Topic 5 - REGULATION
Concept of Regulation
The
Concept of Regulation
Explain
the concept of regulation
Living organisms are subjected to wide variations
in temperature, light, acidity, salinity, wind speeds, availability of water
minerals and nutrients. These environmental factors create a shifting external
setting to which organisms must adjust or die.
The central problem for a living thing is to
maintain a steady state internally in the force of an often harsh and
fluctuating external environment.
Homeostasis is the maintaining of a constant
condition of the internal environment of the body by regulatory process. OR It
is the maintenance of constant internal balance despite fluctuation in the
external environment.
Regulation is the process of controlling
the internal body environment and needs. For the body to function properly
things need to be regulated in the body.
Reasons that show importance of regulation
§
Maintaining
favorable condition such as pH and required ionic concentration for the
functioning of cells, tissues and organs.
§
Enabling
organisms to get rid of body wastes and useless materials for example excess
water and salts
§
Enabling
organisms to get rid of excess materials for example excess water and salts
§
Ensuring
survival of the organisms
Various
Types of Regulation
Mention
various types of regulation
The following are the types of regulation:
§ Temperature regulation (thermoregulation)
§ Blood sugar regulation
§ Osmoregulation
Temperature
Regulation in Animals
The
Concept of Temperature Regulation in Animals
Explain the concept of temperature regulation in
animals
HEAT GAIN BY ANIMALS
There are three ways of heat gain by animals:
§
Metabolism
of food stuffs
§
Shivering
§ Absorption of solar radiation
EAT LOSS BY ANIMALS
Animals lose heat through:
§
Convection
– This is flow of heat from the interior of an animal’s body to exterior in the
surrounding
§
Sweating/Evaporation
– This occurs when animal loose water vapour from their body surface
§
Conduction
– This is transfer of heat by physical contact between two bodies
§
Breathing
out
§
Panting
§
Salivation
§
Defecation
§ Urination
The
Mechanism of Temperature Regulation in Mammals
Describe the mechanism of temperature regulation in
mammals
Ectothermic animals gain heat by:
§
Metabolism
of food stuff
§
Solar
radiation
§ Contractions of body muscles
Each species of ectothermic animal has its own
optimum temperature during which metabolic activities can take place.
The graph below shows the relationship between
external temperature to internal temperature in Ectothermic animal
When the environment is over heated ectotherms:
§ Ectothermic animals example fish migrate to places
with a more suitable temperature for them
§ Use of shade – snakes, frogs, lizards take shade to
avoid being over heated
§ Pant – turtles and tortoise pant during hot day to
loose excess heat
When the environment is over cooled ectotherms:
§ Burrow – toads burrow during cold conditions to
avoid over cooling
§ Bask – snakes, lizards and chameleons bask in the
sun to raise their body temperature
§ Social behavior – bees cluster together to raise
body temperature
§ Flex their body muscles e.g. python flex its
muscles and coil eggs during cold condition
§ Use of metabolic heat – bees contracts their
muscles using prior flying in cool weather to raise their body temperature.
Endothermic animals gain heat only through
metabolism of food substances. The temperature ranges of these animals are as
follows:
§ Mammals 35oC – 40oC
§
Birds
40oC – 45oC
Each species of endothermic animal has their own
optimum temperature during which metabolic activities occur for example
homo-sapiens 36.7oC, House fowl 41oC
Temperature regulation in endothermic animals is a
physiological process. It is controlled by hypothalamus and contains two thermo
receptors hot and cold centers.
When the environment is OVER HEATED:
§
During
hot conditions hot center in the hypothalamus is activated by increase in blood
temperature.
§ Hypothalamus uses nerve impulses and hormones as
error signals to activate responses that increase heat loss from the body.
Examples of error signals that activate responses
that cause heat loss so that the core temperature is brought to its set point
are:
§
Sweating
– Sweat glands secrete sweat and sweat pores open. Sweat evaporates at the
surface of skin with heat.
§
Vasodilation
– Vasodilation is the increase of size of the blood vessels near the skin
surface so that the heat is lost by radiation as a result of direct contact of
vessels with skin.
