Animal & Plant Responses - Animals Flashcards
What does the nervous system consist of? Structurally
CENTRAL NERVOUS SYSTEM (CNS) - brain/spinal chord
PERIPHERAL NERVOUS SYSTEM (PNS) - all nerves in body
What do neurones coordinate?
Activities of sensory receptors , decision making centres in CNS and effectors
What does nervous system consist of - functionally?
Somatic nervous system - for *voluntary control of body movements
Autonomic nervous system - self controlling system for involuntary actions/functions (heart rate , regulation of blood vessel diameter)
What does somatic nervous system consist of?
3 types of nerves :
Sensory nerves - consist of sensory neurones + carry impulse from sense organs —> CNS
Motor nerves - consist of motor neurones + Carry impulse from CNS to muscles/glands
Spinal nerves - in spinal chord - mixed nerves: consist of both sensory/motor neurones
What can the autonomic nervous system be divided into?
SYMPATHETIC nervous system - controls ‘flight or fight’ response
PARASYMPATHETIC nervous system - control ‘rest and digest’ system
- contains both sensory/motor neurones
What happens during ‘flight or fight’ response?
sympathetic nervous system controls release of adrenaline - produced by adrenal glands
- increases HR - increases blood supply to respiring muscles (more O2 + glucose for respiration)
- enables high intensity activities (running away) to be immediate response
Structure/Function of cerebrum ?
Function : vision,hearing,speech,thinking,memory
Structure : consist of 5 lobes and divided into 2 halves (cerebral hemispheres)
- hemispheres joined tgt by band of nerve fibres = CORPUS CALLOSUM
Right hemisphere control left side of body and left hemisphere control right
What is the outmost layer of the cerebrum called and the structure?
Cerebral cortex (grey matter)
- consist of cell bodies of neurones
- highly folded —> increase SA and allows it to contain greater no. Neurones
- good bc more connections between neurones made - more complex behaviours can be carried out
‘White matter’ below cerebral cortex - consist of myelinated axons of neurones
Function and location of hypothalamus?
Area in middle of lower part of brain
- above pituitary gland
Function: monitor blood flowing through it/releases hormones or stimulates pituitary to release hormones (homeostasis )
REGULATE BODY TEMP: initiate homeostatic response if temp is too high/low
OSMOREGULATION: monitor blood conc
If too concentrated - stimulate posterior pituitary gland to release antidiuretic hormone (ADH) —> increase water retention in kidneys
—> hypothalamus generates feeling of thirst - increase water intake
REGULATE DIGESTIVE ACTIVITY: control secretion of enzymes in gut/peristalsis
- also generate hunger feeling if blood nutrient conc is low —> increase food intake
CONTROL ENDOCRINE FUNCTIONS : releases chemicals that cause pituitary gland to release certain hormones to control metabolism, growth/development ,sleep etc
Location and function of pituitary gland?
Bottom of brain , below hypothalamus
Function:
PRODUCE RANGE OF HORMONES - some directly influence/regulate processes , some stimulate release of further hormones from other glands
Divided into 2 sections :
ANTERIOR PITUITARY - produce/release certain hormones
POSTERIOR PITUITARY - store/release hormones produced by hypothalamus
Cerebellum function and location?
Below cerebrum
Function :
Controls motor coordination- e.g balance - require coordination of multiple parts of body
Functions only subconscious - all of the actions it controls are involuntary)
Medulla oblongata structure and function , location?
At base of the brain - joins spinal chord
Contains 3 centres :
Cardiac centre - control HR
Vasomotor centre control blood pressure by controlling contraction of smooth muscles in arteriole walls
Respiratory centre : control breathing rate (has inspiratory and expiratory centre )
What are reflexes?
Involuntary responses to certain stimuli
- rapid/ have survival value
Sequence of components in reflex action?
Detection involves stimulus being detected by receptor cell then impulse sent through:
Stimulus —> receptor —> coordinator (e.g spinal chord)-> effector —> response
Different type of receptor cell?
