Assignment 2: Human Biology

This document contains the solved answers for Assignment 2 in a Human Biology course. The assignment covers a wide range of topics including: lever mechanics, respiratory muscles, neurotransmitter function and modification by drugs, spinal cord anatomy, reflex arcs, brain function (specifically the prefrontal cortex and its role in personality), the autonomic nervous system, the reticular activating system, memory types, sensory perception (smell, taste, and equilibrium), and endocrine system regulation. The answers provided are detailed, though some sections show areas where the student's understanding was incomplete or needed further development. The assignment demonstrates the student's attempt to address the questions, but also highlights areas requiring improvement in clarity, completeness, and depth of explanation.

Assignment 2 – (50 marks) I started the adjustment. it wasn’t well articulated
Q.1. Briefly describe the three categories of levers, an example of each and if each
one works at an advantage or disadvantage. (3 marks)
Ans:
Categories of Levers which are categorized according to the position of the fulcrum,
effort, and load
A first class lever: In this, the fulcrum is the effort and the load it is called as the first
class lever such as Scissors. A first class lever can produce either a mechanical advantage
or disadvantage depending on whether the efforts or load is closer to the fulcrum.
Second class lever: The fulcrum and the effort are called as a second class lever when the
load is between them such as in a wheelbarrow. The second class lever operates at a
mechanical advantage because the load is always closer to the fulcrum than the effort.
Third class leveler: When the effort is between the fulcrum and the load it is the third
class lever as in Forceps. Third class level operates at the mechanical disadvantage
because the effort is always closer to the fulcrum than the load.Categories of Levers
which are categorized according to the position of the fulcrum, effort and load
A first class lever If the fulcrum is between the effort and the load it is called as the first
class lever. Eg Scissors. A first class lever can produce either a mechanical advantage or
disadvantage depending on whether the efforts or load is closer to the fulcrum.
Second class lever If the load is between the fulcrum and the effort it is called as second
class lever. Eg. a wheel barrow. Second class lever operate at mechanical advantage
because the load is always closer to the fulcrum than the effort.
Third class leveler If the effort is between the fulcrum and the load it is the third class
lever. Eg. Forceps. Third class level operate at the mechanical disadvantage because the
effort is always closer to the fulcrum than the load. .
Q.2. Name and describe the locations and actions of the muscles typically used in
breathing. (4 marks) Wrong answer
Ans: The floor of thoracic activity is formed by a diaphragm which contracts during inhalation of
air so that size of thoracic activity increases and the air pressure inside lungs decreases. The
external intercostals that are found between the ribs cause the lateral and anteroposterior
expansion of thorax. The decline in air pressure draws the air inside.
diaphragm ,external intercostal, internal intercostal
The scalenes a shrugging muscle helps the inhalation by lifting sternum and upper ribs.
After proper inhalation, the internal intercostals between ribs pull back the bones in the opposite
direction of movement during exhalation to decrease the size of the thoracic cavity and
diaphragm relaxes causing the pressure reversal and exhalation of the air. contracts during
inhalation of air so that size o. f thoraciy increashe air pside lungsses. extals which causesr
expansiose in air pressure air iName: Diaphragm
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Locations and Actions: Diaphragm originates on the xiphoid process of the sternum, the inferior
six ribs and their costal cartilages, and the lumbar vertebrae and their intervertebral discs and the
twelfth rib. The external intercostals are between the ribs. During active inhalation, they expand
the rib cage laterally, anteriorly and posteriorly.
Name: Scalenes
Locations and Actions: located in the front on either side of the throat, just lateral to the
sternocleidomastoid. This muscle lifts the sternum and the upper ribs during active inhalation. In
active exhalation, the muscles of the abdominal wall--rectus abdominis, internal and external
obliques and transverse abdominis--contract, raising abdominal pressure. This raises the
diaphragm, raising pressure in the lungs and expelling air. froperiintercostals between ribion to
decrease of the thoracic cavity. The diaphraratin to form ad decreass thoracic cavity.
Briefly answer to the following questions: (4 marks)
Q.3.a).Describe four ways drugs can modify the effects of neurotransmitters. It said
describe and not list. Not detailed with properties and characteristics missing
Ans: Followings are the ways where drugs can modify the effects of neurotransmitters.
