returned to its set point. Negative feedback is when any deviation from the set point is made smaller or is resisted. Negative = to decrease Compare and contrast this with the general pattern of how a variable changes over time for positive feedback. The effectors continue the response beyond the set point until the original stimulus is removed. There is a type of positive feedback I described as a “vicious cycle”, when, during hemorrhaging blood from wound(s), the heart progressively weakens the weakening ending in circulatory collapse? How would you say this process is still justified as “positive feedback”. (Hint: the signal can be thought to grow downward as well as well as upward…the sign can be indexed by a blood pressure value). Cardiac Tamponade? Contraction of cardiac muscle generates blood pressure and the heart pumps blood to itself through a system of blood vessels on the outside of the heart. Blood pressure must be maintained to ensure adequate delivery of blood to cardiac muscle. Following extreme blood loss, blood pressure decreases to the point that the delivery of blood to cardiac muscle is inadequate. As a result, cardiac muscle does not function normally. The heart pumps less blood, which causes the blood pressure to drop even further- a deviation further from the set point. The additional decrease in blood pressure further reduces blood delivery to cardiac muscle, and the heart pumps even less blood, which again decreases the blood pressure. The process self-propagates until the blood pressure is too low to sustain the cardiac muscle, the heart stops beating and death results. Please write your answers in blue. SI-reviewed answers will be in green. The deviation from the heart rate set point becoming larger and larger makes this an example of positive feedback. 2. Describe the structure and function of body cavities. Know the position and names of the following cavities and structures and their significance to the extent discussed in class: ventral cavity- houses vast majority of internal organs, 2 major subdivisions: thoracic cavity and abdominopelvic cavity dorsal cavity- encloses the organs of the CNS, subdivisions are cranial cavity (houses brain) and vertebral canal (houses spinal cord) thoracic cavity- houses primarily heart and lungs, subdivided into 2 lateral pleural cavities and a medial mediastinum pleural cavity- 2, each cavity encloses a lung and is surrounded by the ribs pericardial cavity- inferior mediastinum, encloses the heart Mediastinum- houses the heart superior mediastinum- houses major blood vessels, thymus, trachea, and esophagus abdominopelvic cavity- enclosed by abdominal muscles and consists of the more superior abdominal cavity and the more inferior pelvic cavity abdominal cavity- houses majority of digestive organs such as stomach, intestines, liver, and spleen, kidneys, small and large intestines pelvic cavity- contains the urinary bladder, urethra, rectum of large intestine, and all reproductive organs, appendix causes peritonitis if ruptures Diaphragm- separates thoracic and abdominopelvic cavity, contracts-> flattens=increase volume= decrease pressure relax-> dome-shape=decreases volume= increases pressure Please write your answers in blue. SI-reviewed answers will be in green. Know cavity locations of the organs mentioned in class, to the extent discussed in class. In general, what is the function of the inner surface of body cavities? 3. Describe the structure function of serous membranes. Generally, what is the function of a serous membrane? Protects organs that move by dissipating friction so that they do not rub against each other. What are the common anatomical features of all serous membranes? I can think of three, can you (Hint: 2 membranes, 1 fluid space)? Parietal serous membrane (outer): layer that lines the wall of the cavities Visceral serous membrane (inner): layer covering the internal organs (the viscera) Serous fluid: separates between the two films and produced by the membranes; slippery. How does the anatomy of a serous membrane dovetail with its function? Structure/Anatomy: two membranes with slippery fluid, organs enclosed by the membranes. Visceral=against outer surface, parietal= surrounds visceral, in between= serous fluid Please write your answers in blue. SI-reviewed answers will be in green. Function: Reduces friction from organs enclosed by serous membranes. Ex allows the heart to beat frictionlessly in between the lungs Know the names of the three types of serous membranes discussed, where they are located and any clinical conditions which they may be involved. I spoke of one of these in class and one I asked you to read about. Pleural: puncture in lungs, pleural itis Pericardium: cardiac tamponade Peritoneum: Parietal serous membrane: located at parietal pericardium (pericardial cavity), lining of pleural cavities (parietal