Homeostasis Flashcards
What are the factors for which organisms have tolerance limits
Body temperature - the condition of temperature in the body must be maintained as in cells and organisms there are enzymes which require a specific optimum temperature to function at to catalyse biochemical reactions in the body
Water availability
blood glucose level
carbon dioxide concentration in the blood and tissue
water and solute balance
What is the impact on a organism if body temperature increases above the tolerance limit
increase in temperature results in enzymes denature, leading to the biochemical reactions to not occur efficiently or not at all
What is the impact on a organism if water availability is lower than tolerance limit
if water availability is below an organism’s tolerance limit, it can experience dehydration due to the lack of water disrupting cellular process, reduced blood volume and therefore blood pressure, metabolic imbalances by disrupted homeostasis in regulating temperature and osmoregulation, it can also lead to death.
What is the impact on a organism if body temperature decreases outside of tolerance limit
a decrease in temperature means less interaction between substrate and enzyme,
what is the impact on organism if blood glucose levels decrease outside of tolerance limit
What is the impact on organism if blood glucose levels increase above tolerance limit
What is the impact on organism if carbon dioxide concentration in the blood and tissue increases above tolerance limits
Define what homeostasis is
The maintenance of the same levels in chemical and non chemical in organisms (cells) that ensures optimum conditions for the organism to function
What is the impact on organisms if pH increases above pH tolerance limit
What is the impact on organisms if pH decreases outside of tolerance limit
why are tolerance limits important
they are crucial in defining a range of environmental conditions within which an organism can maintain homeostasis. These limits ensures optimum functioning of biological process, supporting survival, growth and reproduction.
What is the role of sensory receptors
they recognise that something has changed and passes the message along to the control centre
What is the role of effectors
they make a change that restores the status quo
explain what the stimulus-response model (homeostasis flow diagram) is and how it works
The stimulus-response model is a model that shows that a change in the external or internal environmental conditions is detected and appropriate response occurs. The model shows that a stimulus is detected by a receptor, the receptor conveys the message through the control centre, the control centre then triggers a response by activating an effector, the effector removes the stimulus or initiates an action that negate the stimulus. This restores the status quo, allowing balance (homeostasis to be restored)
explain what the negative feedback loop is
Negative feedback is a response that results in the inhibition of a stimulus
Define a stimulus
A change in the environment
State the general name for the group of specialised cells that detect stimuli.
receptors
State the general name for what responds to the message from receptors
control centre
State the general name for the group that makes a change to restore the status quo
effectors
describe the importance of homeostasis in maintaining the conditions for organisms within their tolerance limits
Homeostasis is important in maintaining the conditions of organisms as if the conditions fall outside of the tolerance limit (optimum zone) then it negatively impacts its function,
What is the role of the control centre
it receives the message from receptors and signals for a response
Describe the structure of a nerve pathway from receptor to effector
The receptor detects a specific stimulus and converts the stimulus into electrochemical impulses, these impulses travel along a sensory neuron which transmits the signal from receptor to central nervous system. Within the CNS the signal is passed to an interneuron. The interneuron process the information. The processed information is then transmitted from CNS to an effector via a motor neuron. The effector responds to the signa; from the motor neuron by producing an appropriate action to the stimulus.
describe the role and pathway of reflex responses
the role of the reflex response is to provide an automatic response to a stimulus. The brain is not directly involved as the signal from the receptor travels along the sensory neuron to the spinal cord, then along an interneuron to a motor neuron that signals the muscles (effector) to respond.
describe the role of synapses
synapses are a junction between two neurons or between a neuron and an effector cell. They allow the electrochemical impulse to be transmitted from one neuron to the next, where when the electrochemical impulse reaches the presynaptic terminal triggers the release of neurotransmitters from synaptic vesicle into the synaptic cleft.
describe the role of neurotransmitters
neurotransmitters cross the synaptic cleft to bind to specific receptors on the postsynaptic membrane to generate a new electrochemical impulse in the postsynaptic neuron to continue the signal transmission.
