Urinary System Anatomy PDF

URINARY SYSTEM The urinary system is also called the renal system. It is a vital system in the human body that helps to maintain homeostasis. The urinary system is composed of 4 major organs, which are; i. 2 kidneys ii. 2 ureters iii. 1 urinary bladder iv....

URINARY SYSTEM The urinary system is also called the renal system. It is a vital system in the human body that helps to maintain homeostasis. The urinary system is composed of 4 major organs, which are; i. 2 kidneys ii. 2 ureters iii. 1 urinary bladder iv. 1 urethra. [ ANATOMY OF THE KIDNEY The kidney are bean shaped, retroperitorial organs located at posterior abdominal wall. They are reddish brown in colour. However, cadaveric kidneys are brown in colour. Each Kidney lies between T12 & L2 Vertebral level. They are completely covered by renal capsule and renal facial. The kidney has a 2 surfaces, 2 poles (superior & inferior) 2 borders (Lateral & Medial). The anterior surface of each kidney is rough and notched while the posterior surface is somewhat flat and smooth. Two superior poles of each kidneys houses the suprarenal gland or adrenal gland. The lateral border of each kidney is concave while the medial border is convex. The medial border of each kidney contains the lilium of the kidney where vessels enters and leaves the kidney. The cross section of the kidney reveals 2 distinct layers or region, the renal cortex or renal medulla. The human kidney is 11cm long from the superior pole to the inferior pole, 6cm wide, and 4cm thick. The Kidney weighs 160gram in male and 120grams in female. The lateral border is convex, while the medial border is concave. The right kidney is 2 – 4cm lower than the left Kidney. This is because of the bulk of the liver is on the right side. Each Kidney is covered and supported by three layers: - Renal facial, adipose tissue and renal Capsule The Anterior surface of the kidney is notched and convoluted more than the posterior surface which is smooth. NOTE: the medial borders of each kidney houses the helium which is the entry point of the kidney, where vessels enters and leaves the kidney. Each Kidney receives about 20% of the cardiac output. Renal artery brings blood to the kidney and the renal vein takes blood out of the kidney. A cross section of each kidney has 3 distinct layers:  Renal Cortex  Renal Pelvis  Renal Medulla DIAGRAM SHOWING THE CROSS-SECTIONAL AREA OF THE KIDNEY [ RENAL CORTEX The Renal Cortex is the outermost part of the Kidney. It is greater in appearance and forms a number of projections (renal column) which extends down to pyramids. The granular appearance is as a result of capillaries and structures of the nephroid. The renal medulla is lighter in colour and has an abundance of blood vessels and tubules. It comprises of 8 – 12 renal pyramids. The pyramids are cone shaped section of the kidney, these pyramids narrow at the medulla to form renal calyces, 2 – 4 of these renal calyces’ unit to form the minor calyce. Several minor calyces unite to form the major calyces which later unite to form the renal pelvis. The renal pelvis empties urine into the ureters. Microscopically, the kidney contains 1 – 1.5 million nephrons, the nephron is the functional unit of the kidney and they are involved in ultra-filtration of blood, to form urine and remove toxic waste from the body. There are 2 types of Nephrons in each Kidney: i. Cortical nephron which is about 60 - 70% ii. Juxtamedullary nephrons which is about 20 – 30% The Cortical nephrons are concerned with producing normal or dilute urine while the Juxtamedullary nephron produces concentrated urine. The Nephrons are basically made up of two parts. 1. Renal Corpuscle 2. Renal Tubule DIAGRAM OF NEPHRON THE RENAL CORPUSCLE: Comprises of the afferent and efferent arterioles; the glomerulus and bowman’s capsule. It concerns with the filtration process during urine formation. They form filtration membrane which has capillaries and endothelium that filter blood. Renal Corpuscle consist of the glomerulus and bowman’s capsule. GLOMERULUS: This is a type of Capillary bed formed within the bowman’s capsule, comprising of simple sqamus. They have pores which forms the filtration membrane that filters blood to form glomerular filtrate that subsequently form urine. When the renal artery enters the parenchyma of the kidney, it divides into segmental arteries. Glomerulus is formed by Afferent and Efferent arterioles. Segmental arteries divide into interlobular arteries, interlobular arteries divides into arcuate arteries, arcuate