Hey guys, thank you guys so much for tuning in today. Today we're going to be talking about the first chapter to anatomy and physiology and this chapter is sometimes called orientation because it's pretty much just introducing you to what's to come in the course, general terms and principles. So if you made it to anatomy and physiology, pat yourselves on the back.
That is a big deal because everything you learn in this course is going to follow you from here on out. When you take your TEAS exam, there are are going to be anatomy and physiology questions on the exam. When you start the nursing program, you will see anatomy and physiology there.
Even when you start your career as a nurse, there will be anatomy and physiology. Please like, comment, share, and subscribe to this channel and I promise I'll try to make this video as short and painless as possible. Well, what is anatomy and physiology?
Well, anatomy is going to be the study of the human body structure, where things are located. Physiology, on the other hand, is going to be the study of the human body's function, how these structures work. Now, anatomy is going to take up a lot of the lab portion of the class, whereas physiology is going to take up a lot of the lecture time in the class.
Now, both structure and function work closely together. It's something that we like to call the dogma of anatomy and physiology. And this dogma pretty much states that structure dictates function. How something is structured will always benefit its function.
There are different types of anatomy and physiology. There is systemic anatomy, which studies the human body's organ systems. There is regional anatomy, which studies the different regions of the human body.
There is surface anatomy, which studies the surface markings of the human body. And then there are even more specific subfields of anatomy. There's gross anatomy, which studies the structures inside of organs and organ systems that we can see with our naked eye.
Structures that we don't need a microscope to observe. An example of that would be the left ventricle of the heart. We can spot out the left ventricle of the heart without using a microscope.
And then there is microscopic anatomy, the study of structures of the human body that do require a microscope for observation. And then even microscopic anatomy has its specific fields of study. There's histology, which is the study of tissue.
And then there's cytology, which is the study of cells. Physiology also has its own subfields. There is neurophysiology, which studies the brain and nervous system.
There is cardiovascular physiology, which studies the heart and blood vessels. And as you can see, both cardiovascular physiology and neurophysiology have the organ system that is being studied in its name. For example, neurophysiology is studying the nervous system. Neuro means nerve. It's in the name.
In cardiovascular, that's kind of self-explanatory. There are seven characteristics that an organism must have to be considered alive and I'm sure you guys probably remember the characteristics of life. from introductory biology. So all living things should be composed of one or more cells, which we know cells to be the basic units of life. All living organisms should be able to metabolize.
These metabolic processes can build up, which is something we know as anabolic metabolism, or these chemical processes can break chemicals down in the body, which is something that we know as catabolic metabolism. Cats break stuff. down.
All living things should be able to excrete waste products that are no longer needed in the body. Growth. All living things should be able to grow in cell size or grow in cell number.
All living organisms should be able to respond to environmental changes known as stimuli. Movement. All living organisms should be able to move or have movement within them whether it's their cells that are moving or their flow of blood.
Reproduction. All living organisms should be able to reproduce cells to replace damaged or old ones. This is a process known as mitosis.
Organisms should be also able to reproduce similar offspring. This is something that we know as meiosis. Levels of structural organization.
I like to look at these levels as stair steps because they start off small and gradually get bigger. and by time you reach the top of the stair steps you should reach a fully functioning organism. The chemical level is the smallest level. This can be anything from small tiny atoms.
These atoms will combine to make larger structures called molecules. Now depending on the book, you have. Molecules might be labeled under its own level called the molecular level, but as long as you know that atoms combine to make molecules, you'll be fine. Now these molecules will then combine to form cells. This is called the cellular level.
Then these cells will combine and work together to form tissue. This is called the tissue level. Tissue will then combine to form a specific organ.
This is called the organ level. Now some of these organs will work together with one another to carry out a function. This creates an organ system such as the bones and joints.
They work together to form the skeletal system. And finally, all of the organ systems in the body will come together in harmony to form you, the organism. The anatomical position is the frame of reference used in science and in the medical field.
In the anatomical position, the body is standing up straight, shoulders and feet width apart, upper limbs at sides of the trunk, and head and palms are facing forward. So it's important to always refer to the body as if it's in anatomical position. Left and right is always referred to the left or right side of the body you are describing, not your own left and right. As my professor would say, it's never about you, but always about the patient.
