Histology Sheet 22 PDF 2024

23 22 Baree abu ghanam Waqar al faqeer Ghada abu el ghanam  We remove the excess H2O, we remove the waste products that are designed to be removed in the urinary system, and excess ions in case you eat a salty meal, or you drank a lot of water, the kidneys are the ones res...

23 22 Baree abu ghanam Waqar al faqeer Ghada abu el ghanam  We remove the excess H2O, we remove the waste products that are designed to be removed in the urinary system, and excess ions in case you eat a salty meal, or you drank a lot of water, the kidneys are the ones responsible for it. Detoxification of specific drugs and removal of specific drugs is the main command in the urinary tract. Deamination of amino acids, we have urea, the kidneys are responsible for this clearance and filtration of the blood. 25% of the cardiac output does go to the kidneys, where it will be filtrated. And then, you can imagine how much of the blood flow they get in every cardiac output. Urinary tract made of, two kidneys, each one will receive a urinary artery, and then the urine will be filtered and enters the tube called ureter after that the urine will be collected in the urinary bladder (is a hollow sac that's supported by a thick muscle), when it contracts, it will lead to emptying it and go to the urethra (is the passageway, it's the canal that will lead the urine to the outside). So far, similarities and differences between females and males, this is not something we discuss. We usually discuss the difference in the urethra between females and males, regarding its length, its structure, and the alignment of the urethra. Structure-wise, it is located resting on the posterior abdominal wall. It's not covered by peritoneum, so it is retroperitoneum. you need to be oriented a bit when it comes to the kidney structure. A cut to the kidney will show us dark regions and light regions. A convex lateral and a concave medial. So, this is called the hilum, this is where the blood vessels and ureter will inter-enact. the kidney is surrounded by a renal capsule, which is further covered and protected by adipose connective tissue. This is to protect it and to support it. everything else is wrapped with renal fascia, which is a part of the connective tissue in the surrounding region  We talked about the liver. It's an important organ. Why? Because everything that has been absorbed from the GI tract has to pass through the liver. So, instead of the venous range of the liver, it goes through the systemic circulation. It breaks down into another set of capillaries, the sinusoids of the liver. So, they work on the blood. They filter it. They clean it up and put its input. Because of the hepatocytes, they do act as endocrine cells. What happens is that each kidney will receive one large renal artery. Where does this go? It goes into the hilum. They will break down into smaller arteries. We call them segmental arteries. These will further break down into smaller ones that’s called interlobar arteries will ascend toward the cortex. They will give us what are called arcuate arteries, they break down into smaller ones. We call them cortical radiates, these are extremely tiny arteries, they will give rise to the blood vessel (afferent arterioles). That will enter the nephron, and the blood inside it will be filtered. This is the last station of the blood supply. The blood will be filtered in the nephron, whatever is left of the blood will come out as efferent artery will continue towards the venous which will eventually come out by what we call the renal vein. NOTE: Most of the absorption at the proximal convoluted tubule (rich with microvilli + simple high cuboidal). The glomerulus is the leaky capillaries. And they are further covered by these podocytes (are the visceral layer of the bowman's capsule). Interspacing between specialized cells, we call them mesangial cells. pay attention to the podocyte’s small pedicles they interdigitate with the neighboring cells. There is a tiny space in between. These small slit-like spaces. These are very important. Because whatever will exit the capillaries, eventually will be caught first by the basement membrane. And then they will be caught again by the slits.  There are many things that will not pass. Because these slits are extremely tiny. And then, whatever has been filtered, will enter space. The capsular space. And then it will continue its journey through the proximal convoluted tube. Distal convoluted tubule: simple cuboidal cells of the distal tubules differ from those of the proximal tubules in being smaller and having no brush border and more empty lumens. Fewer mitochondria. Acidophilic appearance. ‫اغلب المعلومات مراجعه كانت‬ ❖The filtration membrane The filtrate that entered the proximal convoluted tubule. Before it entered the capsule. What structures did this filtrate pass through? This is what we call the filtration membrane. The glomerular capillaries and podocytes (completely encircle the capillaries) form a leaky barrier known as filtration membrane.  * Permits filtration of water and small solutes but prevents filtration of most plasma proteins and blood cells * The filtrate crosses three filtration barriers: -a glomerular endothelial cell is quite leaky because they have large fenestrations (0.07–0.1 μm in D.). Located among the glomerular capillaries are mesangial cells (regulate glomerular filtration). - the basement membrane consists of minute collagen fibers and negatively charged glycoproteins (repel plasma proteins and hinders their filtration). -a filtration slit formed by a podocyte: Extending from each podocyte are thousands of footlike processes termed pedicels that wrap around glomerular capillaries. The spaces between pedicels are the filtration slits (permits the passage of molecules smaller than 0.006–0.007 μm; restricts protein filtration such as albumin). Afferent efferent The basement membrane of the pedicles and the basement membrane of the endothelium. They're fused together, and then we have the endothelial cells. So, these are leaky, we have openings between the endothelial cells. Those are the biggest, the leakiest, the easiest structures to pass through. There's a guard or gate. Then, they will be faced by the basement membrane (It is charge-oriented), many collagen fibrils are present, which are the network-forming types. They are collagen type 4. Negatively charged, many proteins that have a negative charge, will be repelled. Whatever has passed, it will reach the slits. Their dimension. Or the space between them. It's extremely tiny 0.06 to 0.07 micrometers. Fewer molecules will succeed in passing through the filtration membrane. And then, they are inside the capsular space.  *From collecting ducts, urine drains into the minor calyces, which join to become major calyces that unite to form the renal pelvis. *From the renal pelvis, urine drains into the ureters and then into the urinary bladder. *Urine is then discharged from the body through the single urethra. ❖JUXTAGLOMERULAR APPARATUS (JGA) A specialized sensory (Near the vascular pore) structure that utilizes feedback mechanisms to regulate glomerular blood flow and keep the rate of glomerular filtration relatively constant. 1.Macula densa: DCT cells become more columnar and closely packed where its straight part contacts the arterioles 2.Juxtaglomerular granular (JG) cells: modified smooth muscles in tunica media of the afferent arteriole-----secretory phenotype--- renin (protease) 3.Lacis cells: mesangial cells that have supportive, contractile and defensive functions as these cells inside the glomerulus. These cells of the distal convoluted tubule. Near the vascular pore. Enhancement, augmentation. These low cuboidal cells. They will appear actually more or less like a columnar cell. The cells that are in the tunica media of the arterioles. will adapt to a more secretory phenotype.  What is a phenotype? It means. That they are different types. So, they stop the cells that contract and relax. They become secretive cells. They give them a protein called renin. And we have another type of cell we call them Lacis cells. ‫ والدم‬more filtrate ‫ بصير‬kidney ‫ باتجاه ال‬blood flow ‫اذا زاد ال‬ ‫الي بطلع بزيد كمان فهذول الخاليا بحسوا بزياده تدفق الدم فبروحوا ببعثوا‬ ‫ ثابت بكل الوقت بغض‬GFI ‫إشارات عشان يقلل الدم الي بيجي بحيث يكون‬ ‫النظر عن الضغط او التدفق تبع الدم عشان يحميها من الدمار اذا زاد عن‬ ‫قدرتها بس مش دايما بحميها الها سعه معينة‬ ❖The ureters  * Strong tube-like structure which will carry the urine from kidneys (renal pelvis that’s get the urine from major calyx) towards the urinary bladder, the section shows us mucosa and thick layer of muscularis (very IMP their contraction helps pushing the urine downward). * Peristaltic contractions of the muscular walls of the ureters push urine toward the urinary bladder (hydrostatic pressure and gravity also contribute). * The ureters are 25–30 cm long and are thick-walled. (Reed only) * At the base of the urinary bladder, the ureters curve medially and pass obliquely through the wall of the posterior aspect of the urinary bladder. * No anatomical valve at the opening of each ureter into the urinary bladder * As the urinary bladder fills with urine, pressure within it compresses the oblique openings into the ureters and prevents the backflow of urine ( physiological valve). * Wall of the ureters: three layers, the deepest coat, the mucosa, is transitional epithelium and an underlying lamina propria. * Mucus secreted by the goblet cells of the mucosa prevents the cells from coming in contact with urine * The muscularis is composed of inner longitudinal and outer circular layers of smooth muscle. * The adventitia (areolar CT) containing blood vessels, lymphatic vessels, and nerves. ‫ فعشان ما يرجع لفوق لما ينقبضوا العضالت فعشان هيك بمشي‬urine ‫ لنها مليانه‬urinary bladder ‫ما بصير يفتح بسرعة عال‬ ‫ لفوق لنه فش فيها صمامات تمنع رجوعه‬urine ‫ انقباض بسكر وما برجع ال‬urinary bladder ‫بالجدار تبعها عشان هيك لما يصير لل‬ Urothelium, endothelium, transition epithelium stratified ‫ بشبهه اما لما ينشد بصيروا الخاليا اصغر فببين‬stratified cuboidal ‫بنقدر نشده لما تفضى ومش مضغوطه ببين‬ ‫عنده نواتين يعني فهو اشي مميز‬binucleation ‫ بس هو ال فبعرفه من ال‬squamous retroperitoneal‫ لنها‬serous ‫ما فيه‬ The urine can’t go back to the ureters, we need to prevent that, but how? The ureters will run through the wall of the urinary bladder before their opening in the trigone How does that help preventing the back flow of urine? When the urinary bladder contracts the ureters, tubule will close because they are running in the wall of the bladder, so when contraction the 2 walls of the ureters will shut up, preventing the urine to go back to the kidneys → the same concept of the valves, so we need to shut the tubules when the bladder is emptying. ❖ The urinary bladder Muscular sac like the stomach in thickness of the muscle that’s called detrusor muscle. Also have 3 layers of smooth muscle inner, middle and outer. It’s held in their space by