Unit 1 - Anatomy and physiology for health and exercise - the nervous and endocrine systems

Question 1

What is homeostasis?

Answer 1

A stable internal environment

Question 2

How does the body maintain homeostasis?

Answer 2

By means of the nervous and endocrine systems: → the nervous system via a complex web of nerves → the endocrine system supports homeostasis through a series of glands and hormones (chemical messengers)

Question 3

The nervous system is a communication network, which has what three basic elements?

Answer 3

→ sensation → analysis → response

Question 4

Which are the two main principle sections of the nervous system?

Answer 4

→ the central nervous system (CNS) → the peripheral nervous system (PNS)

Question 5

What is the CNS?

Answer 5

The CNS is comprised of the brain and spinal cord and is responsible for interpreting sensory input and generating appropriate and responses. These processes can range in complexity from basic reflex actions to intricate thoughts, memories and emotions.

Question 6

What is the PNS?

Answer 6

The PNS consists of the nerves that connect the CNS to the rest of the body and the external environment. These are the means by which the CNS receives sensory input and initiates responses.

Question 7

Name two subdivisions of the PNS.

Answer 7

→ somatic - nerves which serve the outer areas of the body and skeletal muscle, they are largely responsible for the voluntary control of movement. → autonomic - supplies neural input to the involuntary systems of the body (e.g. heart, digestive systems and endocrine glands)

Question 8

Name the subdivisions of the autonomic system.

Answer 8

→ sympathetic system (war) - serves to increase levels of activation in preparation for activity → parasympathetic system (peace) - serves to decrease levels of activation during rest and recovery.

Question 9

Describe the basic structure of a neuron.

Answer 9

A neuron essentially behaves like any form of cable or wire, it allows signals or impulses to travel from one part of the body to another.
→ Cell body: nucleus and various organelles
→ Dendrites: spread out like the branches of a tree. These sense the stimulus, like heat, pain or pressure
→ Axon: a long cylindrical projection running from the cell body. Along this, the nervous impulses travel.
→ Myelin sheath: lipid/protein covering the axon for insulation - vital for rapid transmission of impulses
→ Axon terminal: at the end of the axon, representing the interface between the neuron and other cells, such as other neurons or muscle cells

Question 10

What is an action potential?

Answer 10

It describes the wave of electrical activity that passes along electrically excitable cells, such as those found in nerves and muscles.
The action potential passes along the outer membrane of the cells and is created through the controlled movement of electrolytes (sodium and potassium) into or out of the cells.

Question 11

What is at the end of the axon terminals?

Answer 11

At the end of the axon terminals are swellings (synaptic end bulbs) which contain small sacs of neurotransmitter, which in case of skeletal muscle is acetylcholine (Ach).

Question 12

Describe how the muscle action potential is triggered through Ach.

Answer 12

• When the action potential reaches the end of the axon terminals the Ach is released into the space at the ends.
• The Ach then diffuses across the space between the axon terminals and the muscle cell membrane.
• The Ach then binds with specialised receptors on the muscle membrane, which triggers a muscle action potential.
• This stimulates muscles to contract.

Question 13

In the early stages of training, especially in resistance training, the majority of performance improvements are likely to be the result of changes of what?

Answer 13

Changes in the way the central nervous system controls and coordinates movement.

Question 14

Which part of the body is mainly responsible for the control of hormonal activity?

Answer 14

1. the hypothalamus
2. the pituitary gland

Question 15

What are hormones?

Answer 15

Hormones are chemicals derived from lipids or proteins.
Each hormone will have a target cell or cells that have specific receptors in their membranes which will only be triggered by the “right” hormone.

Question 16

What is the principle fuel for vigorous activity?

Answer 16

Carbohydrate (specifically glucose)

Question 17

What happens if we have too little blood glucose?

Answer 17

It can be extremely damaging, will inhibit performance but could eventually be fatal.

Question 18

What happens if we have too little blood glucose?

Answer 18

It can damage the vascular system.

Question 19

How is insulin released in the body?

Answer 19

After consuming a meal, glucose enters the blood at the small intestine causing a rise in blood glucose levels. As this blood is circulated through the pancreas the elevated levels of glucose trigger the release of insulin.

Question 20

What results in a drop in blood glucose levels?

Answer 20

After insulin is released by the pancreas, the circulating insulin binds with the receptors of its target cells (in this case skeletal muscle or liver cells) and the cell membrane becomes more permeable to glucose. Glucose then diffuses out of the bloodstream and into the cell.

Question 21

Insulin encourages the synthesis of what?

Answer 21

Protein and fat within the body.

The extent to which this occurs is determined by the nature of the meal consumed and the existing nutritional status of the individual.

Question 22

What is glucagon?

Answer 22

Glucagon serves to maintain blood glucose levels by triggering the release of glycogen from the liver.

Question 23

What are the effects of exercise on insulin and glucagon?

Answer 23

As activity levels increase, glucose uptake by the body’s cells also increases. This is the result of an increased sensitivity of the cells to insulin, thus insulin levels will drop during physical activity.

At the same time glucagon secretion by the pancreas increases, thus helping maintain a steady supply of blood glucose.

Question 24

What is adrenalin (epinephrine)?

Answer 24

• Hormone produced by the adrenal glands, situated on top of each kidney.
• Belongs to the hormone category called catecholamines.
• Helps prepare the body for activity, more specifically they are part of the stress response.

Question 25

When the hypothalamus triggers the adrenal glands to secrete more adrenalin in preparation for the activity, what specific physiological effects will occur to help sustain exercise activity?

Answer 25

• increases heart rate and stroke volume
• elevates blood glucose levels
• redistributes blood to working tissues
• opens up the airways

Question 26

Describe testosterone and oestrogen.

Answer 26

• Testosterone is produced in the testes of the male and in small amounts in the ovaries and adrenals of the female
• Males produce up to ten times more testosterone than females
• Oestrogen is produced primarily in the ovaries in the female and in small amounts in the adrenals in males
• Women of reproductive age have significantly higher levels of estrogen than males.
• Testosterone plays a fundamental role in the growth and repair of tissue. Raised levels of testosterone are indicative of an anabolic (tissue building) training status.
• Oestrogen has an influence on fat deposition around the hips, buttocks and thighs.

Question 27

What is cortisol?

Answer 27

A hormone typically referred to as a catabolic hormone (associated with tissue breakdown).

Under times of stress, such as exercise, cortisol is secreted by the adrenal glands and serves to maintain energy supply through the breakdown of carbohydrates, fats and protein.

High levels of cortisol - due to overtraining, excessive stress, poor sleep and inadequate nutrition - can lead to a significant breakdown of muscle tissue.

Question 28

What is the growth hormone?

Answer 28

It is released from the pituitary gland in the brain and is regulated by the nearby hypothalamus.

It is stimulated by several factors including oestrogen, testosterone, deep sleep and vigorous exercise.

Primarily an anabolic hormone, responsible for most of the growth and development during childhood up until puberty.

Also increases the development of bone, muscle tissue and protein synthesis, increases fat burning and strengthens the immune system.

Question 29

What is the thyroid hormone?

Answer 29

The thyroid gland is located at the base of the neck.

It releases vital hormones that are primarily responsible for human metabolism.

The release of thyroid hormones is regulated by the master gland, the pituitary.

Thyroid hormones are responsible for carbohydrate, protein and fat metabolism, basal metabolic rate, protein synthesis, sensitivity to adrenalin, heart rate, breathing rate and body temperature.

Question 30

What can low thyroid function lead to?

Answer 30

• Fatigue
• depression
• sensitivity to cold and weight gain