Exam 2 Review: Endocrine, Respiratory, Digestive, and Metabolic Systems

Chapter 16: The Endocrine System

Overview of Endocrine Glands and Hormones

The endocrine system consists of glands that secrete hormones directly into the bloodstream to regulate various body functions. Hormones act as chemical messengers affecting target organs and tissues.

• Hormone Classes: Amino acid-based (e.g., peptides, proteins) and steroid hormones (derived from cholesterol).

• Mechanisms of Action: Hormones bind to specific receptors on target cells, triggering cellular responses.

• Control of Hormone Release: Regulated by feedback mechanisms (mainly negative feedback).

Pituitary Gland

• Anterior Pituitary: Releases hormones such as growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and gonadotropins (FSH, LH).

• Posterior Pituitary: Stores and releases oxytocin and antidiuretic hormone (ADH).

Thyroid and Parathyroid Glands

• Thyroid Hormones: Thyroxine (T4) and triiodothyronine (T3) regulate metabolism, growth, and development.

• Parathyroid Hormone (PTH): Regulates calcium levels in the blood.

Adrenal Glands

• Adrenal Cortex: Produces corticosteroids (e.g., cortisol, aldosterone).

• Adrenal Medulla: Secretes catecholamines (epinephrine and norepinephrine) for the fight-or-flight response.

Pancreas

• Insulin: Lowers blood glucose levels.

• Glucagon: Raises blood glucose levels.

Other Endocrine Organs

• Pineal gland, thymus, gonads (testes and ovaries) also secrete hormones with specific effects.

Example: Insulin deficiency leads to diabetes mellitus, characterized by high blood glucose levels.

Chapter 22: The Respiratory System

Major Functions and Anatomy

The respiratory system is responsible for gas exchange, supplying oxygen to the blood and removing carbon dioxide.

• Major Organs: Nose, pharynx, larynx, trachea, bronchi, lungs, alveoli.

• Respiratory Membrane: Site of gas exchange between alveoli and capillaries.

Mechanics of Breathing

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

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

Gas Exchange and Transport

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

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

Control of Respiration

• Regulated by respiratory centers in the brainstem (medulla and pons).

• Influenced by chemical factors (CO2, O2, pH).

Example: Hyperventilation decreases CO2 levels, leading to respiratory alkalosis.

Chapter 14: The Digestive System and Body Metabolism

Digestive Processes and Anatomy

The digestive system breaks down food into absorbable units and eliminates indigestible remains.

• Major Organs: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

• Accessory Organs: Salivary glands, liver, gallbladder, pancreas.

Digestive Processes

• Ingestion, Propulsion, Mechanical Digestion, Chemical Digestion, Absorption, Defecation

Enzymes and Absorption

• Enzymes break down carbohydrates, proteins, and fats into absorbable molecules.

• Most absorption occurs in the small intestine.

Regulation of Digestion

• Controlled by neural and hormonal mechanisms.

Example: Lactase deficiency leads to lactose intolerance, causing digestive discomfort after consuming dairy.

Chapter 24: Metabolism and Nutrition

Overview of Metabolism

Metabolism includes all chemical reactions in the body, divided into catabolism (breakdown) and anabolism (synthesis).

• ATP Production: Cellular respiration converts glucose to ATP, CO2, and H2O.

• Key Pathways: Glycolysis, Krebs cycle, electron transport chain.

Carbohydrate, Lipid, and Protein Metabolism

• Carbohydrate Metabolism: Glycogenesis (formation of glycogen), glycogenolysis (breakdown of glycogen), gluconeogenesis (formation of glucose from non-carbohydrates).

• Lipid Metabolism: Lipolysis (breakdown of fats), lipogenesis (formation of fats).

• Protein Metabolism: Deamination (removal of amino group), transamination (transfer of amino group).

Energy Balance and Nutrient Utilization

• Energy intake must balance energy expenditure to maintain body weight.

• Vitamins and minerals are essential for metabolic pathways.

Example: Excess caloric intake leads to fat storage and weight gain.

Key Tables

Hormone	Source	Main Effect
Insulin	Pancreas (beta cells)	Lowers blood glucose
Glucagon	Pancreas (alpha cells)	Raises blood glucose
Thyroxine (T4)	Thyroid gland	Increases metabolic rate
Cortisol	Adrenal cortex	Stress response, increases blood glucose

Key Equations

• Cellular Respiration:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 36ATP$

• Oxygen Transport (Henry's Law):

$C = kP$

where C is the concentration of dissolved gas, k is Henry's law constant, and P is the partial pressure of the gas.

Additional info: Some details (e.g., specific hormone actions, metabolic pathways) were expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.