1) Stimulating or inhibiting their synthesis, drug L‐dopa is used beacuse it is a precursor
of dopamine. For a limited period of time, taking L‐dopa boosts dopamine production in
affected brain areas.
2) Enhancing or blocking their release, Amphetamines promote release of dopamine and
norepinephrine. Botulinum toxin causes paralysis by blocking release of acetylcholine
from somatic motor neurons.
3) Activating or blocking their receptor, An agent that binds to receptors and enhances or
mimics the effect of a natural neurotransmitter is an agonist . Isoproterenol is a powerful
agonist of epinephrine and norepinephrine. It can be used to dilate the airways during an
asthma attack. An agent that binds to and blocks neurotransmitter receptors is
an antagonist .Zyprexa, a drug prescribed for schizophrenia, is an antagonist of serotonin
and dopamine.
4) Stimulating or inhibiting their removal For example, cocaine produces euphoria—
intensely pleasurable feelings—by blocking transporters for dopamine reuptake. This
action allows dopamine to linger longer in synaptic clefts, producing excessive
stimulation of certain brain regions. . The drugs can modify the effect of
neurotransmitters by various ways i.e., they can be agonist or antagonist. Antagonist
effect can be observed through blocking the effect of neurotransmitter, such as Curare
blocks acetylcholine which is needed for the functioning of skeletal muscles. Agonist
effect is to increase the effect of neurotransmitters, as an example Neostigmine is an
organophosphate insecticide and chemical nerve agent which deactivates the enzyme
which breaks the acetylcholine and thereby increasing the effect of acetylcholine, causing
twitching and paralysis of muscle because of too much neurotransmitter around. The
other ways by which drugs can modify effects of neurotransmitters is by reducing its
activity like by α-methyl-paratyrosine blocks the synthesis of dopamine causing stress
and depression while amphetamine improves the synthesis of dopamine causing anxiety.
Q.3.b).Describe the three ways neurotransmitters can be removed. Had to redo this one
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Ans:
1) By degrading with enzymes in synaptic terminals; certain neurotransmitters are
inactivated through enzymatic degradation example acetylcholinesterase monoamine
oxidase which is the fastest way
2) Uptake by cells. Many neurotransmitters are actively transported back into the neuron
that released them (reuptake) or are transported into neighboring neuroglia
(uptake)..example astrocyte uses excitatory amino acid transporter 2 (EAAT2) to remove
glutamate
3) By diffusion: Some of the released neurotransmitter molecules diffuse away from the
synaptic cleft .example Nitric oxide which is not stored in synaptic vessels and diffuses as
soon as it is produced.
Q.3.c).Describe the two conditions that allow maintenance of the resting membrane
potential in excitable cells. An attempt but not well detailed
Ans: The two conditions that allow maintenance of resting membrane potential is:
a)Electrical gradient which causes the membrane to become more positive outside and
more negative inside.
b) concentration gradient through which ions move from high concentration area to lower
one Unequal distribution of ions in the ECF and cytosol. A major factor that contributes to the
resting membrane potential is the unequal distribution of various ions in extracellular fluid and
cytosol.
The resting membrane potential is determined by three major factors: (1) unequal
distribution of ions in the ECF and cytosol, (2) inability of most anions to leave the cell,
and (3) the electrogenic nature of the Na+/K+ ATPases.
Voltage differential on each side of the membrane and
Neurotransmitter receptors on the post-synaptic cell of a neuromuscular synapse
Q.3.d).Briefly describe what causes the depolarizing phase. Same with 3c
Ans: When membrane potential of axon reaches the threshold, Na+ voltage-gated ion
channels open and Na+ flows inside the axon to rest along the inner surface of axon
membrane, causing it to depolarize from -55mV to +30mV. As the depolarization occurs
more Na+ voltage gated channels open, causing a positive feedback mechanism. Na+ K+
pumps to expel the Na+ out of the cell quickly to maintain a low Na+ content inside the
cell.
When a depolarizing graded potential or some other stimulus causes the membrane of the
axon to depolarize to threshold, voltage‐gated Na+ channels open rapidly. Both the
electrical and the chemical gradients favor inward movement of Na+, and the resulting
inrush of Na+ causes the depolarizing phase of the action potential .
Voltage gated Na+ channels open rapidly then both the electrical and chemical gradients
favor the inward movement of Na+. The inward rush of Na+ causes depolarization phase
of the action potential.
