Homeostasis - All PPTS Removed PDF

Homeostasis  Maintaining a constant internal environment in response to changes.  What is the internal environment? The internal environment consist of the tissue fluid surrounding the cells and the blood plasma, which is the liquid part of the blood. (extracellular...

Homeostasis  Maintaining a constant internal environment in response to changes.  What is the internal environment? The internal environment consist of the tissue fluid surrounding the cells and the blood plasma, which is the liquid part of the blood. (extracellular fluid) Fluids inside the cell are intracellular fluid. Both of these need to be regulated.  Organisms survive most effectively within their tolerance limits. Factors for which organisms have Organisms survive most effectively within their tolerance limits. Factors for which organisms have tolerance tolerance limits include: limits include: – body temperature – body temperature – water availability – blood glucose level – water availability – carbon dioxide concentration in the blood and tissues. There are impacts on an organism when conditions fall outside its tolerance limits. – blood glucose level – carbon dioxide concentration in the blood and tissues. There are impacts on an organism when conditions fall outside its tolerance limits.  Tolerance limits refer to the upper and lower limits of a specific environmental conditions within which an organisms can survive.  Tolerance range represents the difference between the maximum and minimum tolerance limits to a given abiotic factor  Organisms with a wide range of tolerance are usually distributed widely, while those with a narrow range have a more restricted distribution.  Lower Upper Tolerance Tolerance Limit Limit TOLERANCE LIMITS Organisms survive more effectively within tolerance limits. TOLERANCE RANGE Organisms with a high tolerance range are widely distributed on Earth.  Tolerance Limits Tolerance limits are the range of conditions required for the survival of an organism. The limits include physical and chemical environmental factors. These factors can be internal and external to the organism. Tolerance range =Tolerance limits represent max. and min. amounts of an abiotic factor that the organisms can tolerate before it affects life processes Question 1 Which one of the following statements regarding an animal’s tolerance limits is NOT correct? 1.They may be determined by the environmental conditions required by the species 2.They relate to abiotic factors in the environment of the organism 3.They are fixed characteristics of all individuals of that species 4.They determine distribution and abundance of the animal. Question 2 All organisms share tolerance limits for a number of different factors. This does NOT include 1.water availability 2.light intensity 3.body temperature 4.nutrient availability Question 3 The Tolerance limits of an organism in its environment are defined by the range of 1. biotic and abiotic factors 2.biotic, but not abiotic factors 3.physical and chemical factors 4.zones of physiological stress Question 1 Name four different variables that humans have tolerance limits for; 1. 2. 3. 4. 4 Marks Question 2 Explain why the knowledge of tolerance limits is crucially important in assessment of the risk that an animal species like rabbits will become a pest in a new site like Australia. 3 Marks Question 1 Which one of the following statements regarding an animal’s tolerance limits is NOT correct? 1. They may be determined by the environmental conditions required by the species 2. They relate to abiotic factors in the environment of the organism 3. They are fixed characteristics of all individuals of that species 4. They determine distribution and abundance of the animal. Explanation: Within any population, there are variations. Not all individuals have the exact fixed characteristics but rather vary amongst populations of the same species. Question 2 All organisms share tolerance limits for a number of different factors. This does NOT include 1. water availability 2. light intensity 3. nubody temperaturetrient availability Explanation: only plants are affected by light intensity for the process of photosynthesis. Question 3 The Tolerance limits of an organism in its environment are defined by the range of 1. biotic and abiotic factors 2. biotic, but not abiotic factors 3. physical and chemical factors 4. zones of physiological stress Explanation: Tolerance limits represent the maximum and minimum amounts of abiotic factors (physical and chemical factors). Question 1 The four different variables that humans have tolerance limits for include; body temperature 1 mark water availability 1 mark blood glucose level 1 mark carbon dioxide 1 mark Question 2 Tolerances for environmental factors can vary widely among species and among individuals of the same species. (1 Mark) Organisms live within a range of too much and too little, the limits of tolerance. (1 Mark) How well an organism functions between the upper and lower limits of different environmental conditions is a measure of how well it is adapted to its environment. (1 Mark)  Homeostasis is the maintenance of the “steady state” in response to changes in the internal and external environments.  