§
Flattening
of body hairs: Hair erector muscles on the surface of the body reduce
insulation so that heat loss is simplified.
§
Panting
– This is a process of opening mouths and hanging out of tongue. Dogs do this
process. Panting causes heat loss by evaporation.
§ Closing of stunt vessels, a process done by whales
closing of stunt vessels directs most of core blood to reach the skin and
increase pressure gradient between the skin and the environment hence heat is
lost easily to the environment
When the environment is OVER COOLED:
Examples of corrective mechanisms, which conserve
body heat, are:
§
Shivering
is a reflex shaking of muscles. The process results into generation of heat.
§
Erection
of skin hairs: hair erector muscles erect causing the skin hair to stand and
collect air around them which act as insulation for heat loss.
§
Vasoconstriction
of blood capillaries: Vasoconstriction is a process of narrowing the blood
capillaries leading to the skin. This in turn reduces the temperature gradient
of the body and environment and heat loss decreases.
§
Opening
of shunt vessels, a process done by whales. Opening of shunt vessels and back
to the internal blood circulation. The process reduces heat loss to the
surrounding
§ Increase in metabolic activity. An increase in
respiration is affected by an increase in thyroxin secretion. During cold
conditions, hypothalamus stimulating hormone which in turn stimulates the
secretion of thyroxin hormone which influences fast respiration hence an
increase in heat gain.
EFFECT OF OVER HEATING
If the core temperature rises above 40oC the
thermo-regulating mechanism back down. Positive feedback occurs and a person
goes into a state of hypothermia and suffers heat stroke.
EFFECT OF OVER COOLING
If the core temperature falls below 32oC the
pulse rate weakens. The patient becomes sluggish. This condition is called
hypothermia.
VARIOUS WAYS MAMMALS ARE ADAPTED FOR
COLD AND HOT CLIMATIC CONDITIONS
Adaptation of human beings in cold environment:
§
Presence
of hair In cold conditions hair erector muscles erect causing the still hair to
stand and collect air around them which acts as insulation for heat loss
§
Possession
of heat under epidermis: fat is a bad conductor of heat, thus prevents heat
loss
§
Ability
of narrowing skin blood capillaries: human beings constrict skin blood
capillaries; this reduces the amount of blood passing close to the skin. This
prevents heat loss by convection.
§ Ability to shiver: During cold conditions human
beings are able to perform involuntary muscles contractions, shivering generate
heat
Behavioural Adaptations
§
Wearing
of heavy black clothes: During cold conditions human being put on heavy
clothes, examples sweaters and coats. Heavy clothes create layer of air between
the body’s surface and the clothes. Trapped air is a bad conductor of heat.
§
Use f
heating systems in houses Human beings during cold conditions use heating
systems of different types to warm houses so that they can make their living
conditions comfortable.
Adaptations of human beings in hot climate
§
Ability
of flattening of skin hair. During hot conditions human beings relax hair
erector muscles these cause body hair to lie flat on the body surface and
reduce insulation so that heat loss is affected
§
Ability
of widening the size of the skin blood vessels During hot conditions human
beings can enter a state of vasodilation where the skin blood vessels near the
skin surface expand. Vasodilation enables excess heat to leave the body by
radiation as a result of direct contact of vessels with the skin
§ Possession of sweat glands Sweat glands secrete
sweat on the body’s surface through sweat pores. Excess heat is lost when sweat
evaporates
Behavioural Adaptation
§
Use of
Shade: During hot conditions human beings take cover in shade areas to avoid
being over heated
§
Wearing
of light-white clothes These reduce absorption of heat during hot condition
§
Use of
air conditioners Air conditioners reduce excess heat in houses
Adaptations of a blue whale in cold
environment
§
Possession
of air Circular muscles near the body surface (between endothermic and
epidermis) Circular muscles near the body surface shunt the blood away from the
body surface during cold conditions then prevent heat loss by convection
§
Possession
of bladder (fat layer inside the epidermis). Bladder acts as a thermal
insulator. Bladder controls the flow of heat from the body core to the body
surface. The process occurs during cold condition
Adaptation of blue whale during warm
condition
Possession of circular muscles near the body
surface (i.e. between endothermic and bladder) where the animal is surrounded
by warm sea circular muscles open blood vessels near the body surface. This
allows an animal to get rid of excess body heat.
