39 Questions
What does hydrocephalus literally mean?
Water-head
How is cerebrospinal fluid (CSF) described in the passage?
Clear fluid
What is the range of the normal circumference of an infant's skull?
32 to 37 cm
What is the purpose of transillumination in hydrocephalus detection?
To utilize the light-scattering properties of CSF
Through which structure does CSF flow into the spinal column?
Ventricles
Why is it difficult to directly measure the CSF pressure?
It is inconvenient
Which device is specifically used to measure pressure in the urinary bladder?
Cystometer
What fluid can be used in a manometer to measure high pressures?
Mercury
What is the function of a tonometer?
Measure eye pressure
What is the systolic blood pressure range for Stage 2 hypertension?
140-179 mmHg
Which type of sphygmomanometer gauge utilizes the height of mercury to indicate pressure?
Mercury gauge
Which device can be used to measure both positive and negative pressure?
U-shape tube manometer
What information can direct cystometry provide?
Function of the exit valves (sphincters)
Which method involves inserting a needle through the abdominal wall to measure bladder pressure?
Direct cystometry
By which anatomical passage is the catheter inserted for measuring bladder pressure?
Urethra
What is the function of the retention balloon in urinary catheterization?
To lodge the catheter at a specific position
Which structure among the following is not labeled in the image of male urinary catheterization?
Kidney
What causes the highest pressure in the human body?
Weight bearing joints
How does the surface area of a joint affect the pressure exerted on the bone?
Larger surface area reduces pressure
What is the maximum volume of the bladder before voiding in adults?
500ml
At what pressure does the micturition reflex occur in the bladder?
30cm H₂O
What is the normal voiding pressure range in the bladder?
20 to 40cm H₂O
How are finger bones adapted to reduce pressure?
Finger bones are flat to increase surface area
Which part of the eye is mostly water?
Aqueous humor
What happens if there is a build-up of aqueous humor in the eye?
The optic nerve is damaged
A change of only 0.1mm in the diameter of the eye impacts which aspect of vision?
Clarity of vision
Which term refers to the increase in eye pressure that can lead to blindness?
Glaucoma
What is the function of tonometers in eye care?
To measure eye pressure
Which two fluids maintain the eye's dimensions?
Aqueous humor and vitreous humor
Which of these structures is directly affected by increased intraocular pressure in glaucoma?
Optic nerve
What condition is characterized by tunnel vision in moderate cases and blindness in severe cases?
Glaucoma
What is intrathoracic pressure sometimes determined by?
Measuring the pressure in the esophagus
What is a significant cause of pressure increase in the stomach?
Air swallowed during eating
What happens when a blockage forms in the intestine?
Pressure builds up between the blockage and the pylorus
Which of the following can cause death if the pressure becomes too great?
Pressure due to blockage in the intestines restricting blood flow
How is the pressure in the gut generated?
By the bacterial action producing gas
How is a blockage in the intestine sometimes treated?
Intubation or surgery
What do the pressure changes in the esophagus and stomach indicate during inhalation and exhalation?
They are coupled to the pressure in the lungs
What does a more significant pressure increase in the stomach result in?
Burping
Study Notes
Pressure inside the Skull
- The brain contains 150 cm³ of cerebrospinal fluid (CSF) in a series of interconnected openings called ventricles.
- CSF is generated inside the brain and flows through the ventricles into the spinal column and eventually into the circulatory system.
- If the aqueduct, a narrow opening, is blocked at birth, CSF is trapped inside the skull, increasing internal pressure, leading to Hydrocephalus (water-head).
Detection of Hydrocephalus
- Measuring CSF pressure directly is not convenient.
- Instead, doctors measure the circumference of the skull just above the ears (normal value: 32-37 cm); a larger value may indicate hydrocephalus.
- Transillumination is also used to detect hydrocephalus, making use of the light-scattering properties of CSF inside the skull.
Devices Used to Measure Pressure
- U-shaped tube manometer: measures both positive and negative pressure.
- Tonometer: measures eye pressure (positive pressure only).
- Cystometer: measures urinary bladder pressure.
- Sphygmomanometer: measures blood pressure (positive pressure only).
Manometer
- A U-shaped tube containing a fluid, connected to the pressure to be measured.
- Can measure both positive and negative pressure.
- Fluid used can be mercury (for high pressure measurements) or water or a low-density fluid (for low pressures).
Sphygmomanometer
- Clinical instrument for measuring blood pressure.
- Can be provided by one of two types of gauges: Mercury gauge or Aneroid type.
Blood Pressure Ranges
- Normal: 90-129 (systolic) and 60-79 (diastolic).
- Stage 1: 130-139 (systolic) and 80-89 (diastolic).
- Stage 2: 140-179 (systolic) and 90-109 (diastolic).
- Critical: Over 180 (systolic) and over 110 (diastolic).
Eye Pressure
- The clear fluids in the eyeball (aqueous and vitreous humors) maintain the eyeball's size and shape.
- A change of only 0.1mm in the eyeball's diameter has a significant effect on vision.
- Glaucoma: intraocular pressure is too high, damaging the optic nerve.
Glaucoma
- Partial blockage of the drain system increases pressure, restricting blood supply to the retina.
- This affects vision and can lead to tunnel vision (moderate cases) or blindness (severe cases).
Tonometers
- Instruments used to measure eye pressure.
- Measure the amount of indentation produced by a certain force.
Measurement of Urinary Bladder Pressure
- Direct cystometry: inserting a needle through the abdomen directly into the bladder.
- Passing a catheter with a pressure sensor into the bladder through the urinary passage (urethra).
Pressure in the Skeleton
- The highest pressure in the human body is found in weight-bearing joints.
- The larger the surface area of the joint, the lower the pressure exerted on the bone.
- Bones are adapted to reduce pressure (e.g., finger bones are flat to increase surface area).
Pressure in the Urinary Bladder
- Pressure in the bladder is caused by the accumulation of urine.
- When the pressure reaches about 30cm H₂O, a reflex called micturition occurs.
- Contraction of the bladder wall produces a momentary pressure of up to 150cm H₂O.
Pressure in the Digestive System
- The body has an opening through it, the digestive tract, which is rather tortuous and extends over 6 meters from the mouth to the anus.
Esophagus
- Pressure in the esophagus is coupled to the pressure between the lungs and chest wall (intrathoracic pressure).
Stomach
- Pressure in the stomach increases due to the stretching of the stomach walls.
- Eating increases pressure slowly due to increased volume.
- Air trapped in the stomach causes burping or belching.
Gut
- Gas generated by bacterial action increases pressure, which is higher than atmospheric.
- Pressure in the digestive system is coupled to that in the lungs through the flexible diaphragm that separates the two organ systems.
Blockage
- A blockage in the small or large intestine can cause a pressure build-up between the blockage and the pylorus.
- If this pressure becomes great enough to restrict blood flow to critical organs, it can cause death.
Learn about the flow of cerebrospinal fluid (CSF) in the brain, its generation, and the consequences of blocked ventricles on internal pressure.
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