Anatomy and Human Physiology: Common Organelles and Cell Functions

1. ANATOMY AND HUMAN PHYSIOLOGYBM2206Dr.V.VASANTHYASSISTANT PROFESSORDEPT OF BIOMEDICAL ENGG.

2. Within cells there is an intricate network of organelles that all have unique functions. These organelles allow the cell to function properly. Arranged below according to location (nucleus, cytoplasm, and surface) is a description of common organelles. You may click on the organelle's name in the list below to directly reach the feature on that structure.

3. Cell wall CentriolesChloroplastsChromosomesCytoskeletonEndoplasmic reticulumNuclear membraneNucleolusGolgi apparatusLysosomeMitochondriaPlasma membraneRibosomesVacuoles

4. - Usually in the form of chromatin- Contains genetic information- Composed of DNA- Thicken for cellular division- Set number per species (i.e. 23 pairs for huma Chromosomes

5. - Surrounds nucleus- Composed of two layers- Numerous openings for nuclear traffic Nuclear membrane

6. Spherical shape- Visible when cell is not dividing- Contains RNA for protein manufacture Nucleolus

7. - Paired cylindrical organelles near nucleus- Composed of nine tubes, each with three tubules- Involved in cellular division- Lie at right angles to each other Centrioles

8. - A plastid usually found in plant cells- Contain green chlorophyll where photosynthesis takes place Chloroplasts

9. - Composed of microtubules- Supports cell and provides shape- Aids movement of materials in and out of cells Cytoskeleton

10. - Tubular network fused to nuclear membrane- Goes through cytoplasm onto cell membrane- Stores, separates, and serves as cell's transport system- Smooth type: lacks ribosomes- Rough type (pictured): ribosomes embedded in surface Endoplasmic reticulum

11. - Protein 'packaging plant'- A membrane structure found near nucleus- Composed of numerous layers forming a sac Golgi apparatus

12. Digestive 'plant' for proteins, lipids, and carbohydrates- Transports undigested material to cell membrane for removal- Vary in shape depending on process being carried out- Cell breaks down if lysosome explodes Lysosome

13. Second largest organelle with unique genetic structure- Double-layered outer membrane with inner folds called cristae- Energy-producing chemical reactions take place on cristae- Controls level of water and other materials in cell- Recycles and decomposes proteins, fats, and carbohydrates, and forms urea Mitochondria

14. Each cell contains thousands- Miniature 'protein factories'- Composes 25% of cell's mass- Stationary type: embedded in rough endoplasmic reticulum- Mobile type: injects proteins directly into cytoplasm Ribosomes

15. - Membrane-bound sacs for storage, digestion, and waste removal- Contains water solution- Contractile vacuoles for water removal (in unicellular organisms) Vacuoles

16. - Most commonly found in plant cells- Controls turgity- Extracellular structure surrounding plasma membrane- Primary cell wall: extremely elastic- Secondary cell wall: forms around primary cell wall after growth is complete Cell wall

17. Outer membrane of cell that controls cellular traffic- Contains proteins (left, gray) that span through the membrane and allow passage of materials- Proteins are surrounded by a phospholipid bi-layer. Plasma membrane

19. Functions of Blood • 1 - Transportation: • oxygen & carbon dioxide • nutrients • waste products (metabolic wastes, excessive water, & ions) • 2 - Regulation - hormones & heat (to regulate body temperature) • 3 - Protection - clotting mechanism protects against blood loss & leucocytes provide immunity against many disease-causing agents

20. 1 - Formed elements: Red blood cells (or erythrocytes) White blood cells (or leucocytes) Platelets (or thrombocytes) 2 - Plasma = water + dissolved solutes

22. Determining the hematocrit

23. Erythropoiesis • formation of erythrocytes • the body must produce about 2.5 million new RBCs every second • in adults, erythropoiesis occurs mainly in the marrow of the sternum, ribs, vertebral processes, and skull bones • begins with a cell called a hemocytoblast or stem cell (below) • rate is regulated by oxygen levels: • hypoxia (lower than normal oxygen levels) is detected by cells in the kidneys • kidney cells release the hormone erythropoietin into the blood • erythropoietin stimulates erythropoiesis by the bone marrow