arteries divide into inter lobular arteries, inter lobular arteries divides into afferent arteriole, afferent divided into glomerular capillaries. Several glomerular capillaries unite to form efferent arterioles, efferent arterioles unite to form peritubular capillaries, peritubular capillaries unite to form interlobular veins, interlobular veins unite to form arcuate veins, arcuate veins unite to form interlobular vein, interlobular veins unite to form renal vein. 20% of the cardiac output goes to the kidney through the renal artery. Deoxygenated blood leaves the kidney through the renal vein. Nerve supply is by the renal plexus while lymphatic drainage is unto the lateral aortic lymph nodes. [ THE RENAL TUBULE: This comprises of the proximal convoluted tubule, the loop of Henle, the Distal convoluted tubule and collecting duct. This portion of the nephrons are responsible for selective reabsorption and selective secretion during urine formation. Renal tubules comprises of;  The proximal convoluted tubules   The loop of Henle  Distal Convoluted tubules and  The collecting duct The loop of Henle further consist of:  Thick descending loop of Henle  Thin descending loop of Henle  Thick ascending loop of Henle  Thin ascending loop of Henle THE PHYSIOLOGICAL FUNCTION OF THE KIDNEY The Kidney performs the following physiological functions. 1. It plays a role in Homeostasis: this it does by the excretion of waste products of metabolism such as urea, uric acid, creatinine and bilirubin. 2. Maintenance of fluid and electrolytes balance, water balance and maintenance of acid-base balance.  HEMATOPOIETIN FUNCTIONS: The kidney stimulates the production of erythrocytes by secreting erythropoietic hormone. Erythropoietin which stimulates the bone marrow to produce blood cells.  ENDOCRINE FUNCTION: The Kidney is responsible for the production of endocrine hormones such as; o Erythropoietin o Thrombopoietin o Prostaglandin o Renin; and o Calcitriol  REGULATION OF BLOOD PRESSURE: The Kidney regulates blood pressure by regulating the amount of urine produced by extracellular fluid volume.  REGULATION OF BLOOD CALCIUM LEVEL: The Kidney regulates blood capsule level by activating vitamin D to its acidic form (125 Dihydroxycholecalciferol) vitamin D is necessary for the metabolism of calcium in the small intestine.  PROCESS OF URINE FORMATION Urine formation is a blood cleansing process that occurs in the nephrons of the Kidneys. About 1500ml of urine is produced per day. Urine is formed in the Kidney when Blood is being filtered by the glomerulus. It involves 3 basic steps; they are; This process is in 3 stages: i. Glomerular filtration ii. Tubular reabsorption iii. Tubular secretion, selective secretion I. GLOMERULAR FILTRATION As the name implies, it occurs in the glomerulus. This phase of urine formation occurs in the renal capsule. The process of blood of passing through the glomerulus into the bowman’s capsule into the tubules form urine. This process is called glomerular filtration. This is the first step of urine production. In the stage, water and some of the solutes in blood plasma moves across the wall of the glomerulus into the Bowman Capsule to form glomerular filtrate. It is important to note that, in an adult female, about 150 liters of glomerular filtrate is formed daily, while in an adult male, about 180 liters of glomerular filtrate is formed. NOTE: Males have more than female. More than 99% of glomerular filtrate returns to the blood stream, while only about 1-2% are excreted as urine. [ Substances that are filtered during glomerular filtration includes:  Water  Uric acid  Potassium  Creatinine  Glucose  Sodium ion  Potassium ion  Bicarbonate etc. TUBULAR REABSORPTION: is the filtered fluid or glomerular filtrate flows along the renal tubules, the tubular cells reabsorb about 99% of the filtered water and solute which are still useful to the body. The water and useful solutes returns to the blood as it flows through to the peritubular capillaries and vasa recta. TUBULAR SECRETION (SELECTIVE SECRETION) As the filtrate flows down the renal tubule, the tubular cells secretes water products such as drugs, uric acid, creatinine, urea into the fluid, also, some metabolic waste that are still remaining within the blood are secreted to the tubular cells. URINE A huge amount of blood goes to the kidney because they help remove toxic substances that cells produces. Glucosuria is a condition when glucose is found in urine, this can be an indication of an under lying health condition which can be diabetes mellitus. (this means not all glucose was absorbed by blood). On the other hand, not all toxic substances are excreted in some cases. Concentrated urine is formed when the fluid content/blood volume is low. Dilute urine is formed when there is a lot of fluid in the body i.e. fluid content is high. FACTORS THAT AFFECT GLOMERULAR FILTRATION RATE 1. Renal Blood Flow: increase in renal blood flows also causes an increase in the volume of Blood. 