Raghad El-massri. Omar Fahed. Mohammad Khatatbeh

Transcription

1 1 Raghad El-massri Omar Fahed Mohammad Khatatbeh

2 introductory lecture The first slide contains the syllabus of Dr.Khatatbah's material - We have different type of cells in our body so a group of cells forms a tissue group of Tissues forms an organ group of organs forms a system The hole systems of the body forms an organism. -There are systems(such as : Nervous and endocrine systems) that control and regulates the activity the other systems of the body. -all our cells are suspended in the solution of the body, which is called the extracellular fluid and it's also called the internal environment -The properties of internal environment: Certain concentrations of oxygen, nutrients, ions, PH, certain temperature and a certain amount of water -this internal environment is having everything almost constant within available range that is important to keep cells in one condition which is optimal for the survival of these cells. So any change in that environment may change the activity of the cell, actually, if there is a big change it may to lead to cell death. therefore at any time there is any change of any constituent around these cells, this process is sensed by sensors. We have a lot of sensors that sense the change of temperature, solution concentration and so on. So the sensor will send a command towards a control system to return back the normal situation of the internal environment, that s homeostasis. -so the homeostasis is a situation of constant conditions of the internal environment of the body. -how can we develop a disease in this case? if the whole body failed to regulate these conditions then a disease will appear, so the body is trying to maintain the best conditions for survival. 1 P a g e

3 For example: in Diabetic patients, they have a problem in the system that regulates the amounts of the glucose in the extracellular matrix so we have a disturbance in the internal environment of the body another example: when we have a disease in the lung or the heart or whatever resulting in decreased oxygen concentration, the body system tries to force other systems to function well to regulate oxygen concentration but because of that big disease at the level of the lung it is very hard to regulate the amount of oxygen in the external or internal environment resulting in a disease -everything in your body is regulated, even temperature and PH. Any change in PH or temperature will affect the reactions which need optimal PH and temperature to occur, that will affect the function also. -The importance to regulate blood pressure It is important for the movement of the blood. -you don t have to memorize all slide number 6 -What is physiology in general? it is the study of the functions that we are having in our body.how these functions are taking place? how we are regulating this functions? and so on We have a lot of examples in this introductory course we will regard to regulatory processes (you not expected to know the details of this regulatory processes but to understand the principle that we are having in our body) Feedback mechanisms: 1-Negative feedback in this mechanism, we start with a condition -either increase or decrease- and the final effect is the reversal of the initial condition, because of that it is called "negative feedback mechanism". Variable response effectors (the sequence to change the initial condition) -Examples of negative feedback: 2 P a g e

4 a- If there was a decrease in the blood pressure (blood pressure is important for the movement of blood from one part of the body to other part) it will be sensed then a command will be sent to the regulatory centers-mainly in brain -, these centers send stimulations to some organs like heart- finally the blood pressure returns back normal (increases). b-when we have a decrease of calcium concentrations, it will be sensed, so that results in a release of hormones from parathyroid gland, that parathyroid hormones act on bones to release calcium. in addition, these hormones act on the kidney then activating vitamin D that will affects the intestine to get more absorption of calcium,so we are increasing back calcium concentrations to normal. c-any increase of glucose level is sensed by some cells in pancreas, resulting in increase of insulin,that insulin moves glucose from internal environment to inside the cells and by removing that glucose toward inside the cell we are reducing glucose concentrations d- on the other hand, when we have a decreased levels of glucose, it will increase glucagon hormone, that moves glucose from tissues toward the interstitial fluid back. e-when the body temperature is increased, the body starts to lose temperature by sweating, so the temperature will return back to its normal condition. 2-Positive feedback mechanism: it is the opposite mechanism of negative feedback, so if we start with an increase of any condition, the final effect is even more increase. Ex: during delivery process of a newborn, there is contraction of the uterus that results in releasing of "oxytocin" hormone that causes more contraction in uterus until getting delivery. Once the delivery is finished, everything will return back at normal condition. The cell structure and function: (study it from handout better than record) We have many organelles inside the cell, like nucleus which contains the genetic material, endoplasmic reticulum (ER), Golgi apparatus, mitochondria..etc -Many of these organelles are membranous structures(that has its own membrane) such as mitochondria, nucleus, lysosomes, peroxisomes, Golgi apparatus and endoplasmic reticulum. 3 P a g e