24. Red Blood Cells (or erythrocytes) • 1 - biconcave discs • 2 - lack a nucleus & cannot reproduce (average lifespan = about 120 days) • 3 - transport hemoglobin (each RBC has about 280 million hemoglobin molecules) • 4 - Typical concentration is 4-6 million per cubic mm (or hematocrit [packed cell volume] of about 42% for females & 45% for males) • 5 - contain carbonic anhydrase (critical for transport of carbon dioxide)

27. 1 - formed in the bone marrow from cells called megakaryocytes 2 - have no nucleus, but can secrete a variety of substances & can also contract (because they contain actin & myosin) 3 - normal concentration in the blood is about 250,000 per cubic millimeter 4 - remain functional for about 7 - 10 days (after which they are removed from the blood by macrophages in the spleen & liver) 5- play an important role in hemostasis (preventing blood loss) Platelets (or thrombocytes)

28. 1 - Water - serves as transport medium; carries heat 2 - Proteins Albumins 60-80% of plasma proteins most important in maintenance of osmotic balance produced by liver Globulins alpha & beta some are important for transport of materials through the blood (e.g., thyroid hormone & iron) some are clotting factors produced by liver gamma globulins are immunoglobulins (antibodies) produced by lymphocytes Fibrinogen important in clotting produced by liver Plasma

30. Coagulation Pathway

31. Action potentials arriving at the synapses of the upper right neuron stimulate currents in its dendrites; these currents depolarize the membrane at its axon hillock, provoking an action potential that propagates down the axon to its synaptic knobs, releasing neurotransmitter and stimulating the post-synaptic neuron (lower left). Action potential

32. Ion channels • Main articles: Ion channel and Passive transport • Ion channels are integral membrane proteins through which ions can cross the membrane. Most channels are specific for one ion; whereas that ion passes through relatively quickly, other similar ions pass through very infrequently.[12] For example, although potassium and sodium ions have the same charge and differ only slightly in their radius, potassium channels allow few sodium ions through, and vice versa. The pore through which the ion passes is typically so small that ions must pass through it alone and single-file.[13] Channels are either fully open or fully closed. When the channel is open, ions flow through it by passive transport, i.e., at a rate determined by the membrane voltage Vm and concentration difference across the membrane.[8] The action potential is a manifestation of different ion channels opening and closing at different times

33. The ionic currents of the action potential flow in response to concentration differences of the ions across the cell membrane. These concentration differences are established by ion transporters, which are integral membrane proteins that carry out active transport, i.e., use cellular energy (ATP) to "pump" the ions against their concentration gradient.[17] Such ion pumps take in ions from one side of the membrane (decreasing its concentration there) and release them on the other side (increasing its concentration there). The ion pump most relevant to the action potential is the sodium–potassium pump, which transports three sodium ions out of the cell and two potassium ions in.[18] Consequently, the concentration of potassium ions K+ inside the neuron is roughly 20-fold larger than the outside concentration, whereas the sodium concentration outside is roughly ninefold larger than inside.[19][20] Similarly, other ions have different concentrations inside and outside the neuron, such as calcium, chloride and magnesium.[20]

34. Chemical synapses Main articles: Chemical synapse, Neurotransmitter, Excitatory postsynaptic potential, and Inhibitory postsynaptic potential Action potentials that reach the synaptic knobs generally cause a neurotransmitter to be released into the synaptic cleft.[89] Neurotransmitters are small molecules that may open ion channels in the postsynaptic cell; most axons have the same neurotransmitter at all of their termini. The arrival of the action potential opens voltage-sensitive calcium channels in the pre-synaptic cell; the influx of calcium causes vesicles filled with neurotransmitter to migrate to the cell's surface and release their contents into the synaptic cleft.[90] This complex process is inhibited by the neurotoxinstetanospasmin and botulinum toxin, which are responsible for tetanus and botulism, respectively. Synapses

