Tissues

1. Tissues

2. Tissue is…. • A collection of cells organized for a particular function • Collections of tissue are then arranged into organs

3. Tissue types Mammals have 4 basic tissue types • Epithelial • Connective • Muscle • Nerve

4. Epithelial Tissue • Collections of cells packed together is sheets • They lie the body’s surface and openings • They also cover the openings of the • Intestinal tract • Reproductive tract • Urinary tract • They line the tubes in the body such as blood vessels and heart

5. Epithelial functions Functions of epithelial 1. Defense • Skin, respiratory tract 2. Secretions • Tears and saliva help to moisten the tissue • Urine and sweat • Milk from mammary

6. Functions of Epithelial 3. Absorption • Very highly selective • Intestines, lungs and kidneys absorb from surrounding fluid • Cells lining the blood vessels provide point of exchange for materials in the blood and ECF 4. Conserve materials • Prevent excess loss of fluid and nutrients from the ECF

7. Epithelial • Every epithelial tissue (ept tissue) has an underlying connective tissue layer  > Ept tissue has no direct blood flow so the connective tissues provide 1. Support 2. Nutrients 3. Removes waste

8. Classifications of Epithelial 1. Simple • One cell layer  2. Stratified • Multiple layers  3. Transitional • Multiple layers with the shape of the cell changing

9. Shape of cells 1. Squamous • Very flat 2. Cuboidal • Cube shaped  3. Columnar • Taller than they are wide The 2 most appropriate terms are combined to describe the tissue

10. Cell shapes Simple squamous epithelium • Single layer of flat cells • Located where there is need for exchange • Ex: blood vessels are lined with it for transfer of fluids, nutrients and gases and wastes

11. Cell shape Simple cuboidal Ept • Single layer of cells that are almost square • Located in many glands and tubules of the kidneys • Functions – secretions or absorption

12. Cell Shapes Simple columnar ept • A single layer of cells that are taller than wide • Located in glands, stomach and intestines • Stratified cuboidial and columnar also exist in certain glands and ducts Stratified squamous ept • Ex: skin

13. Cell shapes Transitional Ept • Specific to urinary tract only • It can be stretched • Relaxed it looks several layers thick • As bladder fills, stretches, when full it seems on a few cells thick • It also can prevent exchange of fluid between urine and underlying tissue

14. Integument • Also called skin • 2 way barrier over the body Functions • Damaging agents are kept out • Fluid and nutrients are kept in

15. Specialized skin cells • Hair, fur and sweat glands • Help maintain stable body temp Pigment • Protects body from UV radiation • Clinically the skin is the first impression of an animals overall health. Many diseases appear on the skin – fleas, hair loss and skin sores • Parasitic, nutritional and endocrine diseases affect the skin

16. Skin Skin – 2 layers 1. Epidermis 2. Underlying dermis Epidermis • Stratifies squamous ept • Originated from the basal layer and move outward and shed from the surface Dermis • Connective tissue layer that contains • Blood vessels • Nerves • Glands

17. skin Hypodermis • 2nd layer of connective tissue • Supports the skin (epidermis with dermis) • Hypo = beneath

18. Specialized skin cells • The footpads/digital pads of dogs and cats are specialized skin cells • Thickened layer • Resist physical trauma • A pad of fat is under this to act as a cushion

19. Hair Is a Modification of epidermal cells Functions • 1. Insulation • 2. Protection • 3. Sensation

20. Hair • Originates from the follicle in the dermis • Hair shaft is made of Ept cells • Growth occurs as cells are attached to the base of the hair

21. Arrector Pili • Muscle that is attached to the connective tissue around the hair follicle • Contracted = the hair stands upright Cold weather improves insulation effect of the hair.

