Protection, Support & Movement GEC_MT109: Lecture Topic 6 __________ GLORINA DIVINA P. OROZCO, LPT, Ph.D. CASE – Biology Dept Learning Outcomes: Section 6.1 • Describe the integumentary system of invertebrates. • Explain the difference between hair and nails. Protection: Integumentary Systems • The integumentary system is the external covering of an animal. • It primarily protects against mechanical injury and invasion by microorganisms. • Some diverse integumentary functions that have evolved include: – Regulation of body temperature – Excretion of wastes – Vitamin D formation Protection: Integumentary Systems (continued) – Reception of environmental stimuli such as: • Pain • Temperature • Pressure – Locomotion – Movement of nutrients and gases The Integumentary System of Invertebrates • Single-celled protozoa have only a plasma membrane for an external covering. • Other protozoa have a thick covering called a pellicle, outside the plasma membrane. • Most invertebrates have n integument consisting of a single layer of columnar epithelial cells called an epidermis(figure 6.1). • Specializations outside of this epithelial layer may be in the form of cuticles, shells, or teguments (figure 6.2a,b). Figure 6.1 Integument of Invertebrates. The Integumentary System of Vertebrates • Skin is the vertebrate integument. • Skin has two main layers: – The epidermis – The dermis • A hypodermis consists of loose connective tissue, adipose tissue, and nerve endings, and separates the skin from the deeper tissues. Figure 6.2 Cuticles. (a) A crustacean cuticle. (b) An insect cuticle. Figure 6.2 Cuticles. (a) A crustacean cuticle. (b) An insect cuticle The Integumentary System of Vertebrates (continued) • The skin of jawless fishes – Jawless fishes, such as lampreys and hagfishes, have relatively thick skin (figure 6.3). – The skin of cartilaginous fishes (e.g., sharks) is multilayered and contains mucous and sensory cells (figure 6.4). – The skin of bony fishes (teleosts) contains scales (figure 6.5). – The skin of amphibians consists of a stratified epidermis and a dermis containing mucous and serous glands plus pigmentation cells (figure 6.6). The Integumentary System of Vertebrates (continued) – The skin of nonavian reptiles reflects their greater commitment to a terrestrial existence (figure 6.7). – The skin of avian reptiles shows many typically reptilian features with no epidermal glands (figure 6.8). – The skin of mammals consists of several layers of a variety of cells (figure 6.9). Figure 6.3 Skin of Jawless Fishes Figure 6.4 Skin of Cartilaginous Fishes. Figure 6.5 Skin of Bony Fishes. Figure 6.9 Skin of Mammals. The Integumentary System of Vertebrates (continued) – The notable features of mammalian skin are: • Hair • A greater variety of epidermal glands than in any other vertebrate class • A highly stratified, cornified, epidermis • A dermis many times thicker than the epidermis • Hair is composed of keratin-filled dead cells that develop from the epidermis. • Nails, like hair, are modifications of the epidermis and are flat, horny plates on the dorsal surface of the digits. Learning Outcome: Section 6.2 • Compare hydrostatic skeletons, exoskeletons, and endoskeletons. The Skeletal System of Invertebrates • Animals have three types of skeletons: – Hydrostatic skeletons – Exoskeletons – Endoskeletons • These skeletons function in animal movement that requires muscles working in opposition (antagonism) to each other. The Skeletal System of Invertebrates (continued) • The hydrostatic skeleton is a core of liquid (water or a body fluid such as blood) surrounded by a tension-resistant sheath of longitudinal and/or circular muscle (figures 6.10a-c). • Hydrostatic skeletons are found in invertebrates and can take many forms and shapes: – – – – – The gastrovascular cavity of acoelomates The rhynchocoel in nemerteans A pseudocoelom in aschelminths A coelom in annelids A hemocoel in molluscs Figure 6.10a Hydrostatic Skeletons. (a) Sea anemones. Figure 6.10b How a hydrostatic skeleton changes to shorten or open. Figure 6.10bc The Skeletal System of Invertebrates (continued) • Rigid exoskeletons have locomotor functions because they provide sites for