M3s1 Types Of Muscles

Question 1

The muscular system

Answer 1

-contractile organs
-through contraction, these organs can perform a number of important functions like movement - from the gross physical movements of our skeleton (walking) to the more finely tuned intricate movements like beating of the heart, breathing, digestion, and constriction of blood cells, all which serve to move substances throughout the body
*refer to goodnotes for image of types: cardiac muscle cells, skeletal muscle cells and smooth muscle cells

Question 2

Types of muscles

Answer 2

Skeletal muscles
-help with human body movement
-most attached to bones via tendons
Ex. In arm

Cardiac muscle
-found in heart
-contracts rhythmically, and is modulated by neural activity and hormones

Smooth muscle
-controlled by nervous system or hormones
-may be either generally inactive and then respond to stimulation or be rhythmic
-think intestines
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Question 3

Characteristics of muscles

Answer 3

• refer to goodnotes for images
  -characterized based of their morphology (form) or how they function

Morphological characterization
-either striated or smooth
Striated: marked by light and dark bands (striations)
-found in heart and skeletal muscles
-characterized by long muscle fibres (cells) with multiple nuclei which are located peripherally for skeletal muscle or centrally for cardiac muscle
-cardiac muscle also features intercalated discs (unique to cardiac muscle, intercalated discs connect heart muscles to each other)
Smooth: found in blood vessels, digestive system or other viscera
-each smooth muscle fibre (cell) contains a single centrally located nucleus
-smooth muscle has fusiform-shaped (spindle-like) cells without striations

Functional characterization
-either voluntary or involuntary
Voluntary: muscle is consciously controlled in order to perform a specific function like walking, reaching, talking
-these are the skeletal muscles, for example muscles of the upper limb
Involuntary: not consciously controlled
-consist of smooth muscle and cardiac muscle
Exs. Muscles of intestines (smooth) and the heart (cardiac)

Question 4

3 types of muscles

Answer 4

Skeletal
Appearance:
-peripheral nuclei
-have striations (due to binding pattern of thick and thin filaments that make up secramere?)
-multinucleated
-long cylindrical/ rod (up to 30 cms long)
Location:
-attached to bone (act as leavers)
Regulation:
Voluntary (exercise)

Cardiac
Appearance:
-have striatations (due to binding pattern of thick and thin filaments that make up secramere?)
-uni/binucleated
-branching muscle cell and come into contact with other cells at the branching points
Location:
-heart
Regulation:
Involuntary (pace maker)

Smooth
Appearance:
-no striations ( as thick and thin filaments not arranged into secrameres)
-uninucleated
-fusiform (tapers) meaning wide in middle and tapers at ends
Location:
-walls of hallow organs like stomach, esophagus, intestines, and most of our blood vessels
Regulation:
Involuntary (peristalsis)

Question 5

How do muscles function

Answer 5

Excitability:
-ability of muscle tissue to receive and respond to electrical signals from nerves or stimulation from hormones

Contractility:
-muscle is excited by a nerve or hormone, causes the muscle to shorten, resulting in contraction