Holding It All Together - Control, Communication and Protection Flashcards
Central Nervous System
- Brain and spinal cord
- Combines information from the entire body and coordinates activity across the whole organism
Peripheral Nervous System
- Outside brain and spinal cord
- Spinal nerves and cranial nerves
- VOLUNTARY (SOMATIC):
> Sensory neurons carry info. from nerves to CNS
> Motor neurons carry info. from CNS to muscle fibres throughout the body - INVOLUNTARY (AUTONOMIC):
> Sympathetic - mobilises
> Parasympathetic - counteracts
Neurons
- Info. travels in one direction from cell body to axon terminal
- Produce electrical impulses
- A nerve is a bundle of individual neurons
Voluntary Functions
Skeletal muscles
Involuntary Functions
- Smooth and cardiac muscles
- E.g. heart rate, digestion, pupillary response, etc.
Autonomic Nervous System
- Sympathetic = fight or flight response
- Parasympathetic = rest and restore
Endocrine System
- Hormones released into the blood
- Slower but longer lasting
- “Ductless”
Thyroid Hormone
- Increases basal metabolic rate
- Cells start working harder which causes an increase in the heat our cells produce (thermoregulation)
Thyroid Problems: Too Much
- Hyperthyroidism
- Heat intolerance
- Tachycardia
- Raised BP
- Weight loss
- Muscle tremors
Thyroid Problems: Too Little
- Hypothyroidism
- Cold intolerance
- Lethargic
- Bradycardic
- Weight gain
- Dry, scaly skin
Insulin
- Modulates blood glucose (normal: 4-6mmol)
- Secreted by beta cells as a response to an increase in blood glucose level
- Causes liver, skeletal muscle and adipose tissue to uptake glucose into cell, used for energy or stored in the form of glycogen or fat
Glucagon
- Stimulates release of glucose
- Secreted by alpha cells as a response to low blood glucose
Parathyroid Hormone
- Modulates calcium and phosphorus concentration
- Secreted in response to decrease in plasma calcium level
- Calcium removed from bone into bloodstream; calcium excretion by kidney is reduced; Vitamin D production increased (more calcium absorbed by gut)
Parathyroid Problems: Too Much
- Hyperparathyroidism
- Calcium deposits in the lungs
- Kidney stones
- “Salt and pepper skull”
Parathyroid Problems: Too Little
- Hypoparathyroidism
- Caused by decreased calcium in the blood, a result of hypoparathyroidism:
> Convulsions
> Arrhythmias
> Tetany
> Spasms and stridor
Cortisol
- Released in times of stress
- Adrenal cortex
- Steroid-based hormone
- It:
> Increases blood glucose
> Increases blood lipids
> Suppresses immune response
> Inhibits growth and repair
Cortisol Problems: Too Much
- Cushing’s Disease
- Moon face
- High BP and enlarged heart
- Muscle weakness and osteoporosis
- Increase in fat deposition
Cortisol Problems: Too Little
- Adrenal Insufficiency or “Addison’s Disease”
- Bronze pigmentation
- Hypoglycaemia
- Weight loss
- Weakness
Aldosterone
- Steroid-based hormone
- Modulates BP
- Main role is to increase retention of sodium, therefore, increasing BP
- Adrenal cortex
Aldosterone Problems: Too Much
- Hypertension: increase in BP due to increase in BV
- Retaining sodium in the plasma, osmotic pull on water increasing BV
Aldosterone Problems: Too Little
- Decrease in amount of sodium in blood meaning water will most likely follow it
- Hypotension: decrease in BV meaning a decrease in BP
- Possibly dehydration as BV is dropping
Adrenaline
- Adrenal gland from medulla
- Amine
- Released into the bloodstream, causes a hormonal extension of the sympathetic response
- Produces responses of sympathetic activation - increase HR, vasoconstriction/dilation and bronchodilation
Sex Hormones: Female
- Oestrogen:
> Maintenance of many tissues, menstrual cycle regulation, secondary sex characteristics, metabolic effects - Progesterone:
> Release of eggs from ovary, implantation, maintenance of pregnancy
Sex Hormones: Male
- Testosterone:
> Responsible for maturation and maintenance of the male sex organs, sperm production and secondary sex characteristics
Growth Hormone
- Stimulates growth in many tissues
- Increases height (long bone growth), bone density, muscle mass and mobilises glucose and fats into the bloodstream
- Plays an important role in maintaining some tissues in later life
Growth Hormone Problems
- GH secretion at its maximum during puberty
- Insufficient GH = dwarfism
- To much = gigantism
Oxytocin
- Causes powerful uterine contractions during labour
- Causes milk let-down during suckling
- Important in social and pair bonding, and reduces social stress
Anti-Diuretic Hormone (ADH)
- Reduces diuresis (reduction in the urine output)
- Released by neurons in the hypothalamus, axons project to the posterior pituitary
- Increased release of ADH with increased osmolarity of the plasma - detected by specialised receptors in the brain
- Reduce the amount of water lost in urine - helps to maintain solute concentration (osmolarity) of body fluids within normal limits
ADH Problems: Too Much
- Really concentrated urine - retaining so much water
- Hyponatraemia - retaining so much water that the sodium in our blood is diluted
ADH Problems: Too Little
- Lose a lot of water
- Thirsty as there is lots of water lost in urine
