ITM 101 Physiology - Introduction to Physiology PDF

ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL ❖ The science of human physiology attempts to explain the Origin of Nutrients in the Extracellular Fluid specific characteristics and mechanisms of...

ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL ❖ The science of human physiology attempts to explain the Origin of Nutrients in the Extracellular Fluid specific characteristics and mechanisms of the human body that make it a living being. It links the basic sciences with medicine The Respiratory System provides oxygen for the body and and integrates multiple functions of the cells, tissues, and organs removes carbon dioxide. into the functions of the living human being. o The blood picks up oxygen in alveoli, thus acquiring the oxygen needed by cells. Cells are living units of the Body o The alveolar membrane is only 0.4 to 2.0 micrometers thick, and oxygen rapidly diffuses by molecular motion Cells are the basic living unit of the body. Tissues and organs through this membrane into the blood. are made up of different cells supported by intracellular The Gastrointestinal Tract digests foods and facilitates structures. absorption of nutrients. o The entire body of a single person is composed of 35 o It dissolves nutrients, including car- bohydrates, fatty to 40 trillion human cells, of which the red blood cells acids, and amino acids, that are absorbed from constitute over 25 trillion. ingested food into the extracellular fluid of the blood. Liver metabolizes nutrients changing chemical compositions of Each cell possesses basic characteristics absorbed substances to more useful forms. It also eliminates o For the cell to produce energy in the form of certain waste products produced in the body and toxic Adenosine triphosphate, oxygen reacts with simplest substances that are ingested. structures of fat, carbohydrates, and proteins. Cells The Musculoskeletal System includes the muscles and bones, also reproduce and regenerate on their own to tendons, cartilages, and filaments. It is used to obtain food for maintain the needed amount in the body. These cells nutrition and provides motility for protection. are suspended in the extracellular fluid (internal environment), in which its constituents are controlled. Removal of Metabolic End Products Mechanism of Homeostasis— Maintenance of Nearly Constant Internal Lungs help excrete carbon dioxide from the blood, releasing it to Environment the lung alveoli. breathing out carries carbon dioxide into the atmosphere. Carbon dioxide is the most abundant of all the Homeostasis is the maintenance of nearly constant conditions in metabolism products. the internal environment. All tissues and organs essentially work Kidneys help regulate blood volume and blood pressure. One of together to achieve a common goal, to maintain a relatively its main functions is to excrete waste products, slats, water, urea constant environment. and uric acid, and excess of ions to regulate the Extracellular The various ions, nutrients, waste products, and other fluid composition. constituents of the body are normally regulated within a range Liver performs a distinct function in detoxification, the removal of values, rather than at fixed values. Some ranges may have of ingested drugs and chemicals. The end waste products are narrow indexes and slight variations may cause fatal outcomes primarily eliminated in the feces. such as sickness or worse, death. Regulation of Body Functions EXTRACELLULAR FLUID TRANSPORT AND MIXING SYSTEM—THE BLOOD CIRCULATORY SYSTEM The Nervous System is composed of three major parts, sensory input, central nervous system (integrative portion), and motor Extracellular fluid is output. It directs the activity of the muscular system and transported through the body in two controls function of many internal organs. stages. The first stage is movement of ○ Sensory receptors detect the state of the body and its blood through the body in the blood surroundings. vessels. The second stage is movement ○ The central nervous system is composed of the brain of fluid between the blood capillaries and spinal cord. and the intercellular spaces between ○ The motor output basically carries out one’s desire. the tissue cells. The Hormones System controls many metabolic functions of All the blood in the cells, including growth, rate of metabolism, and activities circulation traverses the entire circuit associated with reproduction. It is being secreted by the an average of once each minute when endocrine glands. the body is at rest and as many as six ○ Thyroid hormone increases the rates of most chemical times each minute when a person is reactions in all cells, thus helping set the tempo of extremely active. The capillary walls bodily activity. Insulin