Study Guide: Human Body Systems – Nutrition, Digestion, Gas Exchange, Circulation, Nervous System, and Senses

Chapter 21: Nutrition and Digestion

Overview of Nutrition and Digestion

The process of nutrition involves obtaining and using food to support life processes. Digestion is the mechanical and chemical breakdown of food into molecules small enough for the body to absorb.

• Alimentary Canal: The continuous digestive tube from mouth to anus, including the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

• Accessory Organs: Organs that aid digestion but are not part of the alimentary canal, such as the liver, pancreas, and gallbladder.

Functions of Major Digestive Organs

• Mouth: Mechanical breakdown (chewing); chemical digestion of carbohydrates by salivary amylase.

• Pharynx and Esophagus: Transport food to the stomach via peristalsis.

• Stomach: Secretes gastric juice (including pepsin for protein digestion); churns food into chyme.

• Small Intestine: Main site of chemical digestion and nutrient absorption; enzymes from pancreas and bile from liver aid digestion.

• Large Intestine (Colon): Absorbs water and forms feces.

• Liver: Produces bile to emulsify fats.

• Gallbladder: Stores and releases bile.

• Pancreas: Produces digestive enzymes and bicarbonate to neutralize stomach acid.

Important Digestive Enzymes

• Salivary Amylase: Breaks down starches in the mouth.

• Pepsin: Digests proteins in the stomach.

• Pancreatic Amylase: Continues carbohydrate digestion in the small intestine.

• Lipase: Breaks down fats in the small intestine.

• Trypsin and Chymotrypsin: Further protein digestion in the small intestine.

Diagram and Structure Recognition

• Be able to label the digestive system diagram, including all major organs and accessory structures.

• Recognize digestive structures in a fetal pig dissection (e.g., stomach, liver, intestines).

Example: The pancreas releases pancreatic amylase into the small intestine to digest carbohydrates into simple sugars.

Chapter 22: Gas Exchange

Overview of Gas Exchange

Gas exchange is the process by which organisms obtain oxygen from the environment and release carbon dioxide. In humans, this occurs in the respiratory system, primarily in the lungs.

• Respiratory System: Includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.

• Alveoli: Tiny air sacs where gas exchange occurs by diffusion.

Mechanism of Breathing

• Inhalation: Diaphragm contracts and moves downward, increasing thoracic volume and drawing air into the lungs.

• Exhalation: Diaphragm relaxes, thoracic volume decreases, and air is expelled from the lungs.

Transport of Gases

• Oxygen: Carried mainly by hemoglobin in red blood cells.

• Carbon Dioxide: Transported dissolved in plasma, as bicarbonate ions, or bound to hemoglobin.

Diagram and Structure Recognition

• Be able to label the respiratory system diagram, including trachea, bronchi, lungs, and alveoli.

Example: Oxygen diffuses from the alveoli into the capillaries, while carbon dioxide diffuses from the blood into the alveoli to be exhaled.

Chapter 23: Circulation

Overview of Circulatory System

The circulatory system transports nutrients, gases, hormones, and wastes throughout the body. The human system is a closed, double circulatory system with a four-chambered heart.

• Heart: Pumps blood through two circuits: pulmonary (to lungs) and systemic (to body).

• Blood Vessels: Arteries (carry blood away from heart), veins (carry blood to heart), capillaries (exchange of substances with tissues).

Pathway of Blood Flow Through the Heart

1. Deoxygenated blood enters right atrium via vena cava.

2. Moves to right ventricle, pumped to lungs via pulmonary artery.

3. Oxygenated blood returns to left atrium via pulmonary veins.

4. Moves to left ventricle, pumped to body via aorta.

Blood Pressure

• Normal Blood Pressure: Approximately 120/80 mmHg (systolic/diastolic).

• High Blood Pressure (Hypertension): Consistently above 140/90 mmHg; increases risk of heart disease and stroke.

• Low Blood Pressure (Hypotension): Below 90/60 mmHg; may cause dizziness or fainting.

Diagram and Structure Recognition

• Be able to label the heart diagram, including chambers, valves, and major vessels.

• Recognize structures in a sheep heart dissection.

Example: The left ventricle has the thickest wall because it pumps blood to the entire body.

Blood Vessel	Direction of Flow	Oxygen Content
Artery	Away from heart	Usually oxygen-rich (except pulmonary artery)
Vein	Toward heart	Usually oxygen-poor (except pulmonary vein)
Capillary	Connects arteries and veins	Site of exchange

Chapter 28: Nervous Systems

Overview of the Nervous System

The nervous system coordinates the body's responses to internal and external stimuli. It consists of the central nervous system (CNS) and peripheral nervous system (PNS).

• Neuron: The functional unit of the nervous system; transmits electrical impulses.

• Central Nervous System (CNS): Brain and spinal cord.

• Peripheral Nervous System (PNS): Nerves outside the CNS.

Structure of a Neuron

• Dendrites: Receive signals from other neurons.

• Cell Body (Soma): Contains nucleus and organelles.

• Axon: Transmits impulses away from the cell body.

• Myelin Sheath: Insulates axon, speeds up impulse transmission.

• Axon Terminals: Release neurotransmitters to communicate with other cells.

Pathway of an Impulse Through a Neuron

1. Impulse received by dendrites.

2. Travels through cell body.

3. Moves along axon.

4. Reaches axon terminals, triggers neurotransmitter release.

Example: Touching a hot object triggers a sensory neuron to send an impulse to the spinal cord, resulting in a reflex action.

Chapter 29: The Senses

Overview of Sensory Systems

The senses allow organisms to detect and respond to changes in their environment. Sensory receptors convert stimuli into electrical signals interpreted by the nervous system.

• Vision: The eye detects light and sends signals to the brain for image processing.

• Hearing, Taste, Smell, Touch: Other senses involve specialized receptors and pathways.

Structure of the Eye

• Cornea: Transparent front layer; refracts light.

• Iris: Colored part; controls pupil size.

• Pupil: Opening that lets light into the eye.

• Lens: Focuses light onto the retina.

• Retina: Contains photoreceptors (rods and cones) that detect light.

• Optic Nerve: Transmits visual information to the brain.

Example: The lens changes shape to focus on near or distant objects (accommodation).

Additional info: These notes are structured to cover the main concepts, structures, and processes from the specified chapters and sections, including labeling diagrams and recognizing structures in both human and comparative anatomy (e.g., fetal pig, sheep heart). For detailed diagrams, refer to textbook figures and lab handouts.