This steady state is achieved through a range of mechanisms:  Structural: physical features  Physiological: internal processes and mechanisms that detect and respond to conditions  Behavioural: particular behaviours that help organisms survive Water Glucose is 75- balance 95 mg/dL approx. 0.9% NACL Temperature Carbon between 36 - dioxide 5-6% 38⁰C Homeostasis Definition The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions 16  The Stimulus-Response Model Stimulus: any change in the environment which can be detected Receptor: specialised cell or group of cells that detects the change Message: nerves or hormones Effector: muscle or gland that carries out a response Response: a change in the organism due to the stimulus St im u l u s – a de te ctable chan ge i n the i n t e r n a l o r e x t e r n a l e n v i r o n m e n t (examples; light, temp, CO2) INTERNAL STIMULUS EXTERNAL STIMULUS e.g. Decrease in body temperature e.g. seeing a speeding car approaching Increase in level of carbon Temperature of the external dioxide environment Decrease in blood glucose level Texture of ground Increase in amount of salt in the Hearing the phone ring blood Heat from hot bath Reduction in calcium level of the blood Sensory Receptors  They detect changes to internal and external environment  The receptors send nerve impulses to the central nervous system to process and interpret the information  Transmission :- the relay of information via nerves and/or hormones to an effector  Control Centre :-receives and processes information obtained from sensory receptors (CNS). It will then send a signal to the effector. Signals are transmitted by nerves (rapid) or hormones (slower).  Effector is an muscle or a gland that carries out a response as a result of a stimulus  responds to nerve impulses or hormone message by reducing the stimulus. 1. Stimulus A stimulus is a variable in the internal or external environment that is able to be detected by the organism. 2. Receptor Receptors are found in the cells or tissues that are able to detect a change in the external or internal environment as a stimulus and as a result, generate nerve impulses. 3. Transmission Transmission refers to the relay of information via nerves and/or hormones to an effector. 4. Effector An effector is usually a gland or muscle that brings about a response after receiving the information. 5. Response The response is an action which occurs due to the initial stimulus. 6. Feedback The impact of the response on the initial stimulus. Feedback may be positive or  Feedback:- the impact of the response on the initial stimulus. Feedback may be positive or negative.  Negative Feedback System  Forms a looped system that restores the condition to a steady state.  Response counteracts/reverses the initial fluctuation/stimulus, then the process is referred to as negative feedback.  A good example of a positive feedback system is child birth.  During labour, a hormone called oxytocin is released that intensifies and speeds up contractions.  Increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born.  The birth ends the release of oxytocin and ends the positive feedback mechanism. Positive feedback systems  are uncommon in the body.  The stimulus from one part of the body will cause another part to enhance/amplifies the effect of stimulus.  Such systems are unstable because they cause an escalation in the original condition. Blood clotting makes use of a positive feedback loop. When an injury is detected, resting platelets receive chemical signals that cause them to activate. These activated platelets produce more signals that cause even more platelets to activate until a blood clot is formed. Below is a diagram showing this loop.  Tolerance Limits: Temperature Humans body temperature is 37oC and is tolerated between 36oC and 38oC.  Most of our body heat is released during cellular aerobic respiration oxygen + glucose →carbon dioxide+ water + energy 6O2 + C6H12O6 →6CO2+ 6H2O + energy  From the energy that is released 40% is useable energy for movement, growth etc and 60% is dissipated as heat. More reactions = more heat released Tolerance Limits: Water  Tolerance Limits: Water  The water/solute concentration in the extracellular and intracellular environment is another factor that needs be maintained.  Shifts away from the normal levels can lead to swelling or shrivelling of cells due to osmosis.  Tolerance Limits: Water Human body water has a solute concentration of about 0.09%. The solute concentration affects osmosis. Osmoregulation  CO2 is a product of aerobic respiration which diffuses into blood  5-6% of CO2 remains as CO2 but 90-95% is converted to carbonic acid inside red blood cells.  Concentration of CO2 will increase during exercise and decrease during inactivity  Tolerance Limits: Blood Carbon dioxide concentration CO2 is carried in blood plasma and red blood cells in solution. It is critical in maintaining the pH of the blood between 7.35 and 7.45.  Tolerance Limits: Blood Carbon dioxide concentration Deviations in blood pH due to changing CO 2 levels can be fatal.  Tolerance Limits: Blood glucose level Blood glucose levels are normally between 75-110 mg/dL, 1dL = 100mL The level is controlled by pancreatic hormones – insulin and glucagon Diabetes is a result of high blood glucose levels Tolerance Limits: Blood glucose level https://www.youtube.com/watch?v=Iz0Q9nTZ Cw4  In multicellular organisms it is crucial to coordinate the activities of their specialised systems.  