Lecture 1 Body Fluids and Homeostasis PDF

General Physiology - Health sciences Functional Organization of the Huma Body and Homeostasis Prof. Dr. Shereen Samir Lecture Objectives At the end of this lecture you will be able to: 1) Describe the functional organization of the human body...

General Physiology - Health sciences Functional Organization of the Huma Body and Homeostasis Prof. Dr. Shereen Samir Lecture Objectives At the end of this lecture you will be able to: 1) Describe the functional organization of the human body 2) Recognize the components of body fluids 3) List the main differences between ICF and ECF 4) List the functions of the body water 5) Explain the mechanisms of regulation of body water 6) Define the concept of homeostasis and list its mechanisms and significance  01 Organization of the human body Contents 02 Body fluids and its distribution 03 Body Water and its functions and regulation 04 Concept of homeostasis and its regulatory mechanisms  Introduction Physiology is the science that study the functions and mechanism of action of different body systems, organs, and cells  Body systems (11) Nervous Circulatory Digestive Respiratory Reproductive Urinary Endocrine Muscular Skeletal Lymphatic Integumentary  Organization of the human body Human body systems Organs The cell is the basic unit of structure and function in the Tissues body Cells 8 Percentage: 60% of the total body weight in adult men (i.e. 42 L in an adult weighing 70 Kg) 50% of BW in adult women because their bodies contain much fat. More than 70% of BW in infants, so water loss leads to rapid dehydration. In old age the water content is decreased 9 Intracellular Fluid (ICF) Extracellular Fluid (ECF) Fluid inside cells Fluid outside cells 2/3 of Total body fluids 1/3 of Total body fluids i.e. 28 Liters i.e. 14-15 Liters ECF ECF ICF 10  ECF is known as the internal environment that supplies the cells with nutrients and other substances  ECF is composed of; Plasma Interstitial fluid Transcellular fluid Fluid inside blood vessels Fluid in between Fluid in body cells cavities e.g. CSF About 3 L About 1 L About 10 L 11  The ECF contains large amounts of Na+, Cl-, Ca and HCO3 ions  while ICF contains large amounts of K+, Mg2+, protein and HPO4 ions  These differences are extremely important to the life of the cell. Def  Body water is kept constant by adjusting water input and water output Insensible water loss (about 700ml) Sweating (100 ml) Endogenous water 200 ml/day Feces (about 100ml) Exogenous water 2200 ml/day Urine (about 1500 ml) Water Input Water output 2400 ml/day 2400 ml/day 13 ↓ blood volume Thirst Center Thirst sensation ↑ plasma osmolarity Increased water intake ↓ plasma osmolarity ↑ blood volume 14 ↓ blood volume Hypothalamus ↑ plasma osmolarity ↓ed Urine Volume ADH ↓ plasma osmolarity Posterior Pituitary ↑ blood volume 15 Def.,  They are the mechanisms that keep the internal environment constant. Importance:  This is very important for the normal cellular functions  E.g.: body water, temperature, blood glucose, ions, pH and arterial blood pressure (ABP) 16 Def  Feedback mechanisms are the mechanisms that keep the function of system s constant  Types: Useful to keep homeostasis: e.g. regulation of CO2 and Negative Feedback body temperature Harmful : e.g death cycle Positive Feedback May be useful in labor and lactation 17  The cell is basic unit of the human body  Body fluids constitutes 60% of TBW and divided into ICF and ECF  The composition of ICF and ECF is not the same Summary & Wrap up  Body water is kept constant by balance between water input and output  Homeostasis is to keep the internal environment constant  Negative feedback keep the homeostasis but positive disturb homeostasis  Questions 1-The intracellular fluids contain 2-As positive feedback mechanism is high concentrations of: important in : a) Na ions a) Regulation of arterial blood pressure b) Proteins b) Regulation of body temperature. c) Chloride ions c) Regulation of blood level of glucose d)Calcium ions d) Delivery of the baby during labour e) HCO3 ions e) Regulation of blood pH  References 1. Costanzo, Linda S. "BRS Physiology (Board Review Series)." (2018). 2. Ganong, William F. "Review of medical physiology." (2020). THANK YOU