bio 3

BIOL 106 Exam 3 Study Guide
Covers material from Chapters 19, 26, 27, 28
Chapter 19 – Human Evolution
• Humans are 99.9% similar at the DNA level
• How did human populations evolve varying skin tones?
o Melanin pigment produced by melanocytes located in the dermis (outermost layer of skin)
that gives skin its color or tone
§ More melanin means darker skin
o Skin tone correlates to geography
§ Peoples populating areas near the equator with higher UV exposure have darker skin
due to more melanin production
§ Peoples populating areas near the poles have reduced UV exposure have lighter
skin, less light less melanin
• Mitochondrial Eve
o DNA is found in the mitochondria of all our cells, we inherit mitochondrial DNA from our
mothers only
§ Mothers pass mitochondrial DNA on to their children
§ All modern humans can trace history back to one female
• Mitochondrial Eve
• Lived in Africa 150,000-200,000 years ago
• Hominids
o Any member of the biological family Hominidae
§ Living and extinct great apes
• Humans, orangutans, gorillas, chimpanzees, bonobos
o Chimpanzees are the most closely related to humans
§ Last common ancestor was shared 7 million years ago
o Evolutionary Milestones in early hominids
§ Australopithecus – 2.6 MYA
• Could walk upright
• Used tools
§ Homo erectus – 800,000 years ago
• Controlled fire
§ Homo sapiens – 800,000-200,000 years ago
• Big brain
• Problem solving
Chapter 26 – Overview of Animal Physiology
• Anatomy - study of the integrated hardware of the body
• Physiology – study of the way a living organism’s physical anatomy functions
• How is the human body organized?
o Levels of organization
§ Cells – smallest anatomical unit
§ Tissues – integrated groups of specialized cells
• Epithelial
• Connective
• Muscle
• nervous
§ Organs – di]erent tissue types working together to carry out common function

§ Organ systems – organs that interact chemically and physically
• Highest level of organization
• Homeostasis – maintaining relatively stable internal environments (set point) even when the external
environment changes
o Temperature (thermoregulation)
§ Regulates body temperature to be maintained around 37°C
§ In cold external environments:
• Vasoconstriction – reduction of blood vessel diameter just below skin
surface
o Redirects blood to core of body to maintain heat
o Decreases heat loss from surface of skin
§ Why our noses, fingers, and toes get cold first
• Shivering – involuntary action of skeletal muscles
o Generates body heat, increasing internal temperature
§ In hot external environments:
• Vasodilation – expansion of blood vessel diameters just below skin surface
o Increases blood flow to the skin
o Increases heat loss
• Sweating – evaporation of water from sweat glands
o Releases heat, reducing internal temperature
o Blood glucose
§ Regulated by hormones released from kidneys
• Insulin – decreases blood sugar
• Glucagon – increases blood sugar
Chapter 27 – Digestive System
• Ingestion – eating a meal
• Digestion – breakdown of food
o Mechanical (physical)
§ Chewing, churning of the stomach
o Chemical
• Waste elimination – removes components of food that aren’t absorbed during digestion
• Components of the Digestive System
o Central Digestive Tract – organs that house food while it is being broken down
§ Upper
• Mouth
• Esophagus – connects mouth to stomach
o Peristalsis
• Stomach
o Chyme
§ Lower
• Small intestine – longest organ in digestive system
o greatest amount of nutrient absorption
o Villi – finger-like extensions from epithelial tissues
§ Increases nutrient absorption
• Large intestine – waste compactor
o Water absorption
o Vitamin and mineral absorption (microbiome)
• Rectum

• Anus
o Accessory Organs – organs that secrete enzymes and other substances to aid in digestion
§ Salivary glands – produce amylase to digest carbohydrates
§ Liver
§ Pancreas
§ Gallbladder
Chapter 28 – Cardiovascular System
Cardiovascular system is composed of:
• Heart - fist sized muscular pump
o Four paired chambers (2 atria, 2 ventricles)
• Blood Vessels – system of tubes of varying diameter that transport blood, gases, and nutrients
o Arteries – vessels that carry oxygenated blood away from the heart
§ High pressure vessels
§ Heart propels blood through arteries (can expand)
§ Aorta - largest artery in the body
o Veins – vessels that return de-oxygenated blood to the heart
o Capillaries – tiny blood vessels located in tissues
§ Narrow and thin cell walls for gas and nutrient exchange (can be only as wide as one
RBC)
• Blood – tissue transport agents (gases, nutrients, wastes, toxins)
o Red blood cells – also called erythrocytes and are involved in carrying oxygen
§ hemoglobin
o Platelets – involved in clotting
o White blood cells – also called leukocytes and are involved in immune response
o Liquid plasma – water and protein
Blood Circulation
• Double circulation – blood passes through the heart 2 times during every trip through the body
(occurs about every minute), each pass has it’s own circuit and function:
o Systemic Circuit
§ Circulation of blood between the heart and the rest of the body
§ Arteries carry oxygen rich blood from the pulmonary circuit away from the heart
§ Veins carry oxygen poor blood from capillaries back to the heart
o Pulmonary Circuit
§ Circulation of blood between the heart and lungs
§ Oxygenation of blood
§ Release of carbon dioxide as waste (product of cellular respiration)
Blood Pressure – calculation of overall pressure in blood vessels
• Based on action of heart muscle
o Systolic Pressure – blood pressure while heart is pumping (driven by pulse)
o Diastolic Pressure – blood pressure between pumps (lower than systolic)
• Blood pressure is calculated by:
o 𝐵𝑙𝑜𝑜𝑑 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 = !"#$%&'( +,##-+,
.'/#$%&'( +,##-+,
Cardiovascular Disease
• Disease of the heart, blood vessels, or both (obstructed flow, blockages)
o Atherosclerosis
o Heart Attack
o Stroke
• #1 silent killer of males and females in the US (32% of annual deaths)