Organ Systems II
Lesson focus - Describe the components and functions of blood, red and white blood cells, hemostasis, and the pathways of circulation; the function of the lymphatic system and types of immunity; upper and lower respiratory anatomy; the functions and notable organs of the digestive system; and the functions of the kidneys and the nephron.
The Cardiovascular System
Components of Blood
Plasma
- A watery extracellular matrix; the straw-colored liquid that remains after the formed elements are separated
- 91.5% water, 8.5% solutes
- Includes hepatocytes, albumins, globulins, fibrinogen, and antibodies
- Often donated for clotting factors
Formed Elements
- RBCs (erythrocytes)
- WBCs (leukocytes)
- Platelets
Functions and Properties of Blood
| Function | Details |
|---|
| Transportation | O₂/CO₂ exchange, nutrients from the digestive canal, hormones, and waste products to eliminating organs |
| Regulation | pH through buffers; adjusts body temperature through water |
| Protection | Coagulation properties, antibodies, and WBCs/phagocytes |
Red Blood Cells (Erythrocytes)
- Contain hemoglobin, the oxygen-carrying protein
- Reversible binding (O₂/CO₂)
White Blood Cells
- Perform phagocytosis and the immune response
- Normally 5,000–10,000 per microliter of blood
- Increased in times of stress (infection, surgery, illness, etc.)
Hemostasis
Hemostasis is the sequence of events that stops bleeding and prevents hemorrhage:
- Vascular spasm
- Platelet plug formation
- Blood clotting
Basic Anatomy of the Cardiovascular System
| Vessel | Function |
|---|
| Arteries | Carry blood away from the heart (generally oxygenated) |
| Veins | Carry blood back to the heart (generally deoxygenated) |
Pathway of Circulation
| Circulation | Pathway |
|---|
| Systemic | Oxygenated blood flows from the left ventricle (via the aorta) to all organs, and deoxygenated blood returns to the right atrium |
| Pulmonic | Deoxygenated blood flows from the right ventricle to the lungs (via the pulmonary artery) and returns oxygenated blood from the lungs to the left atrium (via the pulmonary veins) |
The Lymphoid System
The Lymphatic System
The lymphatic system consists of lymph fluid and vessels as well as major organs, and it allows immune responses to occur.
- Spleen - the largest mass of lymph tissue in the body
- Red bone marrow
- Lymph nodules (e.g., tonsils)
Concept of Immunity
Immunity is the ability to ward off damage or disease through defenses.
Function of the Lymphatic System
- Drains excess interstitial fluid from tissue spaces and returns it to the blood
- Transports nutrients absorbed by the digestive canal
- Carries out immune responses
Innate vs. Adaptive Immunity
| Type | Description |
|---|
| Innate | Present at birth |
| Adaptive | Involves specific recognition of a microbe once it has breached the innate defenses |
The Respiratory System
Overview of Respiration
| Step | Description |
|---|
| Pulmonary ventilation | The act of breathing; air goes in and out |
| External respiration | Gas exchange between the alveoli and pulmonary capillaries |
| Internal respiration | Gas exchange between blood in the systemic capillaries and tissue cells (perfusion) |
Upper Respiratory System
| Structure | Function |
|---|
| Nose | Provides humidity and olfactory senses |
| Nasal cavity | A large space lined with mucous membranes; produces mucus and traps debris |
| Oral cavity | — |
| Pharynx (throat) | Houses the tonsils |
Lower Respiratory Tract
- Larynx (voice box)
- Trachea
- Lungs
- Bronchi
The Digestive System
Functions
- Breaks food into smaller molecules that can be used by cells
- Muscular contractions:
- Break down food to move it throughout the body
- Mix food with digestive enzymes
Notable Organs
The Liver
- Composed of hepatocytes:
- Nutrient metabolism
- Detoxification
- Phagocytosis of bacteria in the blood (Kupffer cells)
- The first organ to absorb/metabolize nutrients from the GI tract:
- Carbohydrates: glycogen → glucose
- Lipids → triglycerides / fatty acids
- Proteins → amino acids (used for ATP production)
The Pancreas
- Carbohydrates: glycogen → glucose
- Low blood glucose stimulates secretion of glucagon
- High blood glucose stimulates insulin
The Urinary System
Functions of the Kidneys
- Excretion of waste (urine)
- Regulation of blood ionic composition (Na⁺, K⁺, Ca²⁺, Cl⁻, HPO₄)
- Regulation of blood pH
- Regulation of blood volume
- Regulation of blood pressure
- Production of hormones
- Regulation of blood glucose level
Regulation of Blood pH
- Excrete excess H⁺
- Conserve bicarbonate for buffer
Regulation of Blood Pressure
| Mediator | Action |
|---|
| Anti-diuretic hormone (ADH) | Increases when BP is low; decreases when BP is high |
| Renin | — |
Production of Hormones
| Hormone | Role |
|---|
| Calcitriol | The active form of vitamin D; regulates Ca²⁺ homeostasis |
| Erythropoietin (EPO) | Stimulates production of RBCs; becomes reduced during kidney failure |
The Nephron - Anatomy
The nephron is the functional unit of the kidney.
| Component | Function |
|---|
| Renal corpuscle | Filters blood plasma; contains the glomerulus (capillary network) and the glomerular (Bowman's) capsule (double-walled epithelium) |
| Renal tubule | The site of major buffer (H⁺ and HCO₃⁻) action for the kidneys; includes the proximal convoluted tubule, the nephron loop (loop of Henle), and the distal convoluted tubule |
The Nephron - Physiology
| Process | Description |
|---|
| Glomerular filtration | Water and solutes move across the glomerular capillaries; filtration of nutrients occurs |
| Tubular reabsorption | Renal tubular cells reabsorb 99% of filtered water and other solutes; reabsorbed nutrients return to the blood |
| Tubular secretion | Waste, drugs, and excess ions are secreted out of the body via the renal tubule and duct cells |
Review
- The cardiovascular system: components and functions of blood, RBCs, WBCs, hemostasis, and circulation
- The lymphoid system: function and immunity
- The respiratory system: overview of respiration and upper/lower anatomy
- The digestive system: functions and notable organs
- The urinary system: functions of the kidneys and the nephron