Micturition is the process of urinating that involves two main steps - the bladder filling with urine until tension triggers the micturition reflex, causing the bladder to empty. This reflex is controlled by the spinal cord but can be inhibited or facilitated by the brain. The urinary bladder stores urine and empties through contraction of the detrusor muscle. Urine enters the bladder via the ureters and exits through the urethra. The micturition reflex maintains control of urination but damage to nerves can cause abnormalities like an atonic bladder with no control or an automatic bladder that empties without brain input.
The basics of autoregulation of Gloemrular filtration rate. This ppt deals with basic renal physiology, tubuloglomerular feedback, myogenic reflex, juxtaglomerular apparatus and renin angiotensin aldosterone system in brief. P.S.- The ppt has animations so kindly view in slide/presentation mode
The basics of autoregulation of Gloemrular filtration rate. This ppt deals with basic renal physiology, tubuloglomerular feedback, myogenic reflex, juxtaglomerular apparatus and renin angiotensin aldosterone system in brief. P.S.- The ppt has animations so kindly view in slide/presentation mode
Micturition (The Guyton and Hall physiology)Maryam Fida
The process by which the urinary bladder empties when it becomes filled.
It is a reflex process
ANATOMY OF URINARY BLADDER BODY = in which urine is collected
NECK = funnel shaped extension and connecting with the urethra.
URETHRAL SPHINCTER.
1. INTERNAL URETHRAL SPHINCTER.
made up of detrusor muscle
2. EXTERNAL URETHRAL SPHINCTER.
made up of skeletal muscle fiber.
EXTERNAL URETHRAL SPHINCTER is responsible for voluntary control of micturition
The walls of the ureter contain smooth musle and are innervated by both sympathetic and parasympathetic nerves.
Parasympathetic stimulation increases peristaltic contraction .
Sympathetic stimulation inhibited MICTURITION REFLEX Filling of urinary bladder 300 – 400 ml
|
stimulation of sensory stretch receptors
present on the wall of bladder
|
Afferent impulses pass via pelvic nerve
|
reaches the sacral segments of spinal cord
|
synapses with postganglionic neuron
|
Efferent impulses via pelvic nerve
causes contraction of detrusor muscle
and relaxation of internal sphincter
|
flow of urine in to urethra and
stimulation of stretch receptors present
in urethra
|
it send afferent impulses via pelvic nerve
|
Inhibition of pudendal nerve
|
Relaxation of external sphincter
|
voiding of urine
Once a micturition begins ,, it is a “self regenerative “.
THAT IS,
the initial contraction of bladder
further activates the receptors to
causes still further increase in sensory
impulses from the bladder and urethra.
These impulses in turn further increases in reflex contraction of bladder.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
2. Micturition
• Micturition is the process by which the urinary bladder
empties when it becomes filled.
• This involves two main steps:
• First, the bladder fills progressively until the tension in its
walls rises above a threshold level;
• this elicits the second step, which is a nervous reflex
called the micturition reflex that empties the bladder or,
if this fails, at least causes a conscious desire to urinate.
• Although the micturition reflex is an autonomic spinal
cord reflex, it can also be inhibited or facilitated by centers
in the cerebral cortex or brain stem.
3. Physiologic Anatomy
• The urinary bladder is a smooth muscle chamber
composed of two main parts:
• (1) the body, which is the major part of the bladder in
which urine collects, and
• (2) the neck, which is a funnel-shaped extension of the
body, passing inferiorly and anteriorly into the urogenital
triangle and connecting with the urethra.
• The smooth muscle of the bladder is called the detrusor
muscle - contraction of the detrusor muscle is a major
step in emptying the bladder
4.
5. Innervation of the Bladder
• The principal nerve supply of the bladder is by way of the
pelvic nerves, which connect with the spinal cord through
the sacral plexus, mainly connecting with cord segments
S-2 and S-3.
• Coursing through the pelvic nerves are both sensory
nerve fibers and motor nerve fibers. The sensory fibers
detect the degree of stretch in the bladder wall.
• The motor nerves transmitted in the pelvic nerves are
parasympathetic fibers. These terminate on ganglion cells
located in the wall of the bladder. Short postganglionic
nerves then innervate the detrusor muscle.
6. Innervation of the Bladder
• skeletal motor fibers transmitted through the pudendal
nerve to the external bladder sphincter - somatic nerve
fibers that innervate and control the voluntary skeletal
muscle of the sphincter.
• the bladder receives sympathetic innervation from the
sympathetic chain through the hypogastric nerves,
connecting mainly with the L-2 segment of the spinal cord.
• These sympathetic fibers stimulate mainly the blood
vessels - sensory nerve fibers also pass by way of the
sympathetic nerves and important in the sensation of
fullness and pain
7.
8. Transport of Urine
• Urine flowing from the collecting ducts into the
renal calyces stretches the calyces and increases
their intrinsic pacemaker activity,
• which in turn initiates peristaltic contractions that
spread to the renal pelvis and then downward
along the length of the ureter
• peristaltic contractions in the ureter are enhanced
by parasympathetic stimulation and
• inhibited by sympathetic stimulation
9. Transport of Urine
• The normal tone of the detrusor muscle in the
bladder wall have a tendency to compress the ureter,
• thereby preventing backflow of urine from the
bladder when pressure builds up in the bladder during
micturition or bladder compression
• Vesicoureteral reflux – enlargement of the ureters -
can increase the pressure in the renal calyces and
structures of the renal medulla, causing damage -
hydronephrosis
10. The Cystometrogram
• When there is no urine in the bladder, the intravesicular
pressure is about 0,
• but by the time 30 to 50 milliliters of urine has collected,
the pressure rises to 5 to 10 centimeters of water.