what is the junction called between two neurons
synapse
Define a hormone
why do hormones only have an effect on specific target cells but not others
what is the difference in action between steroid hormones and protein hormones
Compare the pathway between the nervous and hormonal system
Nervous - direct via the axons of nerve cells
Hormonal - indirect via blood
Compare the message between nervous and hormonal system
Nervous - electrochemical impulses
Hormonal - chemical
Compare the site of of action between nervous and hormonal system
Nervous - highly specific
Hormonal - target cells (can be widespread)
Compare the speed of action between nervous and hormonal system
Nervous - fast
Hormonal - slow
Compare the duration between nervous and hormonal system
Nervous - short term
Hormonal - long term
How does the negative feedback loop works related to homeostasis
What are nerves
they are electrochemical signals (nerve impulses/action potentials) that travel in pulses along nerve cells from one part of the body.
What are the types of neuron structures
sensory neurons
interneurons
motor neurons
What is the function of a sensory neuron
it carries information towards the central nervous system by signalling to stimulate receptors to trigger action potentials towards the CNS
What is the structure of sensory neurons
Receptor cell, cell body on axon and myelin sheath
What is the function of a interneuron
it is located in the CNS and recieves the signal from the sensory neurons to convey them to the motor neurons.
What is the structure of interneurons
It has a reduced cell body near dendrites and has no myelin sheath on axon
What is the function of a motor neuron
they carry signals from the CNS to the effectors
what is the structure of motor neurons
They have a large cell body near dentrites and has a myelin sheath on axon
What is the nervous system composed of
the central nervous system (CNS) and peripheral nervous system (PNS).
What does the CNS contain
brain and spinal cord
What does the PNS contain
the nerves outside CNS and the stomatic nervous system (SNS) which is voluntary nervous system.
What does the autonomic nervous system (ANS) contain
involuntary nerves which regulates all the autonomic functions like breathing and heat rate.
What is the ANS further broken down into
Into the sympatetic (flight or fight and homeostasis) and parasympathetic (rest and digest) nervous systems
What is the stimulus and response model
a stimulus is detected by a receptor, the receptor conveys the message to a control centre by a sensory neuron (incase of reflex), interneurons in the control centre triggers a response by activating an effector by sending impulses along a motor neuron. The effector removes the stimulus or initiates an action that negates the stimulus (muscles removing body away for stimulus). This restores the status quo.
What is the reflex response
it is an automatic response and the brain in not directly involved as it would slow down the process, thus reflex provides a rapid response to stimuli. It is known that consciousness can override or modify some reflexes.
What is the endocrine system
What is the importance of the circulatory system for the endocrine system
it transports the secreted hormones around the body to allow for hormones to act upon cells that have specific receptors.
What do water soluble hormones act on
membrane receptors and lipids
what do soluble steroid hormones act on
cytoplasmic receptors by entering the cytoplasm through the membrane
what is the relation between hormones and target cells
hormones act on target cells as target cells have receptors that are specific to that hormone.
define what diabetes is
it is a disorder that means the body’s ability to produce and/or respond to the hormone insulin is impaired.
role of insulin
enables all cells (except brain cells) to uptake glucose
What do alpha cells secrete
glucagon
what do beta cells secrete
insulin
what are glucagon and insulin and why
they are antagonistic (opposite of another) hormones as insulin causes cells to uptake glucose where glucagon causes glucose to be released from glycogen stores
What are the types of diabetes
Type 1 diabetes mellitus (not producing)
Type 2 diabetes mellitus (not recognising)
what is type 1 diabetes mellitus
it is an auto immune disorder where the immune system attacks the cells of the pancreas
what is type 2 diabetes mellitus
it is either a deficiency of insulin or more commonly by a reduced responsiveness by target cells to insulin caused by changes to insulin receptors.
What does insulin cause
causes liver cells to convert glucose to glycogen which is stored in the muscles and liver. thus, insulin decreases blood glucose levels
What does glucagon cause
binds to glucagon receptors in the liver causing glycogen to be converted to glucose and released in the blood. Thus, it causes a increases in glucose levels.
