a. Describe a key function of each of the four types of tissues found in animals. 1. Epithelial tissue (squamous, columnar, cuboidal) makes up the lining and coverings. This type of tissue is found in the skin (epidermis and dermis), surrounding the organs of the body, and outer layer of capillaries (diffusion). 2. Connective tissue (loose, adipose, blood, fibrous, bone) holds organs in place and attaches epithelial tissue to other underlying tissues. A collagenous fiber is a dense connective tissue which can be regular or irregular. Regular dense collagen fibers are found in the tendons, which bind muscle to bone, and ligaments, which join bones together. Blood connective tissue is used in transporting substances from one part of the body to another. Adipose tissue stores large droplets of fat that swells when stored and shrinks when used for energy. Bone is rigid connective tissue which provides support for muscle attachment and protects internal organs. 3. Smooth muscle tissue is found surrounding hollow tubes and wave like contractions move food particles through the alimentary canal. Cardiac muscle tissues have intercalated discs where the plasma membrane interlocks. Cardiac muscle tissue holds cells together and allows ions and impulses to travel cell to cell. Skeletal muscle tissue is used for movement and posture, breathing by the diaphragm, and the excretion of waste by sphincters. 4. Nerve tissue sense stimuli and transmit signals from one part of the body to another. Neurons are the basic unit of nervous tissue. Axons carry signals away from the cell body and dendrites carry signals toward the cell body. Nervous tissue provides support for the brain, controls metabolic activities and powers neurons by synthesizing energy and is in charge of the neuron’s growth and repair. b. Explain the difference between negative and positive feedback control mechanisms. 1. Feedback mechanisms are seen in such things as homeostasis. Negative feedback control mechanism can detect a variable that deviates from a specific set point and helps reduce it back to the original state. Positive feedback rarely occurs in the body. Positive feedback notices a deviation from the set point and pushes the variable even further away. Blood clotting is an example of positive feedback. Platelets that clot to stop the bleeding is increasing and growing away from the original set point rather than decreasing as you would see with negative feedback. Negative feedback examples are regulating temperature, blood pressure, hunger (metabolism slows when hungry to conserve energy), insulin and production of blood cells (decrease in O2 detected by kidneys which secrete erythropoietin to stimulate production). c. What is the nature (characteristic) of the negative feedback information used by the mammalian thermostat for thermoregulation. 1. The mammalian thermoregulatory system has adjustable points and integrates sources of information to hypothalamic temperature. Examples are the sensors in the skin register environmental temperature; change in skin temperature sends feedforward information that causes a negative feedback of the hypothalamic set point for thermoregulation. Metabolic heat set point is higher when skin is cold and lower when skin is warm. 2. Exogenous pyrogens are molecules that come from foreign substances in the body such as bacteria or viruses. The body produces endogenous pyrogens (immune system produced) to fight the infection. The detection of pyrogen in the body sends a negative feedback to the hypothalamus and the hypothalamic set point sends a heat production response. This results in shivering, sweating, etc. Chapter 41
a. List the 5 major parts of the mammalian digestive tract and state the major function(s) of each part. (Don’t include accessory glands)
1. Mouth breaks down food mechanically by the action of the teeth creating a larger surface area of the organic nutrients in order to...