Physiology, Sheet NO

Transcription

1 Our lecture today was more than easy, I ll try to mention everything the dr. talked about. What do we mean by physiology?? How organs work The functions of our systems Relations between these systems In general, it s the study of functions, the physics of the body. It s about understanding but it s not about memorization or a descriptive science We study the human body physiology at all levels : Subcellular,cellular, and organ system in health and sickness Whenever we add dys to any word it means not to work properly Dysfunction : when the function goes wrong. Physiology can give you the mechanism let you know how every part works then you can treat it as physician Again it s not about describing any part of the body (height, width, color, ) In the study that has been done in united state ( ) they asked the graduated medical students : which science has helped you a lot in diagnosing your patients?? 70% said physiology was the most important 20% said it was important And the stupid ones said less The category of medicine said it s physiology and organisms because we cant separate them e.g understanding how the brain works and how he respond to different functions, understanding how the lungs inflate and deflate, & understanding how the heart pump the blood. Sorry I couldn t understand the aim of these examples Here the dr. mentioned few tips for studying please refer to the slides if you want to read them. 1

2 The human brain is subdivided to three major levels: 1 - the brain stem : This is the first part to develop during brain growth(so it s the oldest part ) It s the most primitive, however; NO ORGANISM on the earth can live without it from reptile, lower animals,higher animals, cats,dogs,,to human beings What are the main functions of this part?? 1 ) Proper respiratory 2 ) Cardiovascular control (control of heart and vascular system ) * Rising or falling blood pressure may lead to death 3) Conscious level (tell you to wake up in the morning or to sleep when you are tired 4 ) Metabolism & digestion but the 1 st three points are the major functions Be careful : glandular functions are controlled by the hypothalamus NOT by the stem thinking,balance, & feeling are NOT controlled by the stem because animals have brain stem but they can t think The stem is divided to 3 parts : 1 ) midbrian 2 ) pons 3 ) medulla 2

3 Brain stem is the most dangerous part of the brain according to this, which trauma is the most dangerous from the front, the back,or from the lateral side?? From the back, in the movies the bad guy always shoots the good guy from the back side, why?? in order to cause injury to brain stem and this leads to stop the breathing, cardiovascular control, and make him unconscious so we can t live without this part. 2 - limbic system (limbic means al-7afeh) Also called emotional brain which is responsible about: 1 ) feeling (liking,disliking, hate,love,jealousy,.) 2 ) motivation : like what you motive you early in the morning to wake up and come to class 3 ) behavior :the way you present yourself in the society & what gives everybody his distinctive personality Do you expect this part to be bigger in male or female??? It s 13% bigger in female because females are prepared to be mothers & mothers have to raise their kids so they have to have a lot of patience & a lot of love 3 - cerebrum cortex the most sophisticated part of the brain that distinguishes us from other organism,so it s present only in human being & it s huge monkeys have very small cerebrum cortex but huge and highly sophisticated cortex is found in the human beings in the embryo brain stem is formed first then the emotional system & finally cerebrum cortex 3

4 what is the main functions of the cortex?? 1 ) thinking 2 ) memorization but be careful the memory is two parts,the first one in emotional brain because we memorize the happiest & the most painful situations in our lives The second part is found in cortex (the information are stored here ) 3 )formation of communication languages & the ability to talk which is the most important function 4 ) intelligence : people with less IQ,less sophisticated cerebrum cortex are unable to go to the school *fun is important for different levels of brain Quick revision : Brain stem The oldest part,the lowest part of the brain, the least sophisticated, can be found in all living organisms, & important for self preservation sometimes they call it R BRAIN or REPTILE BRAIN because reptiles have only brain stem & spinal cord The limbic system tells us to do what you love to do(e.g. watching movie) but the cortex tells you to do what you have to do (responsible for the logic) (e.g. studying) So this conflict between what you love to do & what you have to do could lead to anxiety,later on could cause insomnia and finally depression 4

5 Central nervous system is divided to : 1 ) somatic part (what we will talk about ) 2 ) autonomic part(we have already studied it) 3 ) enteric (we will study it in GI system ) Somatic nervous system : Soma means body You have always to feed your brain by information so he can give you the outputs or the results Input will be sensation and the output usually will be in the form of motor function What is the most important somatic sensations?? 1 the pain is the most important somatic sensation The inputs to the brain could be visual, auditory, olfactory (smelling) and tasting (special senses ) but somatic sensation means pain, temperature, touch,vibration proprioception 2 itch and tickle sensation 3 proprioception : feeling of part of the body and whole the body in the space, if you flex your arm you don t need to see wither your arm is flexed or extended even if you close your eyes you know that. Proprioception (feeling of every part in the body) is important for balancing so without it the person may fall and have head injury. Input has to be carried to the brain, then the brain interpret the input so the brain knows what happening in the external and internal environment and then sends answers or signals, and these sensations are transported to the brain by action potential through nerves. REMEMBER: We have very sophisticated nervous system and the action potential can t move in two directions 5

6 (A) is multipolar neuron (B) is unipolar neuron What are the differences in function NOT shape of these cells??? Both multipolar and unipolar produce multiple outputs but multipolar is motor(a) & unipolar is sensory(b). (B)The terminal ends of sensory neuron is found in the skin but the soma of sensory neuron is found in brain or spinal cord, it (sensory neuron) have receptors of pain sensation, temperature,. when the stimulus is enough they can create action potential so it can go all the way to the spinal cord then to the brain by passing the soma and the soma(cell body) has nothing to do with the generation of action potential so it has only a trophic function (feeding the nerve ) (A)the soma of motor neuron is found in the dorsal root ganglia remember that dorsal part of spinal cord is responsible for sensation, when the information reach this cell it will have the right to fire the action potential or not. The action potential here start from trigger zone (I m not sure about this) then the action potential will propagate to organs or muscles to contract or relax so the soma has to generate an action potential 6

7 What are the excitable tissues in our body??? 1 nervous tissue(neurons,axons,& dendrites) except supporting cells like ganglia cell, chondrocyte(i think it s wrong ) 2-muscles (smooth, cardiac, & skeletal ) What does excitable mean??? That when we apply two electrodes on that tissue it will contract if it s excitable so the liver is NOT excitable All the parts in your body have resting membrane potential but only the one s that can generate action potential is called excitable tissue Again the most important sensation is : 1 pain 2 itching & tickling 3 proprioception 4 the others The most important factors that determine the resting membrane potential is: 1 ) the membrane is more permeable to K + than to Na + that contributes -86% of the total resting membrane potential -90% because of the membrane is 100 times more permeable and having leakage channels to K + than to Na + NOT voltage -gated channel 2 ) inability of most anions to leave the cell this factor is applied only on nervous cells NOT nerves because proteins are found inside cells and make the inside more ve regarding to the outside 3 ) Na + /K + pump(electroginic nature of the Na + /K + ATPase) contributes only -4% of the R.M.P When you are setting for exam and your brain is firing millions of A.P, sodium ions stay outside the cell and potassium ions stay insidethe cell so Na + /K + pump will be very important 7

8 What is the difference between factor NO. 1 & 3?? NO. 1 is passive transport NO. 3 is active transport (ATP is needed) Our brain occupies 2% of our body and takes 20% of the energy in the body 70% of the brain s energy for Na + /K + ATPase When you are setting for exam always bring with you candies because the brain gets its nutrients from O 2 & GLUCOSE but not from amino acids & fatty acids. HOPE IT WAS HELPFUL, YOUR COLLEAGUE : SALMA JARRAR 8