pleura), & peritoneal cavity. Visceral serous membrane: located at visceral pericardium (pericardial), covers lungs (visceral pleura), & visceral peritoneum (perioneal). Serous fluid: located between two pericardial membranes (filled with pericardial fluid); between two pleural membranes & filled with pleural fluid; between two serous membranes of peritoneal cavity & filled with peritoneal fluid. Know about hemothorax, pneumothorax (what might cause them to occur and how can they lead to a collapsed lung (What is a collapsed lung?) and what might be done to correct this in the emergency room? Stab wound to chest, blade punctures pleural membrane, hole in chest, everytime you breathe out, surface of lung will pull away from chest wall, air will get sucked into serous space, lung is prevented from expanding, less space if air pocket gets bigger. Tube is stuck into would to suck the air out to allow the lung to expand, pneumothorax= unwanted air entering thoracic cavity, hemothorax= unwanted blood entering thoracic cavity Review Sheet 3 (6-2) answer for review sheet 3-6 are directly from textbook from ch 5-8 1. Correlation of organ systems within the context of body cavities Describe organs and organ systems in the context of the cavities they inhabit. Please write your answers in blue. SI-reviewed answers will be in green. Know all terms of organs and parts of organs mentioned and their location within the body cavities to the extent described in class. These include segments of the colon, pelvic organs, etc. Know the organ whose infection and rupture can be the cause of peritonitis, what peritonitis is and why it can be so serious. Appendix- inflammation of peritoneum infected material spreads and causes tissues to swell, infection causes sepsis Chapter 6: The appendix is an organ whose infection and rupture can cause peritonitis, which is the inflammation of the peritoneum. This condition can be serious because it may lead to widespread infection (sepsis) within the abdominal cavity. 2. Body/organ planes Describe the below for an organ or the human body. Describe anatomical position. Chapter 6: The anatomical position is a standard reference position in which a person stands upright, facing forward, with arms at the sides and palms facing forward. This position is essential for accurately describing locations and relationships between body parts. Why is it essential to have a defined anatomical position? "The anatomical position is important because it provides a standard reference point for the description of the body and its parts." Source: Chapter 5. Frontal/coronal - know position and significance Position: "The frontal (or coronal) plane divides the body into anterior (front) and posterior (back) sections." Please write your answers in blue. SI-reviewed answers will be in green. Significance: "The frontal plane is important for understanding body orientation and is commonly used in imaging techniques." Source: Chapter 8. Transverse/horizontal - know position and significance Chapter 6: The transverse (or horizontal) plane divides the body into superior (upper) and inferior (lower) parts. This plane is essential for imaging techniques like CT scans, as it provides cross-sectional views of the body. Sagittal - know position and significance Chapter 6: The sagittal plane divides the body into left and right portions. The midsagittal plane specifically divides the body into equal left and right halves. This plane is significant for movements like flexion and extension. Be able to apply the above terms of plane to an organ, such as the brain, as well as with respect to the human body as a whole. 1. Frontal (coronal) plane: Position: Divides the body into anterior and posterior sections. Brain: Divides the brain into front (frontal lobe) and back (occipital lobe). Chapter: 8 2. Transverse (horizontal) plane: Position: Divides the body into superior and inferior parts. Brain: Separates upper brain (cerebrum) from lower (brainstem). Chapter: 6 3. Sagittal plane: Position: Divides the body into left and right halves. Brain: A midsagittal section divides the brain into equal halves, revealing the corpus callosum. Chapter: 6 3. Surface anatomy Describe regions. Know all labeled regions of surface anatomy displayed on slides XXX. Know their whether they are anterior/ventral or posterior/dorsal. Please write your answers in blue. SI-reviewed answers will be in green. Be able to use the terms superior/inferior, cephalic/caudal, medial/lateral and proximal distal to compare the position of two regions as appropriate. Chapter 6: Superior/Inferior: Refers to the vertical position. For example, the head is superior to the neck, while the stomach is inferior to the chest. Cephalic/Caudal: Cephalic refers to the head end of the body, while caudal refers to the tail end. For example, the nose is cephalic to the mouth. Medial/Lateral: Medial refers to a position closer to the midline of the body, while lateral refers to a position farther from the midline. For example, the heart is medial to the lungs, while the arms are lateral to the torso. Proximal/Distal: Proximal refers to a position closer to the trunk of the body, while distal refers to a position farther from the trunk. For example, the elbow is proximal to the wrist, while the fingers are distal to the wrist. Describe basis for region nomenclature - What is often the basis of the name of a surface region? For the name of any surface region, know its basis if it reflects a bone or muscle deep to that region. The basis for region nomenclature in surface anatomy often derives from the anatomical structures located beneath that area, particularly bones or muscles. Here are some examples: Chapter 6: 1. Brachial Region: The name “brachial” refers to the arm, deriving from the humerus, the long bone of the upper arm. The brachial region is located over the humerus, which provides a reference point for its nomenclature. 2. Femoral Region: The term “femoral” pertains to the thigh and is named after the femur, the thigh bone. This region is associated with the femur and includes structures that are in close proximity to it. 3. Cervical Region: The cervical region refers to the neck and derives its name from the cervical vertebrae that are found in this area. 4. Tibial Region: The tibial region refers to the lower leg, specifically the area around the tibia, the larger of the two bones in the lower leg. Please write your answers in blue. SI-reviewed answers will be in green. 5. Cranial Region: The cranial region pertains to the head, named for the skull (cranium) that encases the brain. Review Sheet 4 (7-2) CHAPTER 7 1. Describe the macro/microanatomical components of spongy bone using the interior of a flat bone as an example and the proximal epiphyses/metaphyses of a femur as an example. Chapter 7: Spongy bone, also known as cancellous bone or trabecular bone, consists of a network of trabeculae (small, beam-like structures) that create a porous structure. In flat bones, spongy bone is sandwiched between two layers of compact bone, while in the proximal epiphyses and metaphyses of the femur, it provides support and reduces weight without sacrificing strength. Two other terms for spongy bone? Chapter 7: cancellous bone and trabecular bone. Does all bone contain spongy bone? Chapter 7: Yes, all bones contain some amount of spongy bones If so, where in general is it located? Chapter 7: located in the interior of bones, especially in areas like the epiphyses of long bones and within flat bones. What tissue exists in between the trabeculae of all spongy bone throughout life? Chapter 7: red bone marrow What are the two other ways of synonymously referring to spongy bone? Chapter 7: 1. Cancellous Bone: This term highlights the porous, lattice-like structure of spongy bone, which is characterized by trabecular networks. 2. Trabecular Bone: This name emphasizes the trabecular architecture of spongy bone, referring to the thin plates (trabeculae) that form its structure. What is the significance of this tissue? I can think of at least two functional attributes predicated on spongy bone structure, can you? Lightens the skeleton Please write your answers in blue. SI-reviewed answers will be in green. Holes in trabeculae stores hematopoietic tissue I described in detail the organization of a single trabecula. You should be able to compare/contrast the structure of a trabecula with an osteon in terms of how it is organized, its lamellae, its size and the different bone cell types present and their location and presence of endosteum? Here’s a concise comparison of a trabecula and an osteon: Trabecula vs. Osteon 1. Organization: Trabecula: Lattice-like structure, arranged in a network. Osteon: Cylindrical structure, concentric lamellae around a central canal. 2. Lamellae: Trabecula: Several layers arranged in a network, not concentric. Osteon: Concentric lamellae (4-20) surrounding a central canal. 3. Size: Trabecula: 50–400 micrometers thick. Osteon: Central canal diameter ~50 micrometers; larger overall structure. 4. Bone Cell Types Present: Trabecula: Osteocytes in lacunae, osteoblasts on the surface, and osteoclasts may be present. Osteon: Osteocytes in lacunae, osteoblasts on the periphery, and osteoclasts on the surface. 