con- trols glucose metabolism, are permeable to most molecules in adrenocortical hormones con- trol sodium and the blood plasma, with the exception potassium ions and protein metabolism, and of plasma proteins, which are too large parathyroid hormone controls bone calcium and to pass through capillaries readily. phosphate. There is a continuous exchange of substances between the Protection of the Body cells and the interstitial fluid and between the interstitial fluid and the The Immune System provides protection with a certain defense blood. mechanism. It includes white blood cells, tissue cells derived 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 1 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL from white blood cells, the thymus, lymph nodes, and lymph Some Important Constituents and Physical Characteristics of the vessels that protects the body from foreign invaders. Extracellular Fluid, Normal Range of Control, and Approximate ○ The immune system distinguishes its own cells from Nonlethal Limits for Short Periods harmful foreign cells and substances; and destroys the Any changes in the levels of these parameters can potentially invader by phagocytosis or by producing sensi- tized identify disease in the early stages. Diseases are basically lymphocytes or specialized proteins like antibodies alteration of the normal homeostatic mechanisms, until it that destroy or neutralize the invader. produces a visible clinical manifestation. The Integumentary System provides protection against injury and foreign invaders. Characteristics of Control Systems ○ The skin skin generally comprises about 12% to 15% of body weight. It includes hair, nails, glands, and other Most control systems of the body operate by negative feedback. structures. It covers , cushions , and protects the o The degree of effectiveness with which a control deeper tissues and organs of the body and generally system maintains constant conditions is provides a bound- ary between the body’s internal determined by the gain of the negative feedback. environment and the out- side world. o Any stimulus is counteracted by a response that is ○ The integumentary system is also important for going to cause negativity to the initial stimulus. temperature regulation and excretion of wastes, and it provides a sensory interface between the body and the external environment. Reproduction The Reproductive System provides formation of new beings like ourselves, hence it may sometimes not be considered a homeostatic function, it helps maintain homeostasis holistically. ○ Producing new beings translates to generating new bodies in which trillions of additional cells can exist in a well-regulated internal environment. ○ Essentially all body structures are organized to help maintain the automaticity and continuity of life · Feed-forward control systems anticipate changes.. o The brain uses feed-forward control to cause the required muscle contraptions. o Sensory nerve signals from the moving parts inform the brain, in retrospect, of whether the inappropriate movement envisaged by the brain has been performed correctly. o The brain corrects the feed-forward signal, it sends to the muscle the next time the movement is going to be required. This process is called adaptive control, which is in a sense more or less a delayed negative feedback control. · Positive feedback can sometimes cause vicious cycles and death, and other times it can be useful. o A system in our body that exhibits the positive feedback response to what we call perturbation with changes that amplify the perturbation and therefore leads to instability rather than stability. Automaticity of the Body · Each functional structure, or organ, helps maintain a constant internal environment. · As long as homeostasis is maintained, the cells of the body continue to live and function properly. 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 2 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL · Each cell benefits from homeostasis and in turn, each cell CELL (PHYSICAL) STRUCTURE contributes its share toward maintenance of homeostasis. This is actually a reciprocal interplay that provides Cell contains highly organized physical structures “intracellular continuous automaticity of the body. organelles” — represent physical structures of chemical · Each cell contributes its share toward maintenance of aggregates that perform functions in a more efficient manner homeostasis. than what can be achieved by dispersed chemicals throughout the fluid matrix. · Extreme dysfunction leads to death, whereas moderate dysfunction leads to sickness. Most organelles of the cell are covered by membranes composed primarily of lipids & proteins ○ Cell membrane Organization of the Cell ○ Nuclear Membrane Reconstruction of a typical