What are the effectors involved in the blood regulation negative feedback loop
liver, muscle and fat cells
What are endotherms
organisms that can generate their own heat through metabolic process
What are ectotherms
organisms that require heat from external sources.
what is blood temperature regulated by
the thermoregulatory centre in the hypothalamus
what mechanisms are involved in responding to fall in temperature
a fall in temperature is detected by the thermoregulatory centre, which stimulates:
- shivering
- constriction of blood vessels (vasoconstriction)
- conserves heats
- redirects blood to core organs (shock response)
- releases hormones that stimulate the thyroid gland to secrete thyroxine which stimulates cell metabolism
These mechanisms increase heat production and minimise heat loss = an overall increase in temperature
what mechanisms are involved in responding to a rise in temperature regulated
a rise in blood temperature stimulates:
- nervous impulses to trigger sweat glands to secrete sweat (the evaporation of sweat removes heat from skin)
- reduce nerve impulses to the blood vessels causing vasodilation increasing (blood flow to skin)
- decreases the secretion of hormones that activate the thyroid gland which reduces the amount of thyroxine secreted (decreasing cell metabolism)
these mechanisms decreases heat production and increases heat loss leading to an overall decrease in temperature.
are both nerves and hormones involved in thermoregulation
yes
how is an decrease in body temperature detected and regulated
thermoreceptors in the hypothalamus detect changes in blood temperature. The hypothalamus releases thyroid releasing hormone (TRH) which stimulates the anterior pituitary to release thyroid stimulating hormone (TSH). TSH triggers the thyroid glands to rlease thyroxine which stimulates cell metabolism and increases heat. The increase in heat triggers the thermoreceptors to decreases the release of TRH.
How is a increase in body temperature detected and regulated
What is osmoregulation
it is the maintenance of water and solutes in the body
what is the role and pathway of a reflex response
the role of the reflex response is to provide an automatic response to a stimulus. The brain is not directly involved in this process as the signal from the receptor travels along the sensory neuron to the spinal cord, then along an interneuron to a motor neuron that signals the muscles (effector) to respond.
What is the nervous system composed of
What is the endocrine system
What does the endocrine system do
How do hormones travel to target sites
via blood, as the hormones are secreted by endocrine glands into the blood via tissue fluid and travel where the blood flows.
What do hormones do, what is there purpose
How can diabetes mellitus be resulted by a hormonal imbalance
Describe the action of thyroid stimulating hormone in metabolism
Describe the action of thyroxine in metabolism
What is the effect of antidiuretic hormone (ADH) on the nephrons in osmoregulation
How does ADH effect the nephrons
What is the link between osmoregulation blood volume and blood pressure.
What is the role of adrenaline in the fight or flight response
the fight or flight response prepares the body to either defend itself or avoid danger. This happens by the brain sending a signal via the sympathetic nervous system to the adrenal glands which secrete adrenaline. The adrenaline acts on many structures including smooth muscles, cardiac muscles, the brain and the pancreas. Adrenaline will cause for smooth muscles around blood vessels of the skeltal muscles to dilate, increasing blood flow, while the smooth muscles around the intestinal blood vessels will constrict, redirecting blood flow to the periphery. Adrenaline also increases the output of heart rate and cardiac to raise blood pressure and blood flow. Also the smooth muscles around the bronchi relax to increase airflow to the lungs allowing more oxygen to be absorbed by blood. The pancreas also is stimulated to increase glucagon secretion to initate the release of glucose. Consequently, the increase of blood flow, oxygen and glucose level result in increase cell metabolism.
what is the role of thyroid stimulating hormone in the production of thyroxine.
thyroid releasing hormone is released by the hypothalamus, and causes the anterior pituitary to secrete TSH which triggers the production and release of thyroxine by the thyroid gland. So an release of TSH from the anterior pituitary triggers the thyroid gland to release thyroxine.
How do the nervous and endocrine system function together
the two systems work together or by individually to detect external and internal signals, transmit information and maintain homeostasis by producing appropriate responses to the external and internal stimuli. They regulate the electrical and chemical processes that relay information throughout and between the brain and body. They also both communicate with each other through the hypothalamus.