22. Claws and hooves - Modified epidermis

23. Keratin A specialized protein that is deposited in the cells • Gives hardness and durability • The claws of dogs and cats surround the last bone of the toe • Hooves are similar to claws • The last bone of the equine foot is suspended within the hoof

24. Laminar Corium • Supports and nourishes the hoof wall • Is connective tissue Growth of the hoof • Occurs in the coronary band when cells are deposited

25. Horns The same as hoof and claw • The center of the horn is a bone that surrounding tissues supplies blood to feed • Horn material is called keratinized epithelium

26. Muscle tissue 3 muscle types exist in mammals • - Skeletal • - Smooth • - Cardiac

27. Skeletal • Attaches to the skeleton • Allows for motion • Under voluntary control • Animals move with nerve signals

28. Smooth Muscle • Involuntary muscle • Located in many hollow organs of the body • Ex: blood vessels • Gastrointestinal tract - Urinary bladder

29. Cardiac muscle • Located in the heart • Involuntary Skeletal muscle is striated voluntary muscle  • A muscle consists of thousands of muscle fibers or muscle cells

30. Myofiber • An entire muscle cell • Have several nuclei • Lots of mitochondria • Organized in parallel rows • Separated by connective tissue that includes blood vessels and nerves

31. The ability of a muscle fiber to contract is a very complicated system • Within the fiber – an organized system of myofilaments exist

32. 2 proteins make up the filaments • Actin • Myosin • They are all organized along the length of the cell

33. During contraction the actin and myosin filaments slide along each other • The filaments have small bridges between them that bind and release as they slide • The contraction starts originally with the stimulation from a nerve cell

34. The stimulation releases calcium stored in the endoplasmic reticulum • This flow of calcium ions causes the filaments to slide across each other • A large amount of mitochondria are present to provide energy.  • During relaxation, the cell will actively transport calcium back to the endoplasmic reticulum

35. Porcine Stress Syndrome (PSS) • Genetically transmitted disease in which the calcium is not transported back to the endoplasmic reticulum • This causes muscles not to relax • Occurs when pigs are stressed for heat or transportation

36. Rigor Mortis • Muscle stiffness • Occurs at death because there is no energy to pump the calcium back to the endoplasmic reticulum • With energy, muscles can not relax

37. Hypocalcemia • Dairy cattle develop a lack of calcium around calving time • The cow drastically increases calcium for mild production • So much calcium is excreted in the mild that the levels on the blood and muscles becomes too low • The cow becomes weak and unable to stand

38. Hypocalcemia • Treatment • Calcium solution placed directly into the bloodstream • Within minutes the cow can stand • Muscles will grow or shrink based on usage and nerve damage

39. Sweeny • Damage to the shoulder nerve in a draft horse causing the muscle to shrink

40. Cardiac Muscle • Striated and involuntary • Myofilaments look the same as skeletal and contraction procedure is the same • No nerve stimulation is necessary for contractions • Specialized pacemaker cells are responsible for the rate of contraction

41. Cardiac • Nerve cells are present to help influence the rate of contraction • The automatic nervous system can increase or decrease the rate • As long as there is oxygen and glucose provided to the muscle cells – the heart beats

42. Smooth • Lacks striation • Contains actin and myosin filaments but not in the same arrangement • Each myofiber is spindle shaped and tapered at each end • Each cell has only one nucleus

43. Smooth Muscle • Arranged in sheets around hollow openings • Contraction makes opening smaller • Example: contraction in blood vessels • Contract much slower than skeletal muscle • Maintain the contraction longer • Controlled by the automatic nervous system

44. Nerve Tissue • Allows communication among areas of the body • Located in brain and spinal cord • Brain and spinal cord together is called the central nervous system

45. Peripheral Nervous System • Nerves located outside of brain and spinal cord

46. Neurons • Cells in nerve tissue • Large • Body of it holds the nucleus and other organelles

47. Axon • A hair like extension from the cell body • Carries nerve impulses • Can end on either tissues or other neurons • Axons from many neurons bundle together to form a nerve • Can be very long • Example: horse – can be 2 meters long

48. Dendrites • Other extensions of the neuron • Axon often ends on a dendrite of another neuron • The site of this connection is called a synapse • When stimulated, the dendrite begins the nerve impulse

49. How nerve impulses happen • Flow of ions passes through cell membrane • In a resting nerve cell – sodium ions are actively transported into extra cellular fluid • At the same time, potassium is pumped into the cytoplasm • Stimulation causes ions to flow across the cell membrane • Stimulation moves down the axon quickly

50. Nerve impulses can be measured as an electrical event in the body