nervous system,stimuli,cns,brain, spinal cord Flashcards
Name + Explain (Response time and how its brought about) the two co-ordinating systems which enable humans to respond to their environment?
- Nervous co-ordinating system: Responds fastest and brought about by impulse travelling ALONG nerves
- Endocrine co-ordinating system: Slower and brought about by hormones carried in blood.
What is the Nervous system and How does the nerves system function (3)
Nervous system- The body’s control and communication centre.
How does the nervous system function:
☛Sensory function- The sensory receptors DETECT changes in EXTERNAL + environment within organism.
⬇️
☛Integrative function- Central nervous system RECEIVES this info and DECIDES which effectors need to react to the stimulus.
⬇️
☛Motor function- Effectors ( Muscles + Glands) bring about the appropriate response
What is stimuli (give internal and external examples (3)) ?
Stimuli- Physical and Chemical changes in the environment
capable of causing a response in an organism.
External:
➜💡Light
➜🌡️Temperature
➜🔊Sound
➜Atmospheric pressure
Internal:
➜BP
➜Blood pH
➜Tensions in muscles
Name + Explain the two parts the human nervous system can be divided into
Central Nervous System- Made up of a CONCENTRATED mass of interconnected neurons (nerve cells) grouped together to form the BRAIN and the SPINAL CORD
- Peripheral nervous system (PNS)
How is CNS protected?
- Tissues of B+S are protected and nourished by 3 connective tissue membranes- Meninges.
- Space between the 2nd and 3rd layer of membrane is filled with cerebro-spinal fluid acting as a CUSHION, protecting CNS against SHOCK and DAMAGE.
*The whole CNS and its meninges = ENCLOSED within a bony case made up of two separate structures:
CRANIUM which protects brain from mechanical injuries.
The vertebral column which is made up of 33 irregular shaped vertebrae, which surrounds the spinal cord and protects it against mechanical injury.
*The S-shaped curvature of the vertebral column prevent jarring of CNS
*
What is the Cerebrum?
What parts is the Cerebrum divided into? (explain)
➪The cerebrum = LARGEST part of brain
➪DIVIDED into 2 cerebral hemispheres by a longitudinal fissures.
➪Hemispheres = Held together by a mass of myelinated nerve fibres bundled into large tracts forming the Corpus Callosum. Providing COMMUNICATION between Cerebral Hemispheres and between Cerebral Cortex and lower parts of CNS , ENABLING them to function as a co-ordinated whole.
- Describe the surface of the Cerebrum
- What are the four cavities in the brain called and what are they filled with? (1)?
- What forms the cerebral cortex (1) and what does it form (1)?
- Where is white matter and what forms it?
➾ Surface is made up of a no. of GYRI (folds) and SULCI (Grooves) that enlarge the surface area so that a number of brain cells can fit into small cranial cavity.
Deeper folds divide cerebrum into 4 lobes.
➾ Ventricles in centre of brain they are filled with cerebro-spinal fluid.
➾ The outer 3mm of the cerebrum form the Cerebral Cortex, this is made of a collection of cell bodies of Neurons and forms grey matter.
➾ Below grey matter is an area of White Matter made of a collection of myelinated nerve fibres.
What are the functions of the cerebrum? (3)
~Motor area in the frontal lobe where all the voluntary movements of the body originate
~ Sensory areas that RECEIVE + INTERPRET impulses from the sense organs
* Temporal lobe = Hearing, Smelling, Tasting
* Occipital lobe = Sight
* Parietal lobe = Skin sensations
~ The association cortex which is involved with higher mental activities e.g. Intelligence, memory, perception, language and consciousness. An association areas in frontal lobe controls emotions.
- Where is the cerebellum located?
- Why is the cerebellum called the tree of life?
*Cerebellum lies behind and below the Cerebrum.
* Made up of 2 hemispheres and has shallow surface folds.
- White matter looks like branches of tree and its surrounded by grey matter which looks like foliage.
What are the 3 functions of the cerebellum?
• Cerebellum processes sensory input it receives from the motor region of the cerebrum and uses it to co-ordinate actions of voluntary muscles so complicated physical actions can be performed in smooth, controlled manner.
• Its partly responsible for CONTROLLING muscle tone.
• Helps maintain Posture and Balance, using information from inner ear.
Where is the hypothalamus located?
What are the functions of the hypothalamus?
- Lies BELOW the thalamus and ABOVE the pituitary gland
Functions:
• Controls autonomic system ∴ It plays a part in maintaining homeostasis by regulating:
Body temperature 🤒
Water balance and thirst 💧
Food intake 🍔
Sleep-wake cycles 😴
• Centre for emotional response and behaviour: Pain, fear, pleasure, drives
• Controls functioning of pituitary by:
Secreting hormones
Controlling release of all hormones from both lobes of the pituitary.
Where is the Medulla oblongata found?
What are the functions of the Medulla?
– Forms lowest part of brain stem.
–When it passes through foramen magnum at base of cranium its known as spinal cord.
Functions:
1. Serves as PATHWAY for IMPULSES to and from the brain.
2. ACTS as REFLEX CENTRE controlling N.B. reflexes, e.g. BP, 😮💨 and ٨ـﮩﮩ٨ـ
3. CONTROLS less N.B. reflexes e.g. Sneezing, coughing.
What is the spinal cord?
AN elongated rod of nervous tissue, that extends from the medulla oblongata, through the foramen magnum.
What are functions of spinal cord? (2)
- Serves as PATHWAY for impulses FROM receptors TO the brain and
FROM the brain TO effectors. - Has an INTEGRATIVE function because it’s the seat of primitive reflex actions called spinal reflexes. They serve to protect the body.