2. Colloid Osmotic Pressure: This has to do with the presume exerted by the proteins that are within the blood as it flows through the capillaries. 3. Hydrostatic Pressure in the Bowman’s Capsule: This has to do with the pressure of water or fluid in the bowman’s capsule. An increase beyond it’s limit will cause an increase in glomerular filtration rate. 4. Constriction of Afferent Arteriole: Constriction of the afferent arterioles will cause a decrease in glomerular filtration rate, while a dilation of the afferent arterioles will cause an increase in glomerular filtration rate. 5. Permeability of the Capillary Membrane: if the capillary membrane at the glomerulus has high permeability for fluid, it means glomerular filtration rate will increase. [ NOTE: Permeability has to do with the ability to allow fluid pass through a membrane. The capillary forms a filtration sheet, ability for it to allow fluid pass through it is permeability. 6. Sympathetic Stimulation: In Adults, Sympathetic stimulation decreases glomerular filtration, while in children, it increases glomerular filtration. Para Sympathetic is the response to sympathetic stimulation. Sympathetic stimulation is known as fight & flight or emergency stimulation. 7. Surface area of the Capillary Membrane: Increased surface area increases glomerular filtration rate, decrease surface area decrease glomerular filtration rate. 8. Hormonal & Stimulation/Hormonal Control: Several hormones are known to cause vasodilation or vasoconstriction affecting blood flow through the glomerulus. Hormones that causes vasodilation and increase glomerular filtration rate are: i. Atrialnatriuretic peptide. ii. Brainatriuretic peptide. iii. Prostaglandin. iv. Dopamine. Hormonal factors that causes Vasoconstriction and decrease in glomerular fluids:  Angiotensin  Noradrenaline  Platelet activating factor  Endothelin CHARACTERISTIC PROPERTIES OF URINE 1. Volume – About 1-2 liter of urine is produced in 24 hours but it varies however, depending on the health state of the individual. 2. Colour: Normal urine has amber or straw colour. It can vary as a result of drug or diet of the individual. 3. Odour: Fresh urine is aromatic, but becomes ammonia like upon standing. 4. Specific gravity: The specific gravity of urine is between 1.001 – 1.035. 5. PH: PH range of urine is between 4.6 – 8.0 6. Turbidity: it is the degree of transparency fleshy voided urine is transparent but becomes turbidity/cloud upon standing. ANATOMY OF THE URETER The Ureter is a fibromuscular tube that runs from the helium of the Kidney to the urinary bladder. It is about 25cm long and it conveys urine from the Kidney to the urinary bladder. Three layers of tissue forms the wall of the ureter from inside out. The mucosa is made up of cuboidal epithelium/cuboidal cells, the muscularis. The muscularis is made up of or formed by smooth muscles arranged in two layers of inner circular and outer longitudinal. The adventitia is made up of connective tissues and collagen type two fibers. Peristatic contraction of the muscularis moves urine from the renal pelvis to the urinary bladder. This wave of contraction is involuntary. It opens into urinary bladder at the posterior aspect of the trigon obliquely. Blood supply to the ureter is through the renal, rectal and vesical. Nerve supply is both sympathetic and parasympathetic. Sympathetic is through T10 and L1, while parasympathetic is S2 – S4. There are 3 constriction points. The first point serves as lodgment for metabolic waste. 