Animal Responses Flashcards
The nervous system is split into the CNS & PNS - what’s the difference
CNS = brain & spinal cord
PNS = rest of neurons that connect CNS-body
The PNS is composed of sensory + motor neurons & sensory receptors outside of the CNS
- they connect & ensure rapid communication between sensory receptors, the CNS & effectors
Divisions of the PNS
What’s the sensory nervous system
- division of PNS
- sensory fibres entering CNS (dendrons of sensory neurons)
- sensory neurones enter the spinal cord through the dorsal root
- motor neurones leave the spinal cord through the ventral root
Whats the motor nervous system & its two divisions
It’s a division of the PNS
It conducts action potentials from the CNS to effectors
Breaks into the somatic nervous system & autonomic nervous system
Somatic versus Autonomic nervous system
What 2 divisions does the autonomic nervous system break down into?
Sympathetic system (fight or flight)
Parasympathetic system (rest & digest)
Sympathetic vs Parasympathetic system
What is the central nervous systems functionm
Made up of the brain & spinal cord
Function: transmit messages to and from the brain
Controls spinal flexes
Function & features of the spinal cord
- many relay neurons
- central grey matter
- many myelinated neurones
- outer white matter
-> rapid transmission of action potentials up and down the spinal cord
+ protected by the veterbrae column
between each vertebrae, peripheral nervous enter & leave the spinal cord, carrying action potentials to form the rest of the body
Structure of the brain
Function & structure of the cerebrum
Function!
Deals with higher functions e.g. conscious thought & actions, emotional responses, speech, thinking, problem solving & memory, vision & hearing
Structure
- divided into 2 cerebral hemispheres
- connected via corpus callosum
- right hemisphere controls left side & vice versa
- largest part of the brea
- has grey & white matter
Function & structure of cerebellum
Function:
Co-ordinates balance & fine control of movement
works subconsciously / involuntarily
Structure:
- below cerebrum
- has complex nervous pathways, strengthened by practice
Medulla oblongata function
- Controls physiological processes & Co-ordinates automatic stuff
(Via negative feedback) - controls non-skeletal muscles e.g. cardiac / involuntary smooth
3 centres: cardiac, vasomotor & respiratory - to regulate vital processes
What do the 3 centres of the medulla do (cardiac, vasomotor, respiratory)
Cardiac - controls heart rate
Vasomotor - controls contraction of smooth muscles in arteriole walls - and therefore blood pressure & circulation
Respiratory - controls breathing rate & depth
Where’s the medulla found
@ the base of the brain, where the brain joins the spinal cord
Hypothalamus functions & features
- Co-ordinates homeostatic responses by negative feedback to maintain a constant internal environment
- e.g. Thermoregulation, osmoregulation
- monitors temperature & water potential of blood flowing through
- has sensory receptors
- can release hormones / stimulate pituitary gland
Pituitary gland function & structure
Produces range of hormones
Acts in conjunction with the hypothalamus
Divided into 2 lobes - anterior & posterior
Found @ the base of the brain
Endocrine gland
Below hypothalamus (attached under it)
What does the anterior lobe of the pituitary gland do
Secrete many hormones which control a no. of physiological processes, e.g. stress, growth, respiration
What does the posterior lobe do:
Stores & releases hormones made by hypothalamus
What are reflex actions
Responses to stimuli which don’t involve any processing in the brain to co-ordinate movement
What’s the reflex pathway
Sensory neurone detects stimuli -> relay neurone -> motor neurone -> this conducts action potential to the effector -> appropriate response
Pathway as short as possible so the reflex is a rapid response
What is the value of reflex actions
The 3 types of reflex actions we have to know
- Knee jerk
- Blinking
- Corneal
Details about the knee jerk reflex
Details about the blinking reflex
Details about the corneal reflex
Whats a spinal reflex
A nervous pathway for reflex passes through part of spinal cord
What is a reflex arc vs cranial reflex
The receptor & effector of reflex arc in the same place
(While a cranial reflex - the pathway goes through the brain, but a direct one)
Example of a co-ordinated response between the nervous and endocrine system
Fight or flight response
Nervous = rapid response
Endocrine = prolonged response
Physiological changes in the fight or flight response
Physiological changes in the fight or flight response
Survival value of the fight or flight physiological responses e.g. what do each of them actually do
- Pupils dilate = more light enters eyes = define more sensitive
- Heart rate / B.P. Increase -> increased rate of blood flow, therefore more oxygen & glucose delivered to muscles -> more CO2 toxins removed
- Blood glucose levels increase = energy supplied for muscle contraction
- Hair erector muscles contract -> hair stands up, therefore aggression sign
- Endorphins released in brain -> wounds don’t prevent activity
- Ventilation rate & depth increases = more gaseous exchange = more O2 enters blood
How is the fight or flight response co-ordinated between both the endocrine and nervous system
- Input into sensory centres in cerebrum, so it passes signals to association ones
- Threat recognised by cerebrum which
-> stimulates hypothalamus to increase activity of sympathetic system, so more hormones released - Sympathetic N.S stimulated by hypothalamus, activates adrenal medulla, so adrenaline secreted into blood stream
Mechanism of adrenaline action
Describe using the image
Adrenaline = 1st messenger (can’t enter target cells)
-> so binds to receptor on CSM
- G protein on inner surface of CSM stimulated
-> adenyl cyclase is activated
- ATP converted to cAMP (second messenger)
cAMP activates the enzyme action inside the cell
What does TSH (thyroid stimulating hormone) do?
Stimulates thyroid gland to release more thyroxine -> increases metabolic rate -> cells more sensitive to adrenaline
What does ACTH do
Stimulates the adrenal cortex to release corticosteroid hormones e.g. glucocorticoids like cortisol-> regulates metabolism of carbohydrates -> more glucose released from glycogen stores
How did nerves from the cardiovascular centre in the medulla alter the frequencies of waves of excitation / heart contractions
They signal to the SAN
How to increase versus decrease heart rate using action potentials, SAN secretion of a hormone, waves of excitation?
Accelerans vs vagus nerve
Vagus = parasympathetic
Accelerans = sympathetic
At rest, the heart rate is controlled by the SAN -> frequency of contractions can be changed by what inputs where
Sensory inputs to the cardiovascular centre
What are the sensory inputs of the cardiovascular centre
- Stretch receptors in muscles
- Stretch receptors in cartoid sinus
- Adrenal medulla
- Blood CO2 concentration
- Chemoreceptors
How do stretch receptors in muscles work to Inc heart rate
How do stretch receptors in the carotid sinus reduce rate of heart
- monitor blood pressure
- higher frequency of heart contractions = detected high blood pressure
Action potentials sent down vagus nerve to reduce rate
How does the adrenal medulla increase heart rate
Secretes adrenaline, noradrenaline, can also be via thyroxine
How does blood co2 conc affect heart rate
How do chemoreceptors lead to a change in heart rate
How can heart rate be artificially controlled
Using an artifical pacemaker fitted under the skin & fat on chest
-> can be connected to SAN or directly to ventricle muscle -> therefore, pacemaker delivers electrical impulse to cardiac muscle
What is a neuromuscular junction
Junction between nervous system and muscles
Stimulation of contraction / action of the neuromuscular junction
Cholinergic synapse vs neuromuscular junction
