Animal Tissues & Systems for Homeostasis

1. Animal Form & Function

2. Chapter 40 • Levels of organization • Tissues (group of cells with common structure & function) • Organs (functional units of tissues) • Organ systems (organs that work together)

3. 4 main types of tissue: • 1) Epithelial • Sheets of tightly packed cells, covers the body, lines organs, and protects • One side is always bound to a basement membrane • Other side faces air or fluid environment • 2) Connective • Supports and binds • Cartilage, tendons, ligaments, bone, & blood

4. 3) Muscle • Body movement • Muscle filaments are made of actin & myosin (proteins) • The fibers contract when stimulated by a nerve • Most abundant tissue in animals • 3 types: • Skeletal – used for movement & is voluntary • Smooth – found in organs & is involuntary • Cardiac – in heart & is involuntary

5. 4) Nervous • Functional unit is a nerve cell (neuron) • Senses stimuli & transmits signals from one part of the body to another

6. 2 major systems that coordinate and control the tissue, organ, and organ systems of animals: • 1) Endocrine • Hormones are chemical messengers • Carried in the blood to all parts of the body • Hormones have specific functions, but only with cells with specific receptors • Come from glands (pituitary, thyroid, etc.) • 2) Nervous • Transmit information between locations • 3 types of cells receive nerve impulses: neurons, muscle cells, & endocrine cells

7. Homeostasis – constant internal environment • The body has a “set point” (i.e. body temp), sensors to detect any variation in the set pt, & physiological responses to help return to the set pt

8. Physiological responses: • 1) Negative feedback loop • Respond to stimulus in a way that reduces the stimulus • Ex: in response to exercise, the body temp rises, which initiates sweating • 2) Positive feedback loop • A variable triggers mechanisms that amplify rather than reverse the change • Ex: childbirth – stimulates uterine contractions

9. Thermoregulation = how animals maintain their internal temperature • Endotherms (mammals/birds) use heat generated by metabolism (warm blooded) • Ectotherms (invertebrates, fish, reptiles) use heat from external sources (cold blooded)

10. Chapter 41 • 4 classes of essential nutrients: • 1) Essential amino acids • 12 of 20 • 2) Essential fatty acids • 3) Vitamins • 4) Minerals

11. 4 main stages of food processing: • 1) Ingestion • Taking in food • 2) Digestion • Breaking down food • 3) Absorption • Cells take up small molecules • 4) Elimination • Passing of undigested material

12. Simple animals utilize a gastrovascular canal • Single opening for food and wastes • Worms & hydras use this • Complex animals use alimentary canals • One-way digestive tubes that have 2 openings

13. Movement of food through the DS is controlled by peristalsis • Waves of contractions by smooth muscle • Food is taken into the mouth • Releases saliva • Aids in swallowing • Begins chemical digestion • Contains amylase (breaks down starch & glycogen)

14. The chewed food forms a BOLUS • The bolus then enters the pharynx (throat) • During swallowing, the EPIGLOTTIS covers the trachea so food goes down the ESOPHAGUS • Esophagus moves food to the stomach through peristalsis

15. Stomach – stores food and secretes gastric juices: • 1) Hydrochloric acid • pH of 2 • Breaks down meat and plants • Kills most bacteria • 2) Pepsin • Hydrolyzes proteins

16. End result of the stomach work is acid chyme which is moved to the small intestine • Duodenum – major site of chemical digestion (1st section of SI) • Works with pancreas & liver • Pancreas produces a buffer • Liver produces bile (fat breakdown)

17. Chemical breakdown in duodenum: • 1) Carbs • amylases • 2) Proteins • Pepsin/trypsin • 3) Nucleic Acids • Hydrolysis of DNA/RNA • 4) Fats • Bile/lipase

19. Chapter 48 • Nerve cell = neuron • Composed of: • Cell body – contains nucleus & organelles • Dendrites – cell extensions that receive incoming messages • Axons – transmit messages • Many axons are covered by a fatty myelin sheath • Speeds rate of transmission

21. Synapse = junction between neurons • Neurotransmitters are chemical messengers that bind to receptors • Sensory receptors • Collect information about the world outside the body as well as inside (ex: rods/cones of eyes & pressure receptors in the skin)

22. Sensory neurons • Transmit information from sensors to the brain/spinal cord • Interneurons • Connect sensory & motor neurons

23. Chapter 49 • Evolution of nervous system • Cnidarians have a nerve net • Cephalization clusters sensory neurons & interneurons • Flatworms have a small brain & longitudinal nerve cord (simplest Central Nervous System) • Annelids (earthworm) & arthropods have a ventral nerve cord • Vertebrates have a hollow dorsal nerve cord

