Often, only one or two sutures are affected. The genetic mutation that causes OI affects the bodys production of collagen, one of the critical components of bone matrix. Occipital Bone: Another unpaired flat bone found at the back of the skull. This happens before the baby's brain is fully formed. The hollow space taken up by the brain is called the cranial cavity. A. because it eventually develops into bone, C. because it does not have a blood supply, D. because endochondral ossification replaces all cartilage with bone. al kr-n-l 1 : of or relating to the skull or cranium 2 : cephalic cranially kr-n--l adverb Example Sentences Recent Examples on the Web Over the weekend, the former Bachelorette star, 37, shared photos of 5-month-old son Jones West wearing a new cranial helmet, which Maynard Johnson had specially personalized for the infant. Craniometaphyseal dysplasia, autosomal dominant. The severity of the disease can range from mild to severe. Treatment often requires the placement of hollow tubes (drains) under the skull to allow this blood to drain away. The cranial roof consists of the frontal, occipital, and two parietal bones. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. While theres no cure, treatments can help improve quality of life. Here are the individual bones that form the neurocranium: 1. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt. Appointments & Locations. They are joined at the midline by the sagittal suture and to the frontal bone by the coronal suture. Interstitial growth only occurs as long as hyaline is present, cannot occur after epiphyseal plate closes. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. Ubisoft delays Skull & Bones for the 6th time,Skull & Bones has been in development for almost a decade and yet Ubisoft still seems unable to decide what to do with the open-world tactical action game. Your skull provides structure to your head and face while also protecting your brain. Subscribe to our newsletter It could be coming from your latissimus dorsi. This is why damaged cartilage does not repair itself as readily as most tissues do. The sutures are flexible, the bones can overlap during birthing, preventing the baby's head from pressing against the baby's brain and causing damage.What are t rachellelunaa rachellelunaa 04/09/2021 Frontal bone -It forms the anterior part, the forehead, and the roof of the orbits. Learn to use the wind to your advantage by trimming your sails to increase your speed as you try to survive treacherous . O Diaphysis The picture also helps us to view the cranial vault in its natural position; the cranial floor is at a distinct angle, starting at the level of the frontal sinus and continuing at an angle to include the small pocket that contains the cerebellum. Chondrocranium or cartilaginous neurocranium: so-called because this area of bone is formed from cartilage (endochondral ossification). Cranial Neuroimaging and Clinical Neuroanatomy: Atlas of MR Imaging and Computed Tomography, Fourth Edition. Cranial bones are connected via immovable joints, called sutures. The bony edges of the developing structure prevent nutrients from diffusing into the center of the hyaline cartilage. Capillaries and osteoblasts from the diaphysis penetrate this zone, and the osteoblasts secrete bone tissue on the remaining calcified cartilage. The inner surface of the vault is very smooth in comparison with the floor. Below, the position of the various sinuses shows how adept the brain is at removing waste products and extra fluid from its extremely delicate tissues. Just above the occipital bone and close to the midline of the skull cap are the parietal foramina. Cranial Base: It is composed of the frontal, sphenoid, ethmoid, occipital, parietal, and temporal bones. The more mature cells are situated closer to the diaphyseal end of the plate. Retrieved from: Lanfermann H, Raab P, Kretschmann H-J, Weinrich W. (2019). The human skull serves the vital function of protecting the brain from the outside world, as well as supplying a rigid base for muscles and soft tissue structures to attach to.. The 8 cranial bones are the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones. By the time the fetal skeleton is fully formed, cartilage only remains at the joint surface as articular cartilage and between the diaphysis and epiphysis as the epiphyseal plate, the latter of which is responsible for the longitudinal growth of bones. This allows the brain to grow and develop before the bones fuse together to make one piece. The foundation of the skull is the lower part of the cranium . Because collagen is such an important structural protein in many parts of the body, people with OI may