Animal & Plant Responses - Animals

Question 1

What does the nervous system consist of? Structurally

Answer 1

CENTRAL NERVOUS SYSTEM (CNS) - brain/spinal chord
PERIPHERAL NERVOUS SYSTEM (PNS) - all nerves in body

Question 2

What do neurones coordinate?

Answer 2

Activities of sensory receptors , decision making centres in CNS and effectors

Question 3

What does nervous system consist of - functionally?

Answer 3

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)

Question 4

What does somatic nervous system consist of?

Answer 4

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

Question 5

What can the autonomic nervous system be divided into?

Answer 5

SYMPATHETIC nervous system - controls ‘flight or fight’ response
PARASYMPATHETIC nervous system - control ‘rest and digest’ system
- contains both sensory/motor neurones

Question 6

What happens during ‘flight or fight’ response?

Answer 6

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

Question 7

Structure/Function of cerebrum ?

Answer 7

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

Question 8

What is the outmost layer of the cerebrum called and the structure?

Answer 8

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

Question 9

Function and location of hypothalamus?

Answer 9

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

Question 10

Location and function of pituitary gland?

Answer 10

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

Question 11

Cerebellum function and location?

Answer 11

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)

Question 12

Medulla oblongata structure and function , location?

Answer 12

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 )

Question 13

What are reflexes?

Answer 13

Involuntary responses to certain stimuli
- rapid/ have survival value

Question 14

Sequence of components in reflex action?

Answer 14

Detection involves stimulus being detected by receptor cell then impulse sent through:
Stimulus —> receptor —> coordinator (e.g spinal chord)-> effector —> response

Question 15

Different type of receptor cell?

Answer 15

Some produce electrical activity in nerve cells to respond to stimuli
Others secrete substances in response to stimuli

Question 16

Knee jerk reflex: sequence of components?

Answer 16

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

Question 17

Nervous pathway of knee jerk reflex?

Answer 17

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

Question 18

How does the knee jerk pathway show why reflex actions are so fast/automatic?

Answer 18

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

Question 19

Blinking reflex nervous pathway?

Answer 19

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

Question 20

Mechanism of the fight or flight response?

Answer 20

1. Sensory neurones detect environmental stimuli that may be dangerous/send impulses to BRAIN
2. 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

Question 21

Effects of cortisol?

Answer 21

Stimulates target organs/tissues to INCREASE BP, blood glucose —> ensure tissues have enough glucose/oxygen for rapid response
- also suppress immune system

Question 22

Effects of adrenaline?

Answer 22

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

Question 23

Second messenger model when adrenaline is released?

Answer 23

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

Question 24

Differences between sympathetic and parasympathetic systems?

Answer 24

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