Cell Communication

1. Cell Communication Chapter 11

2. Cells most often communicate with each other via chemical signals. • Evolution of Cell Signaling • Cell signaling pathways evolved first in: • Microbes (yeast, bacteria) communicate in ways very similar to mammal cells! • The process of converting a signal on the cell’s surface to a specific response is called a: ancient prokaryotes & single-celled eukaryotes signal-transduction pathway

3. Calling locally vs. Long distance • There are 2 types of Communication between nearby cells: • Paracrine signaling = a secreting cell discharges a ____________________ molecule into the extracellular fluid: • Synaptic signaling = a nerve cell discharges a ________________________ molecule into the • Narrow synaptic space between nerve and target cell: local regulator (affects all nearby cells) neurotransmitter affects only target cell(s)

4. Calling locally vs. Long distance • Long Distance Communication: • Hormonal signaling = also called ________________ signaling, occurs when • hormones are released into the __________________________ (animals) • Remember from Chapter 7 that cells can also communicate by direct contact, via _______________________ endocrine bloodstream cell junctions

5. Signal-transduction Pathways: Have three stages Reception: Transduction: receptor molecule changes and causes a sequence of changes in a series of molecules Response: Earl Sutherland figured out this process while studying: signal molecule binds to receptors on a cell’s surface a specific cellular response is triggered epinephrine

6. RECEPTION: • A signal molecule or ____________, binds a specific receptor & (typically) changes its shape. • Receptors: • THREE MAJOR TYPES OF RECEPTORS: • G-protein-linked receptor – Works with help from a __________________ G protein and another protein (usually an enzyme) ligand usually plasma membrane proteins cytoplasmic

7. RECEPTION: • THREE MAJOR TYPES OF RECEPTORS: • Tyrosine-Kinase Receptor – Receptor is an ___________________, phosphorylates, triggers many pathways at once. enzyme

8. THREE MAJOR TYPES OF RECEPTORS: Ion-Channel Receptor – Transport protein opens or closes to INTRACELLULAR RECEPTORS: Some receptors are proteins in the ___________________. They can only be activated by signals which can: regulate ion flow. cytosol or nucleus enter the plasma membrane (steroids)

9. SIGNAL-TRANSDUCTION: • A signal must travel through the target cell to trigger a response. • Signals are transduced in many steps: • Second messengers: usually conformational changes in proteins • Many are phosphorylation cascades cAMP and Ca2+ can diffuse through cytosol & transmit signal quickly • Links to disease and medical research: inability for G-protein to hydrolyze GTP- remains on and producing cAMP- so digestive system excretes excess water= Cholera • Viagra- relaxation of arterial walls resulting in dilation- controlled by a molecule similar to cAMP

10. CELLULAR RESPONSE:Three main types of activities triggered by signals: • Specific enzymes can be controlled. Ex: Storage and release of glucose • Cytoskeleton can be rearranged • Many pathways regulate genes • (Regulate transcription and translation)

11. Amplify the signal- 1signal ligand can activate multiple intermediates • Specificity of signal- response depends on target cell’s enzyme • cascade proteins Example: epinephrine has a different outcome in a liver cell compared to other cells FINE TUNING THE RESPONSE:

12. Scaffolding proteins: Hold multiple components of a pathway together – receptor, enzymes… • Increase signal-transduction efficiency SAP97 (shown as red and yellow ribbon) is a “scaffolding” protein in the central nervous system. It serves as a sort of tether, grabbing proteins inside the cell critical to nerve signaling and keeping them close to N-methyl-D-asparate (NMDA) receptors at the cell surface. NMDA receptors help usher in a neurotransmitter called glutamate that is essential for learning and memory and also plays a role in drug addiction.

13. Chapter 40: Animal Form & Function

14. Ch.40: “Animal Form & Function” This unit focuses on animal form and function. A comparative approach examines ALL levels of animal life (and even some animal-like protists). Common Problems faced by animals include how to: Exchange gases Obtain nutrients Reproduce

15. Two main themes: • Correlation of structure & function: • Capacity of life to adjust to environment on 2 temporal scales: • Short term (regulation) = • Long term = Anatomy & Physiology physiological response (Example: hot – sweat) adaptation via natural selection (evolution)

16. Structural Hierarchy of Life: • Tissue: Group of cells with • common structure & function. • Held together by: • Four main types of animal tissue. ...cell, tissue, organ, system... sticky extracellular matrix that coats the cells or weaves them together. (the word “tissue” = Latin “weave”)

17. Epithelial Tissue • Covers outside of body, lines organs and body cavities: • Functions: protection, absorption, secretion • Parts: Free surface (exposed to air or fluid), cell layer(s), basement membrane: tightly packed together structure fits function.