5. Presence of Endosteum: Trabecula: Lined by endosteum covering marrow cavities. Osteon: Central canal lined by endosteum. What is the endosteum, where would it be located and what is its significance? The endosteum is a thin layer of connective tissue that lines the inner surfaces of bones, including the medullary cavity and trabeculae. It is significant for bone remodeling and repair, containing osteoblasts and osteoclasts. To the extent discussed in class on this slide, you should understand how osteoblasts and osteoclasts affect trabeculae structure. How do osteoblasts and osteoclasts Please write your answers in blue. SI-reviewed answers will be in green. cooperate by combining/coordinating their actions to maintain/enforce blood calcium homeostasis while also maintaining the structure of trabeculae? Osteoblasts and Osteoclasts in Trabecular Structure and Calcium Homeostasis Osteoblasts: Function: Build bone by synthesizing and secreting the bone matrix and promoting calcium deposition. Effect: Strengthen trabecular structure through new bone formation. Osteoclasts: Function: Resorb bone by breaking down the bone matrix and releasing calcium. Effect: Maintain and reshape trabecular structure by removing old bone. Coordination for Calcium Homeostasis: 1. Calcium Regulation: When blood calcium is low, osteoclasts resorb bone to release calcium. When calcium is high, osteoblasts deposit calcium in bone. 2. Signal Feedback: Osteocytes send signals to osteoblasts and osteoclasts based on mechanical strain and calcium levels, ensuring balance between bone formation and resorption. Is this a specific example of bone remodeling? Yes Define bone remodeling in general. Bone remodeling is the ongoing process of bone resorption by osteoclasts followed by the formation of new bone by osteoblasts, which is vital for maintaining bone strength and regulating mineral levels in the body. What are the participants in this remodeling? Please write your answers in blue. SI-reviewed answers will be in green. The primary participants in bone remodeling are osteoblasts (bone builders) and osteoclasts (bone destroyers), with osteocytes playing a role in sensing mechanical strain and coordinating the activities of the other two cell types. Is there another example of remodeling we discussed? (Hint: Changes in the proximal epiphysis/metaphyses of the femur starting during the toddler stage). Remodeling in the proximal epiphysis of the femur occurs during childhood, adapting to mechanical stress as a child begins to walk. This remodeling strengthens the bone and facilitates growth. How is this spongy bone remodeling of these proximal epiphyses beneficial? Spongy bone remodeling in the proximal epiphyses provides strength and support while reducing weight, allowing for efficient movement and load distribution during physical activity. How is the spongy bone and compact bone proportioned in the epiphyses? In the epiphyses of long bones, spongy bone predominates, making up most of the interior structure. It is surrounded by a thin outer layer of compact bone. This arrangement allows for a lightweight structure that provides strength and support while also housing red bone marrow within the spongy bone. 2. For a juvenile long bone versus an adult long bone - using the femur as an example ch6 Compare and contrast key anatomical features. Juvenile Femur: Contains an epiphyseal growth plate (cartilage) for growth in length. Adult Femur: Contains an epiphyseal line, indicating that growth has stopped. For a long bone, what is the name of the defining structure that must still be present for the bone to still be classified as juvenile? Ch 6 Epiphyseal growth plate. What is this structure made of? Ch 6 Made of hyaline cartilage. Please write your answers in blue. SI-reviewed answers will be in green. Once these structures disappear, what exists in its place and what is it called? Ch 6 The epiphyseal growth plate is replaced by the epiphyseal line. In the most basic terms, what does the epiphyseal growth plate promote that can no longer be promoted in its absence? Ch 6 Promotes longitudinal growth of the bone, which ceases in its absence. What is the medullary cavity, what types of bone contained with it and what inhabits it fully in the very young? Ch 6 The medullary cavity is a hollow space within the diaphysis. Types of Bone: Contains compact bone surrounding it and spongy bone at the ends. Inhabitation in Youth: Fully inhabited by red bone marrow for blood cell production. As one ages to over ~20 years of life, one type of marrow recedes in the medullary cavity and another type of marrow proliferates. Ch 6 As one ages beyond ~20 years, red marrow recedes, and yellow marrow proliferates in the medullary cavity. What is the proportion of compact bone to spongy bone in the diaphysis and where is the spongy bone located? Ch 6 Proportions: The diaphysis primarily contains compact bone with some spongy bone lining the medullary cavity 3. Describe the gross anatomy of long bones ch 6 Much of this is summarized above or has already been covered for lecture exam 1. The slide gone over on 7-6 is a good summary of slide of much of this except for the structure of the epiphyses and metaphyses which you should know from previous slides. Slide 7-6 also introduces the location of spongy bone in in diaphysis and more highly resolves