BIO 105 General Biology Flashcards

Organization of the Body

• An organ system is a group of organs that work together to perform a major body function.

Major Organ Systems in Humans (11 Systems)

• Digestive System:
  • Components: Esophagus, stomach, liver, gallbladder, pancreas, small and large intestines.
  • Function: Ingests and breaks down food for nutrient absorption.
• Cardiovascular System:
  • Components: Blood vessels, heart.
  • Function: Transports nutrients, gases, hormones, and wastes to and from cells.
• Excretory System:
  • Components: Kidney, ureter, bladder, urethra.
  • Function: Eliminates liquid wastes and regulates water balance.
• Endocrine System:
  • Components: Pituitary gland, thyroid/parathyroid, thymus.
  • Function: Secretes hormones into the bloodstream for regulation of body activities.
• Respiratory System:
  • Components: Trachea, bronchi, lung.
  • Function: Enables gas exchange to supply blood with oxygen and remove carbon dioxide.
• Nervous System:
  • Components: Brain, spinal cord, nerves.
  • Function: Senses the environment and communicates with and activates other parts of the body.
• Skeletal System:
  • Components: Cartilage, bone.
  • Function: Provides mechanical support for the body and stores minerals; produces red blood cells.
• Muscular System:
  • Components: Skeletal muscles.
  • Function: Enables movement, posture, and balance via contraction and extension of muscles.
• Integumentary System:
  • Components: Hair, nails, skin.
  • Function: Protects the body from the environment, injury, and infection; stores fat.
• Lymphatic and Immune System:
  • Components: Thymus, lymph nodes, lymphatic vessels, spleen.
  • Function: Protects against infections.
• Reproductive System (Female):
  • Components: Ovary, uterus, cervix, vagina.
  • Function: Produces eggs and supports the development of offspring.
• Reproductive System (Male):
  • Components: Prostate, testicle, penis.
  • Function: Produces and delivers sperm and associated fluids.

Regulating the Internal Environment

• Homeostasis: The ability to maintain a consistent internal environment under changing conditions.
  • Requires coordinated efforts of cells, tissues, organs, and organ systems.
  • Examples of internal conditions maintained: heart rate, blood pressure, water and mineral balance, temperature, blood glucose, etc.

Feedback Mechanisms

• Information is sent to a control center, which directs a response from a cell, tissue, or organ.

• Negative Feedback: Negates change.

  • Example: Regulation of blood glucose levels (glucose homeostasis).
  • Failure to maintain glucose homeostasis can lead to diabetes.

• Positive feedback: Promotes change

  • Example: Lactation
  • Stimulus: Baby suckles at breast
  • Receptor: Sensory receptors in the skin of the breast detect the suckling send impulses to hypothalamus
  • Control center: Hypothalamus signals, posterior pituitary to release oxytocin
  • Effector: Breast is stimulated to eject breast milk

Digestive and Urinary Systems

• Why We Eat/Drink:
  • Food/drink provides building blocks and nutrients.
  • These are broken down (digestion) for growth, maintenance, and repair.
  • Energy production through metabolism (chemical reactions that occur in the body).
  • Absorption (transfer of nutrients into blood circulation).

Functions of the Digestive System

• Digestion: Breaks down foods the body ingests into a usable form.
• Absorption: Transfers nutrients out of the digestive tract and into blood circulation.
• Excretion: Eliminates waste material that can’t be absorbed.
• Ingestion: Allows the consumption of food by the body

Components of the Digestive System

• Digestive Tract: A muscular tube from the mouth to the anus.
• Accessory Digestive Organs: Support the digestive tract's functions.
  • Salivary glands: Produce enzymes and saliva to start carbohydrate breakdown.
  • Liver: Produces bile, which aids in the absorption of fats.
  • Gallbladder: Stores bile and empties into the small intestine.
  • Pancreas: Produces digestive enzymes and a buffer that neutralizes stomach acid.