cell, showing the internal ○ Membrane of ER organelles in the cytoplasm and nucleus. ○ Membranes of mitochondria, lysosomes, and Golgi Apparatus The Protoplasm Lipids in the membranes provide a barrier that impedes movement of water & water soluble substances from one cell The protoplasm compartment to another identifies the substances that Proteins in membranes often provide specialized pathways make up the cell and these are the “pores” for passage of specific substances through membranes following. ○ Also as enzymes which catalyze a multitude of · Water constitutes 70 percent to different chemical reactions 85 percent of most cells. · Ions/electrolytes (K+, Mg+2, PO4-3, SO4-2, HCO3-, and small CELL/ PLASMA MEMBRANE quantities of Nat, Cl-, and Ca+2). 55% proteins, 25% phospholipids, 13% cholesterol, 4% other o The ions in electrolytes provide the inorganic lipids, and 3% carbohydrates chemicals for cellular reactions. Basic structure — lipid bilayer with interspersed large globular · Proteins (10-20%): structural proteins and globular (functional) proteins proteins, which are mainly enzymes). o Proteins can be identified as either structural protein globular functional protein. Take note, structural proteins, such as collagen, helps in the structure and formation of the body. In globular are often enzymes. · Lipids (2%): phospholipids, cholesterol, triglycerides, and neutral fats. o They are often seen also in the cell membrane. o Fat cells has about triglycerides to up to 95% of the cell mass. They are representatives of cells that can be energy storehouses. · Carbohydrates (1% of total cell mass, 3% in muscles, 6% in liver): glycogen o The small amount of carbohydrates in the cells is usually stored in the form of glycogen, this is an insoluble polymer of glucose. 3 main types of membrane lipids “glycolipids” eatnorwor ○ Phospholipids - most abundant, has 2 sides Outer - (fatty acid portion) hydrophobic and Physical Structure of the Cell soluble only in fats (e.g. O2, CO2, alcohol); Cell and Its Organelles are Surrounded by Membranes faces each other Composed of Lipids and Proteins that: Inner - (phosphate end) hydrophilic and Surround the cell and its organelles. Some of the soluble in water (e.g. ions, glucose, urea); principal organelles of the cell are your cell faces interstitial fluid & cell cytoplasm membrane, the nuclear membrane, the endoplasmic ○ Sphingolipids - derived from the amino alcohol reticulum, the Golgi apparatus, the mitochondria, sphingosine, functions to protect from harmful lysosomes, and centrioles. factors, signal transmission, and adhesion sites for Prevent free movement of water and water-soluble extracellular proteins substances from one cell compartment to another. ○ Cholesterol - help determine the degree of Proteins provide pathways (channels) to allow permeability of the bilayer to water- soluble movement of specific substances through the constituents of body fluids. Also controls much of the membranes. Many functions of the cell are to control fluidity of the membrane as well. the trafficking of chemicals and substances, which is Membrane proteins “glycoproteins” why there is an abundance of cell membranes. ○ Integral proteins - protrude all the way through the membrane. 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 3 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL Provide structural channels “pores” that ○ Uses hydrolytic enzymes to splits organic compounds allow preferential diffusion of some into two or more parts by combining hydrogen from a substances over others. water molecule with one part of the compound and Carrier proteins for transporting substances combining the hydroxyl portion of the water molecule that otherwise could not penetrate the lipid with the other part of the compound — to become bilayer (e.g. through active transport) highly diffisuble (e.g. protein hydrolyzed to form Receptors/ second messengers relaying the amino acids) signal from the extracellular part of the Peroxisomes receptor to the inte- rior of the cell. ○ Formed by self-replication (or perhaps by budding off ○ Peripheral proteins - attached only to one surface and from the smooth SR) do not penetrate all the way through; function almost ○ Contain oxidases — combining oxygen with hydrogen entirely as enzymes or as controllers of transport of ions derived from different intracellular chemicals to substances through cell membrane pores. form hydrogen peroxide (H2O2) — which is a highly Membrane carbohydrates “glycocalyx” - loose carbohydrate oxidizing substance and is used in association with (proteoglycans) coat on the outside of the entire surface of the catalase — to oxidize/ catabolize many substances cell that might otherwise be poisonous to the cell ○ overall negative surface charge that repels