Chapter 40 Animal Form and Function PDF

Chapter 40 13.11.2024 Basic Principles of Animal Form and Function Dr. Salamah Alwahsh...

Chapter 40 13.11.2024 Basic Principles of Animal Form and Function Dr. Salamah Alwahsh Palestine Polytechnic University PowerPoint® Lecture Presentations for Biology for Medical Students Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Hierarchical Organization of Body Plans In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells. Most animals are composed of specialized cells organized into tissues that have different functions. Tissues make up organs, which together make up organ systems. Organ Systems Tissue Structure and Function Different tissues have different structures that are suited to their functions. Tissues are classified into four main categories: Epithelial, connective, muscle, and nervous Epithelial Tissue - Covering and Lining Epithelial tissue covers the outside of the ّ the organs and cavities body and lines ‫تبطن‬ within the body ‫الخاليا التي تشكل االنسجة هذه تكون متراصة ومتّصلة ببعضها‬ ‫البعض‬ Classified on two features: simple, (a single layer of cells), stratified, (more than one cell layer.) Structure and function in animal tissues ‫مكعبية الشكل‬ Epithelial Tissue Cuboidal Simple Pseudostratified epithelium columnar ciliated epithelium columnar epithelium Diffusion, specialized in absorption ‫تساعد على االنتشار واالمتصاص‬ Stratified ‫طبقية‬ squamous epithelium Simple squamous epithelium The shape of epithelial cells may be cuboidal, columnar, or squamous Pseudostratified columnar epithelia line the respiratory tract They exist in one layer, but the arrangement of nuclei at different levels makes it appear that there is more than one layer Goblet cells scattered between the columnar epithelial cells secrete mucous into the respiratory tract  Transitional/ uroepithelial epithilia cells appear only in the urinary system (the bladder and ureter) Cells are arranged in a stratified layer, but they have the capability of appearing to pile up on top of each other in a relaxed, empty bladder, as illustrated in Figure As the urinary bladder fills, the epithelial layer unfolds and expands to hold the volume of urine introduced into it The tissue transitions from thick to thin Simple columnar epithelial cells absorb material from the digestive tract Goblet cells secret mucous into the digestive tract lumen  Connective Tissue Connective tissue mainly binds and supports other tissues It contains sparsely (thinly) packed cells scattered throughout an extracellular matrix The matrix consists of: fibers in a liquid, jellylike (semi-solid), or solid foundation (ground)  There are three types of connective tissue fiber, all made of protein: – Collagenous fibers provide strength and flexibility ‫ مفاجيء‬،‫تلقائي‬ – Elastic fibers stretch and snap back to their original length – Reticular fibers join connective tissue to adjacent tissues Connective tissue The fibers and foundation combine to form six major types of connective tissue: Loose connective tissue binds epithelia to underlying tissues and holds organs in place Cartilage is a strong and flexible support material – Chondrocytes make the matrix and fibers of the tissue Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints It contains large amounts of collagen fibers and few cells or matrix material  Connective Tissue – Adipose tissue stores fat for insulation and fuel – Blood is composed of blood cells and cell fragments in blood plasma – Bone is mineralized matrix and forms the skeleton – Osteon is a subunit of compact bone – Lacuna is a space in cartilage and bone that contains living cells Loose connective tissue is composed of Fibrous connective tissue from the loosely woven collagen and elastic fibers. tendon has strands of collagen The fibers and other fibers lined up in parallel components of the connective tissue Tendons (which connect muscles matrix are secreted by fibroblasts to bones) and ligaments (which connect bones to bones)  Connective Tissue Collagenous fiber Loose Chondrocytes connective Cartilage 120 µm tissue 100 µm Elastic fiber Chondroitin sulfate Nuclei Fat droplets Fibrous connective Adipose 150 µm tissue tissue 30 µm Osteon White blood cells Bone Blood 700 µm 55 µm Osteoblast forms the bones Red blood Central canal Plasma Oseoclast breaks down the bone cells The matrix in connective tissues gives the tissue its density  Muscle Tissue Muscle tissue consists of long cells called muscle fibers, which contract ‫ تنقبض‬in response to nerve signals It is divided in the vertebrate body into three types: – Skeletal muscle or striated muscle, is attached to bones and is responsible for voluntary movement – Smooth muscle mainly lines ‫تبطن‬ّ internal organs and is responsible for involuntary body activities – Cardiac muscle is responsible for contraction of the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Muscle Tissue Multiple nuclei Muscle fiber Sarcomere Skeletal Nucleus Intercalated 100 µm 50 µm muscle disk Cardiac muscle