Pathway of Food Through the Digestive System

1. Mouth:
   • Teeth reduce the size of food, increasing the surface area for digestion by enzymes.
   • Enzymes in saliva start breaking down carbohydrates.
2. Pharynx:
   • Connects the oral cavity to the esophagus.
   • Epiglottis blocks the windpipe to prevent food from entering the lungs.
3. Esophagus:
   • Transports food to the stomach via peristalsis (rhythmic muscle contractions).
4. Stomach:
   • Acidic gastric juices start breaking down food.
   • Pepsin breaks down proteins.
   • Mucus prevents gastric juices from breaking down the stomach lining.
   • Pyloric sphincter regulates the movement of food from the stomach to the small intestine.
5. Small Intestine:
   • Most digestion of carbohydrates, proteins, and fats occurs here.
   • Nutrients are absorbed into the bloodstream.
6. Large Intestine:
   • Water is reabsorbed.
7. Rectum:
   • Undigested materials are excreted as feces.

Digestive Tract Structure

• Central Structure: Muscular tube called the digestive tract (mouth to anus).
• Accessory Digestive Organs:
  • Liver, gallbladder, pancreas, salivary glands.
• Divisions:
  • Oral cavity (mouth) and pharynx.
  • Esophagus (delivers food to stomach).
  • Stomach (preliminary digestion).
  • Small intestine (most digestion and nutrient absorption).
  • Large intestine (water absorption and some nutrient absorption).
  • Rectum (waste storage).
  • Anus.

Time Spent in Digestive Organs

• Mouth: Less than a minute.
• Stomach: About 1-2 hours.
• Small intestine: 7-8 hours.
• Colon (large intestine): About 12-14 hours.

Movement of Food

• Food is pushed along by peristalsis (rhythmic contractions of smooth muscles).
• Valves called sphincters regulate the movement of material between compartments.
• Food is pushed by the tongue into the pharynx and moves to the esophagus via muscle contraction.
• Esophagus muscle contractions and gravity push food into the stomach.

Stomach Digestion

• Digests food through mechanical churning and chemical means.
• Proteins are a primary target of the stomach’s digestive juices.
• Stomach contents are very acidic, breaking down food and killing microorganisms.
• Material leaving the stomach is a mixture of food and digestive juices called chyme.

Small Intestine Sections

• Duodenum: Receives chyme from the stomach and secretions from the pancreas and liver.
• Jejunum: Region of most digestion and nutrient absorption.
• Ileum: Absorption continues.

Accessory Organs: Liver, Pancreas, and Gallbladder

• Pancreas: Secretes digestive enzymes and buffers into the small intestine.
  • Enzymes help break down fats, proteins, and carbohydrates.
  • Buffers raise the pH of the acidic chyme coming from the stomach.
• Liver:
  • Produces bile to help dissolve fats in the small intestine.
  • Helps metabolize toxins (alcohol and other drugs).
  • Controls which nutrients will be stored and which will be sent into circulation.
• Gallbladder: Stores and concentrates bile produced by the liver.

Nutrient Absorption in the Small Intestine

• Intestinal folds, villi, and microvilli increase the absorption surface area.
• 90% of the digestive tract's nutrient absorption occurs in the small intestine.
• Absorbed nutrients are taken up by adjacent capillaries (carbohydrates and proteins) or lymphatic vessels (fats).

Large Intestine

• Holds and compacts material left over from digestion, turning it into feces.
• Feces pass through the rectum and anus to exit the body.
• Absorbs water and vitamins produced by resident bacteria (the gut microbiome).

Urinary System Functions and Components

• Filters bodily fluids, removes waste, and conserves water and other materials.
• Major organs: Kidneys, ureters, urinary bladder, urethra.
• Functions:
  • Filters waste materials from the blood.
  • Regulates blood volume.
  • Conserves useful materials.
• Kidney: Produces urine.
• Ureter: Transports urine toward urinary bladder.
• Urinary bladder: Temporarily stores urine.
• Urethra: Transports urine out of body.

Nephron

• The nephron is the (microscopic) functional unit of the kidney
• Each kidney contains about 1 million nephrons
• Each nephron is made out of manycells

Male and Female Urinary Tracts

• Male urinary tract

  • Urethra: transports urine from urinary bladder to exterior of body

• Female urinary tract

  • Shorter urethra = more UTIs
  • Urethra: transports urine from urinary bladder to exterior of body

System Interactions

• Respiratory system moves O2 into, and CO2 out of, the body.
• Cardiovascular system transports materials to and from all other systems.
• Digestive system transforms food into a form that can be transported throughout the body.
• Urinary system filters bodily fluids, removes waste while conserving water and other materials.