other Secretory Vesicles negatively charged objects ○ formed by the ER — which pinch off to be Golgi ○ attaching cells to one another through glycocalyx apparatus — Golgi apparatus releases into the ○ act as receptors for binding hormones cytoplasm in the form of storage vesicles named ○ Some moieties enter into immune reactions “secretory vesicles/secretory granules” CYTOPLASM ○ store protein proenzymes (enzymes that are not yet Cytosol - jelly like fluid portion of the cytoplasm and contains activated) — secreted later through the outer cell mainly dissolved proteins, electrolytes, and glucose membrane into the pancreatic duct and then into the Dispersed in the cytoplasm are neutral fat globules, glycogen duodenum, where they become activated and granules, ribosomes, secretory vesicles, and five especially perform digestive functions on the food in the important organelles: intestinal tract ○ Endoplasmic reticulum (ER) ○ Golgi apparatus ○ Mitochondria ○ Lysosomes ○ Peroxisomes Endoplasmic Reticulum ○ a network of tubular structures (cisternae) and flat vesicular structures in the cytoplasm ○ Manufacture: proteins, carbohydrates, lipids ○ helps process molecules made by the cell and transports them to their specific destinations 1. Rough (Granular) ER + Ribosomes - Attached with minute granular particles “ribosomes — composed of a mixture of RNA and proteins; they function to synthesize new protein molecules in the cell 2. Smooth (Granular) ER - functions for the synthesis of lipid Mitochondria substances and for other processes of the ○ Powerhouse; self-replicative cells promoted by intrareticular enzymes ○ Mainly for chemical reaction of O2 with 3 types of Golgi Apparatus foods: glucose (carbo), fatty acid (fats), amino acids ○ composed of four or more stacked layers of thin, flat, (proteins) enclosed vesicles lying near one side of the nucleus ○ 2 Lipid Bilayer protein membranes ○ Function in association with ER — small transport Outer membrane vesicles/ ER vesicles continually pinch off from the ER Inner membrane and shortly thereafter fuse with the Golgi apparatus Cristae - infoldings of the inner —> transported substances from ER are processed in membrane form shelves or tubules the Golgi apparatus to form lysosomes, secretory which oxidative enzymes are vesicles, and other cytoplasmic components attached; Lysosomes the inner cavity of the ○ vesicular organelles that form by breaking off from the mitochondrion is filled with a Golgi apparatus that provide an intracellular digestive matrix that contains large system to digest the following: quantities of dissolved enzymes damaged celllar structures; necessary for extracting energy food particles ingested by the cell; from nutrients unwanted matter such (e.g. bacteria) ○ Citric Acid Cycle: synthesizes a high-energy substance called adenosine triphosphate (ATP) — which is then 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 4 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL transported out of the mitochondrion and diffuses FUNCTIONAL SYSTEMS OF THE CELL throughout the cell to release its own energy — end products are H2O & CO2 ENDOCYTOSIS — Ingestion by the Cell Diffusion - involves simple movement through the membrane caused by the random motion of the molecules of the substance. - Substances move through cell membrane pores or, in the case of lipid-soluble substances, through the lipid matrix of the membrane. Active transport - involves actually carrying a substance through the membrane by a physical protein structure that penetrates all the way through the membrane Specialized function of the cell membrane that allows large particles enter the cell A. Pinocytosis - ingestion of small globules of extracellular fluid, forming minute vesicles in the cell cytoplasm - only means whereby most large macromolecules, such as most proteins, can Cell Cytoskeleton — Filament & Tubular Structures enter cells; process also requires the ○ Rigid and have large numbers of filamentous or presence of calcium ions in the extracellular tubular structures, which are composed of fibrillar fluid proteins synthesized by ribosomes in the cytoplasm - Uses specialized protein receptors on the ○ Intermediate filaments small pits (coated pits) on the outer surface strong ropelike filaments that often work of the cell of the membrane, that are together with microtubules, providing specific for the type of protein that is to be strength and support for the fragile tubulin absorbed structures - On the inside of the cell membrane beneath Types: desmin filaments in muscle cells, these pits is a latticework of fibrillar protein neurofilaments in neurons, and keratins in called clathrin — which invaginates inward, epithelial cells and fibrillar proteins surrounding the ○ Microtubules invaginating pit cause