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Q.4.Answer to the following questions: Wrong and incomplete answer; asked for
anatomy not anatomy and physiology. Meaning the External physical structure,
function not included, grey matter is internal.
Q.4.a).Describe the gross external anatomy of the spinal cord. (3 marks)
Ans: still incomplete
The spinal cord is the cylinder of nerve tissue within the vertebral canal which is thick
like a finger and oval in shape. The length of the adult spinal cord ranges from 42 to 45
cm (16–18 in.). Its diameter is about 2 cm (0.75 in.)
The vertebral column grows faster than the spinal cord so in an adult the spinal cord only
extends to L1. Elongation of the spinal cord stops around age 4 or 5, but growth of the
vertebral column continues.
Two conspicuous enlargements can be seen.
The cervical enlargement is the superior enlargement which extends from the fourth
cervical vertebra (C4) to the first thoracic vertebra (T1).
The lumbar enlargement, the inferior enlargement which extends from the ninth to the
twelfth thoracic vertebra
Conus medullaris is where the spinal cord terminates as a tapering, conical structure,
which ends at the level of the intervertebral disc between the first and second lumbar
vertebrae (L1–L2) in adults.
Filum terminale is the non‐nervous fibrous tissue of the spinal cord that extends
inferiorly from the conus medullaris to the coccyx.
Spinal nerves
The posterior (dorsal) root and rootlets
The anterior (ventral) root and rootlets
It extends through the spinal column from the foramen magnum to L1.
31 spinal nerve pairs originate from thoracic, cervical, sacral and lumbar areas of the
cord.
All segments of cord arise to a spinal nerves pair.
Medullary cone (conus medullaris) = tapered tip of cord
Cervical (brachial plexus) nerve and lumbar enlargements (providing nerves to the
lumbar and sacral plexus)
The equine cauda stem from the conus medullaris and the lumbar enlargement, these are
the L12 - S5 nerve roots (resembles a horse tail).
Spinal Cord – Gross Anatomy Structure
• Long and cylindrical
• 42cm in length and 1.8cm thick
• Has two enlarged portions o Cervical enlargement (C4 and T1) Receives sensory input
from the upper limbs
 Sends motor output to the upper limbs
 Lumbar enlargement (T9 and T12) Receives sensory input from the lower limbs
 Sends motor output to the lower limbs
 Ends in a cone-shaped structure called the conus medullaris from where a fibrous
extension of the pia, filum terminale, and mater extends inferiorly to anchor the cord to
the coccyx
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• Lumbar and sacral spinal nerves project downward and extend inferiorly before exiting
through the intervertebral foramina
• Below the SC these nerves are called cauda equina
• SC is divided into 31 segments based on the origins of the spinal nerves
• The cervical nerves exit just above their corresponding vertebrae
• All other spinal nerves exit just below their corresponding vertebrae Spinal Cord
Functions
• Conducts sensory signals up the cord
• Conducts motor signals down the cord
• Integrate certain reflexes Spinal Cord – Cross Section
• Flat from front to back and elliptical in shape
• Has two grooves that run its length separating it into right and left halves o Anterior
(Ventral) median fissure o Posterior (Dorsal) median sulcus
• The central portion has a canal called the central canal
• Each cord segment is associated with a pair of ganglia called the dorsal root ganglion
• Ganglia are located just outside the SC
• They contain cell bodies of sensory neurons
• Axons of these neurons enter the cord via the dorsal root
• Ventral root contains axons from motor neurons that carry information from cell bodies
in the CNS to the periphery
• The dorsal and ventral root merge and exit as the spinal nerve through the inter vertebral
foramina
•Gray Matter: A butterfly shaped structure that occupies the central portion of the cord.
The two lateral masses are connected by the gray commisure that surrounds the central
canal. The posterior horn projects posteriorly, the anterior horn anteriorly and the small
lateral horns laterally. Consists of cell bodies of inter neurons and motor neurons,
neuroglia cells and unmyelinated axons.
•White Matter: The area surrounding the gray mater. Divided into three columns
namely, anterior, posterior and lateral funiculus. Consists almost entirely of myelinated
motor and sensory axons. Columns of white mater carry information either up or down
the cord. Fibers run in three directions – ascending, descending, and transversely.
