C3.1 Integration of Body Systems

Question 1

Define System Integration.

Answer 1

Multicellular organisms have developed a hierarchy of organisation that allows for effective communication and interaction with their environment.

Question 2

Define Tissue.

Answer 2

Group of cells of the same type that carry out a function.

• Cells in tissue adhere (stick) to each other.
• Cells within tissue communicate with each other, and cells elsewhere in organism.

Question 3

Define Organ.

Answer 3

Group of tissues that work together to carry out a specific function of life.

• Tissues within organ are interdependent.

Question 4

Define Organ System.

Answer 4

Group of organs that interact with each other to perform an overall function of life.

Question 5

Define Organism.

Answer 5

Living individuals made up of interconnected parts (organ systems, composed of organs, made up of tissues with constituent cells).

Question 6

Organs in a system can be physically linked or dispersed around body.

Example?

Answer 6

For example, the nervous system is physically linked, while the endocrine system is dispersed around the body.

Question 7

Tissues within organ are interdependent.

Example?

Answer 7

For example, within a plant, the spongy mesophyll tissue and palisade mesophyll tissue are dependent on each other.
* Spongy mesophyll tissue relies on the concentration gradient of CO2 and O created by photosynthesis in palisade mesophyll tissue.
* Palisade mesophyll tissue depends on spongy mesophyll for a supply of CO2 and removal of O.

Question 8

Tissues may contain two or more cell types.

Example?

Answer 8

For example, the epithelium that forms the wall of the alveoli in the lung has two cell types: AT1 (alveolar Type 1) cells and AT2 (alveolar Type 2) cells.
* AT1 are extensive and thin, allowing diffusion of gases.
* AT2 secrete a surfactant that prevents the collapse of alveoli.

Question 9

Define Emergent Properties.

Answer 9

Properties that arise when the interaction of individual components produces new functions.

Question 10

Emergent properties.

Example?

Answer 10

For example, nerve cells interacting with muscle cells to stimulate movement.

Question 11

Which two systems are used for internal communication?

Answer 11

• Nervous System
• Endocrine System

Question 12

What is the role of ____ in internal communication?

The Nervous System

Answer 12

Nervous Signalling:
* Electrical
* By Neurons
* Highly Focused
* Very Rapid
* Short

Question 13

What is the role of ____ in internal communication?

The Endocrine System

Answer 13

Hormonal Signalling:
* Chemical
* In Bloodstream
* Widespread (Throughout Body)
* Slower
* Long

Question 14

What system is used for the transporation of materials and energy in organs?

Answer 14

• Circulatory (Blood) System

Question 15

What is the role of ____ in the transporation?

The Circulatory System

Answer 15

• Living cells need constant supply of energy, provided by cell respiration.
• Cells therefore require a respiratory substrate (glucose or oxygen, in aerobic).
• The bloodstream:
  * Supplies both.
  * Supplies water and carbon compounds needed for growth or repair.
  * Removed waste products (carbon dioxide produced in cell respiration).

Question 16

What is the function of ____?

The Brain

Answer 16

• Received information → Processes it → Stores some of it → Sends instructions to all parts of the body to coordinate life processes.
• Information is received from sensory receptors.

Question 17

Define Memory.

Answer 17

Capacity to store information.

Question 18

What is the role of ____ in the brain?

Memory

Answer 18

• Can store information for long or short term.
• Essential for learning.
• Processing leads to decision making.

Question 19

What is the ____ made up of?

Nervous System

Answer 19

Made up of:
1. The central nervous system (CNS)
2. Nerves connecting the CNS to all other organs in the body.

Question 20

What is the ________ made up of?

Central Nervous System

Answer 20

Made up of two organs:
1. The Brain
2. The Spinal Cord (inside the backbone)

Question 21

What is the ________ made up of?

Spinal Cord

Answer 21

Made up of two tissues:
1. White Matter—Contains myelinated axons and other nerve fibres, which convey signals from receptors to the brain and from the brain to the organs of the body.
2. Grey Matter—Contains the cell bodies of motor neurons and interneurons, with many synapses between these neurons. The synapses are used for processing information and decision-making.