In animals, this is achieved by two interdependent systems: ▪ Nervous system ▪ Endocrine system The Nervous System  The functions of the nervous system include: - Coordination and control of bodily activities - Storing experiences (memory) - Establish patterns of response based on prior experiences (learning) - Programming of instinctive behaviour - Regulation of internal and external environments  The nervous system is composed of: ▪ the central nervous system (Brain and Spinal Cord) ▪ the peripheral nervous system (all the nerves in the body) PNS Transmission of information to and from the CNS (from sensory receptors to CNS, from CNS to effector) CNS Storing, arranging, managing and processing the information  The PNS is made of two systems, nerves that we can control and others that we cannot ▪ Somatic nervous system contains nerves that we voluntarily control (movement, breathing) ▪ Autonomic nervous system contains involuntary nerves (such as the heart, base breathing rate, gut movement, filling of the bladder)  The nervous system is divided into two main types  The PNS comprises sensory and motor divisions Peripheral nerves all enter or leave the CNS, either at the spinal cord (spinal nerves) or the brain (cranial nerves). They can be sensory, motor, or mixed. Ear Eye Smooth muscle Skeletal muscle AT EII EII Sensory Division Motor Division Sensory nerves arise from sensory receptors and Motor nerves carry impulses from the CNS to effectors: carry messages to the CNS for processing. muscles and glands. The motor division comprises two parts. The sensory system keeps the CNS aware of the Somatic nervous system: the neurons that carry impulses external and internal environments. This division to voluntary (skeletal muscles) includes sense organs such as ears, eyes, and Autonomic nervous system: the neurons that regulate taste buds, as well as internal receptors for visceral functions over which there is generally no conscious monitoring thirst, hunger, and body position. control, e.g. heart rate, pupil reflex.  Nervous system is a system of neurons or nerve cells throughout the body that carries information rapidly in the form of electrical impulses  In humans, a neuron maybe up to 1 meter in length  They are able to transmit small electric currents at great speeds of up to 100 metres per second. Although many people use nerves and neurons interchangeably, they are not the same. Neurons are nerve cells, each one comprising dendrites, axons, and a cell body. Neurons are classified as sensory, motor, or relay neurons. Nerves are bundles of neuron axons in the peripheral nervous system. Nerves can be classified as afferent (sensory axons) or efferent (motor axons), or mixed (comprising both afferent and efferent axons).  Nerves consist of bundles of neurons running parallel Electrical impulse ▪ The electrical impulse can only travel in one direction ▪ The electrical impulse is caused by changing concentrations gradients of sodium (Na+) and potassium (K+) ions.   The CNS and PNS are composed of nerve cells called neurons. Structure Function Cell body Contains the nucleus, cytoplasm, mitochondria, endoplasmic reticulum, Golgi body and lysosomes. Axon Long fibre that conducts nerve impulses from the cell body to the axon terminals. Myelin Sheath An insulating layer that increases the rate at which a nerve impulse is conducted along the axon. Axon terminals Small branches of the axon form connections (synapses) with other neurons in the nervous system. Dendrites Extensions of the cell body that receive chemical signals form axon terminals of other neurons. Signals are converted into nerve impulses and transmitted to the cell body. Dendrites - ‘Antennae-like’ extensions from the cell body - Receive signals and information from other cells - Contain protein receptors that receive chemical messages from other cells - Carries signal toward the cell body Axon - carries electrical impulses from the cell body to the axon terminals - Axon terminals release chemical messages that affect other nearby cells - Axons are covered by a myelin sheath which provides support & aids the passage of impulses - An impulse along an axon can travel at speeds of about 100 metres per second. Sensory neurons transmit impulses from sensory receptors to other neurons Sensory receptor(pressure receptor) in the skin. Two axonal branches, one central (to the CNS) and one peripheral (to the sensory receptor). In complex organisms, sensory neurons relay their information to the central nervous system. Myelin sheath Cell body or soma containing the organelles to keep the neuron alive and functioning. Axon branches LA Motor neurons transmit impulses form the central nervous system to muscles or glands. Dendrites Cell body Myelin sheath LA  Cell body Relay neurons are also called association or interneurons. They are located in the CNS and carry impulses from sensory to motor neurons (as in reflexes). Dendrites: Bushy extensions of the cell body, specialized to Axon receive stimuli Axon branches LA  Sensory receptors detect stimulus  Sensory receptors are specialised Nerve impulse is transmitted along cells that detect changes in the sensory neuron to the CNS. internal or external environment. ▪ Most are sensitive to one type Information is processed by the control of stimulus centre and a response is coordinated. ▪ Located in sensory organs (eye, mouth, skin, ears, nose…) Nerve impulse is transmitted along motor neurons from CNS to effectors.  