2nd Constriction crosses pelvic brim. 3rd point enters parenchyma, into body of urinary bladder. The urinary bladder is a hollow viscoid organ located in the pelvis, it is fibro muscular. An empty urinary bladder is pear shaped, while a urine filled urinary bladder is ovoid in shape. The urinary bladder has a fundus body and neck. It is made up of 3 layers of connective tissues which are; the mucosa, muscularis and adventitia. The mucusa of urinary bladder is made up of transitional epithelium and thrown into folds called ruggae. The muscularis is made up of 3 ill defined smooth muscular layers arranged in inner longitudinal, middle circular and outer longitudinal. These 3 layers of muscles are collectively called detrusor muscle. At the neck of the urinary bladder, they form a circular band called the internal urethral sphincter. The adventitial layer is made up of loose areolar connective tissue. The Adult urinary bladder is capable of storing 700 – 800mls of urine. However, when it falls to 300 – 400mls, micturition reflex is triggered. At the posterior wall of the urinary bladder is triangular area called the trigone. It’s two superior poles are formed by the ureters as they enters the urinary bladder. Blood supply to the urinary bladder is through the superior and inferior vesical arteries. Nerve supply is both sympathetic and parasympathetic. NOTE: the parasympathetic stimulation will cause emptying of bladder while sympathetic will cause filling. However, in most children, parasympathetic overrides sympathetic. MICTURATION/URINATION REFLEX This describes how urine is voided from urinary bladder when it fills to capacity. It involves both voluntary and involuntary muscle contraction of muscles of urinary bladder and the pelvic flow. When the volume of urine exceeds between 200 – 400mls, the bladder wall is stretched and the urge to micturate (urinate) is felt. Nerve impulse is transmitted to the spinal cord through S2 and S3 Segment of the spinal cord sends signal through its reflex arc to the detrusor muscle of the urinary bladder, causing it to contract and expel its content to the urethra. Contraction of the urinary bladder is followed by voluntary contraction of the pelvic muscles and relaxation of the external urethra sphincter which result in conscious voiding of the urine. NOTE: Although emptying of the urinary bladder is a reflex, in early childhood one has to learn initiate it and stop it. That is why when children urinary bladder fills between 150 – 200mls, voids urine without conscious control. ANATOMY OF THE URETHRA The Urethra is a small fibromuscular tube that serves to discharge urine from the urinary bladder. There is sex difference between the male and female urethra. The female urethra is about 4cm long, it lies directly posteriorly to the pelvic symphysis, the clitoris and the vagina opening. It’s course is oblique, inferior and opens anteriorly as the external urethra orifice. In males the urethra measures between 15 – 20cm in length and it is sub divided in 4 sub anatomical parts, which are: 1. Prostatic urethra 2. Membranous urethra 3. Bulbous urethra 4. Spongy urethra The Prostatic urethra is part of the urethra that traverses/passes through the prostrate gland. It measures about 3 – 4cm. The Membranous Urethra is the part of the urethra that lies within the levator ani muscle or the pelvic diaphragm, it measures about 2-3cm. The bulbus urethra lies within the root of the penis with the cruva bulb of the penis. It is about 1-2cm. The spongy urethra is the longest part of the male urethra that transverses the entire length of the corpus spongiosum erectile tissue of the penis. It measures between 8-12cm. the spongy urethra opens at the glands of the penis as the external urethra orifice. The Urethra is made up of two layers of connective tissues-mucosa and muscularis. The Muscularis is made up of smooth circular muscles while the mucosa is lined by stratified columnal non-keratinized epithelium. NOTE: the male urethra has two functions. Serves a passage for urine and passage for semen during ejaculation. But in female it serves only for passage for urine. The female urethra lies between the clitoris and the vagina orifice. DIAGRAM OF THE URETHRA  REGIONS OF THE BODY AND BODY CAVITIES The human body is divided into regions for descriptive purpose. There are basically two broad regions that are sub divided into smaller region. The two region are:  Axial Region  Appendicular Region The axial region comprises of the head, neck and turso. Turso is further divided into thorax, abdomen and pelvis. The axial region has 5 sub-regions. The appendicular regions comprises of the upper and lower extremities also known as lower limbs. In general, the human body has 7 sub regions, broadly they are grouped into axial and appendicular. The Head Region: The head region is the most proximal (superior) part of the body. It comprises of the cranium and face. From below the neck to the pelvis is called the turso the covering alphabet represents a distinct layer of the covering. S – Skin C – Cutaneous connective tissue A – Apponeurosis L – Loose connective tissue P – Pericanium/Periosteum THE SKIN: is the uppermost layer of the scalp, it is usually hairy and made up of sebaceous glands and pacimian corpuscles. The skin of the scalp is made up of 4 distinct layers like any other area of skin in the body. Namely; i. Stratum Corneum ii. Stratum Spinosum iii. Stratum Basale iv. Stratum Granulosum It is the most superficial layer of the scalp. Most of those layers mentioned above is seen in the dermis of the skin. This layer forms a bridge between the skin and the aponeurosis. It is fibro-fatty in nature. (fibrous but have plenty of fat).  