Compare the action between the nervous and endocrine systems
Pathway - nervous is direct via axons of nerve cells, endocrine is indirect via blood
Message - nervous is electrochemical impulses, endocrine is chemical
Site of action - nervous is highly specific, endocrine is wide spread on target cells
Speed - nervous is fast, endocrine is slow
Duration - nervous is short term and endocrine is long term.
how do the two systems work to control body temperature
the blood temperature is regulated by the thermoregulatory centre in the hypothalamus. Thus a fall in temperature is detected by the thermoregulatory centre which stimulates the nervous system to send electrochemical impulses to cause shivering and for blood vessels to constrict (vasoconstriction), and the endocrine system to cause the hypothalamus to release TRH to stimulate the anterior pituitary to release TSH which then stimulates the thyroid gland to release thyroxine to then stimulate cell metabolism to increase body temp.
Where if a rise in temperature is detected by the thermoregulatory centre it stimulates nervous impulses to trigger sweat glands to secrete sweat (to decrease temp as the sweat evaporates), reduce the nerve impulse to the blood vessels causing vasodilation increasing blood flow to the skin, and decrease the secretion of TRH, TSH to reduce the amount of thyroxine secreted by the thyroid gland to decrease cell metabolism
how do the two systems work to enable osmoregulation
Hormones are involved are involved in osmoregulation.
Osmoreceptors in the hypothalamus detect and increase in solute concentration in the blood, as a response ADH is released and travels via the blood to receptors on the cell walls of the collecting duct. This increases the permeability of the duct walls by increasing the number of aquaporins on the filtrate side of the duct. This means that more water will be reabsorbed from the filtrate and less water will be present in the urine. This will decrease the concentration of solutes in the blood as there is an increase of water reabsorption into the blood through osmosis
how do the two systems maintain blood sugar levels
if low blood glucose levels the pancreas releases glucagon from the alpha cells of the pancreas, glucagon flows through the blood and goes to the liver which has receptors that are complementary in shape to the glucagon on the cells of the liver which causes glucagon to turn into glucose, which the glucose is then released into the blood to increase blood glucose levels.
If blood glucose levels are high the pancreas releases insulin from beta cells of the pancreas, which stimulates cells to absorb glucose from the blood, which reduces the amount of glucose in the blood to decrease blood glucose levels.
How do the two systems monitor pH in the brain to maintain a constant carbon dioxide level in the body
How can the reflex response be modified
while the brain is not directly involved the brain can modify such reflexes to be either increased, decreased or blocked. This happens due to the nerve impulse that travels along the spinal cord along a motor neuron sends an impulse up the spinal cord to the brain.
what is an example of the nervous system stimulating hormone secretion
the secretion of insulin bu the pancreas and the secretion of adrenalin by the adrenal medulla.
Describe the role of anti-diuretic hormone in osmoregulation
ADH is synthesised in the hypothalamus and stored in the posterior pituitary gland. It is secreted by the pituitary in response to an increase in the concentration of solutes in the blood detected by osmoreceptors in the hypothalamus. ADH is transported in the blood and binds to receptor molecules on the cells of the collecting ducts in the kidneys. Its role is to make the collecting duct walls more permeable to water by increasing the amount of aquaporins present in the cell membranes on the filtrate side of the collecting duct. Consequently, the effect of ADH is to increase the reabsorption of water into the blood by osmosis, reducing the solute concentration.
What role does the hypothalamus play in thermoregulation
It acts as the control centre for temperatures regulation by detecting changes and initiating responses
How does sweating help regulate body temperature
sweating cools the body through the evaporation of sweat from the skin, which removes heat from the surface
What is vasodilation and how does it help in cooling the body
vasodilation is the widening of blood vessels near the skin which increases blood flow and heat loss
What is vasoconstriction and its role in temperature regulation
Vasoconstriction narrows the blood vessels to reduce heat loss by decreasing blood flow to the skin, it helps conserve body heat in conditions
How does the body respond to overheating
The body responds by increasing sweating and vasodilation of blood vessels to optimise heat loss
What is osmoregulation
it is the regulating of water and solute balance in the body
describe the impact of dehydration on homeostasis
dehydration disrupts the fluid balance in the body, leading to increased concentration of solutes and a potential drop in blood pressure to do lower water blood volume
What is the role of adrenal glands in the fight or flight response
The adrenal glands secrete hormones such as cortisol and adrenaline to manage stress and energy metabolism
Describe what the fight or flight response is
it is a physiological reaction involving an increased heart rate and respiration due to the release of the hormone adrenaline in response to stressful or dangerous stimulus