structure of periosteum, both things you should know. 4. The gross anatomy of flat bones ch6 Know the basic “sandwich structure” of flat bone. Compact bone= bread of sandwich, between= trabecular bone Please write your answers in blue. SI-reviewed answers will be in green. Does flat bone contain red bone marrow? If so, where? Ch6 Yes, flat bones contain red bone marrow, typically located within the trabecular spaces of the spongy bone. Review Sheet 5 (8-2 Part 1) 1. Describe the key histological and physiological features characteristic of bone cells Describe the histology, and physiology of osteoprogenitor cells, osteoblasts, osteoclasts, and osteocytes. Where are these cells found and what actions do they perform? Ch6 1. Osteoprogenitor Cells: Histology: Flattened, spindle-shaped cells found in the inner layer of the periosteum and the endosteum. Physiology: Osteoprogenitor cells are stem cells that differentiate into osteoblasts. Location: Found in the periosteum and endosteum. Action: Their primary function is to give rise to osteoblasts, contributing to bone growth and repair. 2. Osteoblasts: Histology: Cuboidal or columnar cells found on bone surfaces. Physiology: Osteoblasts are bone-forming cells that secrete bone matrix (collagen and minerals). Location: Located on the surface of bone tissue, in both the periosteum and endosteum. Action: They build new bone tissue by depositing collagen and aiding in mineralization. 3. Osteoclasts: Histology: Large, multinucleated cells with a ruffled border, found in pits called Howship’s lacunae. Please write your answers in blue. SI-reviewed answers will be in green. Physiology: Osteoclasts are responsible for bone resorption by breaking down bone tissue using enzymes and acids. Location: Found on bone surfaces, particularly in areas of bone remodeling. Action: They resorb bone tissue, releasing minerals like calcium into the bloodstream. 4. Osteocytes: Histology: Mature bone cells housed in lacunae within the bone matrix, interconnected by canaliculi. Physiology: Osteocytes maintain bone tissue and communicate with osteoblasts and osteoclasts to regulate bone remodeling. Location: Found embedded in the bone matrix within lacunae. Action: They help maintain the mineral content of the surrounding bone and sense mechanical stress to signal bone remodeling. Which of these cells is effectively a stem cell? osteoprogenitor cells- produce osteoblast and stem cell Which is a bone destroyer? osteoclast Which is a bone builder? osteoblast How do these “bone building cells” osteoblasts work? Ch 6 Osteoblasts secrete collagen fibers and organic components to form the bone matrix. They then promote the deposition of calcium and phosphate, which hardens the matrix into bone tissue. Once the matrix surrounds them, osteoblasts become osteocytes and help maintain the bone. Which of the 3 cells are effectively different life history stages of the same cell? Ch6 Osteoprogenitor cells, osteoblasts, and osteocytes Please write your answers in blue. SI-reviewed answers will be in green. Which cells participate in bone remodeling? Ch 6 Osteoblasts and Osteoclasts Which cells inhabit lacunae and which create a “Howship’s lacuna”? Ch 6 osteoclast a. How do osteoclasts work? What do osteoclasts produce that dissolves bone and how do osteoclasts produce a sealed microenvironment for this dissolution to take place? Ch 6 Osteoclasts produce hydrochloric acid and lysosomal enzymes that dissolve bone. They create a sealed microenvironment for dissolution by forming a ruffled border that increases surface area and tightly adheres to the bone surface, preventing leakage of acids and enzymes. Describe podocytes and significance of ruffled border. Ch 6 Podocytes are specialized cells found on the surface of osteoclasts that support the ruffled border. The ruffled border increases the surface area for resorption, enhancing the efficiency of bone breakdown by osteoclasts. What dynamic cytoskeletal component drives the production of microvilli? Ch 6 Actin filaments Describe the process of transcytosis and the role of “proton pumps” in osteoclast physiology. Grabs something from one side transfers to other side, involves pinocytosis and exocytosis, important in osteoclast function, takes calcium out of bone and into blood All cells do endocytosis on a small scale b. How do osteoblasts become osteocytes? Ch 6 Regarding osteocytes, are they as anatomical and physiologically isolated as they might first appear under 400X magnification? No Please write your answers in blue. SI-reviewed answers will be in green. If not, how not? I can think of two ways. Ch.6 One way culminates in the formation of gap junctions, the other culminates in interstitial fluid exchange. 