Apponeurosis – also called the cranial apponeurotica or galae apponeurotica. It is a thin layer of fibrous connective tissue that connects the frental and occipital bellies of the occipito frontalis muscle.  The loose connective tissue: - it lies below the apponeurosis made up of loose aneolar connective tissue that comprises a network of reticular fibres, collagen fibres and elastic tissues. This layer is also called the danger zone of the scalp. This is because blood vessels and neuro vascular bundle lies on this layer.  Pericranium/Periosteum: - is the final layer of scalp made up of dense irregular connective tissue that has two distance layers. The fibrous outermost layer and the cambium (innermost layer). It is the layer just before the bone of the skull. It is also found in layers where other bone tissue are found. e.g. the whitish layer you see while trying to separate meat from the body. FACE: this comprises of the orbital area (eye) nasal area (nose), auditory area (ear) and buccal area (mouth). It is important to note that aside the connecting tissues, there are also bones in the head. There are 22 bones in the head, 11 paired. The neck region extends from the first cervical vertebrae to the seventh cervical vertebra. It contains the sternocleidomastoid and trapezius muscles. The cricoid cartilage (Adam apple). Other content of the neck includes; the trachea, esophagus, thyroid gland, parathyroid gland, internal artery, and the jugular veins. The thoracic religions lies between the neck and abdomen. The thorac is separated from the abdomen by the diaphragm. Bony framework of the thorac consist of the sternum anteriorly. The ribs and their coastal cartillages and the thoraxic vertebra T1 – T12. All these forms the ribs cage. The cavity formed within the thorac is called the thoracix cavity which houses and protects delicate organs such as heart and great vessels, the lungs (right and left), the trachea, the thoracic part of the esophagus and the thymus. Landmark features of the thoraxic region is the nipple or areola found on the anterior thorax. Abdomen region: The abdominal region extends from the diaphragm superiorly to an imaginary line drawn across the iliac crest of the hip bone. Vertebral level of the abdomen extends from T10 – L5 (from tenth thoraxic vertebrate the fifth lumber vertebra). Visceral content of the abdomen includes, liver, pancrease, kidney, small intestine, (duodenum, ileum) large intestine (ascending colon, transverse colon, descending colon), gall bladder spleen, stomach. DIAGRAM OF THE THORAXIC CAGE DIAGRAM OF BODY REGIONS Appendicular region: The appendicular region are those parts of the body that are fixed to the or axial part. It comprises the upper extremity or limb. The upper extremity extends from the shoulder to the phalanges. Sub division of the upper extremity are the arm, forearm and the hand. The Arm: It is the first part of the upper extremity which extends from the shoulder to the elbow. It has the numerous bone which affix to the glenoid cavity of a scapular lying between the proximal aspect of the arm and the lateral aspect of the thorax is a triangular area called the axilla (armpit) which serves as passage for nerves and blood vessel supplying the upper extremity. At the proximal aspect of the arm is a muscle contour called deltoid. The arm has two muscle compartments. The exterior and posterior. The exterior is the bisep brachi while the posterior is the tricep brachi. Other muscles that attach the arm to the thorax are the supratus anterior, infraspinatus, teres-major, supranatus, teres minor. The Fore-arm: The fore arm is the part of the upper limb between the elbow and the wrist. It has two bones, the ulna and the radius. In a supine position, the ulna lies medially while the radius lies laterally. Muscles in the fore arm are grouped into flexors and extensors. However, there are some muscles that carry out pronation and supination. Examples of flexor muscles are: flexocapile