Divided into three funiculi (columns) – posterior, lateral, and anterior. Each funiculus
contains several fiber tracks. Fiber tract names reveal their origin and destination. Fiber
tracts are composed of axons with similar functions
•Pathway generalizations: Pathways decussate. Most consist of two or three neurons.
Most exhibit somatotopy (precise spatial relationships). Pathways are paired (one on each
side of the spinal cord or brain).
Q.4.b).Identify the components of a spinal reflex arc, and describe the function of
each. (3 marks)
Ans: An impulse follows a conduction pathway from its origin in the dendrites or neuron
cell body in one part of the body to the impulse's end somewhere else in the body. One
pathway is called a reflex arc and is a functional unit of the nervous system. The basic
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parts of a reflex arc are a receptor, a sensory neuron, a center, a motor neuron, and an
effector.
Function of Components of a Reflex Arc are: Not well described
Sensory Receptor: The receptor activates a nerve impulse in a sensory neuron in
response to a change in the body's internal or external environment.
Sensory neuron: This neuron conducts the impulse from the receptor to its axonal end in
the central nervous system.
Integration Center: This is a receiving area (usually in the central nervous system) in
which the incoming sensory impulse connects with an outgoing motor impulse. The
impulse may be repressed, transmitted, or rerouted in the center area.
Motor neuron: The job of the motor neuron is to transmit the impulse from CNS to the
body organ that will respond
Effector: The effector is the organ of the body that responds to the impulse from a motor
neuron. An effector may be either a muscle or a gland
Q.5.In 1848, a railroad worker named Phineas Gage was seriously injured during an
explosion on the job. A tapered metal rod ranging from 0.25 inches to 1.25 inches in
diameter and over 3 feet long entered his skull just under his left cheek bone and
exited through the top of his skull. The rod was found over twenty feet away.
Amazingly, Gage lived even though he suffered massive damage to the left front of
his brain. His personality and intellectual abilities changed, however. Before the
accident, he was respected as a smart, capable and even-tempered man. After the
accident, he was foul-mouthed and bad-tempered and could not make up his mind.
In the years immediately preceding his death, he began to have epileptic seizures.
Explain the changes observed in Mr. Gage based on your knowledge of the brain. (4
marks) Explain not describe
Ans. The crushing or damage of the occipital bone usually crushes the brainstem,
particularly the medulla oblongata. Damage to important nuclei regulating vital functions,
such as respiration, heart rate and force of contraction, and diameter of blood vessels,
may result in death.
Humans have developed prefrontal cortex a portion in anterior region of frontal lobe. The
area is described most connected area with connections with cerebral cortex,
hypothalamus and cerebellum. Mr. Gage would become rude, moody and unplanned and
impulsive as it has bilateral damage to the prefrontal cortices. He can develop seizures
due to abnormal electrical discharges. The right side would not take care of damaged
portion of brain. Some motor functions would be also lost as it is controlled by primary
motor region in the left section.
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Q.6. Answer to the following questions:
Q.6.a).A patient with chronic skeletal muscle spasms was placed on an anticholinergic
medication. The muscle spasms have gone, but now the patient also reports a loss of
muscle strength. In addition, the patient’s blood pressure is so low that she faints if she
stands up too quickly. Explain the effects of the medication the patient received.(3 marks)
Ans: Adrenaline causes vasodilatation of blood vessels results decrease in blood pressure.
Therefore decrease in the blood pressure results in difficulties in making heart to pump
the required amount of blood. If it is not circulated properly, it results in decline the blood
and subsequently oxygen, causing the loss of contraction ability of the muscles and its
strength.
Q.6.b).Compare and contrast the overall responses of the sympathetic and
parasympathetic divisions. (4 marks) No theme for what is being compared, not well
articulated. This is still not good or incomplete please use the provided material the
comparison is much more than this, over 30 of them. A minimum of 10 will be most
appropriate
Sympathetic Divisions Parasympathetic
Divisions
The sympathetic nervous
system (SNS) prepares
the body for intense
physical activity
The parasympathetic
nervous system is almost
the exact opposite effect
and relaxes the body and
inhibits or slows many
high energy functions
Physiological
response/Activate
response
Fight-or-flight Rest and digest
Muscles contract Muscles relax
Saliva production
decreases
Saliva production
increases
The pupils of the eyes
dilate.
Decreased diameter
(constriction) of the
pupils.