Organisms respond to sensory stimuli via stimulus-response Effectors produce desired response to a model. stimulus. Light from glass of water enters eyes. Sensory receptors stimulated by light. Electrical impulse transmitted along sensory neurons from sensory receptors in the eye to the brain. Information is interpreted by Nerve impulse is transmitted the brain which coordinates along motor neurons from the a response to the visual brain to muscles in the person’s stimulus. arm. Muscles used to pick up glass and raise to mouth.  Muscle – cause muscle cell to contract Gland – cause gland cell to secrete substance Another neuron – conduct another electrical impulse along the neuron The junction between two neurons (between the axon terminal of one neuron, and the dendrites of another neuron) is called a synapse The synapse junction is too wide to allow for the direct spread of electrical impulse from one neuron to the other so uses a chemical called a neurotransmitter.  A nerve pathway consists of a series of neurons with tiny gaps between them called synapses. The electrical current cannot cross the synapse, so a chemical called a neurotransmitter crosses the gap and transfers the impulse to the next neuron in the pathway.  Neurons work by generating a small electrical impulse (action potential) which travels along the action. ▪ The charge activates a calcium channel, and calcium enters the cell. ▪ The calcium cause proteins called neurotransmitters to be released. ▪ They bind to receptors on the next neuron, generating a small electrical impulse. ▪ Repeat!  More than 100 in the body Neurotransmitters are released from one axon terminal through exocytosis and diffuse across the space where they bind to receptors on the receiving membrane. Neurotransmitters are broken down and de- activated by enzymes or can move back into the axon terminal  Neurotransmitters may be either excitatory or inhibitory in their effect (some may be both depending on the receptor they bind to) Excitatory neurotransmitters trigger increase the likelihood of a response Inhibitory neurotransmitters decrease the likelihood of a response ▪Is an involuntary response to a stimulus ▪Not under the control of the brain ▪A reflex arc allows an organism to respond rapidly to a stimulus ▪Some are designed to protect the organisms from harm (pain reflex)  A reflex is an involuntary reaction to a stimulus.  It is an automatic response. Stimulus Reflex Delicious food salivation Spoiled food Nausea An object reaching your eye Blinking When light becomes brighter Pupil of the eye gets smaller Knee is hit by a hard substance Knee jerk reflex Reflex actions are Automatic Rapid Instinctive vital Do not need to be learned Do not need to involve the brain. In this example you move your hand before you are aware of the heat: reflex actions can precede sensation  A collection of glands that secrete specialized chemical messages called hormones, in the circulatory system.  They control activities in a wide range of areas from growth, reproduction, glucose concentration, blood temperature etc  Endocrine glands are ductless, unlike exocrine glands (e.g. sweat glands). Examples of endocrine glands include: Pituitary gland Thyroid gland Parathyroid gland Adrenal glands Pancreas Gonads (ovaries and testes) Pineal gland  A hormone is a chemical messenger. Or, a regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate specific cells or tissues into action. Hormones travel to target sites via the blood.  Hormones are produced in very small amounts, so their concentration in the blood is very low. They are long lasting thus are effective for long term regulation such as growth and reproduction. Those circulating in the blood are eventually broken down by the liver and kidney and excreted.  The endocrine system is coordinated by the pituitary gland, which responds to information from the hypothalamus.  Is made of nerve tissues. Constantly checks the internal environment (the conditions within the Hypothalamus tissues, organs and systems of your body).  If conditions change, the hypothalamus responds.  There are cells in the hypothalamus that secrete hormones into the blood Hypothalamus  These are called Pituitary neurosecretory cells Gland  It secretes hormones that act on the pituitary gland.  Is about 1 cm in diameter.  Often called the ‘master gland’ because it controls the activities of other endocrine glands such as the ovaries, the testes and the thyroid gland.  Stimulates other glands as well as releasing growth hormone and ADH (controls water level). Some hormones are peptides  (short chains of amino acids). Some hormones are proteins  (long chains of amino acids. Others are steroids, derived from cholesterol (lipid soluble).  