Directional terms are another way to make sure that the locations of the body are referenced to correctly. Anterior is a term that references the front of the body or an organ. For example, the esophagus is anterior to the spinal cord. It's in front of the spinal cord. While posterior is a term that references to the back of the body or an organ.
For example, the spinal cord is posterior. to the esophagus, meaning that it is behind or in the back of the esophagus. Now you are probably familiar with the word superior, but it has a slightly different meaning in biology.
So superior in biology means toward the head, which is why this term is sometimes called cranial. For example, the eyes are superior to the nose, meaning that the eyes are closer to the top of the head than the nose. Inferior, which is the opposite of superior, means away from the head or toward the tail. For example, the lips are inferior to the nose. Now, inferior and superior terms are only used to reference positions on the head, neck, and trunk.
For limbs, we use proximal and distal. Proximal means closer to the point of origin. For example, the shoulder is proximal to the elbow, meaning that the shoulder is closer to the point of origin than the elbow.
Now, distal means farther away from the point of origin. origin. An example of this would be the wrist is distal to the elbow, meaning that the wrist is farther away from the point of origin than the elbow.
Now these are the limbs we're talking about. So the point of origin for the limbs is going to be the trunk. Medial means closer to the midline of the body.
For example, the ear is medial to the shoulder. Lateral means farther away from the midline of the body. For an example, the shoulder is lateral to the chest.
The chest is closer to the midline of the body while the shoulder is farther away from the midline of the body. Superficial, meaning closer to the surface of the body. For an example, the skin is superficial to the muscles.
Deep references structures farther away from the surface of the body. And an example of this would be the bone is deep to the muscles. The bone is farther away from the surface of the body, whereas the muscles are closer.
then the bone to the surface of the body. The body can be divided into two main regions. There's the axial region which consists of the head, neck, and trunk. Then there's the appendicular region which consists of the upper and lower limbs.
Now even the sub regions can be divided into smaller regions. I'll actually do a video going over the different regions of the body more in detail. Because regions of the body are more of a lab topic, so your professor probably wouldn't expect you to know too much about regional terms for a lecture exam, not unless your professor is a true weirdo. Planes of section are standard ways of dividing the body and or body parts to examine its inside structure. There are three main planes of section.
There is the sagittal plane, the frontal plane, and the transverse plane. And these three main planes also come with their own types. Now there is also an open plane. oblique plane, which is a less standardized type of plane.
By the way, planes of section and directional terms are not the same thing, so I would recommend getting some practice with both. Sagittal planes divide the body or body parts into right and left sections, and there are two types. There is the mid-sagittal plane, also known as the median plane. This plane is going to divide the body or body parts. parts into left and right equal parts.
Then there is the parasagittal plane which divides the body or body parts into left and right unequal sections. The transverse plane also known as the horizontal plane or cross section divides the superior and inferior part of the body in half. It also can divide the limbs into proximal and distal parts. The frontal plane or the coronal plane divides the body or body parts. into anterior and posterior sections.
And I wanted to use an example of an organ for this slide to show you guys that planes can also be used to divide body parts, not just the body as a whole. And in this example we have a picture of the brain being divided into front and back regions. And knowing that the frontal plane gives you a front section and a back section is an easy way to remember this plane because The section that this plane gives you is in the name, frontal. The oblique plane, which is less frequently used than the other planes, is taken at an angle. And it's mainly used when examining structures inside of the knee.
The body can be organized into different cavities. And a cavity is any space inside of the human body that is filled with fluid. These cavities function to protect our organs so our organs can function properly.
There are two main cavities of the body. There's the dorsal body cavity, which is located on the posterior or back side of the body. And then there's the ventral body cavity, which is located on the anterior or front side of the body.
And even these cavities have their own subdivisions. The dorsal cavity has two subtypes. There's the cranial cavity of the skull, which protects the brain.
And there's a spinal cavity located in the vertebral column and protects the spinal cord. Now both the cranial and the spinal cavity are filled with cerebral spinal fluid. This fluid is also called CSF. And this fluid is what helps your brain and your spinal cord to stay afloat.