Increases heart rate Decreases heart rate
Body speeds up, tenses
up, and becomes more
alert.
Restores body to state of
calm.
Neurons pathways Neurons are very short,
faster system
Longer pathways, slower
system
Neurotransmitters Preganglionic neurons
release acetylcholine
Preganglionic neurons
release ACh, which is
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(ACh), which is
excitatory and stimulates
postganglionic neurons;
most postganglionic
neurons release
norepinephrine (NE);
postganglionic neurons
that innervate most sweat
glands and some blood
vessels in skeletal muscle
release ACh.
excitatory and stimulates
postganglionic neurons;
postganglionic neurons
release ACh.
Salivary gland
arterioles
Vasoconstriction, which
decreases secretion of
saliva
Vasodilation, which
increases secretion of
saliva
Q.7. Answer to the following questions:
Q.7.a).Describe the role of the reticular activating system in sleep, arousal, and
consciousness. (2 marks)
Ans: Different sensory stimuli feed into the Reticular Activating System (RAS) which
feeds in the thalamus and cerebral cortex increase neuronal activity causing arousal from
the sleep and maintaining consciousness. Once the RAS is activated, the cerebral cortex
is also activated, and arousal occurs.
During periods of high ATP use, adenosine accumulates and binds to A1 receprtors
inhibiting cholinergic neurons in the RAS and inducing sleep.
Q.7.b).Compare short-term memory vs. long-term memory with regard to specific
changes that are thought to occur in the brain. (2 marks)
Ans: Short‐term memory is the temporary ability to recall a few pieces of information for
seconds to minutes. Long‐term memory, which lasts from days to years. Brain areas
involved in immediate and short‐term memory include the hippocampus, the mammillary
bodies, and two nuclei of the thalamus (anterior and medial nuclei). Long‐term memory
apparently are stored in wide regions of the cerebral cortex. Short term memory depends
on electrical and chemical mechanism in the brain than forming the new synapse where in
long term memory neurons develops new synaptic terminals.
Short‐term memory is the temporary ability to recall a few pieces of information for
seconds to minutes. Brain areas involved in immediate and short‐term memory include
the hippocampus, the mammillary bodies, and two nuclei of the thalamus (anterior and
medial nuclei). Short‐term memory may later be transformed into a more permanent type
of memory, called Long‐term memory, which lasts from days to years.
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Long‐term memory apparently are stored in wide regions of the cerebral cortex.
Information in long‐term memory usually can be retrieved for use whenever needed.
Memories for motor skills, such as how to serve a tennis ball, are stored in the basal
nuclei and cerebellum as well as in the cerebral cortex. It has been estimated that only 1%
of all the information that comes to our consciousness is stored as long‐term memory.
Moreover, much of what goes into long‐term memory is eventually forgotten.
Some evidence supports the notion that short‐term memory depends more on electrical
and chemical events in the brain than on structural changes, such as the formation of new
synapses.
Q.8.Answer to the following questions:
Q.8.a).Explain the process by which smell sensations are sensed and perceived. (5 marks)
Ans: Smells sensations are sensed and perceived when cells in the nasal passage detects
molecules that carry scents. These molecules are attached to receptors on the cell walls
and send signals to the brain. Several neurons work together to send signals to the brain
about the odour, there are many parts of the brain that are used in order to understand
what the smell is and where it is coming from. These areas are: the anterior olfactory
nucleus, amygdala, olfactory tubercle and the entorhinal cortex. All of these parts in
the brain help with detecting changes that might occur, such as changes in concentration
and spatial awareness.
Q.8.b).Emily was very ill with an upper respiratory infection. Her roommate gave her
some chicken soup to make her feel better. Neither Emily nor her roommate realized that
the soup was too hot to eat until after Emily put a spoonful in her mouth. Now Emily says
she can’t taste anything. Why? When will she be able to taste again?(3 marks)
Ans: Emily burnt her taste buds because of the hot soup, as they are basal cells they
regenerate quickly and she will get new cells in about 7 - 10 days.
A single, long microvillus, called a gustatory hair, projects from each gustatory receptor
cell to the external surface through the taste pore, an opening in the taste bud. Basal
cells, stem cells found at the periphery of the taste bud near the connective tissue layer,
produce supporting cells, which then develop into gustatory receptor cells. Emily cant
taste anything because she burnt her taste sensors. Each gustatory receptor cell has a life
span of about 10 days. This is why it doesn't take taste sensors on the tongue too long to
recover from being burned.
