[Music] it's no secret that organisms can be very complex and have many different parts that have different functions in this video we will discuss the idea of system integration which describes how different parts of organisms can work together to achieve a common goal the scope of our learning will be different parts and organs of the human body which work together through communication and coordination to perform their complex functions strap in for this one because any of these examples can and will likely show up on the IB exam to start the conversation around systems we first need to understand what body systems are and how they are set up the easiest place to start is to look at the smallest units that we use to define life which are cells cells within a multicellular organism have specific roles but in order to perform some larger functions they need to group together and work together in a specific area for a specific purpose which we call a tissue tissues can be made of more than one type of cell and they can perform specific functions that any individual cell would not be able to do if we take a look at our cheeta here this animal has a heart that is made up of cardiac muscle tissue this consists of specialized groups of cells that are designed to contract and move together in unison if two or more types of tissue work together they tend to form larger structures that we call organs we can look at individual muscles within the cheetah like its biceps Fus that we can classify as organs because each muscle contains skeletal muscle tissue connective tissue nerve tissue and blood or vascular tissue when we go another step up in the hierarchy and organs start to work together we call this a system so we can say that the cardiovascular system of the cheetah works by interacting components of the heart and arteries capillaries and veins all of which are organs that contain their own unique cells and tissue types learning about how this hierarchy works is important because it provides different perspectives to study how living organisms work which is what we will do for the remainder of this video as we look through examples of this hierarchy in action but there is something cool here that we need to note which is the fact that when we get all the way to the organism level with systems working together there are new emergent properties that the organism has that add up to be more than the sum of each of the individual parts so we know for the that it has cells that make up tissue that support the beating of the heart which moves blood and nutrients around the body but as a result of this and all of the other systems found within the cheetah that work together the cheetah can become an effective top predator that is extremely quick and agile there is no individual cell or tissue that we can point to that gives them this emergent property but instead is the collective integration of all of its systems this is similar to the fact that you are currently watching understanding and taking notes on this video there is no one system in your body that makes this possible but it is possible through the collection of all of your systems working together so tell your body to hit the Subscribe button because why not from this point on we are going to go through different examples of system Integrations in the human body first up we have the integration of signaling that allows for different organs and systems to communicate with one another signaling is generally performed by two different systems which are the endocrine system and the nervous system the endocrine system is made up of glands that release chemicals called hormones these hormones can move from one area in the body to another carrying a signal that can cause a change within an organ based on a change in internal body conditions an example could be the release of the hormone epinephrine which moves from the adrenal glands to various parts of the body to initiate a fight or flight response the nervous system is made up of specialized cells called neurons that carry electrical signals these electrical signals can be sent to different organs to also facilitate a change to happen an example could be a volary muscle contraction in which an electrical signal is sent from your brain down a neuron and to a muscle to initiate a contraction that let's say makes you lift up your arm to reach something on a high shelf these types of signaling chemical vers electrical work at different speeds and for different durations in general the electrical signals sent via neurons are much faster and shorter lived which is good for muscle contractions chemical signals sent via hormones are are slower and comparatively have a longer duration which is good for changing metabolic rate signaling for growth and development and many other responses that relate to mood sleep stress hunger Etc in addition to signals other components and nutrients are transported around the body between different systems one great example of this is how nutrients that help provide energy to our cells like glucose and oxygen are transported via the bloodstream cells undergo cellular respiration to create ATP which means they need to have the proper nutrients in order to carry out the process and in order to get those nutrients blood vessels either directly or indirectly connect to every tissue in the body this is a very large and very important example of integration of the circulatory system to the rest of the body the next organ to reference for integration is the brain the brain is a highly specialized organ filled with neurons that is designed to interpret and send information to all parts of the body thus controlling and making sure everything is working properly much like the blood system the brain is connected to all other parts of the body to both send and receive information the brain can receive information through different types of receptors that are everywhere from your eyes ears and nose to your skin bladder