Peptide Protein Steroid Structure Short chain of amino Longer chains of amino Lipids, made from acids (polypeptide) acids (from tyrosine) cholesterol There are 3 classes of hormones: peptide, protein or steroid. They are different in structure and the way they work in cells. How they get into the Proteins are mostly polar so do NOT enter the cell. Lipids move directly through cell They attach to receptors in the cell membrane. the phospholipid bilayer. What happens next? Molecules inside the cell form a cascade of Hormones join with reactions which alters metabolism, but can also receptors to form a receptor- affect transcription. hormone complex which goes into the nucleus and affects transcription  Peptide Protein Steroid Examples ADH – affects water levels in the Epinephrine FSH – in women it promotes body. Acts in the kidneys. (adrenaline), made in the development of eggs and the adrenal glands. sperm in men. Prepares for fight of Made in the anterior pituitary flight. Human Growth Hormone – Norepinephrine - as Oestrogen – in women – affects bone and muscle mass, above but mainly works secondary sexual decreases fat cell. Made in the on the cardiovascular characteristics. anterior pituitary gland. system Made in the ovaries. Insulin – lowers blood sugar. Thyroxine –increases Testosterone – development Made in pancreas metabolism of male reproductive system Glucagon – raises blood sugar. Pancreatic.  The action of the hormone is dependent on its physical properties including molecular size and solubility ▪ Are hydrophilic/polar so they can’t diffuse across the membrane and travel into the cell ▪ They bind to receptors on the surface of target cells and activate a series of relay proteins on the inside to activate enzymes and/or alter gene expression  Hydrophilic hormone Examples steroid hormones Non steroid hormones are secreted by exocytosis and travel freely in the blood. Carrier Protein Insoluble in lipids, these hormones are mostly Hydrophilic and do NOT enter the cell directly. They bind to cell surface receptor proteins in the cell membrane. Activation of the receptor stimulates a secondary messenger. Secondary messenger initiates a series of chemical reactions which produces the required response in the target cell. Because peptide hormones are water soluble, they often produce fast responses (short term).  Are lipid soluble and will freely diffuse across the target cell membrane.  They then bind to internal cell receptors to being about a response  receptor hormone complex enters nucleus and binds to DNA to initiate transcription of specific genes.  Steroid hormones (Hydrophobic) diffuse through the cell membrane and bind to the receptor in the cytoplasm or nucleus of the target cell forming a receptor hormone complex.  This complex initiates a cellular response such as the activation of an enzyme, a change in the uptake/secretion of molecules or the transcription of specific genes- increase/decrease gene expression (therefore they control proteins synthesis) in the target cell.  Because steroids work by triggering gene activity, the response is slower than peptide hormones (long term). Release of Hormones due to either nerve or hormones Some hormones are released Some hormones are released when a message from the when a message from other nervous system acts on the hormones acts on the gland. gland. The pituitary gland releases the Examples: hormones which, in turn, affect Insulin release by the other hormones. pancreas Example: Adrenaline from the adrenal GnRH (gonadotrophic Release medulla Hormone form the Oxytocin from cells in the hypothalamus causes the brain in a region called the pituitary to release FSH, which hypothalamus stimulates the release of oestrogen by the ovaries  Blood glucose is regulated to ensure it doesn’t deviate from its tolerance range.  If deviation occurs it is detected by specialised cells in the pancreas which secrete glucagon or insulin (which have opposing effects on blood glucose). Hormone Secreted by Secreted when Effect Insulin Beta cells of the islets of Blood glucose is high Decrease blood glucose Langerhans (Pancreas) concentration Glucagon Alpha cells of the Islets of Blood glucose is low Increase blood Langerhans (pancreas) concentration Cells Cells  TSH  The rate of metabolism in cells is regulated by Thyroid stimulating Synthesised in pituitary (brain) hormone (TSH) and Thyroxine(T4) Stimulates thyroid gland to synthesise T4  Hypothyroidism: Insufficient (thyroxine) thyroid hormones, - symptoms are poor ability to tolerate cold, poor memory and concentration, feeling T4 converted to T3 which stimulates metabolism ie increases heart rate, tired breathing rate, and cellular respiration  Hyperthyroidism: Excess production of thyroid hormones, - symptoms are rapid heart beat, irritability, difficulty in sleeping  Hypothalamus releases thyroid-releasing hormone (TRH).  This causes the anterior pituitary to secrete thyroid stimulating hormone (TSH).  This in turn triggers the production and release of thyroxine by the thyroid gland.  An increase in the level of thyroxine in the blood inhibits the hormones from the This is a classic example of Negative Feedback The response hypothalamus and the pituitary reverses the stimulus = negative feedback. This system plays a role in temperature control  Osmoregulation is controlled by ADH which changes the osmolarity of the blood.  High osmolarity: low water concentration due to dehydration, high salt or sugar blood levels  Low osmolarity: high water The diffusion of water into and out of the blood causes changes in concentration – excess water osmolarity, blood pressure and blood consumption, low level salt/ volume. sugar  If ADH binds to receptors in the kidneys, it increases the permeability of cells to water which increases the quantity of water that diffuses from the filtrate into the blood. This reduces the water excreted in urine.  