Q.8.c).Differentiate between static and dynamic equilibrium. Describe the structures and
physiological mechanisms involved in receiving and transducing vestibular sensations. (3
marks)
Ans: Static equilibrium is the detection of movement in either a horizontal or vertical
motion. Dynamic equilibrium is the detection of rotational movement. Structures
involved in receiving and transducing vestibular sensations would be the vestibular
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nucleus complex and the cerebellum which is used for processing. This allows
maintaining movements of the head and body without getting distorted or confused. The
vestibular pathway is responsible for maintaining visual stability while the head is
moving, it also ensures that the head remains in a safe place while the body is moving as
well as helps to maintain balance.
Static equilibrium refers to the maintenance of the position of the body (mainly the
head) relative to the force of gravity. Body movements that stimulate the receptors for
static equilibrium include tilting the head and linear acceleration or deceleration, such as
when the body is being moved in an elevator or in a car that is speeding up or slowing
down
Answer to the following questions:
Q.9.a).Compare and contrast the mechanisms of action of lipid-soluble vs. water-soluble
hormones. (3 marks)
Ans: it can be better
Water soluble hormones dissolve in water, as they are hydrophilic in nature. Lipid soluble
hormones are cannot dissolve in water. Water soluble hormones form amino acids which
then turn into proteins, as these molecules cannot pass through a cells membrane it
attaches onto the cell through binding receptors. Its examples are Adrenalin, Thyroid-
stimulating hormone (TSH) and Human Growth Hormone (HGH)
Lipid soluble hormones can dissolve in fats and are made from cholesterol. As these
hormones are made from lipids therefore they can easily pass through cell membranes
and attach to binding receptors within the cell. For example, Sex hormones (Testosterone,
Progesterone etc.) and steroids like Glucocorticoids such as cortisone.
Q9.b).Describe the role of the hypothalamus in the regulation of the pituitary gland. (2
marks)
Ans: The hypothalamus is a part of the Central Nervous System (CNS) that controls the
release of hormones throughout the body. The hypothalamus sends signals to the pituitary
gland to release hormones, in order for the pituitary gland to release hormones the
hypothalamus releases a special type of hormone that triggers the pituitary gland to
release its own hormone.
The hypothalamic hormones are an important link between the nervous and endocrine
systems. Neurosecretory cells in the hypothalamus secrete five releasing hormones, which
stimulate secretion of anterior pituitary hormones, and two inhibiting hormones, which
suppress secretion of anterior pituitary hormones. An example is the hypothalamus
secretes both inhibitory and excitatory hormones that regulate prolactin secretion. In
females, prolactin‐inhibiting hormone (PIH), which is dopamine, inhibits the release of
prolactin from the anterior pituitary most of the time. It also synthesizes oxytocin and
Antidiuretic hormone that are stored and released in the posterior pituitary gland. Neurosecretory cells
of hypothalamus secrete OT in response to uterine distention and stimulation of nipples
Q.10. Enuresis, or bedwetting, may be caused by psychological, anatomical or
physiological factors. In the latter case, vasopressin is often prescribed and is a very
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effective treatment. What is vasopressin? How can it prevent enuresis?(2 marks) not well
answered
Ans: Vasopressin is released by the pituitary gland which promotes the retention of water
by the kidney and can cause hypertension. Vasopressin is also known as antidiuretic
hormone (ADH) which decreases urine production. ADH causes the kidneys to return
more water to the blood, thus decreasing urine volume. In the absence of ADH, urine
output increases more than tenfold, from the average 1 to 2 liters to about 20 liters a day.
By using vasopressin before sleep the production of Urine is lowered down and hence
enuresis can be prevented.Vasopressin is also known as antidiuretic hormone ( ADH)
which is is a substance that decreases urine production. . ADH causes the kidneys to
return more water to the blood, thus decreasing urine volume. In the absence of ADH,
urine output increases more than tenfold, from the normal 1 to 2 liters to about 20 liters a
day. . Vasopressin is released by the pituitary gland which promotes the retention of
water by the kidney, and can causes hypertension. As vasopressin helps the kidneys to
keep water in the kidneys, there is less chance that the person will wet the bed.
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