Exam 5 Physiology

Innate Immunity

Non-specific immunity that provides a line of defense against foreign pathogens through external and internal defenses.

Innate or Non-Specific Immunity

Include both external and internal defenses that are always present in the body and represent a line of defense against invasion by foreign pathogens

Adaptive or Specific Immunity

Seek out and destroy foreign pathogens if they enter the body

Anatomical and physiological features involved in Non-Specific Immunity

Skin, mucous membranes, stomach acid, fever, inflammation, phagocytic cells, natural killer cells

Phagocytosis

The process by which certain cells engulf and digest pathogens and debris.

First phagocytic leukocyte

Neutrophils

Second phagocytic leukocyte

Monocytes (which become macrophages)

Third phagocytic leukocyte

Dendritic cells

Diapedesis

The movement of white blood cells through capillary walls into tissues.

Why is pus beneficial?

It indicates the presence of active immune response; composed of dead cells and pathogens, signaling clearance of infection.

Organs where fixed phagocytes might be found

Liver (Kupffer cells), Spleen, Lymph nodes

Benefits of a fever

Inhibits pathogen replication, enhances immune response

What did Emil Von Behring discover?

He discovered antibodies and demonstrated passive immunity using antitoxins.

What contribution did Edward Jenner make?

Developed the first vaccine (for smallpox) using cowpox virus.

B lymphocytes - Plasma Cells

Produce antibodies

B lymphocytes - Memory Cells

Provide long-term immunity

Dendritic Cells

Present antigens to T cells

Helper T lymphocytes

Activate B and T cells

Killer T lymphocytes

Destroy virus-infected and cancer cells

Mast Cells

Release histamine during allergic reactions

Neutrophils

First responders in inflammation; phagocytic

Macrophages

Engulf pathogens; antigen-presenting cells

How does a membrane attack complex kill a bacterial cell?

It forms pores in the bacterial membrane, leading to cell lysis.

Primary vs. Secondary Immune Response

Secondary is faster due to memory cells that recognize the antigen.

Passive Immunity

Antibodies from another source; short-term (e.g., breast milk, antiserum)

Active Immunity

Own body produces antibodies; long-term (e.g., vaccines, infection)

How do vaccines work?

Introduce antigens to trigger an immune response and memory cell formation.
Cells involved: B cells and T helper cells

What is apoptosis?

Programmed cell death. Cytotoxic T cells cause apoptosis in mutated/cancer cells.

What is an allergy?

An inappropriate immune response to a harmless substance.

Example of Allergy

Pollen

Drugs for seasonal allergy

Antihistamines, corticosteroids, decongestants

Ventilation

Movement of air in and out of lungs

Gas exchange

O₂ and CO₂ exchange between lungs and blood

Cellular respiration

Oxygen is needed to make ATP

Approximate number of alveoli

300 million

Why so many alveoli?

To increase surface area for gas exchange

Type 1 alveolar cells

Perform gas exchange

Type 2 alveolar cells

Secrete surfactant

Function of Conducting zone

Air passage, humidifies, warms, and filters air

Function of Respiratory zone

Gas exchange

Parietal pleura

Lines thoracic cavity

Visceral pleura

Covers lungs

What are pleura stuck together by?

Surface tension of pleural fluid

Boyle’s Law

Pressure and volume are inversely related (↑volume = ↓pressure)

Inhalation changes

Diaphragm contracts → thoracic cavity expands → pressure drops → air flows in

Exhalation changes

Diaphragm relaxes → thoracic cavity decreases → pressure rises → air flows out

What is surfactant?

Reduces surface tension to prevent alveolar collapse

Distress in underdeveloped lungs

Respiratory Distress Syndrome (RDS)

Asthma

Bronchoconstriction due to hypersensitivity

Emphysema

Alveolar damage, loss of surface area

COPD

Chronic airflow limitation (e.g., emphysema + chronic bronchitis)

O₂ (arterial) partial pressure

~100 mmHg

O₂ (venous) partial pressure

~40 mmHg

CO₂ (arterial) partial pressure

~40 mmHg

CO₂ (venous) partial pressure

~46 mmHg

The Bends

Nitrogen gas comes out of solution during rapid ascent, forming bubbles

Peripheral chemoreceptors

Located in carotid/aortic bodies; detect blood O₂, CO₂, pH

Central chemoreceptors

Located in medulla; detect CO₂ and pH in cerebrospinal fluid

Rhythmicity center

Medulla; sets breathing rhythm

Apneustic center

Pons; promotes inhalation

Pneumotaxic center

Pons; inhibits inhalation

Chemical equation

CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺

First way of O₂ transport

Bound to hemoglobin

Second way of O₂ transport

Dissolved in plasma

First way of CO₂ transport

As bicarbonate (HCO₃⁻)

Second way of CO₂ transport

Bound to hemoglobin (carbaminohemoglobin)

Third way of CO₂ transport

Dissolved in plasma

Oxyhemoglobin

Hemoglobin bound to O₂

Deoxyhemoglobin

Hemoglobin without O₂

Carbaminohemoglobin

Hemoglobin bound to CO₂

Carboxyhemoglobin

Hemoglobin bound to CO (carbon monoxide)

Anemia

Low RBC count or hemoglobin → ↓O₂ carrying capacity

Polycythemia

High RBC count —> ↑viscosity, possible clot risk

Sickle Cell Disease

Abnormal hemoglobin causes RBCs to sickle. Treatment: Hydroxyurea, transfusions, gene therapy.

Myoglobin

Is an oxygen-binding protein that is similar to hemoglobin but has a higher affinity for oxygen and only 1 oxygen binding site instead of 4.

Major Buffering System in the body

Bicarbonate buffer system regulates pH levels in the blood and extracellular fluid, helping to maintain acid-base homeostasis. Normal pH is around 7.4.

The lungs regulate ______ concentration and the kidneys regulate _____ concentration in the blood.

CO₂, HCO₃⁻

Acidosis

Low blood pH; due to ↑CO₂ or ↓HCO₃⁻

Alkalosis

High blood pH; due to ↓CO₂ or ↑HCO₃⁻