muscle attachment and counter-forces for muscle movements. • Exoskeletons also support and protect the body, but these are secondary functions. • Certain regions of the arthropod body have a thin’ flexible cuticle and joints (figure 5.11). • The exoskeleton of invertebrates also contains calcium carbonate crystals that make it hard and inflexible, except at the joints. Figure 6.11 Exoskeletons. (a) A cicada nymph. Figure 6.11b Articulation of an arthropod limb. The Skeletal System of Vertebrates • The most familiar endoskeletons, both cartilaginous and bony, first appeared in the vertebrates. • This endoskeleton consists of two main types of supportive tissue: – Cartilage • Provides a site for muscle attachment • Aid in movement at joints • Provides support The Skeletal System of Vertebrates (continued) – Bone (figure 6.12) • Provides a point of attachment for muscles • Transmits the force of muscle contraction from one part of the body to another – The skeleton of fishes – Most jawed fishes have an axial skeleton. (figure 6.13) – The skeleton of tetrapods evolved to be supportive on land (figure 6.14). The Skeletal System of Vertebrates (continued) • The human skeleton has two major parts: – The axial skeleton • • • • Skull Vertebral column Sternum ribs – The appendicular skeleton • Appendages • Pectoral girdle • Pelvic girdles 28 Human Skeletal System © 2019 McGraw-Hill Education Frog Skeletal System Figure 6.13 Fish Endoskeleton. Figure 6.12 Bone. Learning Outcomes: Section 6.3 • Describe three types of nonmuscular movements. • Explain the sliding-filament mechanisms of muscle contraction. Movement: Nonmuscular Movement and Muscular Systems • Movement (locomotion) is characteristic of certain cells, protists, and animals. • Nonmuscular movement involves the following structures: – Pseudopodia – Cilia – Flagella • The contractile proteins actin and myosine are involved. Movement: Nonmuscular Movement and Muscular Systems (continued) • Amoeboid movement does not involve muscles. – Pseudopodia are involved (figure 6.15). – Ciliary movement involves metachronal (coordinated) waves passing along rows of cilia (figure 6.16). Figure 6.15 Mechanism of Amoeboid Movement. Figure 6.16 Ciliary Movement. Protists’ Movement https://youtu.be/Ln69k7LyTsU An Introduction to Animal Muscles • Animals may have one or more of the following types of muscle tissue: – Smooth muscle – Skeletal muscle – Cardiac muscle • Muscle tissue exhibits contractility, excitability, extensibility, and elasticity. An Introduction to Animal Muscles (continued) • The muscular system of invertebrates – Locomotion of soft-body invertebrates involves: • Pedal locomotion in snails and planarians • Successive muscle contraction in earthworms (figure 6.17) • Looping movements in leeches (figure 6.18) • Water-vascular system of echinoderms (figure 6.20) • Terrestrial locomotion in invertebrates also involves walking (figure 6.22). • Flight • Jumping (6.23) Figure 5.17 Successive Stages in Earthworm Movement. Figure 6.18 Looping Movements. Figure 6.19 WaterVascular System of an Echinoderm. Figure 6.20 Jump of a Flea. The Muscular System of Vertebrates • Most of the musculature of fishes consists of segmental myomeres (figure 6.24). • Skeletal muscle structure is illustrated in figure 6.25. • The sliding-filament model of muscle contraction is shown in figure 6.26. – This involves sliding of myofilaments within myofibrils. • The nerve-muscle motor unit is shown in figure 6.27. – Nerves control skeletal muscle contraction. – The process of contraction is controlled by calcium ions (figure 6.28). Figure 6.24a Fish Musculature. Figure 6.25 Structure of Skeletal Muscle Tissue. Figure 6.26 Sliding-Filament Model of Muscle Contraction Figure 6.27 Nerve-Muscle Motor Unit, https://drive.google.com/file/d/17bQCQjQP9CAiTOD4MoJ3AgF7cBpJ6IJ4/vie w?usp=sharing Overview of Muscle Anatomy & Contraction Figure 6.28 Model of Calcium-Induced Changes in Troponin That Allow Cross-Bridges to Form Between Actin and Myosin. https://drive.google.com/file/d/1ZeErnMbOTSBUl_q5sXChdHpSSbsYJ WEr/view?usp=sharing Action Potential & Actin-Myosin Binding Thank you for listening!! Be ready for a QUIZ next meeting