1st Test Flashcards
What is reflex action?
When does it occur?
A spontaneous response of the body to a stimulus
It occurs automatically without conscious thought or effort
Ex- knee jerk reflex
- touching a hot object
What is the nervous system?
1) major control center
2) communication network
3) sense network
What are the 2 main divisions of the nervous system?
Central nervous system
Peripheral nervous system
What is the central nervous system? What is the job of the CNS?
Brain & spinal chord
Command center
Interpret signals
Outputs info
What is the peripheral nervous system?
Nerves that extend from the CNS
Gathers info from inside & outside of your body
What is the PNS made up of?
Made up of nerves that extend from the brain & spinal cord
How does the nervous system work?
Messages are transmitted through electrical impulses or charges
What are neurons?
The basic building block of the nervous system. These are messengers & receivers of transmissions or stimuli
What is the structure of a neuron?
Cell body
Dendrites
Axon
What is the cell body?
Consists of nucleus that sends and receives and sends nerve impulses; the nucleus is contained within the cell membrane
What are dendrites?
Branching projections of the cell body; they receive and carry impulses toward the cell body
What are axons?
Each neuron has only one axon which carries impulses away from the cell body* the axon branches at its end to form terminals through which signals are sent to target cells
What do most axons have?
A coating or sheath of fatty material called myelin. The myelin sheath insulates the nerve fiber which speeds up the transmission
What are the types of neurons?
Sensory neurons
Motor neurons
Interneurons
What are sensory neurons?
Have specialized receptor ends that are located in the skin & other sensory organs
What do sensory neurons do?
Receive stimuli, such as sound or touch and send these impulses to your brain and spinal cord
*sensory to the CNS
What are motor neurons?
Carry impulses from the CNS to the muscles & glands
What are inter neurons?
Neurons within the brain & spinal cord that relay impulses from sensory neurons to motor neurons
What 2 subdivisions is the PNS broken down into?
Autonomic nervous system
Somatic nervous system
What is the autonomic nervous system responsible for?
Controlling the involuntary functions of the body such as body heat, heart rate, & digestion
What is the ANS divided into?
Sympathetic nervous system
Parasympathetic nervous system
- they have opposing effects on the same organs & normally balance each other out
What does the sympathetic nervous system do? What happens during these examples?
Responds to the body’s needs during increased activities and emergencies
*fight or flight
During the examples heart rate & breathing increases as blood flow to the muscles increases
What does the parasympathetic nervous system do?
Opposes the actions of the sympathetic system by slowing down body functions
- slows down heartbeat
- opens blood vessels
- lowers blood pressure
What is the somatic nervous system? What does this involve?
Includes cranial and spinal nerves that transmit impulses from the CNS to skeletal movements
This involves voluntary responses which are under your control
What is the spinal cord?
A cylinder of nerve tissue about 18” long & about at thick as your index finger
What is the spinal cord protected by?
The vertebrae (spine) Cerebrospinal spinal fluid which acts like a shock absorber & by 3 layers of connective membranes called the spinal meninges
What is the brain?
Receives and processes messages Coordinates muscle movement Weighs about 3 lbs Makes up 2% of body weight But uses 20% of oxygen inhaled 20% of blood pumped through heart
What is the brain protected by?
The 8 cranial bones that form the skull & by 3 layers of membranes called the cranial meninges
What cushions the brain?
Cerebrospinal fluid between the meninges
What are the main divisions of the brain?
Cerebrum
Cerebellum
Brain stem
What is the cerebrum? Site of? Divided into?
Largest & most complex part of the brain
Site of most conscious and intelligent activities
Divided into 2 halves called cerebral hemispheres
Connected In cross over fashion
Right side controls the left side of the body
Left hemisphere
Language Logic Arithmetic calc. Analysis Critical thinking
Right hemisphere
Imagination Visual thinking Form Artistic activities Emotions
What are the 4 lobes of the hemisphere
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
What is the cerebellum?
2nd largest part of the brain
Located beneath the occipital lobes of the cerebrum
What are the main purposes of the cerebellum?
Maintaining posture & balance
Coordinating skeletal muscle movement
What is the brain stem?
3” long stalk of nerves cells and fibers that connects the spinal cord to the rest of the brain
What does the brain stem control?
Controls breathing heartbeat & eye reflexes
* the activities of the brain stem are not under conscious control
What does the brain stem consist of?
Medulla oblongata
Pons
Midbrain
What is the medulla oblongata?
Lowest part of the brain stem; contains vital control centers that regulate heartbeat, breathing, blood pressure, digestion
What are pons?
Just above the medulla.
Serves as a pathway for nerve impulses passing to & from the cerebrum
What is the midbrain?
Shortest part of the brain stem
Lies above pons
Controls eye movement- the size & reactions of the pupils
What is the thalamus?
2 egg shaped lobes above the midbrain
Important relay center for incoming sensory impulses
What is the hypothalamus? Located? Controls?
Located behind the eyes & under the thalamus
Controls various body processes & keeps body conditions balanced (body temp, appetite)
What is the endocrine system?
Works with the nervous system to coordinate & regulate body functions
What do endocrine glands do?*
Send messages to organs and systems of the body via chemical messengers called hormones
What are endocrine glands?
Ductless or tubeless structures that secrete hormones
What are hormones?
Chemical substances produced by ductless glands that regulate the activities of different body cells
What is the pituitary gland? Located?
Regulates & controls the activities of all other endocrine glands
Master gland
Located at midpoint of the skull, behind the eyes
What is the thyroid gland?
Produces hormones that regulate: Metabolism Bone growth Body heat Consists of 2 lobes, located one on either side of the trachea
What are the parathyroid glands? Located?
Produce parathyroid hormone which regulates the body’s calcium & phosphorus balance
Smallest glands of the endocrine system
Located in the lobes of the thyroid gland
What are adrenal glands? What do they do?
2 glands located on top of the kidneys
Secretes a mixture of hormones that regulate numerous body functions such as: maintaining blood pressure & the metabolism of fats, proteins & carbs
What is the pancreas? What does it do?
Serves the digestive & endocrine systems
Secretes digestive enzymes & 2 hormones, glucagon & insulin- which regulates the level of blood sugar
What are gonads?
These glands regulate reproduction & secondary sexual characteristics
Ovaries- produce & release ova
Testes- produce & release sperm