its borders to close special type of stiff filament composed of over the attached proteins, as well as over a polymerized tubulin molecules used in all small amount of extracellular fluid cells to construct strong tubular structures - invaginated portion of the membrane breaks Makes up the centrioles & mitotic spindles away from the surface of the cell, forming a participate in cell division, allows cells to pinocytotic vesicle inside the cytoplasm of move, and provides a tracklike system that the cell directs the movement of organelles in the cells Nucleus ○ Control center — sends messages to the cell to grow and mature, replicate, or die ○ Contains large quantities of DNA which comprise genes — determine the characteristics of the cell’s proteins, intracellular enzymes and nuclear activities; also control and promote cell reproduction (mitosis) Nuclear membrane/ Nuclear envelope two separate bilayer membranes, separates the nucleus from the cytoplasm Penetrated with several thousand nuclear pores B. Phagocytosis - ingestion of large particles, such as Nucleoli bacteria, whole cells, or portions of degenerating simply an accumulation of large tissue. amounts of RNA and proteins of - Only certain cells have the capability of the types found in ribosomes; not phagocytosis—notably, tissue macrophages surrounded by a membrane and some white blood cells. RNA is used in conjunction with - initiated when a particle such as a specific proteins to assemble bacterium, dead cell, or tissue debris binds “mature” ribosomes that play an with receptors on the surface of the essential role in forming proteins phagocyte. - In the case of bacteria, each bacterium is usually already 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 5 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL attached to a specific antibody which attaches to the phagocyte receptors — dragging the bacterium along with it. - This intermediation of antibodies is called opsonization - Phagocytosis occurs in the following steps: 1. The cell membrane receptors attach to the surface ligands of the particle. 2. The edges of the membrane around the points of attachment evaginates outward to surround the entire particle; then, progressively more and more membrane receptors attach to the particle ligands. All this occurs suddenly in a zipper-like manner ○ to form a closed phagocytic vesicle. 3. Actin and other contractile fibrils in the SYNTHESIS OF CELLULAR STRUCTURES BY ER AND GOLGI cytoplasm surround the phagocytic vesicle APPARATUS and contract around its outer edge, pushing The structures of the cell are synthesized by the ER and Golgi Apparatus. the vesicle to the interior Many of the products of ER, which are proteins, are further processed in 4. The contractile proteins then pinch the stem the cytoplasm. of the vesicle so completely that the vesicle separates from the cell membrane, leaving Granular ER - responsible for Cytoprotein formation. The the vesicle in the cell interior in the same ribosomes synthesize the protein and exclude them to the wall way that pinocytotic vesicles are formed. of the ER to Endoplasmic vesicles and tubules, which is now an Endoplasmic Matrix. When proteins enter the ER, the enzymes in the ER will cause rapid changes including the congregation of carbohydrates to form glycoproteins. In addition, the proteins are often cross-linked, folded and shortened to form compact molecules. The endoplasmic reticulum also synthesizes lipids. Small ER vesicles (transport vesicles) continually break from the smooth endoplasmic reticulum. Most of these vesicles migrate to golgi apparatus. The golgi apparatus processes the substances formed in the ER (there is post-processing). The golgi apparatus performs the compaction and processing of the products of the endoplasmic reticulum, and small and large vesicles would break out from the golgi apparatus and carry them to secretory substances. So the transport instantly fuse with the golgi apparatus. Lysosomes - digests the Pinocytic and Phagocytic foreign substances in the cell. These are produced by the Endoplasmic Reticulum, and often globular and enzymatic in function. As soon as Pinocytic or Phagocytic vesicles are formed, Lysosomes are attached to vesicles and empty the Digestive Enzymes. This is now referred to as the Digestive Vesicle, and they have hydrolyzing properties. It will destroy proteins, carbohydrates, lipids, and other substances in the vesicle. The products of digestion are often small molecules. Proteins EXTRACTION OF ENERGY FROM NUTRIENTS BY THE end up being Carbohydrate, Carbohydrates end up being MITOCHONDRIA Glucose. This can diffuse from the membrane of the vesicle and Almost all systems in the body are dependent on the mitochondrion go to the cytoplasm. because the carbohydrates are going to be converted to glucose by the digestive tract, and they will reach the liver before they reach the cell. Any undigested substances are left behind in the form of residual body that is excreted through the cell membrane by a reverse endocytosis (exocytosis), which is basically the opposite of endocytosis. 