blood vessels and digestive tract once it receives information it can process it and develop an appropriate response if needed information can be stored in memories for either short or long term which AIDS in strengthening different neural Pathways that support learning continuing our conversation with the brain and nervous system the spinal cord also plays a very important role in integrating different systems of the body the complete nervous system is made up of two parts called the central nervous system which consists of the brain and spinal cord and the peripheral nervous system which contains all of the peripheral neurons that connect to other body systems and Branch from the spinal cord there are two main types of tissue that are found within the spinal cord called gray and white matter now we mentioned on the last slide that the brain is the integration processing center of the body but the cool thing about the spinal cord is that it can also process information on its own without ever having to send info to the brain in order to carry out a reaction this occurs in the gray matter of the spinal cord which is made up of motor neurons cell bodies and interneurons and because this connection does not go to the brain we do not consciously think about any process that is sent there we therefore call this a unconscious process that happens involuntarily AKA without us AC ly thinking about it the best example of this is a reflex let's say that you picked up a pan on the stove that you didn't know was very hot The receptors in your skin would perceive this temperature change through a sensory neuron that sends a signal to the gray matter in the spinal cord the signal gets passed to an inter neuron which relays it off to a motor neuron which can act on the muscles in your hand and arm making you drop the pot and pull your hand away this all happens very quickly and unconsciously because it was not sent to the brain to be processed but instead was was processed in the gray matter of the spinal cord all conscious processing is done in the brain and sent out via neurons that are packed into the white matter of the spinal cord which would be like you deciding to use your leg muscles to stand up or chew and initially swallow your food these are conscious actions that you are actively thinking about and Performing and can therefore inherently control in either case voluntary or involuntary it is the connection between the Central and peripheral nervous systems to all other systems that allow for this integration and transfer of information to happen humans like many other animals have the ability to perceive information from the outside world through their senses and all of our senses which include sight hearing tasting smelling and feeling only work because of specialized neurons called Sensory neurons which we started to discuss on the last slide these neurons are diverse in their function as they are specially designed to collect information based on the sense that they are tied to and then relay that information to the brain so if we look at site specific photo receptors in the eye are designed to capture different wavelengths of light that trigger electrical signals to be sent to the brain through Sensory neurons in the retina and for feeling there are specially designed mechano receptors within the skin that send electrical signals based on the deformation or movement of the skin some of these Sensory neurons have axons that connect directly to different hemispheres of the brain While others connect directly to the spinal cord which then is connected to the brain in either case all of the information in order to be processed and understood has to make its way to the central nervous system which is done through Sensory neurons while there is much input going into the brain from Sensory neurons there is also output happening from the brain that makes changes based on the sensory input both hemispheres of the brain control the movement of skeletal muscle through specific neurons called motor neurons and because the information is being processed and sent out from the brain it is happening consciously so if you are receiving sensory information via the sense of smell that something is rotten in your garbage can you will likely act on that information and remove the garbage from the kitchen this requires movement from your skeletal muscles which are consciously stimulated and Contracting only because information is being sent from your brain instructing that to pull on your bones and perform that specific action the area of the brain that processes these motor movements called the motor cortex is found here and again is located in both brain hemispheres and has many neurons within the Outer Gray matter portion of the brain tissue when looking at either Sensory neurons from two slides ago or motor neurons from the last slide we generally refer to both of them as nerves and we can't get this term nerve confused with the term neuron which is referred refering to a single nerve cell within the nervous system when we look at specific nerves within the body the reality is that they generally carry within them many fibers that make up axons of both sensory and motor neurons which we call nerve fibers so when we look at a cross-section of a nerve as we see here it is made up of many individual nerve fibers or individual neurons the entire nerve bundle is surrounded by a protective sheath and the individual nerve fibers can also have their own protective melinated cating though some neurons have less of this than others and we can distinguish the two as being either melinated or unmyelinated section C2 covers more specific details on individual neurons and how they function circling back to reflexes we stated before that the spinal cord has the ability to process information within its gray matter that can create an involuntary response while this is one type of involuntary reflex the brain also has the ability to coordinate reflexes that can