The Nervous System and endocrine

• The Nervous System

The nervous system in vertebrate animals consists of two parts:
–Central Nervous System (CNS)
–Peripheral Nervous System (PNS)
The central nervous system consists of
–The brain
–The spinal cord
The peripheral nervous system consists of
–Sensory nerves
–Motor nerves
A nerve cell is called a neuron.

• The Nervous System
  This allows an animal to detect what is going on in the world around it.
  It includes the brain, the spinal chord and the nerve cells.
  The nervous system controls receptors such as the eye and the ear and it also control the effectors the most important of which are muscles.


• The Endochrine System


• The Endochrine System


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• This is the hormone system in the body.
  Hormones are produced in very small quantities, transported by the circulatory system to specific parts of the body, where they can stimulate or inhibit actions in the target organ or tissue.
  Hormones are produced in many parts of the body e.g. the pituitary gland, the thyroid glands, the parathyroid glands, the pancreas, the adrenal glands and the gonads.


• Milk Let-Down
  External factors such as the sight or sound of a calf or entering the milking parlour and being having teats rubbed.
  This sends a message to the brain which cause the hormone oxytocin to be produced by the pituitary gland.
  This message is carried in the blood to the udder causing milk alveoli to contract releasing milk.


• Endocrine Glands
  The pituitary gland is located at the base of the brain.
  Some of the hormones produced by the pituitary are growth hormone, prolactin, luteinising hormone (LH), follicle stimulating hormone (FSH) and oxytocin.
  Oxytocin is responsible for milk let down and contractions during birth.


• Thyroid glands
  –Located in the neck and produce thyroxine which regulates metabolism in the body and is responsible for growth
  Parathyroid glands
  –Located on the surface of the thyroid glands. They release parathyroid hormone which regulates calcium levels in the bones and blood.
  The Pancreas
  –Secretes insulin into the bloodstream when there are high levels of glucose in the body. The liver and muscle cells take up the glucose. Glucose is stored as glycogen in the liver.
  Adrenal glands
  –Produce adrenalin when the body is under stress.


• Sex Hormones
  Androgens are hormones responsible for male sex characteristics and are produced in the testis. Testosterone is an androgen
  Freemartin condition occurs in twin calves where one is male and the other is female. Hormones pass from the male to the female in the womb leaving the female infertile
  Ovaries secrete oestrogen and progesterone.
  Oestrogen promotes the sex characteristics in females.
  Progesterone allows for the growth of the uterus during gestation.