Human Physiology - The Human Cell PDF

HUMAN PHYSIOLOGY The human cell Physiology Department Helwan University 1 2  The human body’s ability to maintain a relatively constant internal temperature is an example of what?  A. Respiratory heat loss  B. Homeostasis  C. Positive feed...

HUMAN PHYSIOLOGY The human cell Physiology Department Helwan University 1 2  The human body’s ability to maintain a relatively constant internal temperature is an example of what?  A. Respiratory heat loss  B. Homeostasis  C. Positive feedback 3  Choose one answer below that completes the sentence so that it makes a true statement. Positive feedback: A. is the way the body maintains homeostasis B. B. is a response that opposes a stimulus C. C. is a response that enhances a stimulus 4  In homeostasis, what is it that produces the response that moves the physiological variable back towards the middle of its healthy range?  A. the effector  B. the receptor  C. the integrating centre 5  How to establish homeostasis ? (Single best answer) A. a controller detects changes outside and inside the body B. a receptor responds to signal from the centre to correct the error. C. an effector receives the signal information from the sensors about the change D. an integrating centre compares the sensor's input and the set point 6 Lets start 7 8 Objectives  Define commonly used terms in the field of cell biology.  Describe organization of human body  List characteristics of life.  Describe cell structure, function with special emphasis on cell membrane.  Define lipid and membrane proteins and its contribution to cell function.  Define mechanisms involved in cell signaling. 9 Cell  Cell/plasma membrane  Cytosol  Nucleus (contains the genetic code)  Intracellular organelles 10 The human cell structure Cell composition:  Water 70:85 %  Ions  Proteins 10: 20 %  Lipids 2: 95 %  Carbohydrates 1:6 % 11 Cell functions 12 Cell membrane 13 Cell membrane structure 1. Lipids:  Phospholipids: lipid bilayer  Cholesterol: limits the movement of phospholipids, providing stability to the plasma membrane. 14 Cell membrane structure (cont’d) 2. Proteins:  Integral proteins  Peripheral proteins: In general protein in cell membrane are either structural (cytoskeleton.e.g. actin) or functional. 15 Membrane proteins functions The ability of membrane proteins to function depends on their three dimensional shapes and their chemical characteristics. Protein may function as as: 1. Marker proteins: glycoproteins/lipids, cell recognition (immunity) 2. Attachment proteins: e.g. cadherin and integrin (cell communication) 3. Transport proteins 4. Receptor proteins. 5. Enzymes. 16 And …… That’s it for today 17 Don’t forget , that was the most imp…… 18 19 Functions of cell membrane  The student must summarize the functions of the cell membrane. 20 21