B10 - the human nervous system fact test Flashcards
what is homeostasis
homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
what are some examples of what homeostasis controls
- blood glucose concentration
- body temperature
- water levels
what do all control systems include
- cells called receptors which detect stimuli
- coordination centres that receive and process information about receptors
- effectors (muscles contract and glands secrete hormones) which bring about responses to restore optimum levels
what does the nervous system allow
humans to respond to stimuli and coordinate their behaviour
how does the nervous system respond to a stimulus
- stimulus (change in environment)
- receptor (detects a nucleus)
- coordinator (CNS: brain/spinal chord coordinate response)
- effector (muscle or gland causes response)
- response (muscle contracts or gland secretes hormones
what is a voluntary action
a response that involves conscious thought (thinking time)
what is a reflex action
a response that does not require conscious thought (thinking time) and happens very quickly to avoid unnecessary damage to the body
how does the axon of a nerve cell help it be adapted to its function
the axon is a long fibre which is insulated by a fatty (myelin) sheath
they are strong so can carry messages up and down the body
the insulation means that the impulses can travel faster
how do the dendrones of a nerve cell help it be adapted to its function
tiny branches branch further as dendrites at each end. they receive incoming impulses from other neurons
there are many branches allowing each neurons to connect to many other neurons
what is a synapse
a synapse is the small gap between 2 neurons where nerve impulses are relayed by a neurotransmitter
how does an electrical impulse travel through a synapse
- the impulse reaches the end of the neuron
- the impulse causes the release of chemicals known as neurotransmitters
- chemical diffuses across the space between the neurons known as the synapse
- chemical reaches the neuron and joins to the receptors on the end of the neuron
- this triggers an impulse down this neuron
what does the cerebral cortex control
intelligence, personality, conscious thought and high level functions such as language and verbal memory
what does the cerebellum control
balance, coordination of movement and muscular activity
what does the medulla control
unconscious activity such as heart and breathing rate
what is the function of the hypothalamus
regulating centre for temperature and water balance between the body, links the nervous system to the hormonal system via the pituitary gland
why is the brain hard to study and treat
due to its complexity and delicacy
how have neuroscientists mapped regions of the brain to their functions
- studying patients with brain damage
- electrically stimulating parts of the brain
- using fMRI scanning (functional MRI measures brain activity whilst completing tasks)
what is the retina
layer of light sensitive cells found at the back of the eye. when light hits this, the cells are stimulated. impulses are sent to the brain which interprets the information to create an image
what is the optic nerve
a nerve that leaves the eye and leads to the brain. it carries the impulses from the retina to the brain to create an image
what is the sclera
white outer layer which supports the structures inside the eye, it is strong to prevent damage to the eye
what is the cornea
the see-through layer at the front of the eye, allows light through and the curved surface bends and focuses light onto the retina
what is the iris
muscles that surround the pupil
what do the ciliary muscles and suspensory ligaments do
hold the lens in place, control its shape
what is it called when the focus of the eye changes
accommodation
