1. Integumentary Systems
Structure & Functions of Integumentary System
Integumentary system consists of layers of the four types of body tissues:
1) epithelial tissue - outer layer of skin
2) connective tissue - tough & flexible protein fibers that act to hold body together
3) muscle tissue - interact w/ hairs on skin & respond to stimuli like cold and fright
4) nervous tissue - detects external stimuli like pain and pressure (Chapter 19)

2. Skin: The Body’s Protection
Main organ in integumentary system is the skin, which makes it the largest organ in the body since it is 12-15% of body weight!
Made of two layers:
Epidermis: outer layer of skin
Dermis: inner layer of skin

3. Layers of Skin

4. Epidermis
Outermost layer of skin made of 2 parts: exterior and interior portions
Exterior: layers of dead, flattened cells that are continually being shed
Even though dead, are important since contain keratin which helps protect living cells underneath

5. Epidermis
Interior: living cells that continually divide to replace dead cells
Contain pigment melanin that colors skin and protects it from damage by solar radiation
Melanin is not sole protector for sun damage – can get skin cancer if are dark pigmented!
process of shedding takes 28 days (4 weeks)

6. Dermis Inner, thicker portion of skin Contains many structures:
Blood vessels (arteries & veins)
Nerves & nerve endings
Hair follicles
Sweat glands
Sebaceous (oil) glands
Muscles (to make hair stand up)

7. Subcutaneous Layer Beneath dermis is subcutaneous layer
Made of fat and connective tissue
Help body absorb impacts, retain heat, store food

8. Functions of Skin 1. Maintains homeostasis
Regulates internal body temperature
When temperature rises, small blood vessels in dermis dilate (increase in circumference), allowing blood flow to increase, so blood loses heat
When temperature lowers, blood vessels constrict (decrease in circumference), decreasing blood flow, so blood keeps in heat
Feedback loop:
Backward/forward

9. Feedback (Homeostasis) Loop
Internal Body Temperature Changes + -
Blood vessels dilate
Blood vessels constrict
Blood flow increases
Blood flow decreases
Blood loses heat
Blood keeps in heat
Internal Body Temperature Normalizes

10. 2. sensory organ
Nerve cells get information from external environment about pain, pressure, and temperature and send message to brain
3. produces Vitamin D
When exposed to UV light, skin makes Vitamin D, which is essential to help body absorb calcium
Most calcium supplements contain Vitamin D for that same reason
4. protective layer
Shields underlying tissues from physical and chemical damage and from invading pathogens (viruses and bacteria)

11. Skin injury and Healing
Injuries to skin can occur due to scrapes, cuts, or burns, but how skin heals depends on severity
Mild scrape (no blood, epidermis only)
Deepest layer of affected epidermal cells start to divide to fill in gap left by abrasion
Cut (blood, epidermis and dermis)
Blood flows out of wound until clot forms
Scab develops, creating barrier between bacteria on skin and underlying tissues

12. Skin injury and Healing
Bacteria already present in wound gets killed by white blood cells that migrate to site
New skin cells begin repairing wound from beneath
Scab ‘falls’ off when new skin is formed
Large wound needs high amount of connective tissue which may form a scar

13. Healing of a Cut Before Cut in skin Blood pools, creating scab
Skin cells regenerate from bottom up

14. Skin Burns Burn (Sun, chemicals, hot objects)
First degree (mild sunburn)
Death of epidermal cells
Redness and mild pain
Heal in 1 week w/out scar
Second degree
Damage of both epidermal and dermal cells
Blistering and scaring may occur

15. Skin Burns Burn (sun, chemicals, hot objects) Third degree
Destruction of both epidermal and dermal cells
Skin function is lost, so skin grafts are required
Fourth degree
Destruction through skin and into muscles, tendons, ligaments, and bone

16. Bones: The Body’s Support
Skeletal System Structure
Adult human skeleton contains 206 bones! Made of two main parts:
Axial skeleton: skull and bones that support it like vertebral column, ribs, sternum
Appendicular skeleton: bones of arms and legs (appendages), and all structures associated with them (shoulder, hips, wrists, ankles, fingers, toes)

17. Axial vs. Appendicular Skeleton

18. Skeletal joints Bones meet other bones at areas called joints
Joints facilitate movement of bones in relation to one another
Joints can be fixed (non-moveable) or non-fixed (moveable)
Fixed joints: skull

19. Skeletal joints Non-fixed joints: knee, wrist, etc.
- 4 types of moveable joints:
* Ball-and-socket: hips, shoulders
* Pivot: twisting arm at elbow
* Hinge: elbows, knees, fingers, toes
* Gliding: wrists, ankles

20. Types of Joints Found in Human

21. Types of Joints Found in Human

22. Ligaments Joints are held together by ligaments
Ligament: tough band of connective tissue that attaches one bone to another
Joints with a large range of motion (knee) have many ligaments

23. Cartilage Ends of bones are covered in cartilage
Allows for smooth movement between bone ends
Cushions joints

24. Bursae
Certain joints have fluid-filled sacs called bursae (bursa is singular)
Outside of joint between tendon and bone to reduce friction

25. Tendons Muscles are attached to bones with tendons
Tendons are thick bands of connective tissue

26. JOINTS
MUSCLE
BONE
TENDON
JOINT
CARTILAGE
LIGAMENT

27. Types of Bone Two types of bone tissue: Compact bone and spongy bone
Compact bone: hardened bone that contains tubular structures called osteons (or Haversian systems)
Surrounds spongy bone to protect it
Spongy (cancellous) bone: less dense bone with many holes and spaces
Living bone cells are called osteocytes, which receive oxygen and nutrients from small blood vessels