also experience fragile skin, weak muscles, loose joints, easy bruising, frequent nosebleeds, brittle teeth, blue sclera, and hearing loss. This results in their death and the disintegration of the surrounding cartilage. Mayo Clinic Staff. More Biology MCQ Questions Cross bridge detachment is caused by ________ binding to the myosin head. See Answer Question: Cranial bones develop ________. ", Biologydictionary.net Editors. There is no known cure for OI. Instead, cartilage serves as a template to be completely replaced by new bone. These chondrocytes do not participate in bone growth but secure the epiphyseal plate to the osseous tissue of the epiphysis. Cranial bones develop from: tendons O cartilage. The development of the skeleton can be traced back to three derivatives[1]: cranial neural crest cells, somites, and the lateral plate mesoderm. Curvature of the spine makes breathing difficult because the lungs are compressed. Biologydictionary.net Editors. PMID: 23565096 PMCID: PMC3613593 DOI: 10.3389/fphys.2013.00061 The longitudinal growth of bone is a result of cellular division in the proliferative zone and the maturation of cells in the zone of maturation and hypertrophy. The Neurocranium (the brain case) - goes to develop the bones of the cranial base and cranial vault. They are not visible in the above image. If surgery is indicated, some may be more difficult depending on the location of the cranial tumor. Chondrocytes in the next layer, the zone of maturation and hypertrophy, are older and larger than those in the proliferative zone. The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells (Figure \(\PageIndex{1.a}\)). A bone grows in length when osseous tissue is added to the diaphysis. The periosteum then creates a protective layer of compact bone superficial to the trabecular bone. Remodeling occurs as bone is resorbed and replaced by new bone. Bone is now deposited within the structure creating the primary ossification center(Figure 6.4.2c). (figure 6.43, reserve and proliferative zones). Q. This causes a misshapen head as the areas of the cranium that have not yet fused must expand even further to accommodate the growing brain. Differentiate between the facial bones and the cranial bones. "Cranial Bones." Injury, exercise, and other activities lead to remodeling. The ethmoid bone, also sometimes attributed to the viscerocranium, separates the nasal cavity from the brain. The epiphyseal plate is the area of growth in a long bone. Healthline Media does not provide medical advice, diagnosis, or treatment. The two parietal (pah-ri '-e-tal) bones form the sides and roof of the cranium. By the end of this section, you will be able to: Discuss the process of bone formation and development. The bones of the skull arise from mesenchyme during embryonic development in two different ways. As one of the meningeal arteries lies just under the pterion, a blow to the side of the head at this point often causes an epidural hematoma that exerts pressure on the affected side of the brain. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt. The Cardiovascular System: The Heart, Chapter 20. The cranium isn't involved with any sort of movement or activity. The reserve zone is the region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix. Which bone sits in the center of the skull between the eye sockets and helps form parts of the nasal and orbital cavities? The cranial bones are the strongest and hardest of these layers of protection. What kind of protection does the cranium provide? As the matrix surrounds and isolates chondroblasts, they are called chondrocytes. Eight cranial bones and fourteen facial bones compose the face. At birth, the skull and clavicles are not fully ossified nor are the sutures of the skull closed. In the early stages of embryonic development, the embryos skeleton consists of fibrous membranes and hyaline cartilage. Appositional growth allows bones to grow in diameter. When the chondrocytes in the epiphyseal plate cease their proliferation and bone replaces the cartilage, longitudinal growth stops. Skull base tumor conditions are classified by the type of tumor and its location in the skull base. The cranium is like a helmet for the brain. The severity of the disease can range from mild to severe. Cranial bones develop ________ Elevated levels of sex hormones Due to pus-forming bacteria Within fibrous membranes Internal layer of spongy bone in flat bones Previous Next Is This Question Helpful? Source: Kotaku. Cartilage does not become bone. All that remains of the epiphyseal plate is the ossifiedepiphyseal line (Figure 6.4.4). a. bones b. muscles c. bone and muscle d. cartilage and bone; 1. The cranial bones of the skull join together over time. Common symptoms include a sloped forehead, extra bone. In the early stages of embryonic development, the embryos skeleton consists of fibrous membranes and hyaline cartilage. Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum. Some other conditions that can affect the cranial bones include: With all the structures in your head and neck, its sometimes hard to pinpoint when symptoms are coming from an issue with the cranial bones. Those with the most severe forms of the disease sustain many more fractures than those with a mild form. Q. It articulates with fifteen cranial and facial bones. The neurocranium consists of the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid, and frontal bonesall are joined together with sutures. During the third week of embryonic development, a rod-like structure called the notochord develops dorsally along the length of the embryo. As cartilage grows, the entire structure grows in length and then is turned into bone. Several injuries and health conditions can impact your cranial bones, including fractures and congenital conditions. One is a negative feedback hormonal loop that maintains Ca2+ homeostasis in the blood; the other involves responses to mechanical and gravitational forces acting on the skeleton. The 8 (2 paired and 4 unpaired) bones forming the cranium are called the cranial bones. "It was already quite influential and powerful in the region . Archaeologists have discovered evidence of a rare type of skull surgery dating back to the Bronze Age that's similar to a procedure still being used today. Biology Dictionary. There are two osteogenic pathwaysintramembranous ossification and endochondral ossificationbut bone is the same regardless of the pathway that produces it. They articulate with the frontal, sphenoid, temporal, and occipital bones, as well as with each other at the top of the head (see the final image in the five views below). In intramembranous ossification, bone develops directly from sheets of mesenchymal connective tissue, but in endochondral ossification, bone develops by replacing hyaline cartilage. They stay connected throughout adulthood. Find information on why a bone scan is done and what to expect during. However, the exact function of Six1 during craniofacial development remains elusive. Treatment of cranial injuries depends on the type of injury. The Nervous System and Nervous Tissue, Chapter 13. Cross bridge detachment is caused by ________ binding to the myosin head. The total 8 cranial bones form the cranial cavity, which protects the brain, these are frontal bone, 2 parietal bones, 2 temporal bones, the occipital bone, the sphenoid bone, and the ethmoid bone. The epiphyseal plate is composed of five zones of cells and activity (Figure 6.4.3). This developmental process consists of a condensation and thickening of the mesenchyme into masses which are the first distinguishable cranial elements. The raised edge of this groove is just visible to the left of the above image. They stay connected throughout adulthood. Theyre irregularly shaped, allowing them to tightly join all the uniquely shaped cranial bones. Evolutionary,it is the expansion of the neurocranium that has facilitated the expansion of the brain and its associated developments. Activity in the epiphyseal plate enables bones to grow in length. Some craniofacial abnormalities result from the skull bones fusing together too soon or in an abnormal way during infancy. Q. Some of these cells will differentiate into capillaries, while others will become osteogenic cells and then osteoblasts. The erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum not only increase the diameter of the diaphysis but also increase the diameter of the medullary cavity. Craniosynostosis is the result of the cranial bones fusing too early. The cranial vault develops in a coordinated manner resulting in a structure that protects the brain. It includes a layer of hyaline cartilage where ossification can continue to occur in immature bones. A linear skull fracture, the most common type of skull fracture where the bone is broken but the bone does not move, usually doesn't require more intervention than brief observation in the hospital. Radiation therapy and surgery are the most common initial treatments, while sometimes the best thing is close observation; chemotherapy is rarely used. During intramembranous ossification, compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue. Compare and contrast interstitial and appositional growth. They die in the calcified matrix that surrounds them and form the medullary cavity. The world of Skull and Bones is a treasure trove to explore as you sail to