BIO 201 Lecture Exam 2 (Ch. 6 & 7)

Includes: Skeletal system; bone tissue (mostly physiology)

Functions of calcium in the body

blood clotting, helps muscles to contract, and regulates normal heart rhythms and nerve functions, overall bone health/strength

Where do the calcium and other minerals (phosphorous, magnesium, and manganese) come from that make up the hydroxyapatite?

Our diet!

Mitosis of chondrocytes at the epiphyseal plate occurs in a

10 year old child. This is the hallmark event of:

Interstitial growth (chondrocytes secrete new matrix within the cartilage and this causes it to grow in length)

What happens to bone density during deposition? What happens to blood calcium? How is this regulated?

* bone density increases (osteoblasts)
* lower blood calcium levels
* PTH

What happens to bone density during resorption? What happens to blood calcium? How is this regulated?

* bone density decreases (osteoclasts)
* higher blood calcium levels 
* PTH (removes calcium from bone regardless of bone integrity)

How do the bones respond to increased mechanical force? What about decreased mechanical force?

Increased mechanical forces → increase bone formation 

Decreased mechanical forces → decrease bone formation & increase resorption   

How does the body correct LOW Ca++ levels(hypocalcemia)?

Increase amounts of PTH released → normal levels

Take some calcium from bone into blood

How does the body correct HIGH Ca++ levels (hypercalcemia)?

Calcitonin released from thyroid → normal levels 

Decrease amounts of PTH released → normal levels

Put extra calcium in blood into bones

ex: risk factor can be kidney stones

Calcium and what other minerals make up the hydroxyapatite?

phosphorous, magnesium, and manganese

Name 3 kinds of fibers that make up connective tissue.

1. collagen fibers
2. reticular fibers
3. elastin fibers

Osteoid =

organic matrix (mainly collagen)

Name 4 kinds of cells that make up connective tissue.

\n


1. fibroblasts
2. chondroblasts/chondrocytes
3. osteocytes/osteoblasts
4. adipocytes

Name as many examples of connective tissue that you can think of.

* dense regular
* dense irregular
* fluid (blood)
* loose
* adipose
* bone
* cartilage

What is the difference between regeneration and fibrosis with regard to tissue repair?

\n Regeneration involves replacing injured cells with cells of the same type, while fibrosis involves replacing parenchyma tissue with connective tissues, leading to the formation of permanent scar tissue.

What are some problems with scar formation?

* can can pain
* can cause tightness
* can cause itching
* can reduce function and movement (scar tissue contains less elastin than normal skin)

Name 3 types of cartilage.

1. Hyaline cartilage 
2. Fibrocartilage 
3. Elastic cartilage

What is the difference between ligaments and tendons?

Tendons connect muscle to bone, while ligaments connect bone to bone.

Name as many differences between spongy and compact bone that you can think of.

Spongy is more porous, composed of trabeculae, and is found within/inside the end of the bone shaft of long bones (epiphysis), while compact bone is more hard/dense, made of osteons, and makes up the hard outside of bones (surrounds the spongy bones). 

Name the organic and inorganic substances that are secreted by osteoblasts, which are actually the components that make up the hard substance we know as bone.

secrete unmineralized bone matrix or Osteoid: collagen & calcium-binding proteins

Describe Wolff’s Law

Bones that bear a lot of weight remodel at a high rate; our bones become thicker and stronger over time to resist forces placed upon them and thinner and weaker if there are no forces to act against.

Describe what is happening at the epiphyseal plate during growth in length of a long bone.

\
* The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by **mitosis**.
* On the epiphyseal side of the epiphyseal plate, cartilage is formed. On the diaphyseal side, cartilage is ossified, allowing the diaphysis to grow in length

Define remodeling. Where are the osteoblasts during remodeling? What are they doing? Where are the osteoclasts? What are they doing?