The ventral body cavity also has two main subdivisions. Both of these subdivisions are going to be separated by a dome-shaped muscle called the diaphragm. And the diaphragm is an organ that contracts during breathing.
The thoracic cavity encloses the thorax area and is going to be located above the thorax. above the diaphragm. The abdominal pelvic cavity surrounds the abdomen and the pelvis and is going to be located below the diaphragm. And please note that some of these structures are going to be surrounded by a serous membrane. And the serous membrane is going to be a thin sheet of tissue that encloses certain organs and produces serous fluid.
Within the thoracic cavity, you'll find three smaller cavities, the pleural cavity, the mediastinum, and the pericardial cavity. Pleural cavities have a left and right portion. Each surround a lung.
The left pleural cavity surrounds the left lung while the right pleural cavity surrounds the right lung. The mediastinum, meaning middle, is located between the right and left pleural cavities. There are two divisions of the abdominal pelvic cavity. There's the abdominal cavity and the pelvic cavity.
Now as you can see, the abdominal cavity is the area that starts at the diaphragm and ends at the pelvic. bone and in this cavity you'll find the digestive system, the lymphatic system, and the urinary system. Now the pelvic cavity is going to be the area that occupies the bony pelvis. The abdominal pelvic cavity can be divided into different regions. This can be done using the four quadrant system or the non-region system.
Now the four quadrant system is achieved by drawing one transverse line along the umbilical region or belly button and then one mid-sagittal line. And this is a very simple method. It'll give us four equal quadrants, the right upper quadrant, the left upper quadrant, the right lower quadrant, and the left lower quadrant.
And the four quadrant system makes it easier to diagnose abdominal pain. For example, pain in the right lower quadrant could be caused by pain in the appendix, the right ovary in women, or the last section of the small intestine. While pain in the left upper quadrant can indicate pain in the spleen, pancreas, stomach, or part of the large intestine. The non-region system uses four lines and to achieve this system we draw two parasagittal lines then two lines along the transverse planes.
The left and right superior regions are called the hypochondriac regions. They're named this because they're located right below the cartilage of the ribs. Hypo meaning below, chondro meaning cartilage.
The region between those two is called the epigastric region. This is the middle supra region located above the stomach. Epi meaning above, gast meaning stomach.
The left and right middle regions are called the right and left lumbar regions. They're located in the exact same region as the lumbar vertebrae. Between those two regions is the umbilical. region, which is located above the umbilicus.
The left and right and free regions are the right and left iliac regions. Between those two regions is the hypogastric region, which is located right below the stomach. Now this system, the niregion system, is more so used amongst anatomists, while the four quadrant system is more commonly used in the medical field. Serous membranes are thin continuous layers of tissue that fold over on itself to create an enclosed space. The cells inside of serous membranes will secrete serous fluid.
Serous fluid is a slippery, lubricating liquid for organs. This fluid prevents friction between our organs when they rub against one another. Serous fluid can be found around organs like the heart, lungs, and some abdominal organs.
Serous membranes have two layers. There is the visceral layer, which is the inner layer that contacts the organ itself, and then there's the parietal layer, which is the outer layer. The body has three main serous membranes, the pleural membrane, the pericardial membrane, and the peritoneal membrane. Pleural membranes can be found surrounding the lungs. Between the pleural membrane's parietal layer and visceral layer, you'll find the pericardial membranes.
Pericardial membranes surround the heart. The pericardial's parietal layer encircles the heart, while the visceral layer, or inner layer, attaches directly to the heart muscle itself. In between both of these layers, is the pericardial cavity.
The peritoneal membrane surrounds some of the abdominal organs. Now between the parietal and visceral layers of the peritoneal membranes, you'll find the peritoneal cavity, which is a fluid-filled space. So medical imaging provides us with an inside view of our patients using radiation, and different kinds of medical images will provide us with the view of different planes and different cavities of the body.
We have x-rays which provide us with a view of internal body structures using ionized radiation. And this picture here on the right is a chest x-ray which shows us the thoracic cavity. A computed tomography scan, also known as a CAT scan, provides imaging using ionized radiation as well.
And this CAT scan image here on the right shows us a transverse view of the abdominal, pelvic, and peritoneal cavities. A magnetic resonance image, also known as a MRI, will provide us with imaging using magnetic radiation, hence the magnetic inside of its name. Now, this MRI image on the right shows us a mid-sagittal view of the brain.