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 6 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL The principal substances from which cells extract energy are: Acetyl-CoA as a compound is formed in the mitochondrial 1. Oxygen matrix. Now this substance is then acted on by another enzyme 2. Carbohydrates, fats, and amino acids, which react with or series of enzymes in the process called citric acid cycle. oxygen. Almost all of the carbohydrates are converted to glucose by the digestive tract and liver before they reach the cell. Proteins are converted to amino acids and fats to fatty acids, but inside the cell, these substances react chemically with oxygen under the influence of enzymes that control the rate of reaction and channel the released energy in the proper direction. This process, the oxygen reactions, occurs inside the mitochondria and energy released is used in the form of Adenosine Triphosphate (ATP). In the Citric Acid Cycle, Acetyl-CoA are split into hydrogen ions and carbon dioxide. The hydrogen ions are highly reactive and eventually combine with oxygen that has diffused into the mitochondria. This reaction releases a tremendous amount of energy that is used to convert large amounts of ADP to ATP. This requires large numbers of protein enzymes that are actually part of the mitochondria. The initial event in ATP formation is the removal of the electrons, the hydrogen atom, thereby converting it to hydrogen ion. The terminal event of the hydrogen ion is moving through large globular proteins called ATP synthetase, which protrudes to the membranes of the mitochondria, which presents in the The ATP or the adenosine triphosphate is a nucleotide mitochondrial matrix. composed of nitrogenous base adenine, the pentose sugar ribose, and three phosphate radicals. The last 2 phosphate The enzyme ATP synthetase uses the energy and movement of radicals are connected with the remainder through high energy the hydrogen ions to effect the conversion of ADP to ATP, and phosphate bonds. These bonds contain 12,000 calories of hydrogen ions combined with oxygen to form the by-product energy per molecule of ATP under usual conditions the high water. energy phosphate bonds are labile so they can be split instantly whenever energy is required. The newly formed ATP is transported out of the mitochondrion to all parts of the cell, where it synergizes the function of the When ATP releases its energy, a phosphoric acid radical is spit cell. This is called Chemosmotic mechanism of ATP formation. away, and adenosine diphosphate is going to be form the energy that is derived from cell nutrients calls the ATP and phosphoric acid to combine to form new ATP, which, in this case the entire process actually continues over and over again for the body. So most of the ATP produced in the cell is through mitochondria. After entering the cell, the glucose is subjected to glycolysis to form by pyruvic acid. Less than 5% of the ATP forming the cell occurs actually via glycolysis because there are other forms of ATP production, particularly in fat. Pyruvic acid as a product of glycolysis also comes from the degradation of carbohydrates, fatty acids, and amino acids, which are eventually all converted to Acetyl-CoA. 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 7 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL ATP IS USED FOR MANY CELLULAR FUNCTIONS SATP is mainly used in many cellular processes such as: 1. membrane transport as it occurs in the sodium potassium pump which transports sodium out of the cell and potassium into the cell 2. the synthesis of chemical compounds throughout the cell; 3. mechanical work, as occurs with the contraction of muscle fibers or with ciliary and ameboid motion. LOCOMOTION AND CILIARY MOVEMENTS OF CELLS There are specialized mechanisms like locomotion and ciliary movement. The most obvious type here is basically the skeletal muscle, cardiac muscle, smooth muscle, which constitutes about 50% of the body. Two other movements occur in other cells such as Ameboid locomotion and ciliary movement, which can be seen in some of the epithelia of our lining epithelium of the body. 1. AMEBOID MOVEMENT The Amoeboid movement is typically seen in white blood cells. This amoeboid movement is related to the surroundings. An example of amoeboid movement is the movement of white blood cells through tissues. Typically, amoeboid motion begins with the protrusion of pseudopodium from one end of the cell. This results