Anatomy & Physiology Study Notes: Cardiovascular, Lymphatic, Immune, and Respiratory Systems

Cardiovascular System

Blood Vessels and Circulation

The cardiovascular system consists of the heart and blood vessels, which transport blood throughout the body. Blood vessels are classified based on their structure and function.

• Arteries: Carry blood away from the heart; have thick muscular walls to withstand high pressure.

• Veins: Return blood to the heart; have thinner walls and valves to prevent backflow.

• Capillaries: Microscopic vessels where exchange of gases, nutrients, and wastes occurs between blood and tissues.

Key Terms:

• Vasoconstriction: Narrowing of blood vessels, increasing blood pressure.

• Vasodilation: Widening of blood vessels, decreasing blood pressure.

• Blood Pressure: The force exerted by circulating blood on the walls of blood vessels.

Example: During exercise, arteries dilate to increase blood flow to muscles.

Blood Pressure Regulation

Blood pressure is regulated by neural, hormonal, and local mechanisms to ensure adequate tissue perfusion.

• Neural Control: Baroreceptors detect changes in blood pressure and send signals to the brainstem to adjust heart rate and vessel diameter.

• Hormonal Control: Hormones such as epinephrine, norepinephrine, and angiotensin II affect blood vessel tone and cardiac output.

• Local Control: Local metabolic factors cause vasodilation or vasoconstriction in response to tissue needs.

Equation:

$\text{Mean Arterial Pressure (MAP)} = \text{CO} \times \text{TPR}$

Where CO = Cardiac Output, TPR = Total Peripheral Resistance.

Capillary Exchange and Fluid Movement

Capillaries allow for the exchange of gases, nutrients, and wastes between blood and tissues through diffusion, filtration, and osmosis.

• Hydrostatic Pressure: Pushes fluid out of capillaries.

• Osmotic Pressure: Pulls fluid into capillaries.

Equation:

$\text{Net Filtration Pressure (NFP)} = (\text{HP}_c - \text{HP}_i) - (\text{OP}_c - \text{OP}_i)$

Where HP = Hydrostatic Pressure, OP = Osmotic Pressure, c = capillary, i = interstitial fluid.

Lymphatic System / Lymphoid Organs

Functions of the Lymphatic System

The lymphatic system returns excess tissue fluid to the bloodstream, absorbs dietary fats, and provides immune defense.

• Lymph: Fluid collected from tissues and returned to the blood.

• Lymphatic Vessels: Transport lymph; contain valves to prevent backflow.

• Lymphoid Organs: Include lymph nodes, spleen, thymus, tonsils, and mucosa-associated lymphoid tissue (MALT).

Example: Lymph nodes filter lymph and trap pathogens.

Lymphoid Tissues and Organs

Lymphoid tissues are specialized structures that support immune cell development and function.

• Primary Lymphoid Organs: Bone marrow (produces lymphocytes) and thymus (site of T cell maturation).

• Secondary Lymphoid Organs: Lymph nodes, spleen, tonsils, and MALT (sites of immune response initiation).

The Immune System

Innate vs. Adaptive Immunity

The immune system protects the body from pathogens through innate (nonspecific) and adaptive (specific) mechanisms.

• Innate Immunity: First line of defense; includes physical barriers (skin, mucous membranes), phagocytic cells, inflammation, and fever.

• Adaptive Immunity: Second line of defense; involves lymphocytes (B cells and T cells) and the production of antibodies specific to antigens.

Table: Comparison of Innate and Adaptive Immunity

Feature	Innate Immunity	Adaptive Immunity
Specificity	Nonspecific	Specific
Memory	No	Yes
Cells Involved	Phagocytes, NK cells	B cells, T cells
Response Time	Immediate	Delayed (days)

Cells of the Immune System

Various cells contribute to immune defense.

• Phagocytes: Engulf and destroy pathogens (e.g., neutrophils, macrophages).

• Lymphocytes: B cells (produce antibodies), T cells (mediate cellular immunity).

• Antigen-Presenting Cells: Display antigens to lymphocytes (e.g., dendritic cells).

Inflammatory Response

The inflammatory response is a protective reaction to tissue injury or infection, characterized by redness, heat, swelling, and pain.

• Steps: Vasodilation, increased permeability, migration of phagocytes, and tissue repair.

• Chemical Mediators: Histamine, prostaglandins, cytokines.

Example: A cut on the skin triggers inflammation to prevent infection.

Humoral and Cell-Mediated Immunity

Adaptive immunity is divided into humoral (antibody-mediated) and cell-mediated responses.

• Humoral Immunity: B cells produce antibodies that neutralize pathogens.

• Cell-Mediated Immunity: T cells destroy infected cells and coordinate immune responses.

Equation:

$\text{Antibody} + \text{Antigen} \rightarrow \text{Immune Complex}$

Respiratory System

Functions and Anatomy of the Respiratory System

The respiratory system provides oxygen to the body and removes carbon dioxide. It consists of the upper and lower respiratory tracts.

• Upper Respiratory Tract: Nose, nasal cavity, pharynx, larynx.

• Lower Respiratory Tract: Trachea, bronchi, bronchioles, lungs, alveoli.

Example: Gas exchange occurs in the alveoli of the lungs.

Mechanics of Breathing

Breathing involves inspiration (inhalation) and expiration (exhalation), driven by changes in thoracic volume and pressure.

• Inspiration: Diaphragm contracts, thoracic cavity expands, air flows in.

• Expiration: Diaphragm relaxes, thoracic cavity decreases, air flows out.

Equation:

$\text{Boyle's Law}: P_1 V_1 = P_2 V_2$

Where P = pressure, V = volume.

Gas Exchange and Transport

Oxygen and carbon dioxide are exchanged between alveoli and blood by diffusion and transported in the blood.

• Oxygen Transport: Mostly bound to hemoglobin in red blood cells.

• Carbon Dioxide Transport: Dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.

Equation:

$\text{CO}_2 + \text{H}_2\text{O} \leftrightarrow \text{H}_2\text{CO}_3 \leftrightarrow \text{HCO}_3^- + \text{H}^+$

Control of Respiration

Respiratory rate and depth are regulated by centers in the brainstem in response to blood gas levels.

• Medullary Respiratory Centers: Control basic rhythm of breathing.

• Chemoreceptors: Detect changes in CO2, O2, and pH.

Example: Increased CO2 stimulates increased breathing rate.

Respiratory Disorders

Common respiratory disorders include asthma, chronic obstructive pulmonary disease (COPD), and pneumonia.

• Asthma: Airway inflammation and constriction.

• COPD: Chronic bronchitis and emphysema; reduced airflow.

• Pneumonia: Infection of the lungs.

Additional info: These notes expand on brief points from the original file to provide a comprehensive overview suitable for exam preparation.