Tissues and Organ Systems

• Life is organized in a hierarchy from cells to organ systems to organisms
• The 11 organ systems are: integumentary, skeletal, muscular, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive

Four Types of Tissues

• Epithelial tissue covers and protects the body, and lines organs and cavities
• Epithelial tissues are held together by tight, adhesion, and gap junctions
• Endocrine glands secrete hormones into the bloodstream
• Exocrine glands secrete substances via ducts
• Connective tissue provides support and structure to the body
• Loose connective tissue is flexible
• Dense connective tissue is strong, examples are tendons and ligaments
• Specialized connective tissues include bone, blood, cartilage, and adipose tissue
• Muscle tissue generates movement
• Skeletal muscle is voluntary and attached to bones
• Cardiac muscle is involuntary and found in the heart
• Smooth muscle is involuntary and found in organs and vessels
• Nervous tissue conducts impulses
• Neurons transmit signals
• Glial cells support and nourish neurons

Homeostasis and Thermoregulation

• Homeostasis is the body's ability to maintain stable internal conditions
• Thermoregulation is the control of body temperature
• When the body is too hot, vasodilation and sweating occur
• When the body is too cold, vasoconstriction and shivering occur
• Negative feedback loops counteract deviations to maintain stable conditions (e.g., body temperature regulation)

Functions of the Skeletal System

• The skeletal system provides support and is the framework for the body
• It provides leverage for muscles enabling movement
• It protects vital organs like the skull for the brain, and ribs for the heart and lungs
• The skeletal system produces blood cells in red bone marrow
• It stores minerals such as calcium and phosphorus

Bone Structure and Growth

• Compact bone is the dense outer layer and provides strength
• Spongy bone is less dense and contains red bone marrow
• Osteocytes are bone cells
• Ossification is the process of bone formation
• Bone remodeling is the continuous cycle of resorption and formation

Skeletal Organization

• The axial skeleton consists of the skull, vertebral column, and ribcage
• The appendicular skeleton consists of limbs and girdles
• Synovial joints are freely movable
• Cartilaginous joints are partially movable
• Fibrous joints are immovable

Functions of Muscles

• Muscles enable movement, maintain posture, and produce heat

Muscle Types

• Skeletal muscle is voluntary and striated
• Cardiac muscle is involuntary, striated, and heart-specific
• Smooth muscle is involuntary and found in digestive tract and blood vessels

Muscle Contraction

• Actin and myosin are contractile proteins
• The neuromuscular junction is where motor neurons stimulate muscle fibers
• ATP and calcium (Ca²⁺) are required for contraction

Disorders

• Muscular dystrophy involves muscle degeneration
• Tetanus is a bacterial infection causing muscle stiffness
• Cramps are often due to dehydration or electrolyte imbalance

Functions of Blood

• Blood transports oxygen, nutrients, hormones, and waste
• It regulates body temperature, pH, and fluid balance
• Blood provides immune defense and clotting via platelets

Blood Components

• Plasma is the liquid portion of blood, and is 90% water
• Red blood cells (erythrocytes) transport oxygen via hemoglobin
• White blood cells (leukocytes) provide immune defense
• Platelets (thrombocytes) are involved in clotting

Blood Typing and Disorders

• The ABO system includes blood types A, B, AB (universal recipient), and O (universal donor)
• The Rh factor can be Rh+ or Rh-
• Anemia is characterized by a low red blood cell count
• Leukemia is cancer of white blood cells

Components of the Cardiovascular System

• The heart pumps blood
• Arteries carry oxygenated blood away from the heart
• Veins carry deoxygenated blood back to the heart
• Capillaries exchange oxygen and nutrients between blood and tissues

Blood Circulation

• The pulmonary circuit involves the heart, lungs, and back to the heart, facilitating gas exchange
• The systemic circuit involves the heart, body, and back to the heart, facilitating nutrient and waste exchange

Heart Anatomy and Function

• The heart has four chambers: the right atrium and right ventricle (deoxygenated blood), and the left atrium and left ventricle (oxygenated blood)
• Valves prevent backflow, these are named Atrioventricular and Semilunar Valves
• The electrical conducting system includes the SA node (pacemaker), AV node, and Purkinje fibers

Blood Pressure and Cardiovascular Disorders

• Normal blood pressure is 120/80 mmHg
• Hypertension is high blood pressure
• Atherosclerosis is the buildup of plaque in arteries
• Heart attack and stroke are caused by blockage of blood flow;
• Preventive measures include exercise, a healthy diet, avoiding smoking, and managing stress