Alcohol inhibits the production of ADH. The diffusion of water into and out of the blood causes changes in osmolarity, blood pressure and blood volume. Fight – the bodies reaction to defend itself / Flight – Avoid danger!  Adrenaline acts on structures such as  smooth muscle – around blood vessels dilates, increasing blood flow, however around intestinal vessels constrict, directing blood to the periphery. Smooth muscles around bronchi relax, increasing air flow to lungs so more oxygen  cardiac muscle: increases heart rate and cardiac output, raising blood pressure and blood flow  radial muscles in iris contract resulting in pupil dilation  Pancreas: increases glucagon secretion which initiates release of glucose from liver into blood Feature Nervous System Endocrine system Signal Pathway Directly along nerve cells Indirectly via the blood Message electrochemical chemical Speed Fast slow Site of action Localised (cells connected to the neuron) = Target cells which can be distant highly specific (many cells) = widespread Duration of action Short lived Long term Effects Nerve messages cause muscles to contract Hormones cause changes in or glands to secrete metabolic activity A comparison of Nervous and Hormonal signals. Nervous Hormonal Transmission/ By electrochemical impulse By a chemical signal (hormones) message Path Direct via axons of nerve cells to the Indirect via blood to target tissue muscle or gland Site of Action Localized, highly specific Widespread (may be a target organ or more general). Speed of Action Rapid Slow Duration of Short term, reversible Long term, possible permanent Effect changes  Homeostasis is the maintenance of a steady set of internal conditions, requiring the body to work in a coordinated way. Stimuli are detected via sensory receptors, however signalling effectors involves both the nervous and endocrine systems. This includes:  Thermoregulation  Osmoregulation  Glucoregulation  Chemoregulation Property endocrine Nervous Thermoregulation Secretes adrenaline, insulin, and Transmits nerve impulses between thyroxine which increases the rate of thermoreceptors, the hypothalamus respiration and effectors Osmoregulation Pituitary gland secretes ADH which Transmits nerve impulses between regulates osmolarity osmoreceptors, the hypothalamus and effector (pituitary gland) Glucoregulation Pancreas secretes insulin and Transmits nerve impulses from the glucagon which regulate blood brain to the effector (adrenal gland) glucose during the fight or flight response Chemoregulation Secretes adrenaline and thyroxine Transmits nerve impulses between which increase breathing rate to chemoreceptors, the medulla and remove excess carbon dioxide effectors. Glucose  Essential substrate for cellular respiration  Breakdown to release energy to synthesise ATP  Primarily obtained in consumption and digestion of food  Blood glucose tolerance levels = 75 to 95 mg/decilitre, failure to maintain this range results in serious disease Glycogen  A large molecule synthesised from glucose  Contains more energy then glucose as it is glucose units bonded together = more bonds = more stored energy  Store of glucose in animals, fungi and bacteria (plants = starch)  Synthesised when blood glucose is too high and broken down when it is too low.  Synthesised, stored and broken down in the muscles (80%) and liver (20%)  Communication system for blood glucose regulation is hormones released from the pancreas.  Cells in the Islets of Langerhans in the pancreas have chemoreceptors that are sensitive to blood glucose concentration  alpha (α) and  beta (β) cells.  Peptide hormones insulin glucagon  Blood Glucose Regulation The receptors that detect changes in the blood sugar level are in the pancreas. The pancreas contains clusters of cells called the Islets of Langerhans. Within the Islets are beta cells which detect an increase in the sugar levels and secrete the hormone insulin. Other cells, alpha cells, detect a decrease in the sugar level and secrete the hormone glucagon. Stimulus response model; Stimulus = change in blood glucose level Receptor = chemoreceptors in pancreas Transmission = hormones insulin and glucagon via blood Effector = muscle and liver cells which store or release glucose to correct blood glucose levels to within tolerance limits  Maintained by negative feedback model The effects of insulin. The effects of glucagon.  Is a metabolic disorder where; ▪ a person does not produce enough insulin or ▪ the body does not respond properly to insulin  They cannot maintain the tolerance limits of the blood glucose concentration. SYMPTOMS DESCRIPTION Hyperglycemia Blood glucose concentration above tolerance; can cause damage to nerves and eye retina, causing blindness, damage to blood vessels, renal failure, glucose in urine, increased urination, increased thirst and when acute coma, death. Hypoglycemia ¯ Blood glucose concentration below tolerance; causing person to feel weak, headaches, nausea, dizziness, seizures, unconscious  Blood Glucose Regulation Diabetes Type I diabetes is when the body’s immune cells attack and destroy beta cells, so no insulin is made. The cause is genetic but may also be from a bacterial or viral infection. Treatment requires injections and diet. Type II diabetes occurs later in life and involves a lack of response by the body to insulin. The insulin is made but the receptors do not respond. Cause is mainly a sedentary lifestyle, aging, genetics but mostly obesity. Treatment is diet, exercise, weight loss and injections.  