28. Types of Bone

29. Formation of Bone
Skeleton of human embryo is actually made of cartilage, not bone (same as what nose is made of)
Not until embryo is 9 weeks does cartilage get replaced by bone
When blood vessels penetrate cartilage membrane, stimulate it to become osteoblasts (precursors to osteocytes)

30. Bone

31. Human skeleton growth
Human skeleton is almost 100% bone, with cartilage found only in places where flexibility is needed – nose, ears, vertebral disks, and joint linings
Bone grows in length and diameter as result of sex hormones released during growth
Length: from cartilage plates at ends of bones
Diameter: from outer surface of bone
After growth stops, bone-forming cells are involved in repair and maintenance

32. Skeletal System Functions
Function of skeleton is five-fold:
1. Provide framework for tissues of body
Allows muscles to attach to bones so they can provide movement to body
2. Protects internal organs
3. Produce blood cells
Red marrow: where red blood cells, white blood cells, blood clotting factors are produced
found in humerus, femur, sternum, ribs, vertebrae, pelvis

33. Skeletal System Functions
Function of skeleton is five-fold:
4. Store fat
Yellow marrow: many other bones store fat in here
5. Mineral storage
Body’s supply of calcium and phosphorous is stored in bone

34. Skeletal injury & disease
Skeleton is vulnerable to injury and disease
Broken bones
Too much force against bone can cause it to break or fracture
Physician must set bone back in place so new osteocytes may form in broken area and put two ends back together

35. Skeletal injury & disease
Skeleton is vulnerable to injury and disease
Osteoporosis
Loss of bone volume and mineral content which leads to bones becoming more porous and brittle and more susceptible for breakage
More common in older women since they produce lower amounts or estrogen which aids in bone formation

36. Bone Fracture Types

37. Bone Fracture Types

38. Osteoarthritis Joints can become diseased
Arthritis: inflammation of the joints
Bone spurs are outgrowths of bone inside the joints so it limits mobility

39. Muscle Muscles Nearly half of body mass is muscle!
Muscle: groups of fibers, or cells, bound together. Almost all muscle fibers have been present since birth
3 main types of muscle:
Smooth muscle: walls of internal organs and blood vessels
Cardiac muscle: heart muscle
Skeletal muscle: muscles attached to bones

40. Muscle Types

41. Muscle Types

42. Smooth Muscle Made up of sheets of cells that form a lining for organs
Most common function is to squeeze via contractions, exerting pressure on space inside tube or organ to move material inside it
Ex: food bolus gets squeezed through digestive system until it comes out; semen gets squeezed through vas deferens, then urethra

43. Movement of Smooth Muscle
Smooth muscle of vessel or organ
Contraction (AKA peristalsis)
Item to be moved
Contractions are involuntary (can’t be controlled by human) so smooth muscle is considered to be an involuntary muscle
Direction of movement

44. Cardiac Muscle
Found in heart and is adapted to generate and conduct electrical impulses!
Considered an involuntary muscle

45. Skeletal Muscle Muscle that is attached to and moves bones
Makes up majority of muscles in body which work in opposing pairs
Muscle X on one side of bone, Muscle Y on other side of bone
If Muscle X is contracted, Muscle Y is relaxed, and vice versa
Considered a voluntary muscle since contractions can be controlled
How do we contract our muscles?

46. Opposing Muscle Pairs
Muscle Contracted
Muscle Relaxed

47. Muscle Names

48. Skeletal Muscle Contraction
All muscle tissue is made of muscle fibers, which are very long, fused muscle cells
Each fiber is made of smaller units called myofibrils
Myofibrils made of thick and thin filaments
Thick filaments: myosin
Thin filaments: actin
Myofibril can be divided into segments called sarcomeres

50. Muscle Contraction
Relaxed Sarcomere
Z Disc
Actin
Myosin
How do muscles contract? How do they know that you want to “make a muscle?”
Sliding Filament Theory

51. Sliding Filament Theory
Sliding filament theory: when signaled, actin filaments within each sarcomeres slide toward one another, shortening sarcomeres in a fiber and causing muscle to contract
Myosin fibers do NOT move
When skeletal muscle receives a signal (via brain), calcium is released inside muscle fibers, causing two sides of sarcomere to “slide” toward each other = contraction
When signal is gone, calcium gets absorbed, sarcomeres relax and slide away back into place

52. Sliding Filament Theory
Contracted Sarcomere

53. Black = Z disk
Yellow = actin (thin)
Pink = myosin (thick)

54. Muscle Strength and Exercise
Muscle strength does not depend on amount of fibers but does depend on thickness of fibers
You are born with the number of fibers you will always have, but exercise can increase thickness of each fiber making entire muscle bigger
Exercise stresses muscle fibers slightly, so to compensate for workload, fibers increase in diameter by adding myofibrils

55. Muscle Strength and Exercise
Energy that muscles need to contract comes from ATP produced by cellular respiration (aerobic and anaerobic processes)
Most energy comes from aerobic respiration when oxygen (from breathing) is delivered to muscle cells during rest or MODERATE activity

56. Muscle Strength and Exercise
During VIGOROUS activity (when we have tendency to hold our breaths & delivery of oxygen is not as fast as it needs to be), anaerobic respiration kicks in and in addition to ATP being made, lactic acid fermentation makes lactic acid which makes muscles cramp up
Lactic acid build up gets sent into bloodstream, where triggers rapid breathing (panting!)
Inhalation of oxygen again breaks down lactic acid & cramps go away