S1 Science: Life Processes and Body Systems

• These notes cover the topics discussed in S1 Science at Bannockburn High School, including life processes, skeletal, respiratory, circulatory, digestive, and reproductive systems, homeostasis, and scientific skills.

Life Processes

• Living things exhibit movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition.
• Non-living things do not exhibit the characteristics of life (MRS GREN).
• Movement refers to the ability of an organism or its parts to move.
• Respiration is Cellular process of releasing energy from food.
• Sensitivity is responding to changes in the environment.
• Growth is increasing in size and/or cell number.
• Reproduction is producing new organisms.
• Excretion refers to the removal of waste products.
• Nutrition is obtaining food for nutrients and energy.

The Skeletal System

• The skeleton provides movement by allowing muscles to attach to bones.
• The skeleton protects organs from damage.
• The skeleton provides support that keeps the body upright.
• Bones without minerals become rubbery and flexible. This is because acid burns the hard mineral portion.
• Bones without collagen become brittle and easily break. This is because collagen has been removed from the bone.

Osteoporosis

• A bone disease where bone tissue becomes weak, leading to fractures
• Diagnosed via a DXA scan (dual-energy x-ray absorptiometry).
• Symptoms: Severe back pain, loss of height, and a hunched posture.
• Individuals most at risk are white and Asian postmenopausal women.
• Preventative measures include consuming calcium-rich foods and drinks, and avoiding smoking and alcohol.

Joints

• Fixed joints do not allow movement and are found in the skull.
• Ball and socket joints such as the hip and shoulder allow movement and rotation in all planes.
• Hinge joints such as the knee and elbow allow movement in one plane, like a door hinge.
• Synovial joints contain fluid that provides lubrication, enabling smooth movement.
• Ligaments connect bones to other bones.
• Tendons connect muscles to bones.
• Cartilage acts as padding and cushion in the body.
• Cartilage protects and cushions the ends of bones.

The Respiratory System

• The epiglottis prevents food from entering the trachea during swallowing.
• The ribs protect the heart and lungs.
• Cartilage in the trachea prevents it from collapsing.
• Breathing rate is the number of breaths per minute.
• Tidal volume refers to the amount of air moved into or out of the lungs when breathing normally.
• Peak flow measures the speed at which air can be exhaled from the lungs.

The Circulatory System

• The heart's primary role is to pump oxygenated blood throughout the body.

Blood Vessels

• Arteries have thick, muscular walls and carry blood away from the heart at high pressure; a pulse can be felt in arteries.
• Capillaries permit the exchange of substances between blood and tissues, are formed from arteries, and have thin walls.
• Veins have thin walls, contain valves to prevent backflow, and return blood back to the heart.

Exercise and Heart Rate

• Exercise increases heart rate.
• To improve reliability, maintain a consistent pace, practice taking pulse accurately, and repeat the experiment to calculate an average.

Homeostasis

• Homeostasis is the maintenance of a stable internal environment by coordinating organ systems.
• When the body is too hot it sweats, experiences increased blood flow to the skin, and hairs lie flat.
• When the body is too cold it shivers, experiences decreased blood flow to the skin, and hairs stand on end.

Diabetes

• In Type 1 diabetes, family history is a risk factor, with symptoms including thirst, frequent urination, stomach pain, and confusion; treatment involves insulin.
• In Type 2 diabetes, obesity is a risk factor, with symptoms including thirst, frequent urination (especially at night), fatigue, slow healing, and blurred vision; treatment includes metformin and insulin.

Reproductive System

• During sexual intercourse, the penis releases sperm into the vagina.
• Sperm swim from the vagina through the cervix to the uterus and fertilize an egg cell in the oviduct.
• A fertilized egg cell is called a zygote and develops into an embryo, then eventually into a baby.
• Pregnancy lasts for 9 months in humans.
• The baby receives nutrients and oxygen via the umbilical cord during pregnancy.
• Uterine muscles contract during labor to widen the cervix and push the baby through the vagina.
• After the baby is born the placenta is expelled, known as the afterbirth.

The Digestive System

• The body needs food for movement, heat, growth, and tissue repair.
• Digestion is the breakdown of large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream.
• Enzymes speed up reactions without being used up themselves; synthesis enzymes build up molecules, while degradation enzymes break down molecules.