Adaptation of small mammals e.g.
squirrels and bats during cold condition
Adaptation of small mammals e.g. squirrels and bats
during cold condition.
During cold conditions squirrels and some bats
spend the winter in a state of dormant state of hibernation in which they
appear to be asleep and during which no food is eaten
Hibernation takes place in burrows. The temperature
of these animals falls below normal. The chemical activities in the body go
very slow using food stored as fat and glycogen.
Osmoregulation
in Mammals
The
Concept of Osmoregulation
Explain the concept of osmoregulation
Osmoregulation is the maintenance of constant
internal salt and water concentration in an organism. OR It is the process by
which the osmotic pressure of blood and tissue fluid is kept constant.
Osmotic pressure of blood and tissue fluid of an
animal is exposed as the depression of freezing point in relation to the
habitat in which the animal lives.
Factors
which Affects the Contents of Salt and Water in the Body
Mention factors which affects the contents of salt
and water in the body
Factors affecting content of salt and water in the
blood include:
§
Amount
of water taken in the body Large intake of water causes blood to have too much
water while fewer intakes causes less water in the blood. It is advised to take
two liters equivalent to eight glasses of water per day for the body to
function properly. People who are very active might need more than that.
§
Climatic
condition During hot weather there is increased sweating which cause loss of
water by evaporation thus reduced amount of water in the blood. The vice versa
occurs during cold weather.
§
Amount
of salt taken into the body Putting less salt in food causes reduced salt in
the blood while putting too much salt in food causes increased amounts of salt
in the blood. Moderate amounts of salt should be taken too much salt is not
healthy as it may lead to high blood pressure. Excess salts cause the kidney to
work harder as it is responsible for removing excess salts from the body.
§ Hormonal Abnormalities: When
less ADH is produced it leads to increased content of water in the blood and
vice versa.
§ Blood sugar regulation: The
hormones found in the pancreas in the Langerhans control regulation of blood
sugar in the body. These hormones are insulin and glucagon.
§ Insulin hormone:This
is the hormone, which is produced from the B-cell. This hormone is secreted
when there is a large amount of blood sugar in the body. Insulin promotes
conversion of blood sugar into glycogen and stored in the liver and skeletal
muscles. Insulin forces the uptake of glucose by body cells to produce energy.
§ Glucagon hormone: This
is the hormone, which is secreted due to the lower level of glucose in blood
sugar. This Glucagon stimulates liver cells to release glucose into the blood
stream. Glucagon stimulates liver cells to release glucose into the blood
stream.Also Glucagon stimulates absorption of glucose from the ileum.
Blood
Sugar Regulation in Mammals
The
Mechanisms of Regulating Sugar Level in the Blood
Explain the mechanisms of regulating sugar level in
t he blood
Blood sugar regulation is the maintenance of a
relatively constant blood glucose level of the body. The end product of
digestion of carbohydrate is mainly simple sugars or glucose.
Glucose is absorbed from the alimentary canal
active transport into the blood stream. Hence the blood sugar level in the
blood rises to the extent that regulation of it is necessary.
Blood sugar in mammals is regulated using hormones,
which are insulin and Glucagon. These hormones are secreted by a specialized group
of pancreatic cells called islets of Langerhans. The alpha cells of the islets
of Langerhans secretes Glucagon while the beta cells secretes Insulin.
When the blood sugar level rises in the body
insulin is secreted. The insulin accelerates the entry of glucose into the
liver and muscles to be converted into Glycogen.
Glycogen is stored for future use in the liver and
muscles
Role of Glucagon in Blood Sugar
Regulation
Glucagon is secreted in response to a decline in
blood sugar level in the blood stream. Glucagon promotes the conversion of
Glycogen to glucose and inhibits the oxidation of glucose in the liver.