35. Electrical synapses Main articles: Electrical synapse, Gap junction, and Connexin Some synapses dispense with the "middleman" of the neurotransmitter, and connect the presynaptic and postsynaptic cells together.[92] When an action potential reaches such a synapse, the ionic currents flowing into the presynaptic cell can cross the barrier of the two cell membranes and enter the postsynaptic cell through pores known as connexins.[93] Thus, the ionic currents of the presynaptic action potential can directly stimulate the postsynaptic cell. Electrical synapses allow for faster transmission because they do not require the slow diffusion of neurotransmitters across the synaptic cleft. Hence, electrical synapses are used whenever fast response and coordination of timing are crucial, as in escape reflexes, the retina of vertebrates, and the heart.

36. Unit II Cardiac system

37. Circles of Blood The ancient Greeks believed that blood moved through the body like an ocean tide, first moving out of the heart and then ebbing back to it in the same vessels. It was not until the seventeenth century that William Harvey, an English physician, proved that blood did, in fact, move in circles through the body. The walls of arteries are usually much thicker than the walls of veins. Their tunica media, in particular, tends to be much heavier

38. The largest artery is the Aorta. Blood leaves the heart in large arteries, moving into successively smaller and smaller arteries and then into the arterioles, which feed the capillary beds in the tissues. Capillary beds ar

40. Measuring Blood Pressure with a SphygmomanometerBlood pressure is reported in millimeters of mercury (mm Hg) Blood Pressure

41. Arterial blood pressure is directly related to cardiac output and peripheral resistance. Peripheral resistance is the amount of friction encountered by the blood as it flows through the blood vessels. Any factor that increases either the cardiac output or peripheral resistance causes an almost immediate reflex rise in blood pressure.

42. The basic structural and functional unit of the nervous system is the nerve cell or NEURON. It is important to come to grips with the neuron and the terminology relating to its parts now, otherwise much of the material on organization of the nervous system will not make sense to you. Here is a schematic drawing of a typical nerve cell Nervous System

43. The nervous system also contains cells which are not neurons and which do not DIRECTLY participate in the task of sending and receiving electrical signals. These supporting cells are called GLIA. There are several types of glia, but for our present purposes we will be concerned with only two types: those that form MYELIN SHEATHS around axons in the central and peripheral nervous systems.

47. SYMATHETIC increase in heart rate decrease in gastric motility decrease in secretion of salivary and digestive glands  dilation of pupils Ejaculation Vasoconstriction dilation of bronchioles increased secretion of sweat glands PARASYMPATHETIC decrease in heart rate increase in gastric motility increase in secretion of salivary and digestive glands constriction of pupils penile erection contraction of smooth muscle in walls of bladder

48. Electroencephalography • Electroencephalography (EEG) is the measurement of electrical activity produced by the brain as recorded from electrodes placed on the scalp. • Just as the activity in a computer can be perceived on multiple different levels, from the activity of individual transistors to the function of applications, so can the electrical activity of the brain be described on relatively small to relatively large scales. At one end are action potentials in a single axon or currents within a single dendrite, and at the other end is the activity measured by the scalp EEG.

49. In conventional scalp EEG, the recording is obtained by placing electrodes on the scalp with a conductive gel or paste, usually after preparing the scalp area by light abrasion to reduce impedance due to dead skin cells. The technique has been advanced by the use of carbon nanotubes to penetrate the outer layers of the skin for improved electrical contact. The sensor is known as ENOBIO [1]; however, this technique is not in common research or clinical use. Many systems typically use electrodes, each of which is attached to an individual wire. Some systems use caps or nets into which electrodes are embedded; this is particularly common when high-density arrays of electrodes are needed Computer Electroencephalograph

50. Unit III Respiratory System