Smooth Nucleus muscle Fusiform/ Muscle spindle- fibers shape 25 µm  Nervous tissue Nervous tissue senses stimuli and transmits signals throughout the animal Nervous tissue contains: – Neurons, or nerve cells, that transmit nerve impulses – Glial cells, or glia, that help nourish ‫تغذي‬, insulate ‫عزل‬, and replenish ‫تزود‬ ّ neurons Nervous Tissue 40 µm Dendrites Cell body Axon Glial cells Neuron Axons Blood vessel 15 µm Coordination and Control Control and coordination within a body depend on the endocrine system and the nervous system. The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood A hormone may affect one or more regions throughout the body Hormones are relatively slow acting, but can have long-lasting effects Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Signaling Stimulus Stimulus Endocrine cell Neuron Axon Signal Hormone Signal travels Signal travels along axon to everywhere a specific via the location. bloodstream. Blood vessel Signal Axons Response Response (a) Signaling by hormones (b) Signaling by neurons  The nervous system transmits information between specific locations Nerve signal transmission is very fast Nerve impulses can be received ‫ تُستَقبل‬by neurons, muscle cells, and endocrine cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Homeostasis Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment. In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mechanisms of Homeostasis Mechanisms of homeostasis moderate changes in the internal environment. For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response. The response returns the variable to the set point. Negative Feedback acts to reverse a trend… To maintain the variable within a narrow range. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings negative Response: Heater feedback turned off Room Stimulus: temperature Control center decreases (thermostat) reads too hot Set point: 20ºC Stimulus: Room Control center temperature (thermostat) increases reads too cold Response: Heater turned on Homeostatic processes for thermoregulation involve form, function, and behavior Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range. Endothermic animals generate heat by metabolism; birds and mammals are endotherms Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non-avian reptiles Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Endotherm is an animal maintains a constant internal body temperature (a) A walrus, an endotherm (b) A lizard, an ectotherm Balancing Heat Loss and Gain: Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation. Heat regulation in mammals often involves the integumentary system: skin, hair, and nails. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mammalian integumentary system Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle  Insulation Insulation is a major thermoregulatory adaptation in mammals and birds. Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Circulatory Adaptations Regulation of blood flow near the body surface significantly affects thermoregulation. In vasodilation, blood flow in the skin increases, facilitating heat loss. In vasoconstriction, blood flow in the skin decreases, lowering heat loss. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water in sweat = evaporative cooling. Panting increases the cooling effect in birds and many mammals. Sweating or bathing moistens the skin, helping to cool an animal down. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Adjusting Metabolic Heat Production Some animals can regulate body temperature by adjusting their rate of metabolic heat production. Heat production is increased by muscle activity such as moving or shivering. Some ectotherms can also shiver to increase body temperature Thermoregulation is controlled by a region of the brain called the hypothalamus. The hypothalamus triggers heat loss or heat generating mechanisms. Fever is the result of a change to the set point for a biological thermostat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Sweat glands secrete sweat, which evaporates, Thermostat in hypothalamus cooling the body. activates cooling mechanisms. Hypothalamus: thermoregulation Blood vessels in skin dilate: capillaries fill; Body temperature heat radiates decreases; from skin. thermostat Increased body shuts off cooling temperature mechanisms. Homeostasis: Internal temperature of 36–38°C Body temperature Decreased body increases; thermostat temperature shuts off warming mechanisms. Blood vessels in skin constrict, reducing heat loss. Thermostat in hypothalamus activates warming mechanisms. Skeletal muscles contract; shivering generates heat. When bacteria are destroyed by leukocytes, pyrogens are released into the blood. Pyrogens reset the body’s thermostat to a higher temperature, resulting in fever Pyrogens increase body temperature by causing the blood vessels to constrict, inducing shivering, and stopping sweat glands from secreting fluid Carbon dioxide is called a “greenhouse” gas as it absorbs infra- red radiation