refers to the biochemical reactions in an organism including cellular respiration  Is regulated by hormones; thyroid stimulating hormone (TSH) and thyroxine (T4)  TSH is synthesised in the pituitary gland  T4 (thyroxine)is synthesised in the thyroid gland  TSH stimulates production of T4  T4 is converted to the hormone triiodothyronine (T3) which stimulates metabolism in almost every tissue in the body.  T3 increases heart and breathing rate and also rate of cellular respiration.  Secretion of TSH and subsequent synthesis of T4 is regulated by changes in the blood concentration of Thyroxine.  If blood concentration of Thyroxine is low, the pituitary gland increases secretion of TSH  If blood concentration of Thyroxine is high, the pituitary gland decreases secretion of TSH  Blood concentration of Thyroxine is detected by hypothalamus ▪ Iodine is needed for production of thyroxine ▪ a lack of iodine caused the thyroid to enlarge = goitre ▪ Lack of thyroxine (hypothyroidism) = slow thought and speech, lethargy, sleepiness, decreased appetite and cold intolerance ▪ Too much thyroxine (hyperthyroidism) = rapid heartbeat, shortness of breath, increased appetite and heat intolerance The control of the water balance of the blood, tissue or cytoplasm of a living organism. The movement of water to and from cells needs to be controlled. (osmosis)  External and internal changes such as volume of water in food and drinks, amount of sweating and the accumulation of salts due to diet can change the water content of blood, tissues and cytoplasm. Receptors in the hypothalamus control osmoregulation by controlling thirst and the reabsorption of water back into the blood from the nephron in the kidney. maintaining the correct balance of water and salts in the blood. Antidiuretic Hormone (ADH)  Osmoregulation The hormone ADH = Anti Diuretic Hormone is synthesised in the hypothalamus and secreted by the posterior pituitary. Also called vasopressin Diuresis relates to high urine output. ADH works to prevent diuresis (high urine output) and conserve body water. ADH inhibits water excretion (urine).  Antidiuretic hormone (ADH) is also known as vasopressin.  ADH is produced in the hypothalamus and stored before release from the pituitary gland.  ADH is transported in the blood and binds to receptor molecules on the cells of the collecting ducts in the kidneys.  It makes the collecting duct walls more permeable to water by increasing the number of aquaporins present in the cell membrane on the filtrate side of the collecting ducts.  Link between osmoregulation, blood volume and blood pressure  ▪ Substances that promote the formation of urine are called diuretics. ▪ Drinking alcohol increases urine production because its presence in the bloodstream causes the pituitary gland to stop releasing ADH.  As a result less water is leaving the collecting ducts by osmosis ▪ Continued consumption of alcohol leads increased urinatation and dehydration.  This in turn may cause the symptoms of a hangover  Evolved as a protective mechanism to react quickly and respond to threatening situations; ▪ fight for survival ▪ take flight from danger  The response begins with receptors in the nervous system (usually in eyes or ears) transmitting info to the brain.  Nervous System communicates with the hypothalamus which triggers the fight or flight response A message from the hypothalamus goes via the sympathetic nervous system to the adrenal medulla (adrenal glands) which sit on the kidneys. Adrenaline is released. It has multiple effects which prepare the body for swift action. Adrenaline causes Relaxation of smooth muscle around blood vessels in skeletal muscle = more blood in muscles Constriction of blood vessels in digestive system Heart rate and cardiac output increased Blood pressure and blood flow are increased Smooth muscles around bronchi in lungs are relaxed so more air in the lungs The pancreas is stimulated to release glucagon which releases sugar from the liver All this increases cell metabolism  The hypothalamus initiates its actions via the autonomic NS, a system linked to control of; ▪ breathing, ▪ blood pressure, ▪ heart rate and ▪ other involuntary actions  This prepares the body to respond to danger  Once the threat has passed the parasympathetic component tends to reduce the effects of the sympathetic component and reverse the effects to restore the body to normal.  CO2 in the blood needs to be kept within tolerance levels (5-6%)  CO2 in blood is required to stimulate and control the rate and depth of breathing  High levels of CO2 lead to an increase in acidity or lower blood pH.  The opposite if CO2 levels fall below tolerance levels.  