Medical Physiology 6th Edition Quiz

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Essentials of Medical Physiology

About the Book

• Sixth edition of the book, first published in 1999
• Written by K Sembulingam PhD and Prema Sembulingam PhD
• Published by Jaypee Brothers Medical Publishers (P) Ltd

Authors

• K Sembulingam PhD: affiliated with Madha Medical College & Research Institute, Chennai, Tamil Nadu, India
• Prema Sembulingam PhD: affiliated with Madha Medical College & Research Institute, Chennai, Tamil Nadu, India

Foreword

• Written by Dr S Madan Kumar, Director, Madha Medical College & Research Institute
• The book is accepted by the faculty of many universities in and out of India

Preface

• The book is intended for undergraduate and postgraduate students of medical, dental, and paramedical courses
• The book is written in a student-friendly and exam-friendly manner
• The authors are thankful for the popularity of the book and the support of their fellow teachers

Acknowledgments

• The authors express gratitude to various individuals and institutions for their support and encouragement

Contents

• The book is divided into sections, with the first section covering general physiology
• Topics covered in the first section include cell, cell junctions, and transport through cell membrane### General Physiology
• Physiology is the study of functions of various systems and organs in the body.
• It is of different types, namely Human Physiology, Animal Physiology, and Plant Physiology.

Cell

• The cell is the structural and functional unit of the living body.
• Each cell needs nutrition and oxygen, produces its own energy, eliminates carbon dioxide and metabolic wastes, and maintains its environment.
• General characteristics of cells:
  • Need nutrition and oxygen
  • Produce energy for growth, repair, and other activities
  • Eliminate carbon dioxide and metabolic wastes
  • Maintain the environment for their survival

Tissue

• Tissue is a group of cells with similar function.
• There are four primary tissues:
  • Muscle tissue (skeletal, smooth, and cardiac)
  • Nervous tissue (neurons and supporting cells)
  • Epithelial tissue (squamous, columnar, and cuboidal)
  • Connective tissue (connective tissue proper, cartilage, bone, and blood)

Organ

• An organ is a structure formed by two or more primary types of tissues that execute specific functions.
• Examples of organs include the brain, heart, lungs, stomach, intestine, liver, gallbladder, pancreas, kidneys, and endocrine glands.

Organ System

• The organ system is a group of organs that work together to carry out specific functions of the body.
• Examples of organ systems include:
  • Digestive system
  • Excretory system
  • Cardiovascular system
  • Respiratory system
  • Reproductive system
  • Endocrine system
  • Musculoskeletal system
  • Nervous system

Cell Membrane

• The cell membrane is a protective sheath that envelops the cell body.
• It is also known as the plasma membrane or plasmalemma.
• Cell membrane is a semipermeable membrane that separates the extracellular fluid (ECF) from the intracellular fluid (ICF).
• Thickness of the cell membrane varies from 75 to 111Å.
• Composition of cell membrane:
  • Proteins (55%)
  • Lipids (40%)
  • Carbohydrates (5%)

Structure of Cell Membrane

• Unit membrane model: proposed by JD Robertson in 1957
• Fluid mosaic model: proposed by SJ Singer and GL Nicholson in 1972
• Lipid layers: central electron-lucent layer formed by lipid substances, with two electron-dense layers on either side
• Protein layers: electron-dense layers formed by proteins

Lipid Layers

• Phospholipids are the major lipids present in the lipid layer.
• Cholesterol molecules are arranged in between the phospholipid molecules.

Protein Layers

• Integral proteins: pass through the entire thickness of the cell membrane from one side to the other.
• Peripheral proteins: partially embedded in the outer and inner surfaces of the cell membrane.

Functions of Cell Membrane

• Protective function: protects the cytoplasm and organelles present in the cytoplasm.
• Selective permeability: allows only certain substances to pass through it and acts as a barrier for other substances.
• Absorptive function: nutrients are absorbed into the cell through the cell membrane.
• Others: cell membrane also plays a role in cell adhesion, cell signaling, and cell recognition.### Cell Membrane
• Integral proteins provide structural integrity to the cell membrane
• Channel proteins help in the diffusion of water-soluble substances like glucose and electrolytes
• Carrier or transport proteins help in the transport of substances across the cell membrane through active or passive transport
• Receptor proteins serve as receptor sites for hormones and neurotransmitters
• Enzymes: some protein molecules form enzymes and control chemical (metabolic) reactions within the cell membrane
• Cell adhesion molecules or integral proteins are responsible for the attachment of cells to their neighbors or to basal lamina
• Carbohydrate molecules are attached to proteins and form glycoproteins (proteoglycans) or attached to lipids and form glycolipids
• Carbohydrate molecules form a thin and loose covering over the entire surface of the cell membrane called glycocalyx

Cytoplasm

• Cytoplasm is the jelly-like material formed by 80% of water
• It contains a clear liquid portion called cytosol and various particles of different shape and size
• Particles are proteins, carbohydrates, lipids, or electrolytes in nature
• Cytoplasm also contains many organelles with distinct structure and function

Organelles in Cytoplasm

• Organelles are the cellular structures embedded in the cytoplasm
• Each organelle has a definite structure and specific functions
• Organelles are considered as small organs of the cell

Organelles with Limiting Membrane

• Endoplasmic reticulum
• Golgi apparatus
• Lysosome
• Peroxisome
• Centrosome and centrioles
• Secretory vesicles
• Mitochondria
• Nucleus

Endoplasmic Reticulum

• Network of tubular and micrososomal vesicular structures
• Interconnected with one another
• Covered by a limiting membrane formed by proteins and bilayered lipids
• Functions:
  • Synthesis of proteins
  • Degradation of worn-out organelles

Types of Endoplasmic Reticulum

• Rough endoplasmic reticulum
• Smooth endoplasmic reticulum

Rough Endoplasmic Reticulum

• Has a rough, bumpy, or bead-like appearance
• Attached to granular ribosomes to its outer surface
• Functions:
  • Synthesis of proteins
  • Degradation of worn-out organelles

Smooth Endoplasmic Reticulum

• Has a smooth appearance
• Functions:
  • Synthesis of lipids and steroids
  • Storage and metabolism of calcium
  • Catabolism and detoxification of toxic substances

Golgi Apparatus

• Processing, packaging, labeling, and delivery of proteins and lipids
• Functions:
  • Synthesis of non-protein substances
  • Role in cellular metabolism
  • Storage and metabolism of calcium
  • Catabolism and detoxification of toxic substances

Lysosomes

• Membrane-bound vesicular organelles
• Contain hydrolytic enzymes
• Functions:
  • Degradation of macromolecules
  • Degradation of worn-out organelles
  • Removal of excess secretory products
  • Secretion of perforin, granzymes, melanin, and serotonin

Peroxisomes

• Breakdown of excess fatty acids
• Detoxification of hydrogen peroxide and other metabolic products
• Oxygen utilization
• Acceleration of gluconeogenesis
• Degradation of purine to uric acid
• Role in the formation of myelin and bile acids

Centrosome and Centrioles

• Centrosome is the membrane-bound cellular organelle situated near the nucleus
• Consists of two cylindrical structures called centrioles
• Functions:
  • Movement of chromosomes during cell division
  • Determination of shape of the cell
  • Stability of cell shape
  • Cellular movements

Test your knowledge of human physiology with this quiz based on the 6th edition of Essentials of Medical Physiology by K Sembulingam and Prema Sembulingam.