be used to prevent harm to the body for example the papillary reflex is controlled by a nerve that starts in the brain and sends a signal to dilate or constrict the pupil based on the amount of light entering the eye in either case mediated by the brain or by the spinal cord reflexes are coordinated by parts of both the nervous system skeletal and muscular systems and at times the endocrine system to function as we stated earlier the example of this that you need to know for the IB exam exam is with a pain reflex arc in the hand which has an involuntary response with skeletal muscle in this case the skeletal muscle acts as the affector which is part of the body that carries out the final action taken as a response to the initial stimulus so we use another example that is similar to the hot pan example we already talked about you place a finger over a flame on a lit candle Sensory neurons within the skin of your finger send a signal via the neuron to the spinal cord the signal is passed to an interneuron within the spinal cord which relays it to a motor neuron the motor neuron sends a signal back to the muscles at that location which creates the effect of you pulling your hand away and to give you a real life example of this this ironically happened to me the day that I wrote this script as you can see I burned two of my fingers on a grill ouch make sure you remember this specific example and know the pieces to be able to explain it yourself let's move on and talk about a few other examples of system integration that you need to know the cerebellum is a section of the brain tissue that is located near the back of the brain below the two cerebral hemispheres and above the brain stem the function of this tissue is to help coordinate the contractions of skeletal muscles this coordination helps direct the timing of muscle contractions that Aid in the overall balance and posture of your body making sure that the correct muscles are keeping us upright so we are not falling over if you have ever pulled an allnighter studying for your next IB exam you should be aware of the fact that sleep is very important for your health the body and specifically the brain has a method of modulating sleep patterns to follow a specific 24-hour cycle which we call our circadian rhythm this is spearheaded by cells within the hypothalamus called suprachiasmatic nuclei abbreviated scn these cells follow a specific 24-hour Rhythm that sends signals to the pineal gland the pineal gland secretes a hormone called melatonin which has many connections throughout the body and promotes the feeling of drowsiness and a change in body temperature in order for you to sleep this cycle is also aided by information coming from your eyes that capture specific wavelengths of light throughout the day bright light will signal to the scn that melatonin is not needed where wavelengths around dusk and the lack of bright light will signal the scn to prompt more melatonin to be secreted from the pineal gland when you are waking up the light coming into your room and hitting your eyes in the morning also signals for a decrease in melatonin and the cycle repeats small adjustments can be made based on these signals for the cycle to match up properly to changes in day and night timing which is especially important if you have traveled to a different time zone and need to adjust your sleeping cycle another hormone that affects many tissues of the body is is called epinephrine which has another name of adrenaline epinephrine is secreted by the adrenal glands which sit on top of the kidneys and is controlled by the brain and when it reaches its target cells has the overall effect on the body that prepares it for vigorous activity this is mainly accomplished by sending an increased amount of oxygen and glucose to skeletal muscle cells creating a better environment for the muscle to continue to contract under strenuous conditions many organs within the body support the muscles to function which incl include the liver which breaks down glycogen to make glucose available the lungs which dilate their bronchi and bronchial so that more air can flow and oxygen can enter the body accompanied by an increased ventilation rate the heart rate which beats faster to move more of the oxygen and glucose into the muscle tissue and arterials that are also dilated or restricted to direct more blood to the muscles this all comes together to prepare you for a fight or flight response allowing the body to be ready for anything the endocrine system system is designed to send chemical signals around the body but the endocrine system itself only works if it is controlled by some external signal and these signals originate within the hypothalamus which is part of the nervous system the pituitary gland is part of the endocrine system and acts as a mediator between the hypothalamus and the many functions of the endocrine system so knowing this we can say that the pituitary gland helps integrate the nervous and endocrine systems to work together the pituitary gland is made up of two different lobes called the anterior and posterior lobes these loes function in different ways but the outcome is the same the release of hormones into the bloodstream there are many different hormones that are secreted by the loes of the pituitary gland which you can see here these hormones will be specifically talked about in other videos if you need to know them for the test so no need to memorize this list right now the key takeaway from this slide is that you need to remember that the pituitary gland and therefore the majority of the endocrine system because these hormones go on to affect other endocrine glands is controlled by the hypothalamus which is part of the nervous system nervous to endocrine that's the system integration next up we'll talk about system integration within the cardiovascular system and the respiratory system the cardiovascular system includes the heart and all of the attached arteries and veins that move