The Excretory System The Human Excretory System Human

The Excretory System

The Human Excretory System Human metabolism produces a lot of waste • Lungs eliminate CO 2 • Digestive system produces solid waste which is eliminated by large intestine • Kidneys make urine

Kidneys • are filters that remove wastes from blood • Prevent buildup of wastes • Help maintain the body’s internal environment by controlling the volume, composition and pressure of body fluids

Function of the Kidney • Nephrons act as filters • Each nephron is surrounded by capillaries, this close contact allows exchanges to occur by diffusion • they keep the good stuff in: blood cells Sodium Some water Glucose Proteins

Function of the Kidney • and let out the bad: – Urea – Wastes – some water

What Happens to the Waste? • Urine travels to bladder via tubes called ureters • Urine is temporarily stored in the bladder

What Happens to the Waste? • When about 200 m. L urine fill the bladder it stretches and a nerve impulse is sent to the brain signaling the need to go • If you ignore the warnings, bladder gets filled to 400 m. L then sends an urgent message to the brain • If you keep ignoring the warnings, once you get to 600 m. L, you lose voluntary control (but you are probably beyond caring at that point! ; )

What Happens to the Waste? • Urine enters the Urethra and is expelled from the body • Urethra: tube from the bladder leading outside the body

The Musculoskeletal System

Musculoskeletal system Muscular system Skeletal System

Function of the Skeletal System - Protection - protect vital organs in the body (eg. skull protects brain, spine protects spinal cord, ribs protect heart and lungs - Blood-cell production - bone marrow in large bones produce blood cells and releases them into the blood stream. LONG BONES and flat bones(pelvic & ribs)

Function of the Skeletal System • Mineral storage – bones made up of calcium and phosphorus giving bones strength and rigidity. • Support for your muscles • Movement

Components of the Skeletal System • The skeleton is composed of 3 types of connective tissue. – Bone – Ligaments – Cartilage

Bone • The human skeleton is composed of 206 bones • Hard and dense tissue • Bone is composed of bone cells within a matrix of minerals (calcium, phosphorus) and collagen fibers • If your diet is not high in minerals, your body will absorb Ca and P from your bones causing them to weaken

Structure of Bone - Canals inside the bones contain nerves and blood vessels - Only a small percentage of the bone tissue is actually living

Ossification • process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. • ossified tissue have canals that blood vessels run through and bring minerals like calcium and deposit it in the ossifying tissue. • dynamic process, with cells called osteoblasts depositing minerals, and osteoclasts removing bone. • Ossification continues until late teens or early twenties

Ossification in a Foetus • Ossification continues until early adult years • This explains the soft spot on a baby’s head • Kids have more bones than adults do because as a child grows, its bones fuse together.

How does it all connect? • The skeletal system is held together and to other structures by connective tissue. • • Tendons Ligaments Muscles Cartilage

Ligaments - are strong tough elastic bands of connective tissue that can stretch - Hold bones and movable joints together - surround the joint to give support and limit the joint's movement.

Cartilage • hard but slippery tissue that covers the ends of bones where they meet to form a joint. • made up of cells and collagen fibres and is wear-resistant • helps reduce the friction of movement by allowing bones to glide over one another • Absorbs the energy from the shock of physical movement • Found in: – Ears, nose, esophagus, joints, disks between vertebrae

Joints • place in a skeleton where two or more bones meet

Types of Joints - Immovable joints - Also called sutures - where bones are joined tightly allowing for little or no movement (eg. Skull) - Movable joints - allow for movement

Tendons • another type of tough connective tissue on each side of a joint attach to muscles that control movement of the joint.

The Muscular System

Muscles • Bones need muscles to move them • There about 600 muscles in the human body • Made up of bundles of long cells called muscle fibres that contain specialized proteins Muscle Function • contraction for locomotion and skeletal movement • contraction for propulsion • contraction for pressure regulation

Types of Muscles • Cardiac Muscle – Makes heart beat – Controlled by autonomic nervous system • Smooth Muscle – Controlled automatically – Found in lining of organs (eg. stomach, esophagus, uterus, walls of blood vessels) • Skeletal Muscle – Attached to bone – Conscious control

Muscle Attachment • Muscles usually attached to two bones, one movable, one stationary • Origin – Place where the muscle attaches to the stationary bone • Insertion – Place where the muscle is attached to the moving bone

Antagonistic Muscles • Muscles can pull but cannot push so many muscles arranged in pairs that work against each other to make joints move • Flexor – muscle that contracts to bend a joint • Extensor – muscle that contracts to straighten a joint

Antagonistic Muscles • E. g. bicep/tricep • Bicep contracts, tricep relaxes, bones of elbow joint close together bicep is a flexor • Bicep relaxes, tricep contracts, bones of the elbow joint far apart tricep is an extensor