19. Classifications by layers: • Simple epithelium: single layer • Stratified epithelium: • Pseudostratified epithelium: single layer, but appears stratified because: • Classifications by shape: (based on the shape of the cells at the free surface) • Cuboidal • Columnar • Squamous: Simple Cuboidal Epithelial Tissue multiple layers cells vary in length flat like floor tiles

20. Stratified Squamous Epithelial Tissue Ciliated Pseudostratified Columar Epithelial Tissue

21. Connective Tissue • Not tightly packed. Sparse: • Vertebrates have six main types. • Loose Connective Tissue (most abundant type): • Has loosely woven fibers made of 3 kinds of proteins: • Collagenous fibers: • Elastic fibers: • Reticular fibers: branched, tightly woven collagen -- • Among the cells of the loose connective tissue, there are scattered cells of 2 types: • Fibroblasts: secrete extracellular proteins • Macrophages: immune system defense • Binds and supports other tissues. scattered throughout extracellular matrix holds and attaches organs in place strong, resists stretching (collagen protein) stretchy (elastin protein) connects dissimilar tissue

22. (Connective Tissue continued) • Adipose Tissue: • Fibrous Connective Tissue: very dense, found in: • Tendons: • Ligaments: specialized to store fat (pads & insulates body) attach muscle to bone attach bone to bone at joints

23. (Connective Tissue continued) • Cartilage: • Made of collagen fibers embedded in chondroitinsulfate (secreted by chondrocytes.) • Bone: • osteoblasts (bone forming cells) secrete collagen which combines with: • Osteocytes: mature cells trapped within the matrix of minerals • Blood: Connective tissue with a liquid matrix (plasma) -- • Three types of cells: strong yet flexible Ca, Mg, & phosphate ions made in red marrow leukocytes, erythrocytes, platelets (cell fragments)

24. SEM (Scanning Electron Microscope) image of a white blood cell, platelet and red blood cell. White blood cells or leucocytes (far right) fight infection by producing antibodies or devouring invading bacteria. Red blood cells or erythrocytes (far left) carry oxygen from the lungs to the rest of the body. Platelets (middle) are cell fragments that play a role in the ability of blood to clot.

25. Nervous Tissue • Senses stimuli and: • Functional Unit = • Muscle Tissue • Made of long cells which respond to nerve impulses • Capable of considerable: • Most abundant tissue in most animals: • 3 types: Skeletal, cardiac, smooth (more about this later!) transmits signals neuron (nerve cell) contraction 2/3 of a healthy human’s bulk!

26. Organs: Found in all animals except sponges & some cnidarians Made of: Mesenteries: Mammals have a diaphragm to separate: organized tissues. May be in layers. Guess this Organ: Tongue sheets of connective tissue which suspend many Vertebrate organs Kidney Lung thoracic (chest) & abdominal cavities

27. Animal Size & Shape: depends upon how it interacts w/ environment • Must be able to exchange: • Every cell must be bathed in fluid: • Complex animals rely on: • Vertebrate bodies: O2, CO2, nutrients and waste for diffusion to occur branching, folding, &/or circulatory systems interstitial fluid fills spaces between cells (advantage because the chemical makeup of this fluid is controlled by us – not the environment)

28. Internal Environment: Animals maintain homeostasis (“steady state”) – • Relies on 3 parts: receptor, control center, effector • Controlled by feedback mechanisms: • Negative Feedback (controlled by hypothalamus in brain): • Positive Feedback (less frequent): it actually fluctuates reverse changes back to normal (control body temp) intensifies change until completion returns body to normal (uterus contractions)

29. Organ Systems (Main Functions) Digestive: MOUTH, PHARYNX, ESOPHAGUS, STOMACH, INTESTINES, PANCREAS, LIVER, ANUS food processing and solid waste disposal Circulatory: HEART, BLOOD VESSELS, BLOOD transport of materials within body

30. Respiratory: LUNGS, TRACHEA, BRONCHI, BRONCHIOLES, ALVEOLI gas exchange Immune & Lymphatic: BONE MARROW, LYMPH NODES, THYMUS, SPLEEN, LYMPH VESSELS, WHITE BLOOD CELLS fighting infections Excretory: KIDNEYS, URETERS, URINARY BLADDER, URETHRA disposal of waste (urine)

31. Endocrine: PITUITARY, THYROID, PANCREAS, AND OTHER HORMONE SECRETING GLANDS coordination of body activities with hormones Reproductive: OVARIES, TESTES AND RELATED ORGANS reproduction Nervous: BRAIN, SPINAL CORD, NERVES, SENSORY ORGANS coordination of body activities with electrical impulses

32. Integumentary: SKIN, HAIR, CLAWS, SWEAT GLANDS injury protection, waterproofing, and thermoregulation Skeletal: BONES, TENDONS, LIGAMENTS, CARTILAGE support and protection Muscular: SKELETAL , SMOOTH , AND CARDIAC MUSCLES movement, locomotion