blood around the body to deliver nutrients and waste to their appropriate locations as the body needs the beating of the heart is controlled not by the cardiovascular system but by the nervous and endocrine systems the medulla ambling of the brain stem contains within it tissue that is classified as the Cardiovascular Center this nervous tissue sends signals via two main nerves called the vagus nerve and the sympathetic nerve that send electrical signals to the SA node found near the right atrium of the heart contractions sent from the SA node tell the heart muscles to contract which pump blood through Chambers and out of the heart to be moved throughout the body the sympathetic nerve signals the SA node to increase the heart rate where the vagus nerve signals for a decrease in heart rate but how does the Cardiovascular Center know the proper information to send to the SA node to achieve the proper heart rate there are two specific types of receptors called Barrel receptors and chemo receptors that are found within arteries near the heart such as the aorta and the cored arteries that send signals via nerves to the cardiovascular center of the medulla amblagada Barrow receptors monitor blood pressure while different receptors monitor blood oxygen concentrations and blood pH so changes in pressure oxygen levels or pH could drive an increase or decrease in heart rate based on these connections this type of integration control amongst these systems is referred to as feedback control because these changes are made in response to a stimulus and is always trying to balance out the heart rate to either increase or decrease based on what the body needs in the moment and while we are talking about heart rate as mentioned on a previous slide epinephrine also called adrenaline can also increase heart rate because the SA node of the heart responds to the hormone but this only increases heart rate for that fight ORF flight response and does not decrease it another type of feedback control we can see is within the process of ventilation ventilation describes the rate at which someone is breathing which brings in oxygen and eliminates waste like carbon dioxide ventilation is regulated by a negative feedback loops supported by the chemo receptors also found in the aorta these receptors monitor blood pH H if let's say you are using your muscles more frequently which has their mitochondria undergoing more cell respiration to generate at TP that process produces carbon dioxide too much carbon dioxide in the blood will cause the pH to decrease these chemo receptors sense that and send signals to the respiratory Center in the brain stem which then tells the respiratory system to increase the ventilation rate meaning the diaphragm and the intercostal muscles contract at a faster Pace this works to Exhale more carbon dioxide and bring the pH back up to a normal level in the same fashion other chemo receptors within the kateed arteries monitor blood oxygen levels that relay information to the respiratory Center if oxygen levels drop below a certain point signals will be sent to increased ventilation rate to ensure enough oxygen is entering the blood to support the brain make sure to understand both of these feedback control examples for the exam lastly let's take a look at the nervous system and the digestive system and how they are integrated to perform the very important function of moving material through your gut the function of the digestive system is to break down and absorb food that we can use to sustain our body there are many different parts of the digestive system as you can see here but the main idea behind how it works is that the system itself is made up of one long tube that extends from the mouth all the way to the anus so food enters it gets moved through the tube and broken down some of it gets absorbed and whatever is left over ends up exiting now in order for the food to make its way down the tube of the digestive system it obviously needs to be moved and what we know about movement so far is that it is done by muscles and is controlled by the nervous system so when we look at the parts of the digestive tract that food is moved through such as the esophagus stomach small and large intestine all of these structures are lined with smooth muscle which is the third type of muscle that is not skeletal or cardiovascular the smooth muscles are set up in layers around the tube the outer layer creating a longitudinal pattern that follows the path the food is traveling and the inner layer creating circular formations around the tube longitudinal muscle contracts in a WAV likee motion called peristalsis that pushes the food down the tube in Only One Direction which is away from the mouth and towards the anus all of these movements are controlled by signals from nerves but these specific nerves do not originate from the central nervous system a subcompartment of the nervous system called the enteric nervous system has nerve collections along the tube and into these muscle layers signaling for them to contract and perform these peristaltic movements in unison which slowly moves food down the intestines and this system operates on its own separate from the central nervous system which is why you never actively had to think about making sure your food is moving down your gut it just happens automatically by the workings of these enteric nerves but that being said there are two parts of the process in which these central nervous system is active which are at the beginning and the end you are obviously making a conscious choice to consume food and the action of swallowing is initiated by the central nervous system and your conscious thought additionally when you're ready to excrete waste unless you are a baby the process of relaxing and widening the sphincter muscle of the anus is a voluntary process which is processed in the central nervous system everything in between from swallowing to excreting is controlled by the enteric nervous system [Music]