5 -The function of plasma membrane of the cell is to separate ICF and ECF, but the organelles' membranes separate these organelles from the cytosol so the composition of these organelles differ from cytosol. The proteins that have been synthesized in the endoplasmic reticulum, are transported toward the Golgi apparatus by vesicles - vesicles firstly are budding from the ER, then they will fuse with Golgi apparatus which modifies the proteins that came in these vesicles, and finally resend these proteins in a new vesicles to their final destination. Are we having the same proteins in the different sides of the cell? No, We can have different types of protein at different locations in our body mainly at polar cells ( for example we have different proteins at different sides of the plasma membrane that will lead to different functions) How we can transport a specific protein from the Golgi to a certain part not to the other parts? so the the job of Golgi complex is to sort proteins that have to go to their final destination, they are collected together in one vesicle then are sent to certain part of the cell. -The main function of Golgi sorting proteins according to their sequences. Actually, one part of the protein's sequence is called "address" that is read by Golgi then sending them to their final destination. -Ribosomes on the ER : read the MRNA and translate it into a protein. -Lysosomes : have enzymes for degredation. -Peroxisome's function : is detoxification. 4 P a g e

6 Mitochondria have two membranes: outer and inner membranes. these two membranes line different compartments so the intermembranous space for example- has different ion concentrations than the mitochondrial matrix.the main function of mitochondria is the synthesis of ATP molecules by oxidative phophorylation process. We have greater concentration of protons (H+) in the intermembranous space than its concentration in the matrix, that's why protons have a high tendency to move towards the matrix but the inner membrane doesn t permit its movement. We have a protein that is called "ATP synthase" that permits the movement of H+ to the inside of the mitochondrial matrix, every 4 molecules of H+ moving through "ATP synthase" we will have 1 new ATP molecule synthesized. Then the H+ molecules that have entered the matrix will return back to intermembranous space through the complexes of electron transport chain. We need a very high energy to let protons to move. 5 P a g e

7 The cytoskeleton of the cell contains : microfilaments, microtubules and intermediate filaments - The main function of microtubules is support and movement. microtubules act as highways inside the cell and vesicles bind these microtubules through motor proteins. 1 -flagella is composed of microtubules, between these microtubules we have motor proteins that - by changing their positions - can result in the movement of this flagella. 2- as we mentioned above, vesicles move inside the cell by the movement of motor proteins on microtubules. Watch this video: 3-in Neural cell, we have cell body, long axons and terminals. inside these terminals we have neurotransmitters that are synthesized in the cell body then we need to transport these neurotransmitters toward the terminus via microtubules.we are packing this neurotransmitters in vesicles and transport these vesicles along microtubules to their final destination. 4- during division, cells are forming mitotic spindle - which are microtubules- separating chromosomes into two chromatids. In addition, we have actin filaments which are another component of the cytoskeleton some cells have amoeboid movement which is achieved by forming pseudopods, these pseudopods are composed of actin filaments 6 P a g e

8 -also for muscle contraction, we have actin filaments According to these cytoskeleton components we have different geometry of the cells (not all of them are rounded in shape) Ex: 1) Red blood cells are disc shaped,to give us high surface area that is responsible for the least possible volume. Remember that these RBCs move in blood vessels that are narrow in general. 2) Neural cells have long axons, which are needed to the transmission of signals to reach the distant areas of the body. 3) Absorptive cells we have many folds to increase the surface area in order to get more absorption. 4) Muscle cells are elongated in order to contract perfectly. 7 P a g e