CO2 should be maintained at a level where blood has a pH of 7.35  Exercise has many short-term (acute) and long- term effects on the body: Increased activity leads to increased carbon dioxide and hydrogen levels in the blood. ( metabolism) They lower blood pH, increasing acidity, beyond optimal levels. The brain stimulates the heart rate to increase and remove excess carbon dioxide  Monitoring pH pH. CO2 is carried in the blood. It firstly combines with water to form carbonic acid and this dissociates to form hydrogen carbonate (HCO3- )and hydrogen ions H+. H+ ions determine pH. pH is detected in the brainstem in the medulla oblongata and the pons.  If the pH of the body gets too low (below 7.4), acidosis results. This can be serious, because many of the chemical reactions that occur in the body, especially those involving proteins, are pH-dependent. (enzymes)  Ideal pH of the blood = 7.4.  If the pH drops below 6.8 or rises above 7.8, death may occur. 53 ▪ Body temperature is monitored in two ways: ▪Thermo receptors in skin and around the body ▪blood flows through the hypothalamus in the brain and thermo receptors detect a change ▪ If the body temp is not 37°C series of nerve and hormone responses restore it to the correct temperature ▪If body temp is too low then hypothermia (less body reactions) ▪If body temp is too high then hyperthermia (muscle meltdown)  Stimulus is temperature change Response is a change in Receptor is the temperature hypothalamus Effectors in include skeletal Message is nerves and muscles, smooth muscles, metabolic rate, sweat glands hormones ▪ Sweat gland release moisture on the surface of the skin ▪ When this moisture evaporates it encourages heat loss from the body – evaporative cooling  When hairs  lay flat against the skin, air can flow past the surface of the skin and draw heat away from the body.  The blood vessels near the surface of the skin dilate and allow heat loss through the surface of the skin.  This means more heat is lost from the surface of the skin If the temperature rises, the blood vessel dilates (gets bigger). ▪ Decreasing the levels of thyroxine and adrenaline decreases metabolism. ▪ By decreasing reactions like cellular aerobic respiration, heat production is decreased. Decrease heat loss  Hairs raise/goose bumps Nerve  Blood vessels constrict Nerve/hormone (vasoconstriction) Increase heat production  Shivering Nerve  Increase body reactions (thyroxine & adrenaline) Nerve/hormone ▪ Sweat gland shut down and DONOT release moisture on the surface of the skin ▪ Decreased heat loss from the body ▪ The erection of hairs and feathers on the skin helps to trap a layer of air close to the body which provides an insulating barrier to reduce heat loss. ▪ The erector-pili muscle contracts to cause the hair to raise (appears as goosebumps) The blood vessels near the surface of the skin constrict and prevent heat loss through the surface of the skin.  Shivering causes movement (contraction and relaxation of skeletal muscles) which requires energy from aerobic respiration. Aerobic respiration releases heat also which warms the body ▪ Increasing the levels of thyroxine and adrenaline increases metabolism. ▪ By increasing cellular aerobic respiration, heat production is increased.  Increase heat loss increase sweating nerve Hairs lay flat nerve Blood vessels dilate (vasodilation) nerve/hormone Decrease heat production Decrease body reactions (thyroxine & adrenaline) hormone Heat increasing mechanisms Heat decreasing mechanisms Smooth muscles constrict blood Smooth muscles relax around vessels = vasoconstriction. Heat is blood vessels = vasodilation. Heat kept in the body cavity. is lost via radiation. Skeletal muscles shiver Sweating loses heat by Metabolic activity increases evaporation = loss by latent heat of Behaviour – clothes put on, vaporisation huddling Less metabolic activity “goose bumps” = erector-pili Behaviour – less clothes, open muscles make skin hairs stand up stance and trap heat Skin hairs lie flat ENDOCRINE NERVOUS Secretes adrenaline, Transmits nerve insulin and thyroxine impulses between which increases the thermoreceptors, the rate of cellular hypothalamus and respiration (generates effectors. heat) Effectors = erector pili muscles, capillaries, muscle (shivering), sweat glands, thyroid gland. ENDOCRINE NERVOUS Pituitary gland Transmits nerve secretes ADH impulses between (Antidiuretic osmoreceptors, Hormone) which the hypothalamus regulates and effector osmolarity. (pituitary gland) ENDOCRINE NERVOUS Pancreas secretes Transmits nerve insulin and impulses from the glucagon which regulate brain to the blood glucose effector (adrenal gland) during the fight or flight response. ENDOCRINE NERVOUS Secretes Transmits nerve adrenaline and impulses between thyroxine which chemoreceptors, increase the medulla (in breathing rate to brain) and remove excess effectors carbon dioxide Property endocrine Nervous Thermoregulation Secretes adrenaline, insulin, and Transmits nerve impulses between thyroxine which increases the rate of thermoreceptors, the hypothalamus respiration and effectors Osmoregulation Pituitary gland secretes ADH which Transmits nerve impulses between regulates osmolarity osmoreceptors, the hypothalamus and effector (pituitary gland) Glucoregulation Pancreas secretes insulin and glucagon Transmits nerve impulses from the which regulate blood glucose brain to the effector (adrenal gland) during the fight or flight response Chemoregulation Secretes adrenaline and thyroxine Transmits nerve impulses between which increase breathing rate to chemoreceptors, the medulla and remove excess carbon dioxide effectors.