2. Describe the extracellular matrix of bone a. Organic matrix ch 6 Define proteoglycans, hyaluronic acid, ground substance and the role of collagen fibers and their role in contributing to the character of bone. Proteoglycans: Molecules consisting of a core protein and glycosaminoglycan (GAG) chains that provide hydration and structural support. Hyaluronic Acid: A GAG that retains water and contributes to the viscosity of ground substance. Ground Substance: The amorphous material surrounding cells and fibers in bone that contains proteoglycans and hyaluronic acid, providing support and medium for nutrient exchange. Collagen Fibers: Provide tensile strength and flexibility, contributing to the structural integrity of bone. b. Inorganic matrix What is hydroxyapatite? Ch 6 Hydroxyapatite is a mineral form of calcium phosphate that provides rigidity and strength to bone. Is it a salt? If so, what are its components? Ch 6 Yes, hydroxyapatite is a salt composed mainly of calcium and phosphate ions. What cell or cells are responsible for the formation of the organic matrix and hydroxyapatite? Ch 6 Osteoblasts 3. Matrix components that endow a. Compressive Strength Define compressive strength. Ch 8 Compressive strength is the ability of a material to withstand axial loads without failure, typically measured in terms of stress. Please write your answers in blue. SI-reviewed answers will be in green. b. Tensile Strength Define tensile strength. Ch 8 Tensile strength is the ability of a material to resist being pulled apart or stretched without breaking. c. Effect of combining A. and B. What element(s) of the matrix contribute to each of these? Ch 8 Collagen fibers contribute to tensile strength. Hydroxyapatite provides compressive strength. What is an emergent-even synergistic-property of combining compressive strength and tensile strength in one object, such as a bone. Tensile strengthens compressive property of bone How is steel reinforced concrete analogous to the construction of the bone matrix? Steel= tensile strength, makes sturdy structures less likely to shatter in case of earthquake concrete= compressive strength Is there a way one can evaluate the compressive strength of a bone without the tensile strength? Explain. Ch 8 Yes, compressive strength can be evaluated independently through compression testing; however, it does not reflect the material's ability to handle tensile forces. Is there a way one can evaluate the tensile strength of a bone without compressive strength? Explain. Ch 8 Yes, tensile strength can be evaluated through tensile testing, but this does not account for how the material handles compressive forces. If living bone ever experienced a deficit in collagen production or a deficit in hydroxyapatite (or a deficit in both simultaneously) due to some disease or condition, what, affect would such deficits have on the bone? Ch 8 Please write your answers in blue. SI-reviewed answers will be in green. A deficit in collagen would weaken tensile strength, while a deficit in hydroxyapatite would reduce compressive strength, leading to brittle and fragile bones. Imagine being a medical school student in your gross anatomy lab and the instructor presents you with an unpreserved authentic human femur - one from a person who lived decades ago and asked you this question. “In terms of material composition, how does this femur compare with a femur of one of your own legs?” What would be a reasonable answer? Ch 8 An unpreserved human femur would likely have reduced collagen and mineral content compared to a healthy femur, making it more brittle and less strong due to aging and potential decay. Review Sheet 6 (8-2 Part 2) 1. Describe the process of endochondral and intermembranous ossification Define the terms endochondral ossification and intermembranous ossification. Ch 8 intermembranous= parietal bone, meat of sandwich first, the bread Endochondral Ossification: The process where bone develops by replacing hyaline cartilage, forming long bones. Intramembranous Ossification: The process where bone forms directly from mesenchymal tissue, typically seen in flat bones like the skull. Source: Chapter How are these fitting for the process they describe? Ch 8 These terms describe the two main pathways of bone development: endochondral involves cartilage models, while intramembranous involves direct bone formation from connective tissue. What is the state of the skeleton up to 5 weeks post conception? Ch 8 The skeleton is primarily cartilaginous and consists of a basic shape for future bones. At 5 weeks, what ossification starts happening and where? Ch 8 Please write your answers in blue. SI-reviewed answers will be in green. Endochondral ossification begins, particularly in the long bones where cartilage models start forming. What bones are famous for undergoing this type of ossification? Ch 8 Long bones, such as the femur and humerus, Around 8-12 weeks post conception, what type of ossifications really takes off and in what bones? Ch 8 Endochondral ossification