* Remodeling = resorption + deposition 
* Osteoblasts are located on the surface of bone and are responsible for laying down new bone until the resorbed bone is completely replaced.
* Osteoclasts when active are located in resorption bay and have a ruffled border; these cells are responsible for destroying/eating bone

Name some circumstances that would make a person more likely to develop osteoporosis (the “risk factors”).

* most often aged, postmenopausal women
* decrease in sex hormone secretion (due to age)
* Petite body form
* Insufficient exercise to stress bones
* Diet poor in calcium and protein
* Smoking
* Hormone-related conditions (Hyperthyroidism, Low blood levels of thyroid-stimulating hormone, Diabetes mellitus)
* Immobility
* Males with prostate cancer taking androgen-suppressing drugs

How can we help prevent osteoporosis, or at least slow its progression?

1. plenty of calcium in diet in early adulthood
2. reduce carbonated beverage and alcohol consumption 
3. plenty of weight-bearing exercise

Approximately when does epiphyseal plate closure occur in males and females?

* females at 18
* males at 21

What are the purposes of the paranasal sinuses?  Name them.

* to lighten the weight of the skull bones
* serve as resonators for sound production
* lined with cells that secrete mucus (drains into the nasal cavity) to keep the nose from drying out during breathing 
* maxillary sinus
* ethmoid sinus 
* sphenoid sinus
* frontal sinus

Where is the mastoid sinus?  What are some problems that might arise from having sinuses in this location?

Located just behind the ear; this placement is prone to infection

What drives bone remodeling?

calcium levels (homeostasis), and mechanical stressors

**scoliosis**

 a sideways curvature of the spine

**lordosis**

the natural curve of the lower back (lumbar) area of the spine. but with an extreme curve, the lower spine will have a deep curve, causing the abdomen  to stick out and causing the pelvis to curve back and up.

**kyphosis**

An increased front-to-back curve of the spine (looks like a hunchback)

**Atlas**

is the first cervical (neck) vertebra which is present just under the head; supports the skull

**Axis**

is the second cervical (neck) vertebra; it forms the pivot upon the atlas.

Which bone of the lower leg is the weight bearing bone?

The **tibia**; it is significantly larger and stronger than the fibula

Which portion of the femur is most likely to fracture in little old ladies?

The femoral neck; can fracture in relation to osteoporosis

Name 3 functions of the skeletal system besides support, movement and protection.

* produces blood cells 
* stores and releases minerals and fat 
* endocrine regulation

Why are babies born with fontanels (spaces between the bones of the skull where bone formation isn't complete)?

* Important for the normal growth and development of the baby's brain
* Allows the skull to be molded during birth

What is cleft palate?

is an opening or split in the roof of the mouth that occurs when the tissue doesn't fuse together during development in the womb

Osteoporosis

Bone resorption is greater than bone deposition and bones become porous and less dense.

Paget's disease

Abnormal bone deposition with more spongy bone compared to compact bone

Osteomalacia

Bone is deposited but does not mineralize well, (calcium salts are not deposited) causing softness of bone.

Rickets

Bone is soft due to inadequate mineralization of calcium, usually due to a Vitamin D deficiency in children. Leads to bowed legs and other bone deformities

Comminuted

\n Bone is broken in three or more pieces; common in elderly

Compression

Bone is crushed; common in excessively porous bone such as in osteoporosis

Spiral

Fracture occurs when an extreme rotating or twisting force occurs on the bone; common sports fracture

Epiphyseal

Fracture at the ends of long bones, where epiphysis separates from diaphysis.

Greenstick

Bone break is incomplete where one side fractures and the other side bends; common in children.

Depressed

Broken bone is pressed inwards; common in skull fractures

Diaphysis

This region is elongated with long bone growth

Epiphyseal line

The presence of this structure signals the end of long bone growth

Epiphyseal plate

The site of proliferating chondrocytes

Appositional growth

The growth pattern of bone where bone matrix is laid down on the surface to thicken the width of the bone

Vitamin D promotes…

calcium absorption in the GI tract

Interstitial growth

The term for the lengthening of a long bone; occurs in childhood and puberty

Osteogenic cells

These cells are bone stem cells

Osteocytes

These cells are matured osteoblasts, embedded in the bone matrix.