the furthest reaches of the Indian Ocean. Generally speaking, yes. For example, some craniofacial abnormalities can be corrected with surgery. StatPearls Publishing. These include the foramen cecum, posterior ethmoidal foramen, optic foramen, foramen lacerum, foramen ovale, foramen spinosum, jugular foramen, condyloid foramen, and mastoid foramen. Those influences are discussed later in the chapter, but even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone. Legal. Endochondral ossification replaces cartilage structures with bone, while intramembranous ossification is the formation of bone tissue from mesenchymal connective tissue. More descriptive terms include skull base and cranial floor. Red bone marrow is most associated with Calcium storage O Blood cell production O Structural support O Bone growth A fracture in the shaft of a bone would be a break in the: O epiphysis O articular cartilage O metaphysis. All that remains of the epiphyseal plate is the epiphyseal line (Figure \(\PageIndex{4}\)). Anatomic and Pathologic Considerations. Osteogenesis imperfecta (OI) is a genetic disease in which bones do not form properly and therefore are fragile and break easily. But if you have other symptoms, you may have an underlying condition. This is a large hole that allows the brain and brainstem to connect to the spine. In what ways do intramembranous and endochondral ossification differ? Its commonly linked to diseases that affect normal bone function or structure. The most common causes of traumatic head injuries are motor vehicle accidents, violence/abuse, and falls. The flat bones of the face, most of the cranial bones, and the clavicles (collarbones) are formed via intramembranous ossification. "Cranial Bones. Frequent and multiple fractures typically lead to bone deformities and short stature. The cranium is the sum of the cranial and facial bones, as well as the bony part of the larynx. Endochondral ossification replaces cartilage structures with bone, while intramembranous ossification is the formation of bone tissue from mesenchymal connective tissue. The following words are often used incorrectly; this list gives their true meaning: The front of the cranial vault is composed of the frontal bone. Which of the following nerves does not arise from the brachial plexus? The cranium has two main partsthe cranial roof and the cranial base. For instance, skull base meningiomas, which grow on the base of the skull, are more difficult to remove than convexity meningiomas, which grow on top of the brain. Cranial bone development starts in the early embryo from the neural crest and mesoderm cells. 866.588.2264. These form indentations called the cranial fossae. Frequent and multiple fractures typically lead to bone deformities and short stature. These cells then differentiate directly into bone producing cells, which form the skull bones through the process of intramembranous ossification. A separate Biology Dictionary article discusses the numerous cranial foramina. It also allows passage of the cranial nerves that are essential to everyday functioning. The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells (Figure 6.4.1a). In some cases, metal rods may be surgically implanted into the long bones of the arms and legs. The cranium has a very important job: to hold and protect the brain. Neurocranium growth leads to cranial vault development via membranous ossification, whereas viscerocranium expansion leads to facial bone formation by ossification. Development of the Skull. Cranial vault, calvaria/calvarium, or skull-cap. Development of cranial bones The cranium is formed of bones of two different types of developmental originthe cartilaginous, or substitution, bones, which replace cartilages preformed in the general shape of the bone; and membrane bones, which are laid down within layers of connective tissue. Frontal Bone: An unpaired flat bone that makes up the forehead and upper part of the eye sockets. These enlarging spaces eventually combine to become the medullary cavity. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Intramembranous ossification begins in utero during fetal development and continues on into adolescence. The facial bones are the complete opposite: you have two . Braces to support legs, ankles, knees, and wrists are used as needed. Our website services, content, and products are for informational purposes only. This single bone articulates (joins) with the nasal bones, some orbit bones, and the zygomatic bone. 2. Cranial floor grooves provide space for the cranial sinuses that drain blood and cerebrospinal fluid from the lower regions of the meninges (dura mater, arachnoid, and pia mater), the cerebrum, and the cerebellum. During intramembranous ossification, compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue. Bone is a replacement tissue; that is, it uses a model tissue on which to lay down its mineral matrix. Cranial fossae are three depressions in the floor of the cranium. Normally, the human skull has twenty-two bones - fourteen facial skeleton bones and eight cranial bones. Connected to the cranial bones are facial bones that give structure to the face and a place for the facial muscles to attach. In the embryo, the vault bones develop through ossification of the ectomeninx - the outer membranous layer surrounding the brain; while the cranial base develops through an additional cartilaginous stage, 2, 16 the significance of which will be discussed later (Individual bones spanning both regions fuse at a later stage). Natali AL, Reddy V, Leo JT. The Viscerocranium is further divided into: Bones Axial: Skull, vertebrae column, rib cage Appendicular: Limbs, pelvic girdle, upper and lower limbs By shape: Long: Longer than wide; Humerus; Diaphysis (medullary cavity: has yellow bone marrow): middle part of the long bone, only compact bone, Sharpey's fibers hold peristeum to bone Epiphyses: spongey bone surrounded by compact ends of the long bone Epiphyseal plate: hyaline cartilage . There are a few categories of conditions associated with the cranium: craniofacial abnormalities, cranial tumors, and cranial fractures. Craniosynostosis (kray-nee-o-sin-os-TOE-sis) is a disorder present at birth in which one or more of the fibrous joints between the bones of your baby's skull (cranial sutures) close prematurely (fuse), before your baby's brain is fully formed. While these deep changes are occurring, chondrocytes and cartilage continue to grow at the ends of the structure (the future epiphyses), which increases the structures length at the same time bone is replacing cartilage in the diaphyses. Canes, walkers, or wheelchairs can also help compensate for weaknesses. The bones are connected by suture lines where they grow together. The cranial nerves are a set of 12 paired nerves in the back of your brain. Bones grow in diameter due to bone formation ________. The gaps between the neurocranium before they fuse at different times are called fontanelles. Skull & Bones, Ubisoft's pirate battler that's been in development limbo for years now, has been delayed yet again. Cranial nerves send electrical signals between your brain, face, neck and torso. It makes new chondrocytes (via mitosis) to replace those that die at the diaphyseal end of the plate. All of these functions are carried on by diffusion through the matrix. droualb.faculty.mjc.edu/Course%20Materials/Elementary%20Anatomy%20and%20Physiology%2050/Lecture%20outlines/skeletal%20system%20I%20with%20figures.htm, library.open.oregonstate.edu/aandp/chapter/6-2-bone-classification, opentextbc.ca/anatomyandphysiology/chapter/7-1-the-skull, rarediseases.info.nih.gov/diseases/6118/cleidocranial-dysplasia, rarediseases.info.nih.gov/diseases/1581/craniometaphyseal-dysplasia-autosomal-dominant, aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Craniosynostosis-and-Craniofacial-Disorders, hopkinsmedicine.org/healthlibrary/conditions/nervous_system_disorders/head_injury_85,P00785, brainline.org/article/head-injury-prevention-tips, mayoclinic.org/diseases-conditions/fibrous-dysplasia/symptoms-causes/syc-20353197, mayoclinic.org/healthy-lifestyle/infant-and-toddler-health/in-depth/healthy-baby/art-20045964, upmc.com/services/neurosurgery/brain/conditions/brain-tumors/pages/osteoma.aspx, columbianeurosurgery.org/conditions/skull-fractures/symptoms, Everything You Need to Know About Muscle Stiffness, What You Should Know About Primary Lateral Sclerosis, clear fluid or blood draining from your ears or nose, alternating the direction your babys head faces when putting them to bed, holding your baby when theyre awake instead of placing them in a crib, swing, or carrier, when possible, changing the arm you hold your baby with when feeding, allowing your child to play on their stomach under close supervision. The skull and jaws were key innovations in vertebrate evolution, vital for a predatory lifestyle. Most of the chondrocytes in the zone of calcified matrix, the zone closest to the diaphysis, are dead because the matrix around them has calcified. The epiphyseal plate is the area of elongation in a long bone. Development of the Skull. This allows babies to pass through the narrow birth. Research is currently being conducted on using bisphosphonates to treat OI. 1. The cranial bones remain separate for about 12 to 18 months. Modeling allows bones to grow in diameter. If you separate the cranial bones from