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Chapter Three – Human Body
Introduction
This chapter provides a lot of the underlying theory to what we will do next with First Aid and
Resuscitation.
Very important to know and understand how each of these systems works.
Circulatory System
Moves blood around the body.
Components – heart and blood vessels (arteries, veins and capillaries)
Heart is a mechanical pump. Four chambers. About size of clenched fist.
Hearts primary function is to pump blood to the lungs and the rest of the body.
Pathway:
Oxgenated blood comes from the lungs into the LEFT ATRIUM
It flows into the LEFT VENTRICLE and into the AORTA which takes the blood to smaller arteries
throughout the body.
Oxygen rich blood is delivered to organs, muscles and other tissues by arteries.
Capillaries link the smallest arteries and smallest veins.Capillaries allow oxygen and nutrients to
reach every cell in the body.
Venous blood returns to the heart from the body and comes into the RIGHT ATRIUM.
Venous blood flows into the RIGHT VENTRICLE and is pumped to the LUNGS
The LUNGS remove CO2 and add OXYGEN to the blood.
Blood flow from the lungs back into the LEFT ATRIUM – see top.
Arteries – strong elastic walls, carry blood under high pressure, rich red colour
Veins – thin walled and easily seen in wrist, feet. Blood is dark red and at low pressure.
All organs require adequate oxygen from the circulatory system. This needs good supply of oxygen to the
lungs and beating / pumping of the heart.
When breathing and heart both stop oxygen is not supplied to the body. Damage from lack of oxygen begins
in less than four minutes.
Skeletal System
Without the skeletal system we would be jellyfish!
Skeletal system provides support for the body and protection of important organs.
Bones are connected by joints – hip, knee, elbow
Muscles are attached to bones by tendons. Contraction and relaxation of muscles provides movement.
Skeleton consists of:
Skull, Spine, Rib cage, upper limbs, pelvis and lower limbs
Exercise – work through names of bones
The Spine – vertebrae separated by discs and joined by ligaments. Provides upright structure and protection
for the SPINAL CORD – nerve tissue that connects to the brain.
Spinal column has five sections:
Mobile:
- Cervical vertebrae (neck)
- Thoracic vertebrae (mid back)
- Lumbar vertebrae (lower back)
Fixed:
- Sacrum
- Coccyx
The most vulnerable section is ?
Due to:
- narrow canal for spinal cord
- lack of extra support
- force that heavy head and brain exert on cervical spine
Respiratory System
Airway – all structures from mouth to the larynx
Throat – the PARYNX is the area in which most blockages occur. Base of the throat divides into two
separate tubes – one for air to lungs (TRACHEA) the other for food to the stomach (OESOPHAGUS).
Front tube is also known as the wind pipe it runs from the LARYNX (Voice Box) to the lungs.
It then divides into two tubes known as left & right BRONCHUS, which then divide into BRONCHI.
Back tube is also known as the GULLET this carries food and liquid to the stomach. – it is also the path for
vomiting and regurgitation.
It is usually closed and only opens up when food passes down to the stomach (or back up).
LUNGS
Two lungs – left and right.
Fill most of the chest cavity. The base of the lungs sits the DIAPHRAGM.
LUNGS are spongy organs consisting of BRONCHIAL TUBES, AIR SAC and BLOOD VESSELS
(what type ?)
Oxygen and CO2 transfer occurs in the ALVEOLAR SACS by a process known as DIFFUSION.
When we breathe out CO2 is expelled from the body.
BREATHING IN – INSPIRATION
BREATHING OUT – EXPIRATION
Breathing is an involuntary muscular action caused by contraction and relaxation of the DIAPHAGM.
KEY TO RESCUE BREATHING (RESUSCITATION)
Air we breathe in contains 21% oxygen.
Only 5% of OXYGEN in the air is absorbed by the lungs into the blood stream
Air we breathe out contains ? % oxygen.
Nervous System
Central Nervous System (CNS) – brain & spinal cord – brain is the controller, spinal cord delivers
messages.
Breathing Control Centre – located in the brain stem / base of brain. Needs good supply of oxygen to
function properly. Lack of oxygen to the BCC may cause breathing to stop.
Peripheral Nervous System (PNS) – all nerves, ganglia and sensory receptors outside CNS. PNS relays
impulses from CNS to muscles and the autonomic nervous centre.
Digestive System
Food supplies nutrients for energy and body cells to function / grow.
Digestive system breaks down food we eat so that it can be transported to the cells for production of energy.
It also handles waste products from the digestive process.
Major organs:
MOUTH, OESOPHAGUS, STOMACH, LIVER, GALL BALDDER, PANCREAS, DUODENUM,
SMALL INTESTINE, LARGE INTESTINE and ANUS
Integumentary System (Skin)
Outer most layer that protects and covers the entire body.
Inner layer – DERMIS
Outer layer – EPIDERMIS
Contains nerves, blood vessels and fat tissues
Functions:
Protect tissues and organs
Prevent entry of infection
Maintain and regulate body temperature
Prevent dehydration
Detect stimuli
Provide a factory for Vitamin D production & storage
Urinary System
Helps rid the body of waste products.
Blood is filtered through the kidneys where it regulates fluid and electrolytes – adding or removing.
From the kidneys urine drains down the ureters into the bladder and is then pass out of the body via the
urethra.