Coordinated Body Systems & Homeostasis (cocept)

This set of flashcards covers the fundamentals of multicellular organization, organ systems, homeostasis, the stimulus-response model, and feedback loops including temperature and blood glucose regulation.

Multicellular organisms

Organisms that contain trillions of specialised cells which cannot independently obtain everything they need or remove all their wastes.

Organisation of the human body

The hierarchical structure of the body represented by: Cells → Tissues → Organs → Organ systems → Organism.

Aerobic cellular respiration

A process requiring glucose and oxygen to produce energy, carbon dioxide, and water, expressed as: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + energy$.

Glucose

A nutrient mainly derived from the digestion of carbohydrates that travels through the bloodstream to cells for cellular respiration.

Digestive system

Comprised of the stomach, intestines, and liver; its main role is to break food down and absorb nutrients.

Respiratory system

Comprised of the lungs and trachea; its main role is to take in $O_2$ and remove $CO_2$.

Circulatory system

Comprised of the heart and blood vessels; its main role is to transport oxygen, nutrients, hormones, and wastes.

Urinary/excretory system

Comprised of the kidneys and bladder; its main role is to remove urea, excess water, and salts.

Nervous system

Comprised of the brain, spinal cord, and nerves; its main role is rapid communication and coordination.

Endocrine system

Consists of hormone-producing glands used for longer-term regulation of the body.

Homeostasis

The maintenance of a relatively stable internal environment despite changes inside or outside the body, keeping factors like temperature and pH within suitable ranges.

Stimulus

A detectable change in the internal or external environment, such as bright light or increasing temperature.

Receptor

A component that detects a stimulus, such as temperature, light, or pressure receptors.

Coordinator

The part of the stimulus-response model that receives and processes information, involving the brain or endocrine system.

Effector

A muscle or gland that performs a response after receiving information from a coordinator.

Negative feedback

The major mechanism in homeostasis that reverses a change and moves a condition back towards its normal level.

Positive feedback

A feedback mechanism that strengthens or increases the original change instead of reversing it, such as blood clotting or oxytocin during childbirth.

Hypothalamus

A part of the brain that plays an important role in temperature regulation by coordinating responses to keep core temperature around $37^\circ\text{C}$.

Vasodilation

The widening of blood vessels near the skin when the body is too hot, allowing more warm blood to reach the surface and heat to escape.

Vasoconstriction

The narrowing of blood vessels near the skin when the body is too cold, reducing blood flow at the surface to decrease heat loss.

Shivering

A process where muscles rapidly contract and relax to release heat through cellular respiration.

Insulin

A hormone released by the pancreas when blood glucose is too high, causing body cells to take up more glucose and storing it as glycogen in the liver and muscles.

Glucagon

A hormone released by the pancreas when blood glucose is too low, causing the liver to convert stored glycogen into glucose and release it into the blood.

Platelets

Cell fragments that stick to damaged blood vessels and release chemicals to attract more platelets to form a blood clot, an example of positive feedback.

Specialised Cells

Cells that have particular structures and features allowing them to perform specific functions efficiently

Tissue

A group of similar specialised cells working together to perform a particular function

Organ

A structure made of different tissues working together to perform particular functions

Organ system

A group of organs that work together to perform major functions in the body

Coordination of body systems

Body systems depend on each other to supply cells with nutrients and oxygen, remove wastes and maintain stable internal conditions

Digestive + circulatory systems

The digestive system breaks down food and absorbs nutrients such as glucose. The circulatory system transports these nutrients to body cells

Respiratory, circulatory systems

The respiratory system exchanges oxygen and carbon dioxide, while the circulatory system transports these gases between the lungs and body cells

Circulatory + excretory systems

The circulatory system carries wastes such as urea to the kidneys, where the excretory system removes them from the blood.

Set point

The normal or desired level around which a body condition is regulated, such as approximately 37°C for core body temperature.

Homeostatic variable

A condition controlled within a suitable range, such as body temperature, blood glucose, water balance or pH.

Stimulus–response model

The sequence Stimulus → Receptor → Coordinator → Effector → Response that allows the body to detect and respond to change.

Response

The change produced by an effector to deal with a stimulus.

Sweating

The release of sweat onto the skin. Evaporation of sweat removes thermal energy and helps cool the body.

Thermoregulation

The homeostatic control of body temperature to keep core temperature within a suitable range.

Blood glucose regulation

A negative-feedback process that keeps blood glucose within a suitable range, mainly using the hormones insulin and glucagon.

Glycogen

The storage form of glucose found mainly in the liver and skeletal muscles.

Hormone

A chemical messenger produced by an endocrine gland and transported through the blood to specific target cells or organs.

Target cell

A cell containing receptors for a particular hormone, allowing it to respond to that hormone.

Insulin vs glucagon

Insulin decreases blood glucose, whereas glucagon increases blood glucose.

Nervous vs endocrine control

Nervous control is generally rapid and short-lived. Endocrine control is generally slower and longer-lasting and uses hormones transported in blood.

Negative vs positive feedback

Negative feedback counteracts a change and returns a variable toward normal. Positive feedback amplifies a change until a particular event is completed.

High temperature response

Temperature rises - receptors detect change - hypothalamus - sweating + vasodilation - increased heat loss - temperature returns towards normal

Low temperature response

Temperature falls - receptors detect change - hypothalamus - shivering + vasoconstriction - increased heat production/reduced heat loss - temperature returns towards normal

High blood glucose response

Blood glucose rises - pancreas releases insulin - increased glucose uptake and glycogen storage - blood glucose decreases towards normal

Low blood glucose response

Blood glucose falls - pancreas releases glucagon - liver increases glucose release, including through glycogen breakdown - blood glucose rises towards normal

Blood clotting as positive feedback

Platelets stick to a damaged blood vessel and release chemicals that attract more platelets. This amplifies the response until a clot forms.