Biological structures Flashcards
What is the nervous system?
A specialised network of cells that is our main communciation system. It is based on chemical and electrical signals.
What is the function of the nervous sytem?
- Allows the body to respond to chnages in the internal or external environment (stimuli)
- Allows the body to coordinate its actions by communicating with a central “control point” (the brain)
What is the central nervous system?
Brain: centre of consious awareness
- The cerebral cortex
Spinal cord: Extension of the brain (connects via the brain stem)
Responsible for refelex actions such as pulling hand off a plate
What is the peripheral nervous system?
Consists of paired (either side of the body) cranial and spinal nerves
- It sends information about the external and internal environment via sensory neurones to the CNS from receptors
- It then transmits messages from the CNS to muscles or glands
It has two different systems: somatic nervous system and autonomic nervous system
What is the somatic nervous system?
- Transmits information from receptor cells to the CNS
- Recieves information from the CNS that directs muscles to act
- Responsible for voluntary movement and connects the CNS to do the same
What is the autonomic nervous system?
Transmits information to and from internal body organs for autonomic bodily functions. It has two main divisions:
- The sympathetic nervous system gets the body ready for action. It is the “flight or fight” system
- The parasympathetic nervous sytem calms the body down. It is the “rest and digest” system
What is the sympathetic nervous system?
Arousal
- Activates the internal organs by triggering release of adrenaline
- It increases the supply of glucose to ready muscles for increased activity (e.g it increases heart rate and breathing rate)
What is the parasympathetic system?
Calm
- Activates when the body is trying to conserve/store resources
- It has the opposite side effects of the sympathetic nervous system, decreasing the supply of glucose ad oxygen to the muscles and increases the rate of digestion
What is the endocrine system?
A specialised system of tissues, mainly glands, that works alognside the nervous system. It is based on only chemical signals from hormones
What is the function of endocrine system?
Regulates vital functions of the body by releasing hormones, mostly via blood, to communicate messages to target organs.
It operates slower than the nervous system, but the effects are longer lasting
What does the hypothalamus do?
Produces hormones that control the pituritary gland
What does the pituritary gland?
Known as the “master gland” because it releases hormones to control other glands in the endocrine system (e.g ACTH to stimulate adrenal glands)
Gland –> hormone –> effect
What does the thyroid gland do?
Produces hormones such as thyroxine. The thyroid is responsible for controlling metabolism and growth
What is the parathyroid glands?
Produce a hormone called parathyroid
This helps control the levels of minerals such as calcium within the body
What does the adrenal gland do?
Produces hormones such as adrenaline
Responsible for the “flight or fight” response
What does the pancreas do?
Endocrine glands in the pancreas produce insulin and glucagen, which regulate the level of glucose in the blood
What do the gonads (ovaries and testes) do?
Produce sex hormones, e.g testosterone snd oestrogen.
These are important in reproduction and the development of sex organs and secondary sex characteristics
What is flight or fight?
Refers to the way an animal responds when stressed. The body becomes physiologically aroused in readiness to fight or flee from threat
Response is a result of the nervous sytem and the endocrine working together
What is the process of flight or fight?
- When an individual is faced with a threat, an area of the brain called the amygdala is mobilised
- It sends a distress signal to the hypothalamus, which then triggers the pituritary gland to activate the sympathetic branch of the ANS
- This sympathetic activation causes the adrenal medulla (middle of the adrenal gland) to release adrenaline, leading to a range of physiological effects
What are three physiological effects of sympathetic state?
Increases heart rate
Dilates pupils
Inhibits digestion
What are three physiological effects of parasympathetic state?
Decreases heart rate
Constricts ppupils
Stimulates digestion