24. Reflex • Simple automatic nerve circuit in response to a stimulus • Ex: The stimulus is detected by a receptor in the skin, conveyed via a sensory neuron to an interneuron in the spinal cord, which synapses with a motor neuron, which will cause the effector, a muscle cell, to contract

25. Conscious thought is not required in a reflex • Cerebrospinal fluid (CSF) circulates through a central canal in the spinal cord & ventricles of the brain – cushions the brain & spinal cord

26. Gilia – support neurons • Astrocytes (support neurons) • Oligodendrocytes (form myelin sheaths in CNS) • Schwann cells (form sheaths in PNS) • Gray matter • Mainly neuron cell bodies & unmyelinated axons • White matter • White due to the myelin sheaths • Gilia – support neurons • Astrocytes (support neurons) • Oligodendrocytes (form myelin sheaths in CNS) • Schwann cells (form sheaths in PNS) • Gray matter • Mainly neuron cell bodies & unmyelinated axons • White matter • White due to the myelin sheaths

29. Main Brain Anatomy • 1) Brainstem • Medulla oblongata, pons, midbrain • Controls homeostatic functions – breathing rate • Conducts sensory & motor signals between the spinal cord and higher brain centers • Regulates arousal and sleep

30. 2) Cerebellum • Coordinates motor, perceptual, & cognitive functions • Balance

31. 3) Cerebrum • Largest part of the brain • Has left/right hemispheres • Covering of gray matter over white matter • Information processing • Thinking, learning, remembering

33. Other brain parts • Thalamus • Main center through which sensory & motor information passes to & from the cerebrum • Hypothalamus • Regulates homeostasis • Feeding, fighting, fleeing, reproducing, circadian rhythms • Cerebral cortex • controls voluntary movement & cognitive functions • Corpus callosum • Enables communication between left/right hemispheres

34. Chapter 51 • Behavior • What an animal does and how it does it • Result of genetics & environment • Essential for survival & reproduction • Subject to natural selection • Ethology • Study of animal behavior

35. 2 levels of analysis in the study of behavior: • 1) Proximate • The “how” questions & include effects of heredity, genetic-environmental interactions, & sensory-motor mechanisms • 2) Ultimate • The “why” questions & studies of origin of behavior, change over time, & reproductive success

36. Innate behavior • Developmentally fixed – unlearned • Nursing in mammals • Fixed action pattern (FAP) • Sequence of unlearned acts that is largely unchangeable & carried to completion when started • Triggered by sign stimuli • EX: male stickle-back fish which attack red objects – the red object is the sign stimulus, attack is FAP

37. Kinesis • Simple change in activity in response to stimulus • Ex: pillbugs to moisture • Taxis • Automatic movement toward or away from a stimulus • Ex: moths to light • Migration • Complex • Attributed to detection of Earth’s magnetic field or visual cues

38. Circadian rhythms • Occur daily • Signal • A behavior that causes a change in the behavior of another – basis for animal communication • 1) Pheromones – chemical signals • 2) Visual Signals – warning flashes, markings • 3) Auditory Signals – sounds, screeches, growls • 4) Waggle dance – done by honeybees • http://www.youtube.com/watch?v=-7ijI-g4jHg

39. 51.2 • Learning • Modification of behavior based on experiences • Imprinting • Combination of learned & innate components that are limited to a sensitive period in an organisms life and is generally irreversible • Konrad Lorenz • http://www.youtube.com/watch?v=2UIU9XH-mUI&feature=related

40. Habituation • Loss of responsiveness to stimuli • Simple form of learning • Cognitive map • Internal representation of spatial relationship among objects in an animal’s surroundings

41. Associative learning: • Ability of many animals to associate one feature of their environment with another feature • Two types:

42. 1) Classical Conditioning • Learning to associate certain stimuli with reward or punishment • Pavlov

44. 2) Operant conditioning • Occurs as an animal learns to associate one of its behaviors with a reward or punishment • B.F. Skinner

45. Skinner Box

46. 51.3 • Both environment and genetics contribute to behavior

47. 51.4 • Survival and reproductive success • Foraging behavior • Not only eating, but mechanisms used in searching for, recognizing, & capturing food • Optimal foraging model • A compromise between benefits of nutrition & cost of obtaining food

48. Mating systems – varies • 1) Promiscuous – no strong pair-bonds • 2) Monogamous – one male/one female • 3) Polygamous – one individual mating with others

49. 51.5 • Altruism • When animals behave in ways that reduce their individual fitness but increases the fitness of other individuals in the population • Ex: blue jay giving an alarm call • Inclusive fitness • Total effect an individual has on proliferating its genes by producing its own offspring • Provides aid that enables other close relatives to produce offspring • “kin selection”