Unit 3: Nervous and endocrine systems
Human Anatomy & Physiology-II notes · PTU syllabus (BMLS303-18)
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Unit summary
The nervous and endocrine systems coordinate the body. This unit covers the brain, spinal cord, spinal and cranial nerves, the all-or-none principle, neurotransmitters, and the location, structure and functions of endocrine and exocrine glands.
After this unit you can
- Describe the parts and functions of the brain and spinal cord
- Describe spinal and cranial nerves
- Explain nerve impulses and neurotransmitters
- Describe endocrine glands and their hormones
PTU syllabus topics
- Parts
- function and structure of the brain
- spinal cord and spinal/cranial nerves
- all-or-none principle
- role of neurotransmitters
- endocrine and exocrine glands — location
- structure and function
Pituitary
GH, TSH, ACTH, FSH, LH
Master gland
Thyroid
T3, T4
Metabolism
Pancreas (islets)
Insulin, glucagon
Blood glucose
Adrenal
Cortisol, adrenaline
Stress response
Gonads
Oestrogen, testosterone
Reproduction
Topic 1
The brain
Cerebrum
Two hemispheres with cortex; frontal, parietal, temporal, occipital lobes
Thinking, memory, voluntary movement, sensation, speech, vision
Diencephalon
Thalamus and hypothalamus
Relay of sensations; temperature, hunger, thirst, pituitary control
Cerebellum
Behind the brainstem
Balance, coordination, posture
Brainstem
Midbrain, pons, medulla oblongata
Breathing, heart rate, reflexes
- Protection: skull, meninges (dura, arachnoid, pia mater) and cerebrospinal fluid (about 150 mL, made in choroid plexuses; examined by lumbar puncture).
Topic 2
The spinal cord and spinal nerves
- Extends from the medulla to about L1–L2; grey matter (H-shaped) inside, white matter tracts outside. Carries messages to and from the brain and controls reflexes.
- 1Receptor
- 2Sensory neuron
- 3Interneuron in the spinal cord
- 4Motor neuron
- 5Effector (muscle or gland) — e.g., knee jerk
- 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.
Topic 3
Cranial nerves
- I Olfactory
- Smell
- II Optic
- Vision
- III Oculomotor, IV Trochlear, VI Abducens
- Eye movements
- V Trigeminal
- Face sensation, chewing
- VII Facial
- Facial expression, taste
- VIII Vestibulocochlear
- Hearing, balance
- IX Glossopharyngeal
- Taste, swallowing
- X Vagus
- Heart, lungs, gut
- XI Accessory
- Neck and shoulder muscles
- XII Hypoglossal
- Tongue movement
- Autonomic nervous system: sympathetic (fight or flight) and parasympathetic (rest and digest).
Topic 4
Nerve impulse and the all-or-none principle
- Resting potential about −70 mV; a stimulus reaching threshold opens Na⁺ channels → depolarisation (action potential) → K⁺ efflux → repolarisation. Myelinated fibres conduct faster by saltatory conduction.
- All-or-none principle: a stimulus below threshold produces no impulse; at or above threshold, the full-size impulse occurs — the strength of a single impulse does not grade with stimulus strength.
Topic 5
Neurotransmitters
- Acetylcholine
- Neuromuscular junction, parasympathetic
- Noradrenaline
- Sympathetic system
- Dopamine
- Movement and reward; low in Parkinson's disease
- Serotonin
- Mood, sleep
- GABA
- Main inhibitory transmitter
- Glutamate
- Main excitatory transmitter
- At a synapse, the impulse releases neurotransmitter from vesicles; it crosses the cleft and binds receptors on the next cell, then is broken down (acetylcholinesterase) or taken back.
Topic 6
Endocrine and exocrine glands
Ducts
Secrete through ducts
Ductless; secrete into blood
Secretion
Enzymes, sweat, saliva
Hormones
Examples
Salivary, sweat, gastric glands
Pituitary, thyroid, adrenal
Mixed
Pancreas (enzymes and insulin), gonads
—
Pituitary
Base of brain; GH, TSH, ACTH, FSH, LH, prolactin (anterior); ADH, oxytocin (posterior)
Master gland controlling others; growth; water balance
Thyroid
Neck; T3, T4, calcitonin
Metabolic rate; calcium lowering
Parathyroid
Behind thyroid; PTH
Raises blood calcium
Adrenal
Above kidneys; cortisol, aldosterone (cortex); adrenaline (medulla)
Stress, glucose, salt balance; fight or flight
Pancreas (islets)
Insulin (β cells), glucagon (α cells)
Lowers and raises blood glucose
Gonads
Testosterone; oestrogen and progesterone
Sexual characteristics, reproduction
Pineal
Melatonin
Sleep–wake cycle
Key terms
- Cerebellum
- Brain part coordinating balance and movement
- Reflex arc
- Pathway of an automatic response
- Action potential
- Electrical impulse along a neuron
- Neurotransmitter
- Chemical carrying signals across a synapse
- Endocrine gland
- Ductless gland secreting hormones into blood
Quick revision
- Cerebrum, diencephalon, cerebellum, brainstem; meninges; CSF.
- Spinal cord; reflex arc; 31 spinal nerves; 12 cranial nerves; ANS.
- Resting and action potentials; all-or-none; saltatory conduction.
- Acetylcholine, noradrenaline, dopamine, serotonin, GABA, glutamate.
- Exocrine vs endocrine; pituitary, thyroid, parathyroid, adrenal, pancreas, gonads, pineal.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.What is the function of the cerebellum?
- Q2.How many pairs of spinal and cranial nerves are there?
- Q3.State the all-or-none principle.
- Q4.Name the main inhibitory neurotransmitter.
- Q5.Why is the pituitary called the master gland?
- Q6.Which hormone lowers blood glucose?
Long-answer questions
- Q1.Describe the structure and functions of the brain.
- Q2.Describe the spinal cord and the reflex arc.
- Q3.Explain the nerve impulse and synaptic transmission.
- Q4.Describe the endocrine glands and their hormones.
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