intensifies, particularly in long bones as they grow and develop in size. a. Describe the temporal and spatial changes occurring in endochondral ossification throughout life. What are the key events that happen during endochondral ossification from beginning to end? You should work in the following vocabulary into your description, not necessarily in this order listed here: Perichondrium, periosteum, bone collar, periosteal bud(s), chondrocyte hypertrophy, chondrocyte apoptosis, osteoblasts, osteoclasts, primary ossification, woven bone, production of the medullary cavity, secondary ossification. Ch 8 Key Events in Endochondral Ossification: Formation of perichondrium around the cartilage model. Development of a bone collar around the diaphysis. Invasion by periosteal buds, leading to chondrocyte hypertrophy and subsequent apoptosis. Osteoblasts replace the cartilage with woven bone at the primary ossification center. Formation of the medullary cavity as osteoclasts resorb bone. Development of secondary ossification centers in the epiphyses. b. Describe the temporal and spatial changes occurring in intramembranous ossification. What are the key events that occur during intramembranous ossification from beginning to end? You should work in the following vocabulary into your Please write your answers in blue. SI-reviewed answers will be in green. description, not necessarily in this order listed here: Mesenchyme, ossification centers, osteoblasts, osteoclasts, extension of ossification centers (into fingerlike-projections) to form woven bone (where does this occur)? Ch 8 Key Events in Intramembranous Ossification: Mesenchyme condenses to form ossification centers. Osteoblasts secrete bone matrix, forming woven bone. Extension of ossification centers forms finger-like projections into the surrounding mesenchyme. Remodeling occurs to form compact bone, with the remaining mesenchyme differentiating into the periosteum. Remodeling of woven bone, into spongy bone, differentiation of mesenchyme into a periosteum, formation of compact bone. Where do the last two stages underlined and emboldened occur? Ch 8 The last two stages occur at the outer surface of the bone 2. Describe details of the mechanism that promotes elongation of bone growth Describe the position of all the zones of the epiphyseal plate with respect to each other and with respect to the position of the metaphysis/diaphysis and epiphysis. Ch 8 Position of the Zones: Zone of Reserve Cartilage: Closest to the epiphysis. Zone of Proliferation: Next to the zone of reserve, where cells actively divide. Zone of Hypertrophy: Following the zone of proliferation, where cells enlarge. Zone of Calcification: Closest to the diaphysis/metaphysis, where calcification occurs before ossification. Be able to describe the direction of cell migration between the epiphysis and diaphysis as cells migrate through the zones. Ch 8 Chondrocytes migrate from the zone of reserve cartilage toward the zone of ossification, undergoing proliferation and hypertrophy as they move through the zones. Please write your answers in blue. SI-reviewed answers will be in green. Histologically, how do the zones appear different and physiologically what is happening to the cells in each zone? Ch 8 Zone of Reserve: Contains small, inactive chondrocytes. Zone of Proliferation: Shows actively dividing chondrocytes. Zone of Hypertrophy: Contains enlarged chondrocytes preparing for calcification. Zone of Calcification: Appears mineralized, where cartilage is being replaced by bone. What is the “big-picture accomplishment” made as chondrocytes travel the path from the zone of reserve cartilage to the zone of ossification, the zone in which osteoblasts and osteoclasts begin their work. Ch 8 Chondrocytes transitioning from the zone of reserve to the zone of ossification facilitate bone elongation by converting cartilage to bone, allowing for growth. Describe how the epiphyseal plate appears on x-ray and why it appears that way. Ch 8 The epiphyseal plate appears as a radiolucent line on X-rays due to the presence of cartilage, which is less dense than bone. This line becomes less distinct as ossification progresses. Does the epiphyseal plate present a vulnerability of a juvenile long bone to fracture compared to an adult bone? Ch 8 Yes,due to its active growth nature. What is a potential future consequence of having sustained such a fracture? Ch 8 A fracture at the epiphyseal plate can disrupt normal growth, potentially leading to limb length discrepancies or deformities. Ability to add stuff to surface, chondroblast add to cartilage, osteoblast add to bone= appositional growth Osteocytes in hard lacuna, cannot divide Cartilage cells can divide because they don’t have hydroxyapatite Epiphyseal plate- endless supply of chondrocytes, adds new layers of bone to edge of diaphysis making it longer at either end