the facial bones and first cervical vertebra and remove the brain, you would be able to view the internal surfaces of the neurocranium. Doc Preview 128. The answer is A) mark as brainliest. D cells release ________, which inhibits the release of gastrin. Q. Unlike most connective tissues, cartilage is avascular, meaning that it has no blood vessels supplying nutrients and removing metabolic wastes. Function The space containing the brain is the cranial cavity. Within the practice of radiology, he specializes in abdominal imaging. All bone formation is a replacement process. Learn about its causes and home exercises that can help. Cranial bones develop A) within fibrous membranes B) within osseous membranes C) from cartilage models What do ligaments hold together in a joint? The Tissue Level of Organization, Chapter 6. result of the cranial bones fusing too early, This source does not include the ethmoid and sphenoid in both categories, one of the meningeal arteries lies just under the pterion, https://www.ncbi.nlm.nih.gov/books/NBK519545/. Cranial bones develop ________. The cranium refers to the cranial roof and base, which make up the top, sides, back, and bottom of the skull. Cleidocranial dysplasia. The cranial bones remain separate for about 12 to 18 months. As more matrix is produced, the chondrocytes in the center of the cartilaginous model grow in size. 1.2 Structural Organization of the Human Body, 2.1 Elements and Atoms: The Building Blocks of Matter, 2.4 Inorganic Compounds Essential to Human Functioning, 2.5 Organic Compounds Essential to Human Functioning, 3.2 The Cytoplasm and Cellular Organelles, 4.3 Connective Tissue Supports and Protects, 5.3 Functions of the Integumentary System, 5.4 Diseases, Disorders, and Injuries of the Integumentary System, 6.6 Exercise, Nutrition, Hormones, and Bone Tissue, 6.7 Calcium Homeostasis: Interactions of the Skeletal System and Other Organ Systems, 7.6 Embryonic Development of the Axial Skeleton, 8.5 Development of the Appendicular Skeleton, 10.3 Muscle Fiber Excitation, Contraction, and Relaxation, 10.4 Nervous System Control of Muscle Tension, 10.8 Development and Regeneration of Muscle Tissue, 11.1 Describe the roles of agonists, antagonists and synergists, 11.2 Explain the organization of muscle fascicles and their role in generating force, 11.3 Explain the criteria used to name skeletal muscles, 11.4 Axial Muscles of the Head Neck and Back, 11.5 Axial muscles of the abdominal wall and thorax, 11.6 Muscles of the Pectoral Girdle and Upper Limbs, 11.7 Appendicular Muscles of the Pelvic Girdle and Lower Limbs, 12.1 Structure and Function of the Nervous System, 13.4 Relationship of the PNS to the Spinal Cord of the CNS, 13.6 Testing the Spinal Nerves (Sensory and Motor Exams), 14.2 Blood Flow the meninges and Cerebrospinal Fluid Production and Circulation, 16.1 Divisions of the Autonomic Nervous System, 16.4 Drugs that Affect the Autonomic System, 17.3 The Pituitary Gland and Hypothalamus, 17.10 Organs with Secondary Endocrine Functions, 17.11 Development and Aging of the Endocrine System, 19.2 Cardiac Muscle and Electrical Activity, 20.1 Structure and Function of Blood Vessels, 20.2 Blood Flow, Blood Pressure, and Resistance, 20.4 Homeostatic Regulation of the Vascular System, 20.6 Development of Blood Vessels and Fetal Circulation, 21.1 Anatomy of the Lymphatic and Immune Systems, 21.2 Barrier Defenses and the Innate Immune Response, 21.3 The Adaptive Immune Response: T lymphocytes and Their Functional Types, 21.4 The Adaptive Immune Response: B-lymphocytes and Antibodies, 21.5 The Immune Response against Pathogens, 21.6 Diseases Associated with Depressed or Overactive Immune Responses, 21.7 Transplantation and Cancer Immunology, 22.1 Organs and Structures of the Respiratory System, 22.6 Modifications in Respiratory Functions, 22.7 Embryonic Development of the Respiratory System, 23.2 Digestive System Processes and Regulation, 23.5 Accessory Organs in Digestion: The Liver, Pancreas, and Gallbladder, 23.7 Chemical Digestion and Absorption: A Closer Look, 25.1 Internal and External Anatomy of the Kidney, 25.2 Microscopic Anatomy of the Kidney: Anatomy of the Nephron, 25.3 Physiology of Urine Formation: Overview, 25.4 Physiology of Urine Formation: Glomerular Filtration, 25.5 Physiology of Urine Formation: Tubular Reabsorption and Secretion, 25.6 Physiology of Urine Formation: Medullary Concentration Gradient, 25.7 Physiology of Urine Formation: Regulation of Fluid Volume and Composition, 27.3 Physiology of the Female Sexual System, 27.4 Physiology of the Male Sexual System, 28.4 Maternal Changes During Pregnancy, Labor, and Birth, 28.5 Adjustments of the Infant at Birth and Postnatal Stages.