• Additional urine — 200 to 300 milliliters — can collect with
only a small additional rise in pressure; this constant level of
pressure is caused by intrinsic tone of the bladder wall.
• Beyond 300 to 400 milliliters, collection of more urine in the
bladder causes the pressure to rise rapidly.
11.
12. The Cystometrogram
• Superimposed on the tonic pressure changes during
filling of the bladder are periodic acute increases in
pressure that last from a few seconds to more than a
minute.
• The pressure peaks may rise only a few centimeters of
water or may rise to more than 100 centimeters of
water.
• These pressure peaks are called micturition waves in
the Cystometrogram and are caused by the
micturition reflex.
13. Micturition Reflex
• micturition contractions are the result of a stretch reflex
initiated by sensory stretch receptors in the bladder wall,
• Especially by the receptors in the posterior urethra when
this area begins to fill with urine at the higher bladder
pressures.
• Sensory signals from the bladder stretch receptors are
conducted to the sacral segments of the cord through the
pelvic nerves
• and then reflexively back again to the bladder through the
parasympathetic nerve fibers by way of these same nerves.
14. Micturition Reflex
• When the bladder is only partially filled, these micturition
contractions usually relax spontaneously after a fraction of a
minute, the detrusor muscles stop contracting, and pressure
falls back to the baseline.
• As the bladder continues to fill, the micturition reflexes
become more frequent and cause greater contractions of the
detrusor muscle.
• Once a micturition reflex begins, it is “self-regenerative.”
• initial contraction of the bladder activates the stretch
receptors to cause a greater increase in sensory impulses to
the bladder and posterior urethra, which causes a further
increase in reflex contraction of the bladder
15. Micturition Reflex
• cycle is repeated again and again until the bladder has
reached a strong degree of contraction.
• Then, after a few seconds to more than a minute, the self-
regenerative reflex begins to fatigue and the regenerative
cycle of the micturition reflex stops, permitting the
bladder to relax.
• the micturition reflex is a single complete cycle of
• (1) progressive and rapid increase of pressure,
• (2) a period of sustained pressure, and
• (3) return of the pressure to the basal tone of the bladder
16. Micturition Reflex
• Once a micturition reflex has occurred but has not
succeeded in emptying the bladder,
• the nervous elements of this reflex usually remain
in an inhibited state for a few minutes to 1 hour
or more before another micturition reflex occurs.
• As the bladder becomes more and more filled,
micturition reflexes occur more and more often
and more and more powerfully.
17. Micturition Reflex
• Once the micturition reflex becomes powerful
enough, it causes another reflex, which passes
through the pudendal nerves to the external
sphincter to inhibit it.
• If this inhibition is more potent in the brain than the
voluntary constrictor signals to the external
sphincter, urination will occur.
• If not, urination will not occur until the bladder fills
still further and the micturition reflex becomes more
powerful.
18. Role of the Brain
• The micturition reflex is a completely autonomic spinal cord
reflex, but it can be inhibited or facilitated by centers in the
brain.
• These centers include
• (1) strong facilitative and inhibitory centers in the brain
stem, located mainly in the pons, and
• (2) several centers located in the cerebral cortex that are
mainly inhibitory but can become excitatory.
• The micturition reflex is the basic cause of micturition, but
the higher centers normally exert final control of micturition
19. Role of the Brain
• 1. The higher centers keep the micturition reflex partially
inhibited, except when micturition is desired.
• 2. The higher centers can prevent micturition, even if the
micturition reflex occurs, by continual tonic contraction of
the external bladder sphincter until a convenient time
presents itself.
• 3. When it is time to urinate, the cortical centers can
facilitate the sacral micturition centers to help initiate a
micturition reflex
• and at the same time inhibit the external urinary sphincter
so that urination can occur.
20. Voluntary urination
• First, a person voluntarily contracts his or her abdominal
muscles, which increases the pressure in the bladder
• and allows extra urine to enter the bladder neck and
posterior urethra under pressure, thus stretching their
walls.
• This stimulates the stretch receptors, which excites the
micturition reflex and simultaneously inhibits the external
urethral sphincter.
• Ordinarily, all the urine will be emptied, with rarely more
than 5 to 10 milliliters left in the bladder.
21. Abnormalities of Micturition
• Atonic Bladder Caused by Destruction of Sensory Nerve Fibers
- preventing transmission of stretch signals from the bladder.
• person loses bladder control, despite intact efferent fibers
from the cord to the bladder and despite intact neurogenic
connections within the brain.
• Instead of emptying periodically, the bladder fills to capacity
and overflows a few drops at a time through the urethra -
overflow incontinence.
• crush injury to the sacral region of the spinal cord - syphilis
can cause constrictive fibrosis around the dorsal root nerve
fibers (tabes dorsalis)
22. Abnormalities of Micturition
• Automatic Bladder Caused by Spinal Cord Damage Above the
Sacral Region.
• If the sacral cord segments are still intact, typical micturition
reflexes can still occur but they are no longer controlled by
the brain.
• first micturition reflexes are suppressed because of the state of
“spinal shock”
• if the bladder is emptied periodically by catheterization, the
excitability of the micturition reflex gradually increases - then,
periodic automatic bladder emptying occurs.
• Some patients can still control urination in this condition by
stimulating the skin (scratching or tickling) in the genital
region, which sometimes elicits a micturition reflex.
23. Abnormalities of Micturition
• Uninhibited Neurogenic Bladder Caused by Lack of
Inhibitory Signals from the Brain.
• frequent and relatively uncontrolled micturition.
• partial damage in the spinal cord or the brain stem that
interrupts most of the inhibitory signals.
• facilitative impulses passing continually down the cord
keep the sacral centers so excitable that even a small
quantity of urine elicits an uncontrollable micturition
reflex, thereby promoting frequent urination.