Human physiology Dr. Ramadan Saad DEPARTMENT OF physiological Sciences Fakeeh COLLEGE OF MEDICAL SCIENCES

Human Physiology Overview of science and the human body

Learning Objectives This student should be able to: 1)Explain what is meant by levels of organization. 2)List and describe the major needs of organisms. 3)Define HOMEOSTASIS and explain its importance to survival. 4)Describe a homeostatic mechanism. 5)Compare between +ve and -ve feedback mechanisms. 6)Describe distribution of total body water.

Physiology ; study of how the body and its parts work or function.

Why must the medical students study human physiology? (1) Medical science development is closely related to physiology. (2) Physiology provides the theories to explain many diseases.

Major Organ Systems Nervous System –Communication and control Endocrine System –Communication and control Integumentary System –Barrier between interior of body and exterior, thermoregulation Respiratory System –Gas exchange, pH balance Urinary System –Waste removal, water and ion balance

Major Organ Systems Digestive System –Obtain raw materials from exterior Immune System –Protect body from foreign substances, other organisms and cancer cells Musculoskeletal System –Movement, structure, support, protection, heat generation Circulatory System –Transportation of most materials throughout body Reproductive System –Perpetuation of the species

In average young adult male: Body composition % of body weightBody composition 18%Protein, & related substances 15%Fat 7%Mineral 60% Water

Body Water 60% percent of a adult male body weight is water. While, only 50% percent of an adult female body weight is water. Explain why? (because females have higher body content of fat which is poor in water). intracellular compartment.2/3 total body water is in the intracellular compartment. the interstitial fluid.The remaining 1/3 is the extracellular fluid which is divided into plasma & the interstitial fluid. In old age, only about 45% of body weight is water. 60% percent of a adult male body weight is water. While, only 50% percent of an adult female body weight is water. Explain why? (because females have higher body content of fat which is poor in water). intracellular compartment.2/3 total body water is in the intracellular compartment. the interstitial fluid.The remaining 1/3 is the extracellular fluid which is divided into plasma & the interstitial fluid. In old age, only about 45% of body weight is water.

Body Fluids Water content in body is divided into 2 compartments: 1. Extracellular fluid (ECF): - fluid outside the cells.  1/3 volume of fluids in body (  33% of total body water). - contains ions & nutrients needed for cellular life. 2. Intracellular fluid (ICF): - fluid inside the cells.  2/3 volume of fluids in body (  67% of total body water).

Fluid Compartments  60% of body weight Extracellular fluid (  1/3)  33% of TBW   20% of body wt Intracellular fluid (  2/3)  67% of TBW   40% of body wt Interstitial fluid  75% of ECF   15% of body wt Plasma  25% of ECF   5% of body wt

Example: How to calculate total body water (TBW)? Q. Calculate TBW for a 70 kg man. TBW = 60% of body weight TBW = 60% X 70 = 42 L of water

Fluid Compartments Intracellular

Fluid Compartments Interstitial

Fluid Compartments Intravascular (mostly plasma)

Main Cations and Anions In ECF:In ECF: –Cations: sodium –Anions: chloride, bicarbonate. In ICF:In ICF: –Cations: potassium –Anions: phosphate ions, negatively charged proteins. In ECF:In ECF: –Cations: sodium –Anions: chloride, bicarbonate. In ICF:In ICF: –Cations: potassium –Anions: phosphate ions, negatively charged proteins.

Extracellular vs. Intracellular K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ Na + K+K+ K+K+ K+K+ Extracellular Intracellular Cl -