ulnaris, flexocapile radialris, palmarismagos. Example of extensor muscles; extensor digitorium superficialis, extensor carpiulnaris, extensor carpiradialis. Between the distal part of the arm and proximal aspect of the forearm is a depression called the cubital fossa (the depression in the anterior part of the elbow). The Wrist: The wrist lies between the distal part of the forearm and the proximal part of the hand. It has 8 bones. Proximal roll (4); S – Scaphoid L – Lunate T – Triquetrum P – Pisiform Distal roll (4) T – Trapezium T – Trapezoid C – Capitate H – Humate. On the lateral aspect of the wrist, is a triangular depression called the anatomical snuff box. It boarders is found by tendons of extensor pollicis Brevis (posterior and short) and adductor pollicis longus (anterior and long). Muscles of the flexor compartment to the aponeurosis to form a band. The Hand: This extends from meta carpalis to the distal phalanges. It contains five metacarpal bones and 14 phalangial bones. The muscles of the hands are grouped into 2 thenar compartment and Hypothenar compartment. The Muscles are called lumbricoids. The lower extremely extends from the top to the foot. Sub regions of the lower extremity include:  Gluteal region  Thigh  Calf and foot Gluteal Regions: The gluteal regions comprises basically of the gluteus muscles, gluteus maximus, gluteus medius, gluteus minimus. The glutea maximus is the most superficial and largest of the muscles. It forms the bulk of the shape of the buttocks and the hip area. CLINICAL IMPORTANCE The gleutal muscles of gluteal region is used for the administration of intra- muscular injections The gluteus minimus lies beneath the gluteus maximus. Thigh: The thigh is the region of the lower limb between the hip and the knee joint. It is also called the femoral region. It is divided into 3 compartments. Anterior medial and posterior compartments. This compartments surrounds the femur which is the only bone of the thigh. NOTE: The femur is the longest and strongest bone in the human body. The Anterior thigh muscles are basically concern with extension of the thigh. These muscles are quadricep fermoris and the sartorius. The quadricep femoris is made up of 4 muscles. 1. Vastus lacteralis 2. Vastus medialis 3. Vastus intermedialis 4. Femoris muscles Visceral (internal) contents in the thigh region includes muscles, blood vessels, lymph nodes and lymphatic vessels. Blood vessels in the femoral region includes; femoral artery, femoral vein, other vascular bundles are the femoral nerves and the inguinal lymph nodes. POSTERIOR COMPARTMENT This is also called the bare string muscles and they primarily flex the thigh. These muscles includes; biceps femoris, semi tendinosis and semi membranosus. The media thigh muscles are concern basically with adductor of the thigh. They include adduction magnus, adductor previs, adductor longus, gracilis and pectinus. The Leg: This is the part of the lower limbs between the knew and the foot. It has 2 bones, the Tibia located medially and the fibula located laterally. The Tibia is the largest of the 2 bones and most times called the shin bone. Muscles of the legs are grouped into 3 compartment, Anterior, lateral and posterior compartments. The Anterior compartment muscles includes Tibialis anterior, extensors, Hallucis longus, extensor digitorum longus and the fibularis’ muscles. The lateral group of muscles are the smallest and they are fibulans longus and fibularis previs. The posterior compartment muscles includes the gastronemus, soleus. The two muscles are superficially located. The Deep Muscles: includes the Tibilis posterior poplitus, flexor hallucis longus, flexor digitorum longus. THE FOOT The foot is the most distal part of the lower extremities. It extends from the calcaneus to the distal phallenges. The foot contains 22 bones, 7 tarsals, 5 meta tarsal and 10 phallenges. The Tarsal bones are the Talus, the Calcanius Navicular, the Cuboid, and 3 Cunie form. These bones forms arches which enables an individual to stand, walk and run. (Pesplanus is another word for that foot, here, the foot lies parallel to the ground surface).  BODY CAVITIES These are parts of the body that covers vital organs (hollow spaces). They are basically, Dorsal & Ventral Dorsal comprises of Cranial & Vertebral Cavity located on the posterior aspect of the body. The cranial cavity located in the skull is a hollow space which houses and protects the brain and its vessels. It is formed by the bones of the Cranium (Cranial bones). VENTRAL BODY CAVITY This is the hollow space at the anterior aspect of the body beginning from the thorax to the pelvis. It is sub divided into 3; i. The Thoraxic Cavity ii. The Abdominal Cavity iii. The Pelvic Cavity  The Thoraxic Cavity: extends from the first rib and the first thoraxic vertebral to the diaphragm.  