ligament part of it from peritoneum. The epithelium lining is transition. A hollow, distensible muscular organ situated in the pelvic cavity posterior to the pubic symphysis. -In males, it is directly anterior to the rectum. -In females, it is anterior to the vagina and inferior to the uterus. -Folds of the peritoneum hold the urinary bladder in position. -When slightly distended due to the accumulation of urine, the urinary bladder is spherical. When it is empty, it collapses. -Urinary bladder capacity averages 700–800 ml -It is smaller in females because the uterus occupies the space just superior to the urinary bladder. ** The trigone: in the floor (base) of the urinary bladder is a small triangular area. The two posterior corners of the trigone contain the two ureteral openings; the (apex) opening into the urethra the internal urethral orifice lies in the anterior corner, while the base opening into the ureter. Has a smooth appearance The wall of the urinary bladder has three layers 1. The deepest is the mucosa, transitional epithelium (permits stretching) and an underlying lamina propria. 2. The intermediate layer is muscularis (detrusor muscle) **Consists of three layers of smooth muscle: the inner longitudinal, middle circular, and outer longitudinal. **Around the opening to the urethra the circular fibers form an internal urethral (smooth muscle, involuntary) sphincter the external urethral sphincter (skeletal muscle) lies inferior to it. These sphincter part of urethra.  3. Adventitia, a layer of areolar connective tissue, continuous with that of the ureters. All the urinary passages are covered externally by an adventitial layer, except for the upper part of the bladder that is covered by serous peritoneum. The muscles of the urinary bladder relax during filling, and it contracts during voiding. In other words, when urinary bladder slightly distended due to the accumulation of urine, the urinary bladder is spherical. When it is empty, it collapses.  ❖The urethra: A small tube leading from the internal urethral orifice in the floor of the urinary bladder to the exterior of the body---discharging urine from the body. **In males, it discharges semen (fluid that contains sperm) as well. The male urethra first passes through the prostate, then through the deep muscles of the perineum, and finally through the penis, a distance of about 20 cm (8 in.). It is subdivided into three anatomical regions: 1. The prostatic urethra passes through the prostate, and is lined by urothelium (transitional epithelium), when it comes to muscles -The perineum- skeletal muscles that give support to the pelvic region. The skeletal muscles in the perineum will make a thickening at circular arrangement to make the second sphincter (external urethral sphincter). *Remember: skeletal→ external→ voluntary 2. The intermediate (membranous) urethra, the shortest portion, passes through the deep muscles of the perineum (These are the muscles that keep the pelvic structures tucked into the pelvis.), through an external sphincter of striated muscle and is lined by stratified columnar or pseudostratified columnar epithelium. One clicks application for these perineal muscles, they tend to become weaker and weaker as you age. And they become also weaker in females when they have multiple deliveries. What are the consequences? Incontinence. You urinate without being able to control it. So, you need to keep that region quite strong using specific exercises. 3. The spongy urethra, the longest portion, passes through the penis, and is lined by stratified columnar or pseudostratified columnar epithelium, with stratified squamous epithelium (non-keratinized) near the external urethral orifice. The muscularis of the prostatic urethra is composed of mostly circular smooth muscle fibers (will be the sphincter in the perineal region). - The urethra is the passage for the urine and the semen so it’s a structure shared between the urinary system and the genital tract.  **In females: the urethra lies directly posterior to the pubic symphysis (4 cm) The external urethral orifice is located between the clitoris and the vaginal opening. The wall consists of: 1. a deep mucosa: epithelium and lamina propria. 2. a superficial muscularis: it consists of circular arranged smooth muscle fiber and it is continuous with that of the urinary bladder. Near the urinary bladder, the mucosa contains a transitional epithelium that is continuous with that of the urinary bladder. Near the external urethral orifice, the epithelium is nonkeratinized stratified squamous epithelium. Between these areas, the mucosa contains stratified columnar or pseudostratified (will be very limited) columnar epithelium. The muscularis consists of circularly arranged smooth muscle fibers and is continuous with that of the urinary bladder. - The urethra is a part of the urinary system since the genital tract is completely separated. In females, due to the presence of the uterus, and this is even more important during pregnancy, the amount of urine that females can hold in their urinary bladder is much smaller. And that's why in pregnancy, especially in the second and the last trimester, usually females will need to urinate much more frequently. Whereas in males, there isn't any other structure lying on top, so they can hold more urine in it than in females.  ‫‪1e, 2d, 3c, 4d, 5b, 6a, 7e, 8b, 9e, 10d‬‬ ‫تمت كتابة هذا الشيت صدقة جارية عن روح والدة زميلنا عمرو رائد من دفعة تيجان‬ ‫دعواتكم لها بالرحمة والمغفرة‬ ‫‪Thank you‬‬