Italics Topics are Triple Science ONLY
, Chapter 10 – Homeostasis
Definition
- The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in
- response to internal and external changes.
Homeostasis in the body
- Internal conditions controlled include blood glucose concentration, temperature of body, & water content.
- Temperature of the Body is maintained to ensure that enzymes can work properly
- Blood Glucose Concentration is maintained as it can affect water balance, and respiration in cells.
- Water Content of the Body is maintained as it can affect osmotic balance, and the state of cells.
Control Systems
- The automatic control systems may involve nervous or chemical responses, where all control systems include
- receptors, coordination centres, and effectors.
- Receptors – cells that detect stimuli, these are changes in the internal or external parts of the body.
- Coordination Centres – areas that receive and process information from the receptors. They send signals &
- coordinate the response of the body.
- Effectors – usually muscles or glands that bring about responses in the body, restoring optimum conditions.
, Chapter 10 – The Nervous System
- The nervous system uses electrical impulses to enable you to react quickly to your surroundings and coordinate
- your behaviour.
- A conscious action takes longer than a reflex action as it has to travel to the brain and back.
- Reflex actions are automatic and rapid and do not involve conscious parts of the brain.
- Reflex actions control everyday bodily functions such as breathing and digestion, and help to avoid danger.
- A receptor detects a stimulus.
- An electrical impulse travels through the sensory neurone.
- This is where the message/impulse reaches a synapse.
- The message is converted into a chemical impulse where a neurotransmitter
- diffuses it to the relay neurone.
- After the impulse reaches the motor neurone, it will send a message/impulse
- to the effector.
- The effector (usually a muscle or gland) responds.
Stimulus Receptor Sensory Relay Motor Effector Response
, Chapter 10 – The Brain
- The brain is made up of billions of interconnected neurones that control complex behaviour.
- It is kept protected inside the bones of the skull and is encased in protective membranes called the meninges.
Structure
- The cerebral cortex is connected with consciousness, intelligence, memory and language.
- The cerebellum is concerned mainly with coordinating muscular activity and balance.
- The medulla is concerned with unconscious activities e.g. controlling heartbeat, gut movements, & breathing.
- The hypothalamus is involved in controlling the body temperature.
- The pituitary gland produces many different chemicals (hormones).
Research & Brain Damage
- Scientists map regions of the brain to their functions by studying patients with
- brain damage. This is done by electrically stimulating areas & MRI scanning.
- By exposing the brain when removing the top of the skull, scientists can
- electrically stimulate the different areas and analyse the effects.
- As there are no sensory nerve endings, brain surgery is usually done where
- patients are conscious.
- People can experience hunger, anger, fear or thirst as relevant areas of brain
- are stimulated.
, Chapter 10 – Homeostasis
Definition
- The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in
- response to internal and external changes.
Homeostasis in the body
- Internal conditions controlled include blood glucose concentration, temperature of body, & water content.
- Temperature of the Body is maintained to ensure that enzymes can work properly
- Blood Glucose Concentration is maintained as it can affect water balance, and respiration in cells.
- Water Content of the Body is maintained as it can affect osmotic balance, and the state of cells.
Control Systems
- The automatic control systems may involve nervous or chemical responses, where all control systems include
- receptors, coordination centres, and effectors.
- Receptors – cells that detect stimuli, these are changes in the internal or external parts of the body.
- Coordination Centres – areas that receive and process information from the receptors. They send signals &
- coordinate the response of the body.
- Effectors – usually muscles or glands that bring about responses in the body, restoring optimum conditions.
, Chapter 10 – The Nervous System
- The nervous system uses electrical impulses to enable you to react quickly to your surroundings and coordinate
- your behaviour.
- A conscious action takes longer than a reflex action as it has to travel to the brain and back.
- Reflex actions are automatic and rapid and do not involve conscious parts of the brain.
- Reflex actions control everyday bodily functions such as breathing and digestion, and help to avoid danger.
- A receptor detects a stimulus.
- An electrical impulse travels through the sensory neurone.
- This is where the message/impulse reaches a synapse.
- The message is converted into a chemical impulse where a neurotransmitter
- diffuses it to the relay neurone.
- After the impulse reaches the motor neurone, it will send a message/impulse
- to the effector.
- The effector (usually a muscle or gland) responds.
Stimulus Receptor Sensory Relay Motor Effector Response
, Chapter 10 – The Brain
- The brain is made up of billions of interconnected neurones that control complex behaviour.
- It is kept protected inside the bones of the skull and is encased in protective membranes called the meninges.
Structure
- The cerebral cortex is connected with consciousness, intelligence, memory and language.
- The cerebellum is concerned mainly with coordinating muscular activity and balance.
- The medulla is concerned with unconscious activities e.g. controlling heartbeat, gut movements, & breathing.
- The hypothalamus is involved in controlling the body temperature.
- The pituitary gland produces many different chemicals (hormones).
Research & Brain Damage
- Scientists map regions of the brain to their functions by studying patients with
- brain damage. This is done by electrically stimulating areas & MRI scanning.
- By exposing the brain when removing the top of the skull, scientists can
- electrically stimulate the different areas and analyse the effects.
- As there are no sensory nerve endings, brain surgery is usually done where
- patients are conscious.
- People can experience hunger, anger, fear or thirst as relevant areas of brain
- are stimulated.