Abdominal Cavity: This extends from the diaphragm superiorly to an imaginary line running along right to left iliac crest. The Abdominal Cavity is lined by peritorial membrane called peritorium. The Abdominal Cavity contains the distal part of the stomach, ileum, pancrease, spleen, liver.  The Pelvic Cavity: This extends from the imaginary line (right to left iliac cress) of the floor muscle or pelvic diaphragms pelvic hip bone. It is bounded by the hip bones, sacrum and the corkes. Contents of the pelvic cavity in males includes: Urinary bladder, rectum, sigmoid colon, spermatic cord, prostrate gland gand seminal vesicles. In Females, includes: the uterus, fallopian tube, ovaries, rectum, sigmoid colon, urinary bladder, proximal part of the urethra. Other body cavities are: Axilla, cubita fossa, publitia fossa, inguinal canal.  THE MUSCULAR SYSTEM Tissues of the body. There are basically four types of tissues in the human body.  Epithelial Tissue  Connective Tissue  Muscular Tissue  Nervous Tissue  Epithelial Tissue: This covers the body surfaces and line hollow organs, body cavities and ducts also called glands. NOTE: Connective tissues binds organs together, stores energy and helps provide immunity to diseases causing organisms.  Muscular Tissue: Generates the physical force needed to make body structures, movement and generate body heat.  Nervous Tissues: Detects changes in a variety of conditions inside and outside the body and produce or generates act in potential necessary to respond to the change which may result in muscle contraction or glandular secretion. CELLULAR JUNCTIONS Most Epithelial cells are tightly joined together into functional unit by forming cellular function; cellular junctions are formed by plasma proteins within the cellular membrane (plasma membrane) of cells that helps one cell anchor one cell. TYPES OF CELLULAR JUNCTIONS 1. Tight Junction: These are web-like transmembrane proteins that fuse the outer surface of adjacent plasma membrane of cells. DIAGRAM To Seal off the passage way between adjacent cell s is their function. This prevents the contents of one cell from leaking into another cell. 2. Adhrens Junction: Contains plaques which are transmembrane proteins that birds and attaches to microculaneuts of the cell cytoskeleton.  DIAGRAM Adherens Junction helps epithelial cells resist separation during contractive activity e.g. at when food moves down the intestine. 3. Desmosomes: They are membrane glycoproteins that contains plagues which anchors into intermediate filaments of adjacent cells cytoskeleton. FUNCTION OF DEMOSOMES They help prevents pulling apart of cells during contractions and are found mostly in cardia muscles and epidermis of the skin. 4. Hemidesmosomes: There are transmembrane protein that anchor a cell to its basement membrane (ground substance) where it is found. it make sure a cell remains at its position making sure it does not move away. E.g. liver cells remains in the liver and doses not moves to the kidney or any other organ. 5. Gap Junction: They are membrane proteins called connexins which forms tiny fluids filled tunnels/channel and connects neighboring cells together. They aid in the transfer of nutrient and waste products from the cell to extracellular space on from the cell to blood. MUSCLE TISSUES Muscle is a tissue or type of tissue in the human body that provides support and aids movement in the body. Muscle Tissues are elongated cell called myocytes or muscle fibre that uses adenosinetriphosphate (ATP) to generate action potential or force of contraction in responses to stimuli, producing body movement and generate heat. There are basically 3 types of muscles in the human body. They are: Smooth muscle, 3 skeletal muscle and 2 Cardiac muscle. CHARACTERISTICS OF MUSCLE TISSUES All muscles shares certain characteristic features. These are: 1. Electrical Excitability: This is the ability of a muscle to respond to a stimuli by producing action potential. (Ability to do something) Muscles are called excitement tissues because they have the ability to forcefully contract or provide action potential in response to stimuli.  