Chapter 7&8

• hierarchal organization of the animal body from cell to organism. Cell -> Tissue -> Organ -> Organ system -> Organism
• 3 embryonic tissue layers: ectoderm, mesoderm, endoderm
• ectoderm (outer layer) - Epidermis of skin, lining of the oral cavity, nervous system
• Mesoderm (middle layer) - Skeleton, muscles, circulatory system, dermis of skin, reproductive organs
• Endoderm (inner layer)- Inner layer of digestive and respiratory system, major glands (pancreas and liver)
• 4 Adult tissues: epithelial, connective, muscle, nervous
• epithelial: covers surfaces and all 3 germ layers of the body
• connective: derived from the mesoderm, have cell in an extracellular matrix (protein fiber + ground substance (proteins and polysaccharides))
• Muscle tissue: specialized for contraction and is derived from the mesoderm
• Three types of muscle tissue: smooth, skeletal, and cardiac
• Nervous: composed of neurons and neuroglia (supporting cells), produces and conduces electrochemical signals. ectoderm
• skin is the major organ of the integumentary system and accounts 15% of the body weight
• 2 regions of the skin: epidermis, dermis
• epidermis: composed of epithelial tissue, outermost layer of the skin
• Dermis: The outer layer of the skin that gives the skin flexible and elastic properties and contains blood vessels, nerve fibers, sensory receptors, oil and sweat glands, and hair follicles
• Hypodermis or subcutaneous tissue is the layer of fatty tissue beneath the skin (not part of the integumentary system)
• Homeostasis is the maintenance of a constant internal environment despite changes in the external environment.
• Homeostasis in our body controls our temperature, pH, glucose and oxygen concertation using negative feedback
• Homeostasis - Negative feedback: When conditions deviate too far form a set point, a series of biochemical reactions occur to change the conditions back toward the set point. This is called negative feedback.
• Negative feedback is composed of stimulus -> sensor -> integrating center -> effector -> response -> sensor -cycle repeats.
• stimulus: deviation from set point
• sensor: constantly monitors conditions
• integrating center: compared conditions to a set point based on a desired value
• effector: causes changes to compensate for deviation
• response: move system towards set point, if set point is reached, system returns to resting state
• example of negative feedback: body temperature must be carefully regulated. when body temperature decreases, heating mechanism are activated and when body temperature increases, cooling mechanism are activated. both mechanism return the body to an average body temperature.
• homeostasis - positive feedback: actions of the effector is to reinforce rather than reverse the action of the stimulus
• Example of positive feedback is childbirth
• Temperature regulation is the process of maintaining a constant internal body temperature.
• • The body heat of an animal is dependent on the heat produced and heat transferred
• Methos of heat transfer: radiation, conduction, convection and evaporation
• radiation: is heat transfer by electromagnetic radiation (sun)
• conduction: is heat transferred by direct contact, from warmer bodies to cool bodies
• convection: eater or air moving over the surface of an animal con result in heat loss or gain
• evaporation: mechanism of heat loss from an animal body
• Animals are classified based on how body heat is generated: endotherms and ectoderms
• Endotherms: use metabolism to generate body heat and maintain their temperatures above the ambient temperature (birds and mammals)
• ectotherms: have little insulation and high conductivity, fish, amphibians and reptiles, lower metabolic rate and use external sources of heat to warm their bodies
• Smaller mammals have high metabolic rates and need to eat more to maintain their body weight (more energy per unit of body mass)
• smaller organisms (organisms with less mass) have a higher metabolic rate relative to larger organisms. this is because smaller organisms have a smaller surface area to volume ratio and helps maintain a constant internal temperature