Some produce electrical activity in nerve cells to respond to stimuli
Others secrete substances in response to stimuli
Knee jerk reflex: sequence of components?
SPINAL REFLEX
Stimulus - stretching of the quadriceps muscle caused by pressure on the ligament
Receptor - stretch receptors in the quadriceps muscle
Coordinator- the spinal cord
Effector - the quadriceps muscle
Response - contraction of the quadriceps muscle, causing the leg to straighten
Nervous pathway of knee jerk reflex?
Stretch receptors send impulses down SENSORY NEURONE
- this connects via a synapse with MOTOR NEURONE in spinal chord (no relay neurone in this reflex)
- motor neurone carries impulse to effector (quadriceps) which contracts
How does the knee jerk pathway show why reflex actions are so fast/automatic?
Nerve impulses delayed by synapses
- if impulses transmitted via brain (like in voluntary actions) have to travel across many synapses
- in knee jerk reflex - ONLY CROSS 1 SYNAPSE - RAPID
Connections from spinal cord to brain allows info about stimulus to be sent to brain
- BUT by the time it receives/processes the info, response already occurred
Therefore automatic - the brain doesn’t make a decision
Blinking reflex nervous pathway?
Goes via brain , but not via decision making areas/no.synapses is minimal - CRANIAL REFLEX
Irritation/drying of conea send impulses down TRIGEMINAL SENSORY NERVE to medulla where it connects with other neurones to transmit signal to effector
- RELAY NEURONES INVOLVED to transmit impulse to effectors in lower eyelid
Effectors include: orbicularis oculi muscle - close eyes
Superior levator palpebrae muscle - lower upper eyelid
Mechanism of the fight or flight response?
- Sensory neurones detect environmental stimuli that may be dangerous/send impulses to BRAIN
- Amygdala send impulses to other parts of brain - hypothalamus
- Hypothalamus simulated to send impulses via SYMPATHETIC NERVES —> ADRENAL GLANDS
Causes *adrenal medulla to secrete adrenaline - increases sensory awareness - at same time, hypothalamus releases PEPTIDE HORMONE - stimulates anterior pituitary gland to release ACTH (adrenocorticotropic hormone)
ACTH transported —> adrenal glands via blood
Causes adrenal cortex to secrete CORTISOL
Effects of cortisol?
Stimulates target organs/tissues to INCREASE BP, blood glucose —> ensure tissues have enough glucose/oxygen for rapid response
- also suppress immune system
Effects of adrenaline?
Eyes : stimulate muscles in irises to contract - PUPILS DILATE
Increase diameter of bronchioles by relaxing smooth muscles - increase airflow to alveoli
Decrease amount of blood to gut/skin by VASOCONSTRICTION /increase blood flow to brain/muscles by VASODILATION
HR/stroke vol increases AND increase BP
Stimulate *breakdown of glycogen —> Glucose (NORMALLY/EXERCISE) in liver cells to INCREASE BLOOD GLUCOSE CONC
Second messenger model when adrenaline is released?
ENZYME CASCADE
Adrenaline binds to specific receptors on liver cell membranes
G proteins activates ADENYL CYCLASE- change shape/become activated
- now catalyses conversion of ATP —> cyclic AMP (cAMP) - 2nd messenger
- cAMP bind to protein kinase A enzymes - activating them
Active protein kinase A activate phosphorylase kinase enzymes - add phosphate groups to them
Active phosphorylase kinase activate glycogen phosphorylase enzymes
Active glycogen phosphorylase enzymes catalyse breakdown of glycogen—> glucose
- aka: glycogenolysis
Differences between sympathetic and parasympathetic systems?
Sympathetic system :
- ganglia just outside CNS
- short pre ganglionic neurones
- long post-ganglionic neurones
- times of stress
- DILATE PUPLS/reduce digestive activity
Parasympathetic system:
Opposite to sympathetic except for the GANGLIA IS IN TH EFFECTOR TISSUE