Now, in anatomy and physiology, there is one theme of the entire subject. Everything you're going to learn in this course from anatomy and physiology 1 to anatomy and physiology 2 is going to be wrapped up. into one theme and that is homeostasis. So homeostasis is the maintenance of the body's internal environment.
So if the body shifts from its normal state, physiological processes increase or reduce their activity to bring the body back to its normal state. So this can be anything from the body's temperature, blood pressure, or pH. For example, if you're too cold, the body will shiver to increase body heat. or if you're too hot the body will sweat to cool you down. Many variables of the body such as your temperature or your blood pressure have a set point and a way the body maintains the set point is through feedback loops.
These feedbacks lead to output where the output can be negative or positive. So when a change in the body's normal variable or set point is detected, actions are triggered to bring the body back to its normal state. However, There are two types of ways the body can do this.
The body can do this by decreasing the change in variable, which is the negative feedback loop, or by increasing the change in variable, which is the positive feedback loop. So both the positive and the negative feedback loops respond to change differently, but still will result in the body being brought back to its normal state. Negative feedback loops.
So let me break it down for you guys. When a change in variable is detected, and remember a variable can be anything from fluid in the body, temperature, pH, or blood pressure. So once a change in this variable is detected, a receptor will pick up this change. Secondly, the receptor will send the stimulus to the control center. The control center can either be the nervous system or the endocrine system.
Then the control center will send information to effectors. the effector will initiate physiological processes called a response to bring the body back to its normal state. Once the normal state is reached, the negative feedback loop will end.
Positive feedback loops are way less common than negative feedback loops. Now, positive feedback loops occur when something needs to. happen quickly. So an example of that can be found in childbirth. So we're going to use that as an example to break down how a positive feedback loop works.
So first the baby's head will touch the cervix and in this example this is going to be considered the change in variable also known as the stimuli. The data is then sent to the control center which in this case is going to be the brain. The brain will send signals to the uterus, which in this case, the uterus will be the effector. The uterus will then produce the oxytocin hormone, and this is a hormone that increases labor contractions during childbirth and controls vaginal bleeding after childbirth. The oxytocin hormone will then stimulate uterine contractions.
This is going to be your response. Contractions will then move the baby's head closer to the cervix, and contractions will cause more stretching of the cervix. And remember we said that a positive feedback loop will result in more of a product.
And in this example, the product is going to be the oxytocin hormone, which will lead to more contractions until the baby is born. So as you can see in the positive feedback loop, the body isn't trying to decrease the change in variable. It's reinforcing the change in variable.
However, this feedback loop will still lead to the body reaching its normal state after the baby is born. But the body can't give birth. birth to the newborn without increasing output, making this a positive feedback loop.
As I said earlier, structure dictates function is a common principle of anatomy and physiology. For example, the lungs have thin tissue, which is good because this allows gases to quickly cross. However, if the lung tissue were thick, gases would take a longer time to travel through the tissue, making it difficult to maintain homeostasis.
Gradients exist whenever there is one area that has more of something than the other. Things such as nutrient exchange, respiration, and formation of urine all are driven by gradients. There are different types of gradients. There's temperature gradients.
There's concentration gradients, which you probably remember from introductory biology. And then there's pressure gradients. And pressure gradients can either be hydrostatic or osmotic.
The cells of the body will communicate with one another through chemicals or through electricity to maintain homeostasis. Cells that are directly next to one another can use an electrical signal to communicate, whereas chemical messengers are more versatile. They can be used by cells directly next to one another or cells far away from one another.
For example, a nerve cell will stimulate a muscle cell by releasing chemical messengers into the space surrounding the muscle cells. then the chemical messengers will lead to a contraction in the muscle and this is an example of how cells communicate i'm so happy to finally get this video out to you guys because i've been trying to do it all week but i really wasn't feeling too good which is probably why i sound like two different people throughout the whole video but please don't forget to like this video please comment down below and tell me which topic of anatomy and physiology you are most excited to learn about this semester Please don't forget to share this video and subscribe to my channel. Also, feel free to send me video requests. Until next time.