2. Extensibility: This is the ability of a muscle to be stretched forcefully without being damaged. Example is when the urinary bladder fills with urine, it walls becomes stretch but not damaged, also when food passes through the esophagus, it walls become stretched but not damaged. Another example is when the uterus expands as the foetus grows. 3. Contractility: This is ability of muscles to forcefully contract when stimulated by action potential without being damaged. When a muscle contracts, its fibres are shortened and movement occurs. 4. Elasticity: is the ability of muscle to return to is original shape & size, after a forceful contraction or stretched (stress). TYPES OF MUSCLE The types of Muscles are:  Smooth muscles  Cardiac muscles  Skeletal muscles  Smooth Muscles: Smooth muscles also called visceral muscles are spindle shaped muscle cells or myocytes that are located on the walls of hollow organs and blood vessels, they are single (uninucleated cells), they are non- striated (i.e. they do not have stripes), usually arranged in parallel lines and contraction is usually involuntary.  Gardiac Muscle: They are elongated branched cylindrical myocytes located in the walls of the heart, they are striated and contain 1-2 nuclei that are centrally located, they also contain intercalated disc that contains desmosomes and gap junctions. The contraction of cardiac muscles is involuntary. [   Skeletal Muscles: They are so named because they are attached to bones through tendons and apponeurosis. Skeletal muscles make up to 40-60% of the individual’s body weight. They are elongated, tubular or rod-like, they are striated (striped) and multinucleated. Contraction of skeletal muscle is usually under voluntary control. CELLULAR COMPONENTS OF MUSCLE TISSUE (MUSCLE FIBER) The Cell membrane of a muscle tissue or muscle fiber is called sarcolemma. The Cytoplasm of a muscle cell (muscle fibre) is called Sacoplasm. Myoglobin is a reddish-brown pigment that gives muscle tissues is dark red colouration. It is responsible for storing oxygen required for muscle contraction. Sacoplamic Resticulum is the equivalent of endoplasmic reticulum in other cells and it stores calcium ion necessary for muscle contraction. Myofibril contains myofilaments or muscle proteins which play vital role in muscle contraction. There are 3 class/groups of muscle proteins:  Contractile proteins  Regulatory proteins  Structural proteins  Contractile proteins: are responsible for muscle contraction ^ relaxation. And they are: Actine and myocine. o Myocine: is a contractile protein that makes up the thick filament, it has one tail and two heads. o Actine: is a contractile protein that makes up a thin filament, on each actine molecule is a myocine binding sight which binds to myocine during muscle contraction.   Regulatory Proteins: These are proteins that helps to switch the muscles contractile process on and off. They are two: Troponin and Troponyosin. o Trypomyosin: It is the component of the thin filament. When a muscle is relaxed, tryponyosin covers the nyosin binding sight of actine molecules. Displacement trypomyosin by troponin calcium complex uncovers the myosin binding process sight on actine molecule.  Structural Protein: These are proteins that help keep the thick (myosin) and thin (actin) filaments in proper alignment, they include;  Titin  Nebulin  Myomysin  Alpha actinnin  Dystroptin [ MECHANISM OF MUSCLE CONTRACTION Muscle contraction occurs when actine and myocine binds and slides over each other. DIAGRAM Troponin and Tropomyosin are regulatory process myosin and actine are contractile molecules. Explanation Actine and Myocin has a binding molecule, but tropomyosin covers them, but when troponin calcium iron cones, it binds actine and myosin together slider tropomyosin away. Myosin = chick Actine = Thin NOTE: In relaxation tropomyosin comes back to its original state. FUNTIONS OF MUSCLES The Muscular system plays the following important functions in the body; 1. Produce movement 2. Generation of Heat: When muscles contracts, ATP is hydrolyzed or utilized. This process generates heat which helps to maintain body temperature. 3. Maintenance of Posture: Adjustment made by skeletal muscles, helps to maintain an individual’s body posture, whether in sitting, standing, running or any posture/position assumed by the individual. 4. Protection of internal organs: Skeletal muscles help to cover and protect internal visceral organs and tissues. For example, the anterior abdominal muscles help protect he abdominal visceral. 5. Stabilizes Joints: Muscles Tendons and aponeurosis that crosses a joint helps to maintain and stabilize the integrity of that joint.