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Tissues
Groups of cells that have a common structure and function
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Organs
Functional units of tissues
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Epithelial tissue
- Sheets of tightly packed cells, covers body, lines organs, acts as protective barrier
- One side bound to basement membrane
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Connective tissue
- Sports and binds other tissues
- Scattered cells within extra cellular matrix
- Cartilage, tendons, ligaments, bone, blood
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Muscle tissue
- Responsible for body movement
- Made of myosin and actin
- Fibers contract when stimulated by nerve impulse
- Skeletal, cardiac, smooth
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Nervous tissue
Senses stimuli and transmits signals
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2 major organ systems specialized in control and coordination
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Endocrine system
- Hormones are released into blood stream and spread throughout body.
- Hormones only cause effects in cells with specific receptors for that hormone
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Nervous system
- Neurons transmit info between specific locations
- Only 3 types of cells receive nerve impulses: neurons, muscle cells, endocrine cells
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Homeostasis
Animals maintain relatively constant internal environment, Ben when the external environment changes significantly
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Set point
- Homeostatic control system
- Sensors to detect any stimulus above or below the set point, and a physiological response Helps rerun the body for its set point
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Negative feedback system
- Animal responds to stimulus in a way that reduces the stimulus
- In response to exercise, body temp rises, which initiates sweating to cool the body
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Positive feedback system
- Change in some variable triggers mechanisms that amplify the change.
- Childbirth, pressure of head against receptors near opening stimulates greater contractions, which cause greater pressure against the opening , which heightens the contractions.
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Thermoregulation
How animals maintain their internal temperature within a tolerable range
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Endotherms
- Mammals and birds
- Warmed mostly by heat generated by metabolism
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Ectotherms
- Up invertebrates, fish, amphibians, reptiles
- Generate little metabolic heat, get most of their heat from external sources
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Countercurrent exchange
Heat transfer involves anti parallel arrangement of blood vessels such that warm blood from the core of the animal, en route to the extremities. Heat that would have been lost to the environment is conserved in the blood returning to the core of the animal.
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