Cardiovascular System

• Components: Heart, blood vessels, blood, and bone marrow tissue.
• Fluid transport system that consists of:
  • the heart
  • blood vessels
  • the blood
  • and the bone marrow tissue: where blood cells are formed
• Transports substances to and from the body’s cells, including oxygen, carbon dioxide, nutrients, hormones, waste products, and immune system cells and proteins.

Composition of Blood

• Two primary components:
  • Formed elements (blood cells and cell fragments).
  • Blood plasma (fluid portion in which formed elements are suspended).

Formed Elements of Blood

• Three kinds:
  • Red blood cells.
  • White blood cells.
  • Platelets.
• Red blood cells carry oxygen to, and carbon dioxide from, every part of the body.
• White blood cells are central to the immune system.
• Platelets are important in the blood-clotting process.

Blood Plasma

• 92% water, but also contains proteins, nutrients, hormones, wastes, etc.
• Plasma proteins:
  • Albumins: transport hormones and fatty acids and maintain proper osmotic pressure.
  • Fibrinogen: aids in blood clotting.
  • Globulins: aid the immune system and serve as transport proteins.

Blood Vessels

• Arteries: carry blood away from the heart.
• Veins: return blood to the heart.
• Capillaries: connect arteries with veins.
• Arteries and veins include an inner layer of epithelial cells, a middle layer of smooth muscle that allows arteries and veins to widen or constrict in diameter, and an outer layer of connective tissue.
• Capillaries are composed of only a single layer of cells. This allows the movement of blood-borne materials into and out of them along their length.

Blood Circulation

• Pulmonary circulation: Blood circulates between the heart and the lungs (blood is oxygenated).
• Systemic circulation: Blood circulates between the heart and the rest of the body (needed materials are transported to and from all parts of the body).
• The human heart contains 4 muscular chambers:
  • 2 for pulmonary circulation (the right atrium and right ventricle)
  • 2 for systemic circulation (the left atrium and left ventricle).
• A series of valves that open and close ensures that blood flows only one way through the heart.

Heart Rate Control

• Controlled by a specialized set of muscle cells within the heart itself.
• These cells, which form the heart’s sinoatrial node, generate electrical signals that prompt heart muscles to contract.

Heart Attacks

• Nearly 20% of all deaths in the United States today are caused by the blockage of one or more of the coronary arteries that supply heart tissue with blood.
• Normally caused by a buildup of plaque in the wall of a coronary artery, followed by a movement of plaque into the bloodstream, and then formation of a blood clot.
• A heart attack occurs when this process results in the complete blockage of a coronary artery, which cuts off the blood supply to groups of cells within the heart, thus killing them.

Respiratory System

• The central function of the respiratory system is to capture oxygen and to dispose of carbon dioxide.
• It also aids in controlling pH balance in the bloodstream and in producing sounds for speaking.

Components of the Respiratory System

• The nose, nasal cavity, and sinuses.
• Pharynx (upper throat).
• The conducting passageways (bronchi and bronchioles) that lead to the lungs.
• Larynx (voice box).
• Trachea (windpipe).
• The lungs are composed of alveoli (air exchange chambers).

Steps in Respiration

1. Breathing or ventilation is the physical movement of air into and out of the lungs.
2. Gas exchange.

Ventilation

• Physical movement of air into and out of the lungs.
• Elevation of rib cage and contraction of diaphragm decrease pressure in the lungs, causing air to flow in.
• Depression of rib cage and elevation of diaphragm increase pressure in lungs causing air to flow out.

Gas Exchange

• Once in the lungs, oxygen diffuses across the thin wall of an alveolus into an adjacent capillary and binds with hemoglobin protein in red blood cells.
• Oxygen then moves with the blood cells to the heart.
• The heart pumps the blood to body tissues, where the oxygen diffuses into the interstitial fluid and then into nearby cells.
• The carbon dioxide produced in the body's cells moves into nearby capillaries, to be carried to the lungs.