in a continuous exocytosis, which informs a new cell membrane at the leading edge of the pseudopodium and continual endocytosis of the membrane in the rear portions of the cell. The white blood cells reacts to the substances produced by other tissues Questions and Answers Q: Is it worse for secondhand smokers? Cigarette smoke is irritating to the respiratory system because it contains numerous chemicals such as formaldehyde (formalin) and carbon monoxide which are damaging to the respiratory epithelium. That’s why they say that second-hand smoking is also dangerous since the combustion of the cigarette along with the smoke contains these hazardous materials. Q: Can ciliary movement be restored after the individual has stopped smoking? Up to a certain point. When you irritate an epithelium or lining cell of the body such as the respiratory epithelium, it gets replaced by another type of cell. Ordinarily, the upper respiratory system is lined by pseudostratified columnar epithelium. If it is irritated, it gets replaced by 2. CILIARY MOVEMENT squamous epithelium which is more resistant to irritation. This is the A whip-like movement of the cilia on the surface of reason why the skin is made up of squamous epithelium. That’s why one the cells. It occurs in two places of the body: of the common cancers of the lungs is squamous cell carcinoma. This a. The respiratory airways process is called metaplasia. One type of cell is replaced by another. - In the nasal cavity and the lower respiratory airways, the movement of cilia Q: Could positive feedback and negative feedback occur simultaneously? causes a layer of the mucus towards the Or is negative feedback always prioritized? pharynx at the rate of 1 cm per minute. This Both occur simultaneously. One example of negative feedback is way the passages with mucus or particles when a woman is pregnant, she does not ovulate. Before pregnancy, that become entrapped on a mucus are ovulation occurs. During the process of ovulation, the body is subject to continuously cleared. hormones such as estrogen and progesterone. Two other hormones in the b. The uterine tubes of the female brain include the follicle stimulating hormone and luteinizing hormone. - movement of egg cell from the ovary Luteinizing hormone increases so ovulation occurs. In that process, it is reaches its destination in the uterus. sequential. Producing egg cells is positive feedback while pregnancy is 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 8 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL negative feedback since ovulation stops. This can also happen in the thyroid gland. Positive feedback is needed to produce thyroid hormone. To prevent it from getting out of control, you also need negative feedback. Q: What about people who vape? Is the effect similar to their cilia? It actually could be worse than smoking because there are also chemicals in that which should not be inhaled. The chemical making it smell pleasant is fat-based which can be deposited in the lungs. Vaping still irritates the lungs due to combustion. Q: Regarding the executive check-up, is it required for those aged 40+ and is there any program for a free/discounted check-up? Executive check-up is not covered by “usual healthcare”. It is not necessarily diagnostic but it is preventive. That is why it is expensive. Wellness programs of the gov’t can be a crude way of knowing if someone has an illness but for executive check-ups, there is no program. Executive check-ups can reveal hidden illnesses that are not yet felt. This is a good thing but not everyone can afford it. With our current technology, we can know through genetic testing which diseases we are likely to develop. Q: Is there any other function of the cilia in the uterus aside from guiding the egg to the uterus? The egg must be guided to the uterus or else it goes to the abdomen. This in itself is a major function. This is its main function. Q: Does the tail of a sperm count as a form of cilia? No, the tail of a sperm is a flagellum. Flagella are used for movement of the cell itself while cilia are used for movement of particles. They have different structures and microtubular components. Q: Is the cilia hair? Something to note is that ciliated cells in the ear are called hair cells. But they are not hair. Q: Mechanism for water intoxication? It can happen but that is a topic for another day. The simplest explanation is that the body maintains water and electrolytes. If you take in too much water, it will mess up the normal concentrations which is dangerous. You can even get too much oxygen. Electrolytes are very important. 101 INTRODUCTION TO MEDICINE | PHYSIOLOGY AYURA 2027 9 ITM 101 | PHYSIOLOGY LESSON # 1 - Introduction to Physiology 1st YEAR | A.Y. 2023-2024 | AUGUST 11, 2023 DR. SAGUIL