Osteoblasts

These cells lay down bone matrix; bone builders

Osteoclasts

These cells dissolve the bone matrix; bone eaters

\n Chondrocytes

These cells lay down cartilage

Chondro =

cartilage

The medullary cavity and spongy bone in infants is filled with…

red marrow

What is the structural unit for compact bone?

osteons

What makes up 65% of bone mass?

hydroxyapatites (mineral salts)

90% of bone protein =

collagen

An osteon contains osteocytes, lamellae, and a central canal (Haversian system), and is found in compact bone only.

True

What is the primary hormone involved in bone growth?

The growth hormone

What type of tissue is laid down first in long bones?

Hyaline Cartilage

Which hormone increases osteoclast activity to release more calcium ions into the bloodstream?

Parathyroid hormone (PTH)

Wolff's law tells us that

the thickness and shape of a bone is dependent on the stresses placed upon it.

Normal bone formation is dependent on sufficient intake of…

calcium, phosphate, vitamin D

If a child has a deficiency in growth hormone, what can occur as a result?

Decreased chondrocyte activity at the epiphyseal plate

The central canal that runs through each osteon allows for

a passageway for blood vessels and nerve fibers.

The resilience of bone seems to be due to which of the following?

The bonds between collagen fibers that can break to diffuse energy and then re-form

Which hormone is MOST directly involved in regulation of blood calcium levels?

Parathyroid hormone (PTH)

These cells produce cartilage and are active at the epiphyseal growth plate.

Chondrocytes

A friend gives you a bone that is cube-shaped, about one inch long and one inch wide and asks you to classify it since your friend knows you are taking Anatomy and Physiology. You have been studying and tell your friend it is classified as a…

short bone

Thinking of the principle of complementarity, which of the following types of bone tissue helps to lighten the overall weight of a bone and provides spaces for blood vessels and bone marrow?

trabecular bone 

Why are the bones of young children much more flexible than those of older adults?

The bones of young children are not completely calcified as they are still growing while the bones in older adults will be completely calcified, making older bones more hard and rigid. 

When undergoing bone remodeling and repair throughout life, we need to be able to break down bone (resorption). Which cell is best suited for this function?

Osteoclast

These cells are also called bone progenitor cells and give rise to osteoblasts, osteocytes, and bone-lining cells.

Osteogenic cells

These cells are large, multi-nucleate cells similar to macrophages and secrete enzymes that dissolve bone material to be reabsorbed. 

Osteoclasts

These cells are mature bone cells that sit in lacunae and monitor the bone tissue for stress.

Osteocytes

The structure of bone tissue supports its function. Which of the following bone tissues is adapted to support weight and withstand twisting stress?

Compact bone

Which structures help to provide nutrients to the osteocytes in lacunae and also help the osteocytes to monitor the bone tissues?

canaliculi

**Intramembranous ossification** is

the process of bone development from fibrous membranes

If you fractured the shaft of your humerus, this would be a break in the

diaphysis

Choose which bone marking type would most likely increase in size when a weight-lifter repeatedly exercises the muscles that attach and pull on that bone.

tuberosity

Which type of tissue is produced first in long bone development and provides the framework for the bone?

hyaline cartilage

Which of the following is the name of a bone marking that tends to be a round or oval opening through bone?

foramen

Which nutrients are important for proper bone health?

Calcium

Vitamin D (calcitriol)

Vitamin C

Vitamin K

Protein

Foramen

an opening in a bone through which \n certain structures like nerves or blood vessels \n pass

Suture

a type of fibrous joint between bones, \n especially bones of the skull and face

Fontanelle

a fibrous membrane connecting \n bones of the fetal skull

Sinuses

mucus-lined cavities in bones of the \n skull that serve to lighten the skull and humidify \n inhaled air (paranasal sinuses only).

Deposition =

process where new bone is formed

Resorption =

destruction of bone tissue