However if the level of blood glucose is low,
glucagon stimulates the conversion of amino acids into glucose. The glucose
formed is released into the blood stream.
NOTE:Failure
of a pancreas to secrete insulin and glucagon results to a disease called
Diabetes Mellitus
The
Causes, Symptoms, and Effects of High and Low Sugar Levels in the Blood
Outline the causes, symptoms, and effects of high and
low sugar levels in the blood
It's important to treat symptoms of high blood
sugar right away to help prevent complications
Causes
Your blood sugar may rise if you:
§
Skip
or forget yourinsulinororal glucose-lowering medicine
§
Eat
too many grams of carbohydrates for the amount ofinsulinyou took, or eat too
many carbs in general
§
Have
an infection
§
Are
ill
§
Are
under stress
§
Become
inactive orexerciseless than usual
§ Take part in strenuous physical activity,
especially when your blood sugar levels are high and insulin levels are low
Symptoms
Early signs include:
§
Increased
thirst
§
Headaches
§
Trouble
concentrating
§
Blurredvision
§
Frequent
peeing
§
Fatigue(weak,
tired feeling)
§
Weight
loss
§ Blood sugar more than 180 mg/dL
Effects
Ongoing high blood sugar may cause:
§
Vaginal
andskininfections
§
Slow-healing
cuts and sores
§
Worsevision
§
Nerve
damagecausing painful cold or insensitive feet, loss ofhairon the lower
extremities, orerectile dysfunction
§
Stomachand
intestinal problems such aschronic constipationordiarrhea
§ Damage to youreyes, blood vessels, orkidneys
Low Blood Sugar
Symptoms
Symptoms of low blood sugar can occur suddenly.
They include:
§
blurry
vision
§
rapid
heartbeat
§
sudden
mood changes
§
sudden
nervousness
§
unexplained
fatigue
§
pale
skin
§
headache
§
hunger
§
shaking
§
sweating
§
difficulty
sleeping
§
skin
tingling
§
trouble
thinking clearly or concentrating
§ loss of consciousness
If you have hypoglycemic unawareness, a condition
in which you do not know your blood sugar level is dropping, your blood sugar
can drop so quickly you may not even have warning symptoms. When this occurs,
you can faint, experience a seizure, or even go into a coma.
Very low blood sugar is a medical emergency. If you
know that someone is diabetic and he or she is experiencing these symptoms,
help him or her to eat 15 grams of quickly digesting carbohydrate, such as:
§
a half
cup of juice or regular soda
§
1
tablespoon of honey
§
4 or 5
saltine crackers
§
3 or 4
pieces of hard candy or glucose tablets
§ 1 tablespoon of sugar
Causes
Low blood sugar can occur for a number of reasons.
It is usually a side effect of diabetes treatment.
Diabetes and Low Blood Sugar:Diabetes
affects your body’s ability to use insulin. Think of insulin as the key that
unlocks your cells, letting glucose in for energy. People with diabetes use a
variety of treatments to help their bodies use the glucose in their blood. One
very important treatment is insulin injections.
If you inject too much insulin, your blood sugar
may drop too low. People also sometimes inject insulin when planning to eat a
big meal, but then they do not eat enough.
Excess physical activity without eating enough can
also cause a drop in blood sugar levels.
Other
Causes of Low Blood Sugar
You don’t have to have diabetes to experience low
blood sugar. Some other causes of low blood sugar include:
§
certain
medications, such as quinine
§
drinking
too much alcohol
§
some
medical conditions, such as hepatitis or kidney disorders
§
a
tumor that produces excess insulin
§ endocrine disorders, such as adrenal gland
deficiency
Effects
Mildly low blood sugar levels are somewhat common
for people with diabetes; however, severely low blood sugar levels can be
life-threatening. They may lead to seizures and nervous system damage.
Immediate treatment is critical. It is important to learn to recognize your
symptoms and treat them fast. For people at risk of low blood sugar, having a
glucagon kit, a medication that raises blood sugar levels, is important. Talk
to your healthcare provider for more information.