ls2 afet unit 6 support systems in animals

UNIT 6: SUPPORT SYSTEMS IN ANIMALS CAMPBELL & REECE

CHAPTER 50 & NOTES ON EDULINK & LEARNING GUIDE

1. DIFFERENT TYPES OF SKELETONS

The three main types of skeletons are:

Hydrostatic skeletons (lack hard parts)Exoskeletons (external hard parts)Endoskeletons (internal hard parts)

Hydrostatic Skeletons

A hydrostatic skeleton consists of fluid held under pressure in a closed body

This is the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids

Annelids use their hydrostatic skeleton for peristalsis, a type of movement on land produced by rhythmic waves of muscle contractions.

HYDROSTATIC SKELETONSCNIDARIANEMATODE

FLATWORMSANNELIDA

Exoskeletons

An exoskeleton is a hard encasement deposited on the surface of an animal

Exoskeletons are found in most molluscs and arthropods

Arthropod exoskeletons are made of cuticle and can be both strong and flexible

The polysaccharide chitin is often found in arthropod cuticle

EXOSKELETONSARTHROPODSMOLLUSC

ENDOSKELETONS

An endoskeleton consists of hard supporting elements, such as bones, buried in soft tissue

Endoskeletons are found in sponges, echinoderms, and chordates

A mammalian skeleton has more than 200 bones

Some bones are fused; others are connected at joints by ligaments that allow freedom of movement.

ENDOSKELETONSECHINODERMATASPONGES

CHORDATA

2. THE HUMAN SKELETON

2. THE HUMAN SKELETON

a. AXIAL SKELETON: i)Human Skull Consist of 28 bones It consists of flat bones that are connected

on the sides by immovable joints called sutures.

In babies not all the bones of the skull make contact with each other and fontanels are formed.

The lower jaw bone (Mandible) is the only movable bone of the skull – Upper jaw (Maxilla) is not moveable.

The large opening at the base of the skull is called the foramen magnum – it is where the spinal cord enters the skull.

Human Skull

a. AXIAL SKELETON: ii)VERTEBRAL COLUMN Consists of 33 bones called vertebrae. 24 vertebrae are individual single bones. 9 vertebrae are fused to form the sacrum and

coccyx. Cartilage disks are found between vertebrae. The s-shaped structure of the vertebral column

and the disks absorb shock and help to protect the spinal cord.

The first vertebrae – Atlas – carry the weight of the skull, allows the head to nod.

2nd vertebrae – Axis – allows head to move to the side

a. AXIAL SKELETON:ii) VERTEBRAL COLUMN

Vertebrae is divided into 7 Cervical vertebrae

12 Thoracic vertebrae

5 Lumbar vertebrae

5 fused vertebrae = sacrum

4 fused vertebrae = coccyx

a. AXIAL SKELETON: iii) THORAX Consists of the sternum, 12 pairs of ribs and

thoracic vertebrae. It protects the heart and lungs. First 7 pairs of ribs are directly attached to the

sternum by cartilage – called true ribs. Next 5 pairs – false ribs – last 2 pairs of false

ribs are not attached to the sternum – called floating ribs

Intercostal muscles found between ribs – aid in breathing process.

a. AXIAL SKELETON: iii) THORAX

True ribs

False ribs Floating ribs

sternum

b. APPENDICULAR SKELETON

Made up of the shoulder (pectoral girdle), arms, hips (pelvic girdle) and legs.

126 bones.Function: Movement

b. APPENDICULAR SKELETON i) Pectoral girdle and arm

b. APPENDICULAR SKELETON i) Pelvic girdle and leg

3. FUNCTIONS OF A SKELETON

Support Movement Protection Blood cell production Storage Endocrine regulation

a. Support

The skeleton provides the framework which supports the body and maintains its shape.

The pelvis, associated ligaments and muscles provide a floor for the pelvic structures.

Without the ribs, costal cartilages, and intercostal muscles, the heart would collapse.

b. MOVEMENT

The joints between bones permit movement.

Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones.

Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system.

c. Protection

The skeleton protects many vital organs e.g.:

The skull protects the brain, the eyes, and the middle and inner ears.

The vertebrae protects the spinal cord.

The rib cage, spine, and sternum protect the lungs, heart and major blood vessels.

d. Blood cell production

• The skeleton is the site of haematopoiesis, which takes place in red bone marrow.

• Haematopoiesisis the formation of blood cellular components.

e. Storage

• Bone matrix can store calcium and is involved in calcium metabolism.

• The bone marrow can store iron and is involved in iron metabolism.

• Bones are not entirely made of calcium, but a mixture of chondroitin sulfate and hydroxyapatite, the latter making up 70% of a bone.

f. Endocrine regulation

• Bone cells release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition.

• Osteocalcin increases both the insulin secretion and sensitivity.

4. STRUCTURE OF A LONG BONE

A long bone is an elongated bone consisting of a body (diaphysis) and

two terminal parts (epiphyses), such as found in the leg and arm bones (femur, radius, phalanges

and others).

4. STRUCTURE OF A LONG BONE

5. DIFFERENT JOINTS In the human body, there are joints

where two or more bones meet in the skeleton.

Immovable joints do not allow movement and

Synovial joints are movevable joints and allow movement of the bones.

Ligaments hold bones together. Tendons attach muscle to bone,.

STRUCTURE OF A SYNOVIAL JOINT

Different types of synavial joints are:• Ball and socket joint• Hinge joint• Pivot joint• Gliding joint

BALL AND SOCKET JOINT:• Joints of the hips and shoulders• Allows rotating movement of arms

and legs

HINGE JOINT:• Joints of the elbows, knees, fingers

and toes• Only allows movement in one

direction.

PIVOT JOINT:• Joints between atlas and axis• One bone turns on another

GLIDING JOINT:• Joints of the wrist and ankles• The flat surface of one bone glides

over the surface of a bone next to it.

JOINT DISORDERSDo research (self study) on the following disorders, you have to be able to briefly explain what each of them are (will not be marked but there will be question in the exam and semester test about it)

Dislocation Sprains Arthritis Osteoarthritis Rheumatoid arthritis

6. MACRO STRUCTURE OF SKELETAL MUSCLES

Epimysium: Surrounds entire muscle Perimysium: Surrounds bundles of

muscle fibres (Fascicles) Endomysium: Surrounds individual

muscle fibres

6. STRUCTURE OF SKELETAL MUSCLES

MICRO STRUCTURE OF SKELETAL MUSCLES

Sarcolemma: Muscle cell membrane Myofibrils: Threadlike strands within

muscle fibres Actin (thin filament) Myosin (thick filament)

SKELETAL MUSCLES Muscles are attached to bones by

means of tendons. Skeletal muscles produce movement

by contracting. This exerts a force on tendons, which

in return, pulls on bones. Muscles occur in pairs which work

antagonistic against each other. When one contracts the other relaxes.

MOVEMENT OF THE ARM