Question 23

What are non-binary actions?

Answer 23

Many actions are non-binary (as in, we consciously choose to carry them out, but the processing then used is unconscious).
* For example: Striated muscles can be controlled unconsciously and consciously. We consciously choose to stand up and use striated muscles for this action. But, the unconscious postural reflex that keeps us standing uses the same muscles.

Question 24

Changes in the external environment can act as ________ to the nervous system, if perceived by sensory receptors.

Answer 24

Stimuli

Question 25

How do receptors react to stimuli?

Answer 25

1. Stimuli is triggered.
2. Receptor cells perceive stimuli.
3. Signals from receptor cells and from nerve endings that perceive stimuli directly, conveyed to the CNS by sensory neurons.
4. Signals (nerve impulses) are carried along the axons of sensory neurons.
5. Axons of sensory neurons can enter the spinal cord via 1/31 pairs of spinal nerves, or the brain via 1/12 pairs of carnival nerves.
6. Brain receives these signals from the main sense organs located in the head. Spinal cord receives signals from other organs of the body including skin and muscles.
7. Sensory inputs to the brain are received by specialized areas in the cerebral hemisphere.

Question 26

How is a nerve impulse sent from the brain to a muscle?

Answer 26

1. Cell body and dendrites of most motor neurons are located in the gray matter of the cerebral hemisphere.
2. One axon leads from the cell body out to the brain and down the spinal cord.
3. There, it forms a synapse with a second motor neuron, whose axon leads to a specific striated muscle.
4. When a nerve impulse reaches the end of the axons, it stimulates the muscle fibres to contract and the gland cells to secrete.

Question 27

Define Nerve.

Answer 27

A bundle of nerve fibres enclosed in a protective sheath.
* Most contain nerve fibres of both sensory and motor neurons.
* However, some contain only sensory neurons or motor neurons.

All organs of the body are served by one or more nerves.

Question 28

Define Reflex Action.

Answer 28

Rapid, involuntary response to specific stimuli.

• Signal passes through smallest number of neurons → Speeds up reflex.
• Some coordinated by spinal cord, others by brain.

Question 29

Define Reflex Arc.

Answer 29

Sequence of cells that participate in coordination of a reflex.

Question 30

Describe Receptors.

Answer 30

• Sense the change in conditions (called stimulus).
• Detects only one type of stimulus.
• Some have nerve endings that can directly perceive stimuli without the need for a separate receptor cell. For example, pain and heat are detected by nerve endings in the skin.

Question 31

Describe Sensory Neurons.

Answer 31

• Receive signals (from either receptors or their own sensory nerve endings).
• Pass signals to neurons in the CNS via their long axons that carry nerve impulses from the receptor to the spinal cord or brain.
• These axons end at synapses with interneurons in the grey matter (C3.1.5) of the spinal cord or brain.

Question 32

Describe Interneurons.

Answer 32

• Found inside the CNS.
• Have many dendrites, through which nerve impulses travel.
• Process signals from sensory neurons and make decisions on responses. To do so, they combine impulses from multiple inputs and pass them to specific neurons.
• Reflexes are simple because only one interneuron may connect a sensory neuron to a motor neuron, enabling a quick response.

Question 33

Describe Motor Neurons.

Answer 33

• Receive signals via synapses with interneurons.
• If a threshold potential is achieved in it, an impulse is passed along the axon which leads out of the CNS to an effector.
• Axon does not change its position or connections, so the impulse always travels to the same effector cell or small group of effector cells.

Question 34

Describe Effectors.

Answer 34

• Carry out the response to a stimulus when they receive the signal from a motor neuron. There are two types of effector:
  
  • Muscles respond by contracting. For example, muscles in the leg contract to lift the foot off a sharp object.
  • Glands respond by secreting. For example, the smell of food may cause glands in the head to secrete saliva.